Earthquake Analysis

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FUGRO WEST, INC.

FINAL REPORT

EARTHQUAKE ENGINEERING ANALYSES

PARADIP REFINERY PROJECT

ORISSA, INDIA

Prepared for:

INDIAN OIL CORPORATION LIMITED

SEPTEMBER 2008

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Project No. 3193.026

Indian Oil Corporation Limited (Refineries Division) c/o Foster Wheeler Energy, Ltd.

Shinfeld Park

Reading – RG2 9FW, United Kingdom Attention: Mr. Martin Dryden

Subject: Phase 2 Geotechnical Earthquake Engineering Analyses for Paradip Refinery Project, Orissa, India

Dear Mr. Dryden:

Fugro team, comprising of Fugro Geoconsulting Limited (FGCLTD), Fugro Engineers, S.A./N.V. (FESA), Fugro West, Inc. (FWI), and Fugro India (FI) are providing engineering services to Foster Wheeler (FW) for the Indian Oil refining facility located in Paradip, Orissa, India. FWI is providing the geotechnical earthquake engineering services for the project. William Lettis and Associates, a Fugro company, assisted with the seismic source characterization for the seismic hazards analyses component of the project. Enclosed for your review is our report containing the results of Phase 2 analyses. We thank you for the opportunity to work on this project.

Sincerely,

FUGRO WEST, INC.

Priyanshu Singh, P.E. Project Engineer

James V. Hengesh, P.G. Principal Geologist

M. Jacob Chacko, P.E., G.E. Principal Engineer

PDS/MJC

Copies Submitted: Addressee (pdf)

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Indian Oil Corporation Limited Project No. 3193.026 i CONTENTS Page 1.0 INTRODUCTION 1-1 1.1 Project Description 1-1

1.2 Scope and Organization 1-1

1.3 Limitations of this Study 1-2

2.0 REGIONAL TECTONIC SETTING 2-1

2.1 Introduction 2-1

3.0 SEISMIC SOURCE MODEL 3-1

3.1 Introduction 3-1

3.2 Areal Source Zones 3-1

3.2.1 Indian Stable Continental Region 3-2

3.2.2 Oceanic Domain - Bay of Bengal 3-3

3.2.3 Plate Boundary Areal Source Zones 3-4

3.3 Line (Fault) Sources 3-4

3.4 Earthquake Recurrence and Activity Rates 3-5

3.4.1 Introduction 3-5

3.4.2 Seismicity Catalogs 3-6

3.4.3 Magnitude Probability Density Functions 3-7

3.4.4 Activity Parameters 3-8

4.0 PROBABILISTIC SEISMIC HAZARD ANALYSES 4-1

4.1 Project Location 4-1

4.2 Methodology 4-1

4.2.1 Mathematical Formulation 4-1

4.2.2 Empirical Attenuation Relationships 4-2

4.2.3 Epistemic Uncertainty 4-3

4.2.4 Hazard Deaggregation 4-3

4.2.5 Near-Source and Directivity Effects 4-3

4.2.6 Extending the Design Spectra to Long Periods 4-4

4.3 Definition of Design Level Events 4-4

4.4 Results 4-4

4.4.1 Horizontal Design Response Spectra 4-5

4.4.2 Hazard Deaggregation by Fault 4-5

4.4.3 Hazard Deaggregation by Magnitude and Distance 4-6

5.0 DEVELOPMENT OF DESIGN GROUND ACCELERATION TIME HISTORIES 5-1

5.1 Ground Motion Selection 5-1

5.2 Approach 5-1

5.2.1 Modification of Selected Seed Motions 5-1

5.2.2 Time-Domain Spectral Matching 5-1

5.2.3 Baseline Correction 5-2

6.0 SITE RESPONSE ANALYSES 6-1

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6.3.1 Static and Dynamic Soil Properties 6-3

6.3.2 Cyclic Shear Strain-Dependent Shear Modulus and Damping 6-5

6.4 Ground Motion Input Depth 6-5

6.5 Results 6-5

6.5.1 Acceleration Response Spectra 6-5

6.5.2 Profiles of Dynamic Parameters and Peak Ground Response 6-6

6.5.3 Design Response Spectra 6-6

6.5.4 Comparison with Indian Design Code and Phase 1 Results 6-8

6.6 modification factors for other damping ratios 6-8

6.7 Example Use of Design Spectra 6-9

7.0 LIQUEFACTION POTENTIAL AND CYCLIC DEGRADATION 7-1

7.1 Definition 7-1

7.2 Method of Evaluation 7-1

7.3 Subsurface Data 7-1

7.3.1 Boring SPT Data. 7-2

7.3.2 CPT Data. 7-2

7.4 Earthquake Ground Motion Assumed for Analyses 7-2

7.5 Identification of potentially liquefiable layers 7-2

7.6 Results 7-3

7.7 ground settlement Due to earthquake shaking 7-4

7.7.1 Liquefaction-Induced Settlement 7-4

7.7.2 Seismically-Induced Settlement of Dry Fill 7-5

8.0 REFERENCES 8-1

TABLES

Page Table 2-1. Main Segments of Himalayan Main Thrust Fault, Rupture Lengths, Estimated

Magnitudes of Historical Ruptures, and Fault Slip Rates from Paleoseismic Trenching. ...2-2 Table 3-1. Summary of Source Parameters for Areal Sources...3-2 Table 3-2. Summary of Source Parameters for Line Sources ...3-5 Table 3-2a. Completeness Interval of Seismicity Catalog (Stable Continental Zones)...3-7 Table 3-2b. Completeness Interval of Seismicity Catalog (Extended Crust Zones) ...3-7 Table 3-3c. Completeness Interval of Seismicity Catalog (Active Plate Margin) ...3-7 Table 4-1. Coordinates of Representative Location...4-1 Table 4.2. Horizontal Ground Motion Attenuation Relationships ...4-2 Table 4-3. Horizontal Design Response Spectra ...4-5 Table 5-1. Summary of Seed Motion Characteristics ...5-1 Table 6-1. Empirical Correlations for Shear Wave Velocity ...6-4 Table 6-2. 5-Percent Damped Horizontal DBE Spectrum...6-7 Table 6-3. 5-Percent Damped Horizontal MCE Spectrum ...6-8

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Indian Oil Corporation Limited Project No. 3193.026

CONTENTS (CONTINUED)

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Table 3. Modification Factors to Obtain Spectra for Other Damping Ratios ...6-9

FIGURES

Figure Site Location Map ...1-1 Regional Tectonic Setting and Historic Seismicity...2-1 Seismotectonic Model...3-1 Seismic Source Zonation Around Project Site ...3-2 "Hard Soil" Horizontal Spectra for Various Return Periods...4-1 Horizontal Fault Contribution to Hazard Curves for PGA...4-2a Horizontal Fault Contribution to Hazard Curves for SA(0.2s) ...4-2b Horizontal Fault Contribution to Hazard Curves for SA(1.0s) ... 4.2c Horizontal Hazard Deaggregation by Distance and Magnitude for PGA

2475-Year Return Period ...4-3a Horizontal Hazard Deaggregation by Distance and Magnitude for SA(0.2s)

2475-Year Return Period ...4-3b Horizontal Hazard Deaggregation by Distance and Magnitude for SA(1.0s)

