Abstract. We present a new method for inverting coseismic slip distribution based on arc measurements of InSAR inter- ferograms. The method only solves the integer ambiguities on the selected arcs so that the challenging task from global unwrapping of low coherence interferograms can be avoided. The simulated experiment results show that the new method recovered the given slip distribution well at different coher- ence quality levels. However, the conventional method with global interferogram unwrapping fails when the interfero- gram has some isolated areas. In addition, the new method is capable of using surface rupture offset data gathered in the field. We apply the proposed method to study the 2010 Yushu, China Ms 7.1 earthquake. Inclusion of field data can help to enhance the results of fault slip inversion. It derives a maximum slip of ∼ 3 m, larger than the published coseismic slip results on this event, but agreeing with the largest offset of 3.2 m from field investigation.
Coseismic slip distribution on the fault plane of the 1946 Nankai earthquake (M w 8.3) was estimated from inversion of tsunami waveforms. The following three improvements from the previous study (Satake, 1993) were made. (1) Larger number of smaller subfaults is used; (2) the subfaults fit better to the slab geometry; and (3) more detailed bathymetry data are used. The inversion result shows that the agreement between observed and synthetic waveforms is greatly improved from the previous study. In the western half of the source region off Shikoku, a large slip of about 6 m occurred near the down-dip end of the locked zone. The slip on the up-dip or shallow part was very small, indicating a weak seismic coupling in that region. In the eastern half of the source region off Kii peninsula, a large slip of about 3 m extended over the entire locked zone. Large slips on the splay faults in the upper plate estimated from geodetic data (Sagiya and Thatcher, 1999) were not required to explain the tsunami waveforms, suggesting that the large slips were aseismic. Two slip distributions on the down-dip end of the plate interface, one from geodetic data and the other from tsunami waveforms, agree well except for slip beneath Cape Muroto in Shikoku. This suggests that aseismic slip also occurred on the plate interface beneath Cape Muroto.
al., 1993). The GPS observation network of Tohoku University spatially interpolates the nationwide GPS net- work, GEONET, which is managed by the Geospatial In- formation Authority of Japan (GSI). We can improve the spatial resolution of the inversion analysis to estimate the coseismic slip distribution especially around the Miyagi- oki region by using GPS data observed at 383 sites of not only GSI (345 sites) but also Tohoku University (38 sites). Ohzono et al. (2011) estimated the site coordinates before and after the mainshock by using Bernese GPS Software version 5.0 (Dach et al., 2007), and calculated coseismic displacements by taking the differences between the daily site coordinates of before and after the mainshock, namely on March 10 and 11 (after 5:47 on GPS time). Refer to Ohzono et al. (2011) for further details of GPS observation and data processing.
A relationship between the coseismic slip of the main- shock and the static stress drop of similar aftershocks has been examined for the 2007 Noto Hanto earthquake, a large inland earthquake, in central Japan. We have ap- plied the empirical Green’s function method for P- and S-waves to estimate the static stress drop of similar af- tershocks. The static stress drops estimated for P-waves coincide with those for S-waves, and those from both waves show a typical value for a tectonic earthquake of 5 to 20 MPa. Similar aftershocks in the large coseismic slip area show a higher static stress drop than those in the
A large earthquake (M7.2) occurred along the plate boundary off Miyagi Prefecture (Miyagi-Oki), northeastern Japan, on August 16, 2005. In this area, large earthquakes (∼M7.5) have occurred repeatedly at intervals of about 37 years, and more than 27 years have passed since the last event occurred. To estimate the relationship between this earthquake and the previous events, we determined coseismic slip distribution by this 2005 Miyagi- Oki earthquake by adopting the seismic waveform inversion method of Yagi et al. (2004) and compared it with that of the previous 1978 Miyagi-Oki earthquake. We performed two cases of the inversions; inversion using only far-ﬁeld seismograms and that using far-ﬁeld seismograms and local seismograms simultaneously. Both results show that a large slip occurred near the hypocenter and rupture extended to the westward deeper portion. Considering that the rupture area of the 2005 event partly overlapped with the southeastern part of that of the 1978 event, suggests this result the possibility that plural asperities exist which cause the sequence of Miyagi-Oki earthquakes and that the 2005 event ruptured one of such asperities, although the previous 1978 event ruptured all the asperities at one time.
In January 2006, the Japanese Aerospace eXploration Agency (JAXA) successfully launched the ALOS satellite, which carried the L-band PALSAR for acquiring strip-mode SAR imagery on ascending tracks and wide-swath/scanning synthetic aperture radar (ScanSAR) imagery on descend- ing tracks. Compared with the C-band SAR, the PALSAR preserves high coherence in interferometry over regions of rugged topography with high rainfall and dense vegetation. Because the interferograms with different imaging geome- tries can provide more information about surface deforma- tion (Wright et al., 2004; Y. Liu et al., 2012), a more reliable coseismic slip model can be retrieved from interferometry data from both ascending and descending orbits. After the Yushu earthquake, we obtained four ALOS PALSAR images from the JAXA to determine the surface deformation, fault rupture geometry and slip distribution. Our images include two ascending images (Path 487A) and two descending im- ages (Path 139D) (Fig. 1, Table 1). It should be noted that the descending path 139D operated with the ScanSAR mode, which is composed of five sub-swaths and covers an area of ∼ 350-km wide. In this study, we only use sub-swath 2 and 3 to construct the ScanSAR interferograms.