2475-Year Return Period ... 4-3c Idealized Shear Wave Velocity Profile - Profile 1...6-1a Idealized Shear Wave Velocity Profile - Profile 2...6-1b Idealized Shear Wave Velocity Profile - Profile 3... 6-1c Idealized Shear Wave Velocity Profile - Profile 4...6-1d Strain-Dependent Shear Modulus and Damping Relationships

for Site Response Analyses...6-2 Time Histories for Best-Estimate Soil Properties – Bokajan N34E Record, Profile 1, DBE ...6-3a Time Histories for Best-Estimate Soil Properties – Bokajan N34E Record, Profile 1, MCE ....6-3b Profiles of Dynamic Parameters and Peak Ground Response, Profile 1 – DBE...6-4a Profiles of Dynamic Parameters and Peak Ground Response, Profile 2 – DBE...6-4b Profiles of Dynamic Parameters and Peak Ground Response, Profile 3 – DBE... 6-4c Profiles of Dynamic Parameters and Peak Ground Response, Profile 4 – DBE...6-4d Profiles of Dynamic Parameters and Peak Ground Response, Profile 1 – MCE ...6-5a Profiles of Dynamic Parameters and Peak Ground Response, Profile 2 – MCE ...6-5b Profiles of Dynamic Parameters and Peak Ground Response, Profile 3 – MCE ... 6-5c Profiles of Dynamic Parameters and Peak Ground Response, Profile 4 – MCE ...6-5d Development of Ground Surface Design Response Spectra – DBE ...6-6a Development of Ground Surface Design Response Spectra – MCE...6-6b

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PLATES

Plate

Site Plan and Cross Section Locations... 1

Key to Cross Sections... 2

Cross-Section A-A' with Liquefaction Evaluation Results ... 3

Cross-Section B-B' with Liquefaction Evaluation Results ... 4

Cross-Section C-C' with Liquefaction Evaluation Results... 5

Cross-Section D-D' with Liquefaction Evaluation Results... 6

Cross-Section 1-1' with Liquefaction Evaluation Results ... 7

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1-1

1.0 INTRODUCTION

1.1 PROJECT DESCRIPTION

Indian Oil Corporation (IOCL) plans to develop approximately 2,240 acres of area for installing a refinery and petrochemical complex 5 km south of the port of Paradip in Orissa, India. Approximately 1,200 acres of this area has been elevated by placing fill. The project site is divided roughly in the middle by the Santra Creek. The refinery is planned to be located in the area south of the creek whereas the petrochemical complex will be located to the north. The site location is shown on Figure 1-1.

1.2 SCOPE AND ORGANIZATION

Fugro’s studies were conducted in two stages: 1) a preliminary (Phase 1) study based on available geotechnical data; and 2) a final (Phase 2) study that updates the findings from the preliminary study to incorporate site specific geotechnical data collected by Fugro India. As part of the preliminary study, Fugro developed site-specific design earthquake ground motion criteria (response spectra) for use in the preliminary design of the various proposed structures, and conducted preliminary liquefaction potential evaluations. This reports presents the findings from the final study, where our findings have been updated based on the new site specific geotechnical data.

The Final Report is comprised of two parts. The geological setting, history of site development and current soil conditions as understood from the currently available data and documentation were described in Part 1. This Part 2 report summarizes the geotechnical earthquake engineering analyses including probabilistic seismic hazard analyses to estimate the severity of ground motions at the project site, evaluation of local site effects based on the subsurface information recently obtained by FI, as well as evaluation of liquefaction potential, its spatial extent and estimated resulting settlements. The approved scope of services included:

x Task 1 – Development of Seismotectonic Model; x Task 2 - Probabilistic Seismic Hazard Assessment; x Task 3 – Development of Acceleration Time Histories; x Task 4 – Preliminary Site Response Analyses;

x Task 5 – Preliminary Liquefaction Evaluation; and x Task 6 – Reporting.

This Part 2 report is organized as follows. Following the introductory Section 1.0, Section 2.0 describes the regional geologic and seismotectonic setting in the project area. Based on this information, Section 3.0 summarizes the parameters of the seismotectonic model used in the seismic hazard analyses. The results of the probabilistic seismic hazard evaluation

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liquefaction potential is presented in Section 7.0.

1.3 LIMITATIONS OF THIS STUDY

This report has been prepared solely to assist IOCL and it’s engineering team in developing geotechnical earthquake engineering recommendations that will be used for design of structures comprising the Paradip Refinery in Orissa, India. The results herein apply to the specific locations mentioned and are not applicable to other locations. In our opinion, the findings, conclusions, professional opinions, and recommendations presented herein were prepared in accordance with generally accepted geotechnical engineering practice of the project region.

Seismic hazard analysis is a dynamic, rapidly evolving field of earthquake engineering. It is likely that the standard of practice in the project region for these services will evolve over the next few years. For example, research is ongoing to develop a new generation of attenuation relationships based on data from recent earthquakes. Similarly, researchers are reviewing geodetic and geologic information relative to the activity of the faults in the project region. Consequently, the results presented in this study should be reviewed if new data are available during the design of the project.

Although information contained in this report may be of some use for other purposes, it may not contain sufficient information for other parties or uses. If any changes are made to the project as described in this report, the conclusions and recommendations in this report shall not be considered valid unless the changes are reviewed and the conclusions and recommendations of this report are modified or validated in writing by Fugro.

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2.1 INTRODUCTION

The Paradip site is located along the northeast coast of India at the mouth of the Mahanadi River (Figure 1-1). This part of India, south of the Himalayan front is considered a stable continental region (Johnston et al., 1996) and has low rates of earthquake and tectonic activity.

The tectonic framework of northern India is dominated by two main features: (1) the stable continental craton of Peninsular India; and (2) the collision where northern India and Asia converge along the Himalaya plate boundary zone (Figure 2-1). Plate tectonic models based on geological and geomorphological data, earthquake slip vectors, and Global Positioning Satellite (GPS) based plate velocities indicate that the Indian Plate is moving north relative to Asia at a rate of 20±3 mm/yr (Bilham et al., 2001).

Most of this 20±3 mm/yr of convergence is accommodated in a zone of deformation 50-km wide along the southern edge of the Tibetan Plateau. However, several millimeters per year of convergence is accommodated by distributed localized zones of deformation within the Indian Plate, as demonstrated by the 2001 Mw 7.7 Bhuj, 1956 M6.0 Anjar, and ~M7.5 to 8 1819 Kutch earthquakes. The Kutch and Bhuj earthquakes both demonstrate that large magnitude earthquakes in India have been associated with reactivation of older areas of extended continental crust, or failed rift systems.

The geological and tectonic development of India has a long history that extends back to Proterozoic time (>700 million years before present, Ma), and although the general geological history is known, details of the structural and stratigraphic evolution are incompletely understood. The lack of an integrated geological, seismological and geophysical model makes interpretation of the hazards associated with older tectonic structures difficult to assess. However, current models for tectonic development of the region indicate the important roles several primary lithospheric elements including: (1) Proterozoic structural trends such as the Aravalli-Delhi belt, (2) Mesozoic (245 to 66.4 Ma) Gondwana1 age rift structures that follow the continental margin, (3) failed rift systems such as the Mahanadi-Damodar and Godavari rifts; and (4) the current Himalayan collision.

The northeastern coast of India has much lower rates of earthquake activity and tectonic deformation than does the northwest coast of India where the Bhuj and Kutch earthquakes occurred. The Kutch region appears to have continental affinity similar to extended continental crust, but may also express deformation related to the plate boundary system.

The Himalayan main thrust fault, located along the primary Himalayan topographic front, accommodates almost half of the total relative plate motion between India and Asia and is a

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major seismic hazard. The main thrust fault produced seven large magnitude earthquakes (i.e. >M7.5 to 8.5) between 1505 and 1950 (Figure 2-1 and Table 2-1) and some researchers speculate that the fault zone is capable of producing earthquakes on the order of Mw 9. Current and ongoing paleoseismic research (Kumar et al., 2006) demonstrates that previous earthquakes have produced surface ground displacements of up to 20 meters, clearly indicating that these previous events had very large magnitudes. The Himalayan main thrust fault, although located greater than 600 km from the site, was included in the hazard analysis because these large magnitude earthquakes may contribute to the long period part of the site hazard spectrum.

Table 2-1. Main Segments of Himalayan Main Thrust Fault, Rupture Lengths, Estimated Magnitudes of Historical Ruptures, and Fault Slip Rates from Paleoseismic Trenching.

Himalayan Main Thrust Segment

Portion Rupture Length Mw Slip Rate (mm/yr)

eastern 1950 350 8.4

central unruptured 800 -

western 1934 200 8.1 21 ± 1.5 (Lave and Avouac,

2000) 1) Nepalese

1350

eastern 1505 600 8.2 ~6-18 (Kumar et al., 2006);

>7-14 mm/yr (Wesnousky et al. (1999) central 1803 200 7.5 western unruptured 200 2) Central seismic gap 1000 eastern 1905 100 7.7 ? 1905 rupture to NE syntaxis includes 1555 rupture 500 1555 = 7.6 3) NW Indian 600

The Arakan Trench, although also located a great distance from the site, was similarly included in the hazard model. This is the northern extension of the Sumatran-Andaman subduction zone that accommodates relative motion between the Indian Ocean part of the Australian plate and the Sunda Block. The northern extension of the subduction zone could produce earthquake up to 8.5 to >9.0 and therefore has been included in our model.

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3.0 SEISMIC SOURCE MODEL 3.1 INTRODUCTION

A seismic source model was developed for input to the probabilistic seismic hazard analysis (PSHA). The seismic source model includes parameters for the areal source zones, and fault sources. Areal source zones include regions of the relatively shallow crust that are inferred to have uniform style of faulting, earthquake magnitude, and recurrence characteristics, but where sufficient data are not available to model specific faults. Line sources represent specific active faults where data are sufficient to estimate magnitude and recurrence parameters.

Figure 3-1 illustrates the seismic source model for all of the Indian subcontinent as well as the Indian-Eurasian collision zone. This model includes 51 areal sources zones and 12 line sources. Figure 3-2 shows the source zones within approximately 1,000 km of the project area. Circles with radii of 400, 600 and 800 km are provided on Figure 3-2 to illustrate the distances of the various sources from the site. With the exception of Line Source 1 and Zone 23, the sources of high seismicity, such as the Himalayan region, lie at a distance greater than 600 km from the project site.

3.2 AREAL SOURCE ZONES

The seismic source model for the region includes 51 areal source zones that characterize the shallow crust (Figure 3-1). As shown on Figure 3-2, 19 zones lie within approximately 800 km of the Paradip site, of which 12 zones are within 600 km of the site. The high activity regions of the Himalayas lie at a distance greater than 600 km from the project site and only contribute to the long period part of the hazard spectrum.

Areal source zones represent regions with similar tectonic and seismological characteristics and are modeled as having uniform magnitude, recurrence, and style of faulting parameter values. Definition of the areal source zone parameters for input to the PSHA was based on examination of geomorphological characteristics, fault locations and kinematics, and historical seismicity. Parameter values were estimated for: (1) source location; (2) depth of earthquake occurrence; (3) style of faulting; and (4) maximum earthquake magnitude (Mmax) distribution and weights.

The areal source zones around the project area model four main types of lithospheric regions. These include: (1) areas of stable continental crust, which are typically considered continental nuclei; (2) areas of extended continental crust that retain tectonic features associated with rifting and continental fragmentation; (3) areas where rifting had begun, but failed to result in significant continental fragmentation; and (4) active plate boundary zones. The site is located within an area of extended continental crust and has very low rates of seismic activity. The source zone parameters for each of these four main types of lithospheric regions that lie within 800 km of the project site are summarized in Table 3-1.

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No. Name Mmax Weights for Mmax Mmin N(M> Mmin) b-value

Stable Continental Crust Zones

17 Satpura East 7.0, 7.2, 7.4 0.2, 0.6, 0.2 4.5 0.31 0.90 18 Bundelkhand-East 6.75, 7.0, 7.25 0.2, 0.6, 0.2 4.5 0.09 0.90 27 Bundelkhand-South 6.25, 6.5, 6.75 0.2, 0.6, 0.2 4.5 0.09 0.90 35 Singhbhum Nucleus 6.25, 6.5, 6.75 0.2, 0.6, 0.2 4.5 0.07 0.90 37 Bhandara-Singhbhum 6.25, 6.5, 6.75 0.2, 0.6, 0.2 4.5 0.01 0.90 49 Bay of Bengal 6.25, 6.5, 6.75 0.2, 0.6, 0.2 4.5 0.37 0.90

51 Eastern Ghats North - Interior 7.0, 7.25, 7.5 0.22, 0.67, 0.11 4.5 0.03 0.90

Extended Crust and Failed Rifts

24 Bangladesh Margin 7.6, 7.8 0.6, 0.4 4.5 0.30 0.80

25 Bengal West 6.75, 7.0, 7.25 0.2, 0.6, 0.2 4.5 0.07 0.80

26 Narmada Rift 7.25, 7.5, 7.75 0.2, 0.6, 0.2 4.5 0.21 0.80

34 Bengal Margin 7.0, 7.25, 7.5 0.2, 0.6, 0.2 4.5 0.25 0.80

36 Mahanadi-Damodar 6.8, 7.1, 7.5 0.22, 0.67, 0.11 4.5 0.08 0.80

41 Eastern Ghats North 7.0, 7.25, 7.5 0.22, 0.67, 0.11 4.5 0.03 0.80

42 Godavari 6.8, 7.1, 7.5 0.22, 0.67, 0.11 4.5 0.08 0.80

Active Plate Boundary Zones

1 Myanmar 7.8, 8.0 0.6, 0.4 5.0 5.53 0.95

10 Nepalese Central 7.25, 7.5, 7.75 0.2, 0.6, 0.2 5.0 0.63 0.95

11 Nepalese West 7.25, 7.5, 7.75 0.2, 0.6, 0.2 5.0 0.63 0.95

16 Shillong 7.25, 7.5, 7.75 0.2, 0.6, 0.2 4.5 1.01 0.95

23 Arakan Margin 6.75, 7.0, 7.25 0.2, 0.6, 0.2 5.0 0.50 0.95

3.2.1 Indian Stable Continental Region

Most of interior peninsular India comprises the SCR of the Indian plate (Figure 2-1). The SCR province is defined according to criteria set forth in EPRI (1988) and Johnston et al. (1994). The criteria include: (1) evidence for no tectonic activity younger than early Cretaceous (~100 Ma); (2) no deformed forelands or orogenic belts younger than Cretaceous (~65 Ma); (3) no anorogenic intrusions younger than Cretaceous; and (4), no rifting or significant extension younger than Paleogene (~35 Ma). The SCR of India is further divided into regions underlain by extended continental crust and failed rifts. According to Johnston et al. (1994), stable continental regions that are underlain by extended crust have greater seismogenic potential than those underlain by non-extended crust. Therefore, the Indian SCR is divided into three main types of source zones: (1) stable continental regions that consist of non-extended continental crust greater than 500 million years old (Upper Proterozoic or older); (2) areas underlain by extended continental crust; and (3) failed rift systems.

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The Indian SCR is disrupted by areas of extended continental crust along the east and west coasts and Bengal coastal margin, as well as by three failed rift systems. The areas of extended continental crust are represented by the Eastern and Western Ghats, respectively. The Ghats are characterized by significant topographic relief, normal faults, and higher rates of earthquake activity compared to the SCR zones (Figure 2-1). The failed rift systems include the Mahanadi-Damodar, Gadavari, and Narmada rifts systems (Figure 2-1, 3-1; and Table 3-1). The areas of extended crust and failed rift systems contain formerly active normal faults that may be reactivated as a result of the current regional compressive stress regime.

The Indian SCR source zones are characterized by very low rates of seismic activity with only a few recorded events of magnitude > Mw 6. The areas of extended crust and failed rift systems have experienced earthquake up to approximately Mw 7.5 to 8; as seen by events in the Western Ghats, and the Kutch region.

The assessment of maximum earthquake magnitude for the Indian SCR source zones is based on investigations of continental intraplate seismicity worldwide (e.g., Johnston et al., 1994; Gangopadhyay and Talwani, 2003). These studies show that most of the large earthquakes that have occurred in SCR provinces worldwide are associated with pre-existing structures, most commonly regions of extended crust associated with continental margins and failed rifts. Therefore, in establishing the maximum magnitude distributions for each source zone, we have attempted to show a relative increase in the hazard by assigning a lower magnitude distribution to the SCR’s; a relatively higher magnitude distribution for the areas of extended continental crust; and the highest magnitude distribution to the areas underlain by failed rifts (Table 3-1).

3.2.2 Oceanic Domain - Bay of Bengal

The Bay of Bengal source zone represents a background source zone within ancient, non-extended oceanic crust of the eastern Indian plate. The Bay of Bengal is bound on the west by the Eastern Ghats and on the east by the Sumatran-Andaman-Arakan plate boundary. The Bay of Bengal region is characterized by a low level of seismic activity, which is typical of oceanic environments worldwide. There are no significant seismogenic structures within the Bay of Bengal in the site region.

Studies of global seismicity associated with oceanic crust confirm that the vast majority of earthquakes occur at plate boundaries, either as spreading ridge or transform fault events (e.g., Bergman and Solomon, 1981; Okal, 1983). The seismicity of oceanic intraplate settings is characterized by very low rates of activity and small magnitudes. There have been fewer than 35 earthquakes in the oceanic intraplate environment having a magnitude greater than mb 5 (Okal, 1983). Nearly all of the larger earthquakes (M>6) recorded in an intraplate oceanic environment are located either near (<500 km) an active plate boundary, or in a region of extended crust (Okal, 1983). The one exception is the 1999 Mw8.1 earthquake located on the Antarctic plate southwest of Australia (Nettles et al., 1999). The location and mechanism of this earthquake was not consistent with regional stress conditions, and subsequent studies suggest glacial loading/unloading as a triggering mechanism for this event (Kreemer and Holt, 2000).

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Earthquake recurrence in areal source zones is modeled using a truncated exponential magnitude distribution. The recurrence relationships are based on the magnitude frequency distribution for events occurring within the volume of crust defined by the areal source zone boundary and extending from the surface to 40 km depth. For the hazard computation, these events are assigned to a depth range of 10 to 40 km. Deeper activity is recorded along the plate boundary, and those zones are modeled accordingly with a greater depth range.

3.2.3 Plate Boundary Areal Source Zones

In addition to the SCR and oceanic areal source zones described above, the seismic source model also includes areal source zones that encompass parts of the crust within the active zone of plate boundary deformation (Table 3-1). Of the 19 areal source zones that are within about 800 km of the Paradip site, five are areas of active plate boundary deformation. These include Zones 1 and 23 along the northern extension of the Sumatra-Andaman-Arakan subduction zone (Myanmar continental margin), Zones 10 and 11, which lie north of the Himalayan main thrust, and Zone 16, which encompasses the Shilong Plateau. All of these zones are characterized by reverse and strike-slip faulting and have experienced large magnitude historical earthquakes.

3.3 LINE (FAULT) SOURCES

Fault or line sources represent individual faults for which data are sufficient to determine location, maximum earthquake magnitudes distributions and slip rate estimates. Twelve faults have been included in our seismic source model (Figure 3-1). The faults included in the model have been recognized for many years. However, because of the tectonic complexity and remoteness of the Arakan plate boundary and the Himalayan front, studies presenting definitive data on fault location, style of faulting, fault slip rates and earthquake recurrence models are limited. Therefore, we have developed an idealized model that reflects our assessment of the broad scale tectonic features around the site.

Input parameters for line sources include: (1) source location; (2) dip, dip direction, and maximum depth; (3) style of faulting; (4) maximum earthquake magnitude distribution and weights; and (5) slip rate distributions and associated earthquake recurrence intervals. The area vs. magnitude, and subsurface rupture length vs. magnitude relations (all earthquake types) developed by Wells and Coppersmith (1994) were used in estimating the maximum earthquake magnitude distributions for the fault sources. Maximum magnitude distributions and weights for the line sources were developed by considering minimum and maximum fault length estimates, minimum and maximum fault area estimates, and empirical relationships for both length and area. The resulting magnitude distribution is then compared with the historical seismicity and tectonic setting of a particular fault to develop a final weighted maximum earthquake magnitude distribution.

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Fault slip rates and earthquake recurrence intervals were estimated based on published geodetic or fault slip rate data (i.e. Lave and Avouac, 2000; Kumar et al., 2006). The data presented in these papers are fairly consistent in their estimation of fault slip rates and show 6 to 21 mm/yr contraction across the Himalayan main thrust fault. Because the Himalayan main thrust fault is a major interplate collision zone, we compute the “effective slip rate” in the same manner as we would for an oceanic-continent collision. The approach is described below and was used for both the Arakan subduction zone and the Himalayan main thrust fault.

Slip rates along the main thrust fault were estimated taking into consideration the overall plate motion rate, plate-normal component of motion, and amount of seismic coupling or seismic efficiency along the plate interface. Plate motion rates were derived from published vectors determined by local GPS geodic networks and global plate motion models (e.g., NUVEL 1-A). The plate-normal component of the relative horizontal plate-motion vector was used to estimate the slip rate on the plate interface. This reflects the general assumption that only the plate-normal component accumulates strain to be released in great earthquakes, while the plate margin parallel component of motion is partitioned onto other shallow crustal sources. We assume that the additional off fault seismicity is taken into account in our areal source zones.

The slip rate on the plate interface also was corrected to account for the observation that only a fraction of the measured relative plate motion goes into producing the elastic strain energy that is released by earthquakes. The proportion of strain accumulated on the plate interface relative to the total possible strain is described by the seismic coupling coefficient. We estimated seismic coupling coefficients for the Arakan trench subduction zone of about 0.2 to 0.67, and estimated a coupling coefficient of 0.8 for the Himalayan main thrust fault. The seismic coupling coefficient is a significant source of uncertainty in our final slip rate values.

The parameters for the fault sources within 800 km of the site are presented in Table 3-2.

Table 3-2. Summary of Source Parameters for Line Sources

Source Line Maximum Magnitude Distribution Slip Rate Distribution No. Name Mmax Weight Slip Rate Weight

F1 Arakan Trench South 8.17, 8.53, 8.94 0.22, 0.67, 0.11 11.02, 12.51, 14.00 0.20 0.6 0.20

F2 Arakan Trench North 7.98, 8.29, 8.54 0.20, 0.60, 0.20 1.74, 2.90, 4.64 0.20 0.6 0.20

F5 Himalayan Frontal Thrust –Nepal Central 8.40, 8.79, 9.13 0.22, 0.67, 0.11 6.40, 7.39, 8.87 0.20 0.6 0.20

F6 Himalayan Frontal Thrust –Nepal West 8.40, 8.62, 8.86 0.22, 0.67, 0.11 12.27, 13.26, 14.26 0.20 0.6 0.20

3.4 EARTHQUAKE RECURRENCE AND ACTIVITY RATES

3.4.1 Introduction

Differing earthquake recurrence models were used to characterize the various shallow crustal areal and planar sources in the seismotectonic model.

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x The activity of the planar fault sources was modeled by means of the fault slip rate in conjunction with the pure characteristic magnitude model. This was intended to model the large magnitude, characteristic-type events generated on these faults.

3.4.2 Seismicity Catalogs

A composite seismicity catalog covering the period between 1341 A.D. to 2007 and the area between 2-36N and 64-96E was compiled from various catalogs. After the catalogs were merged, duplicate events were identified and removed. As a result of merging the catalogs, several events with conflicting magnitudes were encountered. An automated system was used to remove duplicate events, provided by different sources, from the catalog. The program looks for similarities in time, location, and magnitude to score successive events as duplicates. Fore

and aftershocks were removed using the program CLUSTER2000 (USGS, 2004).

CLUSTER2000 recognizes clusters in space-time in an earthquake catalog. It is intended for use in removing aftershocks or "declustering" the catalog. The methods used are described in Reasenberg (1985). The final catalog includes 5867 earthquakes ranging from M 3.0 to 8.7. Figure 2-1 shows the historical seismicity in the project region. The various seismotectonic features are also shown for reference. These earthquakes are only the mainshock events that remain from declustering the initial catalog.

An evaluation of catalog completeness for different magnitudes was conducted. The estimated completeness intervals as a function of magnitude are shown in Tables 3-3a, 3-3b and 3-3c for stable continental, extended crust, and active plate margin regions, respectively. In computing the annual frequency of earthquakes using the entire data set, the completeness intervals reported in Tables 3-3a through 3-3c were adopted. However, annual frequency computations were also made using data recorded after 1973. The post-1973 catalog was considered complete for the lower range of magnitudes, although it is likely incomplete for large magnitudes. Nevertheless a constant time interval was used to estimate annual rates of seismicity from the post-1973 data.

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Table 3-2a. Completeness Interval of Seismicity Catalog (Stable Continental Zones) Magnitude Range Time

4.5 – 5.0 18 5.0 – 5.5 30 5.5 – 6.0 42 6.0 – 6.5 78 6.5 – 7.0 81 7.0 – 7.5 >103 7.5 – 8.0 >103

Table 3-2b. Completeness Interval of Seismicity Catalog (Extended Crust Zones) Magnitude Range Time

4.5 – 5.0 28 5.0 – 5.5 43 5.5 – 6.0 76 6.0 – 6.5 76 6.5 – 7.0 81 7.0 – 7.5 90 7.5 – 8.0 140 8.0 – 8.5 189

Table 3-3c. Completeness Interval of Seismicity Catalog (Active Plate Margin) Magnitude Range Time

4.5 – 5.0 43 5.0 – 5.5 43 5.5 – 6.0 58 6.0 – 6.5 88 6.5 – 7.0 97 7.0 – 7.5 >99 7.5 – 8.0 >99 8.0 – 8.5 >99

3.4.3 Magnitude Probability Density Functions

The relative distribution of magnitudes for each seismic source was modeled using one of two magnitude probability density functions.

x The truncated exponential model was used for all areal crustal sources because it has been shown to satisfactorily model the seismicity in such sources.

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A qualitative comparison of the probability density function and cumulative probability density for the three models are shown on Figures 3-3a and 3-3b. For this comparison, a characteristic magnitude of 7.75 was assumed. This magnitude was also used as the maximum magnitude in the Truncated Exponential model. The characteristic model was assumed to have a normal distribution with maximum and minimum magnitudes of +/-0.1 units about the characteristic magnitude and a standard deviation of 0.4. As show on Figure 3-3a, the pure characteristic model has the highest probability density around the characteristic magnitude while zero density is assigned to smaller magnitudes. The differences in the probability density between the two models translate to significantly difference recurrence relationships. Figure 3-3b shows the annual recurrence predicted using the three models in combination with a slip rate of 1.0 mm/year, a fault area of 100,000 km2 and a b-value of 1.0. The truncated exponential model has the highest rate for M>4.5 because of the small mean moment per earthquake. Conversely, the pure characteristic model predicts the most frequent recurrence of the characteristic magnitude earthquake.

3.4.4 Activity Parameters

3.4.4.1 Crustal Areal Sources

The activity rate and the slope of the truncated exponential model were estimated by regressing the Gutenberg-Richter (1954) relationship on the historical seismicity data. The model estimates the annual number of earthquakes larger than a given magnitude as:

Log N = a - b M

where: N = cumulative number of earthquakes with magnitude greater or equal to M; a = log of the rate of earthquakes above magnitude 0; and

b = the slope of the semilog plot.

The activity parameters were obtained independently for three main tectonic regions in this seismotectonic model as discussed: (1) the active plate collision area that encompasses the Indian subcontinent from the north, (2) the stable continental region that is representative of majority of the subcontinent, and (3) the areas of extended crust and failed rifts.

Estimates of the slopes of the Gutenberg-Richter relationship (i.e., b-values) were obtained for each region by simultaneous regression on data from all sources within a similar seismic environment. Based on these regressions, the following b-values were estimated: (1) 0.90 for areas within the stable continental crust areas, (2) 0.80 for zones within the extended crust areas, and (3) 0.95 for zones within the plate collision boundary. The activity rate for each areal source was estimated through regression performed for each individual source with the b-values mentioned above. The regressions based on the full historical record

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using the completeness intervals presented in Tables 2a through 2c are shown in Figures 3-4a through 3-4c.

3.4.4.2 Planar Fault Sources

The relative distribution of magnitudes on the planar fault sources was described using a pure characteristic model. The activity of the fault was represented by its slip rate.

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Paradip Refinery Project

Orissa, India

MAGNITUDE PROBABILITY DENSITY FUNCTIONS

FIGURE 3-3a

0.001 0.01 0.1 1 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 Magnitude P roba bi li ty D e n s it y Func ti on

Truncated Exponential, Mmax= 7.75 Characteristic, Mchar= 7.75

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Paradip Refinery Project

Orissa, India

ANNUAL RECURRENCE PREDICTED BY DIFFERENT MAGNITUDE PDF MODELS

FIGURE 3-3b

0.001 0.01 0.1 1 10 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 8.0 8.5 9.0 Magnitude A n nua l N u mbe r of E a rt hqua kes wi th M> m

Truncated Exponential, Mmax= 7.75 Characteristic, Mchar= 7.75

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Paradip Refinery Project

Orissa, India

GUTENBERG-RICHTER FIT TO HISTORICAL SEISMICITY DATA

STABLE CONTINENTAL ZONES

FIGURE 3-4a

0.001 0.01 0.1 1 10 100 4.5 5.5 6.5 7.5 8.5 Magnitude A n n u a l N u mb er o f E a rt h q u akes w it h M > m

Recorded Seismicity after 1909 (Running Time Interval)

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Paradip Refinery Project

Orissa, India

GUTENBERG-RICHTER FIT TO HISTORICAL SEISMICITY DATA

EXTENDED CRUST ZONES

FIGURE 3-4b

0.001 0.01 0.1 1 10 100 4.5 5.5 6.5 7.5 8.5 Magnitude A n n u a l N u mb er o f E a rt h q u akes w it h M > m

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Paradip Refinery Project

Orissa, India

GUTENBERG-RICHTER FIT TO HISTORICAL SEISMICITY DATA

ACTIVE PLATE MARGIN ZONES

FIGURE 3-4c

0.001 0.01 0.1 1 10 100 1000 10000 4.5 5.5 6.5 7.5 8.5 Magnitude A nnual N u mber of E a rt hqu akes w it h M > m

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4.0 PROBABILISTIC SEISMIC HAZARD ANALYSES

4.1 PROJECT LOCATION

For the purpose of this study, site-specific design response spectra were developed for a representative location within the project area. The geographical coordinates of the location used for the seismic hazard analyses are tabulated in Table 4-1.

Table 4-1. Coordinates of Representative Location Latitude (degrees) Longitude (degrees)

20.2529 86.5962 WGS 84 - World Geodetic System

4.2 METHODOLOGY

4.2.1 Mathematical Formulation

Probabilistic seismic hazard analyses (PSHA) were carried out using the computer program HAZ35 (Abrahamson, 2005). Computation of the seismic hazard involves the combination of uncertainties in earthquake size, location, frequency, and resulting ground motions. The estimated annual rate at which the ground motion, A, will exceed a particular value, a, is computed by (Cornell, 1968):

³³

!

a

P

A

a

m

r

f

m

f

r

dm

dr

A

]

[

,

]

M

(

)

R

(

)

[

O

where;

]

,

[

A

a

m

r

P

!

is the probability of the ground motion, A, exceeding the threshold value, a, given the earthquake magnitude and distance from the fault, and

fM(m) and fR(r) are probability density functions describing magnitude and distance.

The computation of this integral is carried out numerically. By assuming that earthquake occurrence can be modeled as a Poisson process, the probability of exceedance in a specified exposure period (typically corresponding to the useful life of a project) may be estimated as follows (Yegian, 1979):

P A

[

!

a t

, ]

1 e

[ ( ) ]Oa t where;

P[A>a,t] is the conditional probability of an earthquake's acceleration (A) exceeding a specified

acceleration (a) during a time interval (t) given that an earthquake will occur, and O (a) is the

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empirical attenuation functions. These empirical functions should model the type of rupture mechanism as well as the regional geology to properly estimate site-specific strong ground motion.

The project site lies at the edge of the stable continental region of the Indian subcontinent and the extended crustal region. For this study the assumption was made that shallow crustal earthquakes in and around the Paradip Refinery site are similar to comparable events in the relatively stable areas of the Eastern United States. Additionally, selection of attenuation relationships reflected the presence of the project site within an extended crust environment.

For the stable continental regions, two equally weighted attenuation relationships were used; Atkinson and Boore (1997) and Toro et al. (1997). For the extended crust areas, the attenuation relationship developed by Toro et al. (1997) for the extended crust environment of the gulf crustal regions was used in conjunction with the Eastern Continental relationships mentioned above. The Toro et al. (1997) gulf relationship was given a weight of 0.50 while the other relationships were given weights of 0.25 each. The various attenuation relationships and their respective weights are presented in Table 4-2.

Table 4.2. Horizontal Ground Motion Attenuation Relationships Seismic Source Attenuation Equation Weight

Atkinson and Boore (1997) 0.5

All Seismic Sources except Extended Crust Sources

Toro et al. (1997) – Eastern and Continental US

0.5

Atkinson and Boore (1997) 0.25

Toro et al. (1997) – Eastern and Continental US

0.25 Extended Crust Zones

Toro et al. (1997) – Gulf Crustal Region

0.5

The subsurface information at the project site is available to a maximum depth of 30 meters. Based on our understanding of the regional geology in the project area, competent bedrock is anticipated to be present at significant depths from the ground surface. Therefore, results were developed for a “hard soil” horizon, with an average shear wave velocity in the upper 30 meters (VS,30) of 500 m/s. Atkinson and Boore (1997) have developed attenuation relationship for soils with VS,30of 500 m/s as well as for competent bedrock. However, the Toro et al. (1997) relationships were developed only for bedrock. Therefore, spectral amplification factors were obtained by comparing the Atkinson and Boore (1997) bedrock and “hard soil” results, and were subsequently applied to the results from the Toro et al. relationships in order to obtain equivalent results applicable at the “hard soil” horizon.

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4.2.3 Epistemic Uncertainty

The PSHA presented in this study was carried out using a decision tree approach. This approach is usually followed to take into consideration uncertainty within the scientific community with respect to parameters that are used in the seismic hazard analyses. Such parameters may be the maximum magnitude on a fault, the long-term slip rate, the median ground motion given an earthquake scenario, and the magnitude probability density function.

In the current study, epistemic uncertainty was considered with respect to the following parameters:

x The empirical attenuation relationship. Three and two empirical relationships were

considered for the extended crust and other zones, respectively. The relationships were weighted as presented in Table 4-2.

x The maximum magnitude on the areal and the planar fault sources. Three different

maximum magnitudes were considered for each zone. The magnitudes were weighted according to the relative confidence in their potential occurrence.

x The slip rate on the planar fault sources. Similar to the case of the maximum

magnitude, three different slip rates were considered for the planar fault sources. These were weighted according to the relative confidence in the estimates.

4.2.4 Hazard Deaggregation

Hazard deaggregation was performed to estimate the contribution of different magnitude events at different distances to the overall hazard. This procedure involves taking the derivative of the total seismic hazard with respect to magnitude and distance to calculate the fractional contribution of selected magnitude-distance bins to the total hazard at a specified hazard level. These results are useful in identifying which seismogenic sources are the primary contributors to the probabilistically estimated hazard, and what magnitude earthquakes associated with these sources are producing the strong ground shaking.

In this report, the results of the deaggregation are displayed as three-dimensional bar charts showing the relationship of magnitude and distance with hazard contribution. These plots are useful for understanding hazard contribution, but may not indicate the specific source when there are multiple sources at the same distance. In addition to the magnitude and distance deaggregation, the results were also deaggregated by fault to evaluate the relative contribution of the different seismic sources adjacent to the site.

4.2.5 Near-Source and Directivity Effects

The design spectra were developed for the random horizontal component without modification for near-source effects. Significant near-source effects, resulting from the constructive interference of seismic waves due to directivity, are not expected to be present at the location of the project because of the large distance (i.e., larger than 300 km) of the nearest planar source (i.e., Line 1 fault) from the site.

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relationships used for this project have traditionally been developed for structural periods up to 2 seconds. As a result, the design spectra from probabilistic seismic hazard analyses are well defined up to periods of approximately 2 seconds. For the proposed tanks being considered for this project, the sloshing periods may be longer. Consequently, design data were extended to longer structural periods than those for which empirical attenuation relationships are available.

A well-established methodology to extend a design spectrum to longer periods is not available in the literature. However, there appears to be consensus among the scientific community (e.g., Silva and Abrahamson, 1992; NEHRP, 2003) that in the absence of data at long periods design response spectra can be extended based on a constant spectral velocity assumption for the intermediate periods and a constant spectral displacement assumption for long periods. For design purposes the “corner period”, marking the transition between constant spectral velocity and constant spectral displacement is a function of the earthquake magnitude and has been tabulated by NEHRP (2003). For this study, the corner period was estimated to be approximately 6 to 8 seconds for various return period events, corresponding to contributing magnitudes ranging from 7.0 to 8.0. Between structural periods of 8 and 10 seconds, the target spectra were extended based on an assumption of constant spectral displacement. Between structural periods of 2 and 8 seconds the target spectra were interpolated using a smooth curve on a tripartite plot.

4.3 DEFINITION OF DESIGN LEVEL EVENTS

Based on the information from Foster Wheeler, the various facilities for the Paradip Refinery project will be designed in accordance with the Indian Standard IS 1893 (Part 4),

Criteria for Earthquake Resistant Design of Structures. According to IS 1893, two levels of

design ground motions are developed:

1. DBE (Design Basis Earthquake) and 2. MCE (Maximum Considered Earthquake).

The DBE is defined per IS 1893 as an event with 5 percent probability of exceedance in 50 years (i.e., a return period of 475 years). The MCE is defined as an event with 2 percent probability of exceedance in 50 years (i.e., a return period of 2,475 years). Additionally, hard soil ground motions were with a 1 percent probability of exceedance in 50 years (i.e., a return period of 4,975 years) were also estimated per the request of Foster Wheeler.

4.4 RESULTS

Results from the seismic hazard analyses are presented in terms of design response spectra for horizontal and vertical ground motions. As described in Section 4.2.2, the results are based on attenuation relationships for a “hard soil” site classification, i.e., shear wave velocity on the order of 500 meters per second.

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4.4.1 Horizontal Design Response Spectra

Figure 4-1 shows the 5 percent-damped acceleration response spectra for the DBE, MCE and 4,975-year return period events. The MCE spectrum coincides with the 2,475-year return period event. The DBE spectrum coincides with the 475-year return period event. The spectra are computed for a generic “hard soil” boundary with an average shear wave velocity in the upper 30 meters of about 500 m/s or greater.

The design spectral ordinates for the horizontal spectra are listed in Table 4-3.

Table 4-3. Horizontal Design Response Spectra Period

(s)

DBE (475-yr return period) (g)

MCE (2,475-yr return period) (g)

4,975-yr return period event (g) 0.01 0.080 0.174 0.232 0.03 0.080 0.174 0.232 0.05 0.168 0.388 0.523 0.07 0.189 0.437 0.589 0.1 0.214 0.496 0.673 0.15 0.209 0.481 0.650 0.2 0.198 0.452 0.608 0.3 0.156 0.359 0.493 0.5 0.110 0.256 0.358 0.75 0.075 0.177 0.251 1 0.060 0.140 0.199 1.5 0.042 0.093 0.131 2 0.034 0.071 0.099 3 0.019 0.039 0.061 4 0.012 0.025 0.042 5 0.008 0.017 0.030 6 0.006 0.012 0.023 7 0.005 0.009 0.018 8 0.003 0.007 0.014 9 0.003 0.005 0.011 10 0.002 0.004 0.009

4.4.2 Hazard Deaggregation by Fault

Figures 4-2a, 4-2b and 4-2c present hazard curves for the PGA, and spectral accelerations at the periods of 0.2 second, [SA(0.2s)], and 1 second [SA(1.0s)], respectively. These hazard curves are obtained from the Atkinson and Boore (1997) “hard soil” relationship. The hazard curves illustrate the variation in ground motion hazard as a function of the level of

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Mahanadi Damodar Zone, that lies adjacent to the site. At long structural periods, significant hazard contributions are also estimated for Line Source 1 – Arakan Trench South.

4.4.3 Hazard Deaggregation by Magnitude and Distance

Figures 4-3a, 43b and 4-3c present the deaggregation of the hazard with respect to magnitude and distance for PGA, SA(0.2s) and SA(1.0s) for horizontal motion. These deaggregation results are obtained from the results for the Atkinson and Boore (1997) “hard soil” relationship. The deaggregation was performed for return period of 2,475 years, representative of the MCE event.

x At short structural periods, the majority of the hazard is from small to intermediate magnitude earthquakes (i.e., 4.5 to 7.0), at short to intermediate distances from the project site (i.e., 10 to 100 km). These events are representative of activity within Source Zones 25 and 36.

x At long periods, a second hazard mode is observed in the deaggregations, with majority of hazard contributions coming from major earthquakes (greater than magnitude 7.5) occurring at distances greater than 300 km. These are representative of events occurring on Line Source 1.

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Paradip Refinery Project

Orissa, India

"HARD SOIL" HORIZONTAL SPECTRA FOR VARIOUS RETURN PERIODS

FIGURE 4-1

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.01 0.1 1 10 Period (s) A c cel er at io n ( g )

475 Year Return Period (DBE) 2475 Year Return Period (MCE) 4975 Year Return Period

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Paradip Refinery Project

Orissa, India

HORIZONTAL FAULT CONTRIBUTION TO HAZARD CURVES FOR PGA

FIGURE 4-2a

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 10−4 10−3 10−2 Acceleration (g)

Annual Rate of Exceedance

475−Year

2475−Year

4975−Year

ZONE 4 − TETHYAN HIMALAYA EAST III ZONE 37 − BHANDARA−SINGHBHUM ZONE 26 − NARMADA RIFT

ZONE 51 − EASTERN GHATS NORTH − INTERI ZONE 49 − BAY OF BENGAL

ZONE 34 − BENGAL MARGIN ZONE 35 − SINGHBHUM NUCLEUS ZONE 41 − EASTERN GHATS NORTH ZONE 36 − MAHANADI−DAMODAR ZONE 25 − BENGAL WEST WT TOTAL EVENTS/YR

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Paradip Refinery Project

Orissa, India

HORIZONTAL FAULT CONTRIBUTION TO HAZARD CURVES FOR SA(0.2S)

FIGURE 4-2b

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 10−4 10−3 10−2 Acceleration (g)

475−Year

2475−Year

4975−Year

ZONE 51 − EASTERN GHATS NORTH − INTERI LINE 1 − ARAKAN TRENCH SOUTH I

LINE 1 − ARAKAN TRENCH SOUTH II LINE 1 − ARAKAN TRENCH SOUTH III ZONE 49 − BAY OF BENGAL

ZONE 35 − SINGHBHUM NUCLEUS ZONE 34 − BENGAL MARGIN ZONE 41 − EASTERN GHATS NORTH ZONE 36 − MAHANADI−DAMODAR ZONE 25 − BENGAL WEST WT TOTAL EVENTS/YR

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Paradip Refinery Project

Orissa, India

HORIZONTAL FAULT CONTRIBUTION TO HAZARD CURVES FOR SA(1.0S)

FIGURE 4-2c

0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2 10−4 10−3 10−2 Acceleration (g)

475−Year

2475−Year

4975−Year

ZONE 26 − NARMADA RIFT ZONE 35 − SINGHBHUM NUCLEUS ZONE 41 − EASTERN GHATS NORTH ZONE 24 − BENGLADESH MARGIN ZONE 36 − MAHANADI−DAMODAR LINE 1 − ARAKAN TRENCH SOUTH I LINE 1 − ARAKAN TRENCH SOUTH II ZONE 34 − BENGAL MARGIN LINE 1 − ARAKAN TRENCH SOUTH III ZONE 25 − BENGAL WEST

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Paradip Refinery Project

Orissa, India

HORIZONTAL HAZARD DEAGGREGATION BY DISTANCE AND MAGNITUDE FOR PGA

2475-YEAR RETURN PERIOD

FIGURE 4-3a

4.5−55−5.5 5.5−66−6.5 6.5−77−7.5 7.5−88−8.5 >8.5 0−5 5−10 10−20 20−30 30−50 50−75 75−100 100−300 >300 0 0.02 0.04 0.06 0.08 0.1 0.12 Magnitude Distance (km) Fractional Contribution

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Paradip Refinery Project

Orissa, India

HORIZONTAL HAZARD DEAGGREGATION BY DISTANCE AND MAGNITUDE FOR SA(0.2S)

2475-YEAR RETURN PERIOD

FIGURE 4-3b

4.5−55−5.5 5.5−66−6.5 6.5−77−7.5 7.5−88−8.5 >8.5 0−5 5−10 10−20 20−30 30−50 50−75 75−100 100−300 >300 0 0.02 0.04 0.06 0.08 0.1 Magnitude Distance (km) Fractional Contribution

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Paradip Refinery Project

Orissa, India

HORIZONTAL HAZARD DEAGGREGATION BY DISTANCE AND MAGNITUDE FOR SA(1.0S)

2475-YEAR RETURN PERIOD

FIGURE 4-3c

4.5−55−5.5 5.5−66−6.5 6.5−77−7.5 7.5−88−8.5 >8.5 0−5 5−10 10−20 20−30 30−50 50−75 75−100 100−300 >300 0 0.05 0.1 0.15 0.2 0.25 Magnitude Distance (km) Fractional Contribution

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5.1 GROUND MOTION SELECTION

Three sets of accelerograms were selected and matched to the DBE and MCE design spectra for “hard soil” conditions (Vs ~ 500 m/s). As described in Section 4, the majority of the hazard at short periods comes from small to intermediate magnitude events (i.e., 5.0 to 7.0) occurring at relatively short distances from the site (10 to 30 km), whereas the hazard at longer periods comes from distant earthquakes with large magnitudes.

In general there are no good time history recordings around the project area. The main considerations while selecting the time histories were: (1) design earthquake parameters (magnitude and distance) resulting from the deaggregation analyses, and (2) the overall shape of the response spectra relative to the target spectrum. Table 5-1 summarizes the relevant parameters of the selected seed time histories. The seed motions were downloaded from the Pacific Earthquake Engineering Research (PEER) Center strong motion database website

(http://peer.berkeley.edu/smcat/) as well as from the Consortium of Organizations for Strong

Motion Observation Systems (COSMOS) website (http://www.cosmos-eq.org/).

Table 5-1. Summary of Seed Motion Characteristics Set Earthquake Magnitude Distance

(km) Recording Station

Designation

1 1988 NE-India, India 7.2 189.9 Bokajan- N34E

S56E

2 1979 Imperial Valley, USA 6.5 15.5 El Centro Array 1 H-E01140

H-E01230

3 1980 Mammoth Lakes, USA 6.3 9.0 Convict Creek I-CVK90

I-CVK180

5.2 APPROACH

5.2.1 Modification of Selected Seed Motions

Design acceleration time histories were generated for this project by spectrally matching recorded acceleration time histories to the design spectra. A time-domain spectral matching procedure was used to better preserve the characteristics of the seed time histories. The procedure usually involves the following steps:

x Spectral matching of the resampled, rotated motions to the design spectra; and x Baseline correction of the spectrally matched motions.

5.2.2 Time-Domain Spectral Matching

A time-domain spectral matching procedure was adopted for this project. Time-domain spectral matching adds finite wavelets in the time domain to decrease the spectral deficiencies

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between the seed motion and the target spectra. The result is a realistic looking time history that preserves the seed motion characteristics while generally achieving a close match with the target frequency spectra at all spectral ordinates.

The time-domain spectral matching was accomplished using the computer code RSPMATCH written by Abrahamson (2003), which generally follows the algorithm as set forth by Lilhanand and Tseng (1988). As stated above, this code calculates the spectral differences between a response spectrum and a target spectrum, and then adds wavelets in the time domain to alter the frequency content to reduce the differences.

The quality of the results are measured by the tolerance to which the matched motions converge toward the target spectrum, and how well the matched motions compare to the original motions in the time domain. In particular, the matched displacement and velocity time histories should look reasonable and reflect some of the predominant characteristics of the original motions.

5.2.3 Baseline Correction

A final baseline correction was necessary to remove any permanent offset imposed on the time history through the spectral matching procedure. This baseline correction was carried out by fitting an nth order polynomial (where n = 4 to 10) to the displacement time history. The second derivative of this polynomial is then subtracted from the acceleration time history.

These matched and baseline corrected time histories were used for the site response analyses, which are described in the following section.

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6.1 METHODOLOGY

Site response analyses were conducted to assist with the development of the near-surface design response spectra for the project. Site response analyses were conducted for the DBE and MCE design levels. Site response analyses for the 5,000 year return period event are considered out of scope and were not conducted. Free-field site response analyses were performed using the computer program SHAKE (Schnabel et al., 1972), as modified by Idriss and Sun (1992). The program models the soil profile as a one-dimensional column consisting of horizontally layered strata overlying a uniform half-space. SHAKE uses an equivalent-linear model to simulate the nonlinear hysteretic behavior of soil. The analysis takes a specified acceleration time history and propagates it up to the surface layers using a frequency-domain solution.

6.2 SUBSURFACE CONDITIONS

Based on the recently completed subsurface exploration program by FI, there is variation in the subsurface conditions across the project site. In order to develop the idealized soil profiles for site-response analyses, the site conditions were evaluated. Details of soil explorations and the subsurface conditions are presented in the accompanying report by FGCLTD. This section presents a brief description of the stratigraphy based on the recent borings, CPTs and downhole shear wave velocity measurements.

A total of ten cross-sections showing generalized stratigraphy at the project site were developed. Plate 1 shows the locations of the cross-section lines along with a key to the symbols used on the cross sections is provided on Plate 2. The cross-sections are presented on Plates 2 through 11. Cross-Section Lines 1-1’ through 5’5’ were developed in the roughly north-south direction. Lines A-A’ through D-D’ were developed roughly parallel to the Santra Creek. The last cross-section, Line E-E’, was developed to show the subsurface conditions at greater depths, obtained from the three deep borings conducted at the site. The following primary strata used for site response analyses were identified at the project site:

x Sand Fill – The sand fill has been placed over most of the site to raise the site grades. Particularly, fill has been placed to cover most of the site south of the Santra Creek, as well as a roughly rectangular area in the northwestern part of the site, immediately north of the Santra Creek. The CPTs and borings conducted by FI indicate that the fill consists mainly of sand, with relatively low fines contents. The sands appear to be generally medium dense to dense.

x Unit 1 – A primarily soft clay layer that ranges in thickness from roughly 1 to greater than 5 meters in some areas. The clay layer appears to be consistently thicker along the Santra Creek.

x Unit 1b – Underneath the clayey Unit 1a, a layer of interlayered firm to stiff clay and loose to medium dense sand layer appears to be present throughout the site. The

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clay layers within this stratum generally appear to be of similar consistency as the clay within Unit 1a. Therefore, Units 1a and 1b appear to have similar geologic age and depositional environments. However, the consistency of the soils within Unit 1b is significantly variable across the site. The layer appears to be a transition zone between Unit 1a (primarily clay and Unit 2 (primarily sand, described below). Unit 1b was identified during our Phase 1 report, and was reported as Unit 2a. The current CPT and boring data shows this layer to consist of highly interlayered sand and clay. Unit 1 b varies in thickness from roughly 2 meters to greater than 6 meters in the southweastern part of the site. Generally, significantly deeper deposits of Unit 1b were identified towards the southeastern side of the project. That area is relatively close to the shoreline along the Bay of Bengal.

x Unit 2 – Unit 2 consists primarily of medium dense to dense, clayey to relatively clean sands. The unit appears to be present across the entire site, with relatively similar consistency, with the exception of the southeastern side of the site. The unit appears to be significantly interlayered with stiff clay in that region. In the southeastern area of the site, Unit 2 appears to be largely of similar consistency to Unit 1b.

x Unit 3 – A stiff to very stiff clay layer is present underneath Unit 2. The layer is significantly interlayered with clayey sand deposits. There are significant variations in the clay consistency. In most areas of the site, there appears to be two distinct clay deposits present at the site, with the deeper deposits having higher shear strengths than to the shallower deposits. Therefore, the unit has been divided into two sublayers – Units 3a and 3b. In some areas, only the stiff Unit 3a or very stiff 3b clays were encountered in the subsurface explorations, and that is shown on the cross-sections. In the southeastern region of the site, the consistency of the clay appears to be relatively low compared to the rest of the site. In that region, the layer appears to have similar overconsolidation ratios as the clays within Units 1a, 1b and 2.

x Units 4 through 6 – Unit 3 is underlain by alternating layers of dense to very dense sand and very stiff to very hard clays. These alternating layers are identified as Units 4 through 6. Unit 6 is typically present at deeper depths and consists of alternating layers of hard clays and very dense sands. Most of the explorations were extended to completion Elevations of -30 to -40 m. The soil profiles at deeper depths are based on the soils encountered in the three deep borings (BH01 through BH03). Those deeper layers are shown on Plate 11, Cross-Section E-E’.

6.3 IDEALIZED SOIL PROFILES

In order to capture the variability of the subsurface conditions within the project area, four idealized soil profiles were developed for site response analyses:

x Profile 1 – indicative of subsurface conditions across most of the project site, and represents typical thicknesses of various strata, excluding areas close to Santra Creek where thicker deposits of softer / looser Units 1a and 1b are present.;

Earthquake Analysis

FUGRO WEST, INC.

FINAL REPORT

EARTHQUAKE ENGINEERING ANALYSES

PARADIP REFINERY PROJECT

ORISSA, INDIA

Prepared for:

INDIAN OIL CORPORATION LIMITED

SEPTEMBER 2008

Paradip Refinery Project

Orissa, India

MAGNITUDE PROBABILITY DENSITY FUNCTIONS

FIGURE 3-3a

Paradip Refinery Project

Orissa, India

ANNUAL RECURRENCE PREDICTED BY DIFFERENT MAGNITUDE PDF MODELS

FIGURE 3-3b

Paradip Refinery Project

Orissa, India

GUTENBERG-RICHTER FIT TO HISTORICAL SEISMICITY DATA

STABLE CONTINENTAL ZONES

FIGURE 3-4a

Paradip Refinery Project

Orissa, India

GUTENBERG-RICHTER FIT TO HISTORICAL SEISMICITY DATA

EXTENDED CRUST ZONES

FIGURE 3-4b

Paradip Refinery Project

Orissa, India

GUTENBERG-RICHTER FIT TO HISTORICAL SEISMICITY DATA

ACTIVE PLATE MARGIN ZONES

FIGURE 3-4c

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Paradip Refinery Project

Orissa, India

"HARD SOIL" HORIZONTAL SPECTRA FOR VARIOUS RETURN PERIODS

FIGURE 4-1

Paradip Refinery Project