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As revealed by Fig. 9(a), the surface coseismic horizontal displacements can be divided into three distinct patterns in three areas. Note that the map has been divided into four areas taking both co- and postseismic displacements pat- terns into account, as mentioned in Section 3.2. Namely, the area extending south of the epicenter and that far to the SE showed similar coseismic displacements although they il- lustrated distinct postseismic behaviors. Firstly, close to the epicentral area (middle part of the map shown in Fig. 9(a)), the horizontal displacements show a S-SSW movement of 10–45 mm. The vectors are located in the Central Range (i.e., on the hanging wall of the Y fault) and show a larger amount of displacement relative to those in the valley (the footwall of the fault), indicating a left-lateral strike slip along the Y fault, which is consistent with the focal mech- anism of the main shock. Secondly, the region south of the epicenter shows a westward motion of 30–40 mm in the footwall of the Y fault and a SSW movement of 40– 45 mm in the hanging wall. This implies a signiﬁcant hor- izontal shortening in addition to the left-lateral slip across the causative Y fault of the earthquake in its southern por- tion. Taking the coseismic horizontal displacements in the above two regions into account, it would appear that the Y fault exhibits two distinct coseismic slip-rupturing between the northern and southern portions. This also raises the pos- sibility that an E-W- or WNW-ESE-trending right-lateral faulting, located across the middle-north of the Peinanshan massif (Fig. 9(a)) occurred during the main shock. The sur- face projection of this potential E-W fault would separate the SSW vectors to the north and the WNW vectors to the south. Finally, in the region to the NE of the epicenter, the displacements are less than 15 mm in the direction between NW and NE. We interpret these small amounts of displace- ments as indicating a region that is located far from the ef- fect of the causative Y faulting and/or the possible E-W- trending fault.
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interpretation is limited by the similarity of surface displacement patterns produced by diﬀerent models. Lyzenga et al. (2000) showed that the surface displacement due to anelastic deformation of overlying sedi- ments can be well ﬁt by a model of slip on a discontinuity close to the top half of the coseismic slip plane. Although the plane is predicted to be slightly above and steeper than the coseismic plane, these diﬀerences are too small and our ability to isolate the shallow part of the signal is insuﬃcient for us to conﬁdently attribute the signal to one cause or the other. Similarly, we were not able to distinguish between a planar fault geom- etry and a fault that ﬂattens to a dip of 1 ∘ below 12 or 12.7 km depth at the base of the coseismic slip patch. They ﬁt the data equally well, and although the nonplanar slip models are more disjointed than the planar model, they are more consistent with the thrust system interpreted from the seismic reﬂection proﬁle dis- cussed in section 4, which shows the fault shallowing into a ﬂat at a depth of around 12 km (depending on the seismic velocity assumptions). The 12 geometries tested all showed afterslip at at least two distinct depths, as in Figure 10.
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The Zagros is known for its pronounced seismic activity. In the following, the discussion of this activity is concentrated along the transect of the Central Zagros illustrated in the cross-section of Figure 10A. [88,101,102] cover the subject for the entire Zagros. The distribution of earthquake foci along the transect studied here reveals a seismogenic zone which includes the competent group of layers of sediments above the Hormuz Formation as well as the upper crust down to a depth of ~20 km . These authors conclude that shortening related to folding correlates with seismogenic faulting in the cover sediments, while the crystalline basement beneath has a lower seismicity and must therefore be considered as being more rigid or, alternatively, deform aseismically by ductile creep. Farther to the north, in the High Zagros and beneath the Sanandaj-Sirjan zone, the basement deforms by aseismic creep. Focal mechanisms indicate thrusting in the southwestern Zagros Fold belt and strike-slip faulting in the adjacent region to the northeast . Slip vectors determined from thrust faults are nearly parallel to the plate convergence direction (and thus orthogonal to the fold axes), whereas for strike-slip faults slip vectors are more oblique suggesting an extensional component parallel to the orogen .
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This analysis is purely focused on coseismic landslide haz- ard, and thus it does not take into account the distribution of vulnerability: that is, the locations of people and infrastruc- ture in these landscapes or how they might be differentially impacted by landslides. While one area may be more haz- ardous than another, the distribution of people and infrastruc- ture may be such that risk is not actually increased. Further, our analysis is probabilistic, defining hazard as the proba- bility of intersecting a landslide; thus, our rules identify lo- cations where the landslide probability is lower, not where probability is zero. This means that it is possible for an alter- nate location chosen based on its lower landslide probabil- ity to be impacted by a landslide, while the original higher- probability location is not. The choice of inventory will in- fluence the specific results and, although we adjust for bulk shaking intensity by normalising conditional probability by bulk probability, differences between inventories are likely to remain (e.g. in spatial patterns of shaking intensity and their relation to topography). Rock type is a critical influ- ence on landslide occurrence (Chen et al., 2012; Harp et al., 2016; Roback et al., 2018), but we have excluded it from our analysis because it is extremely difficult for an untrained observer to identify and to translate it into meaningful esti- mates of material strength and thus landslide probability. We also expect that the length scales over which lithology varies will often be long (on the order of kilometres) relative to the other factors examined here.
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The Remote Annex bases its routing table on the information you specify in the gateway section of the configuration file. As a passive gateway, the Remote Annex then updates the table according to information it receives from other routers but does not broadcast routing information itself. This means that a Remote Annex with a SLIP interface forwards packets addressed to the host at the remote end of the connection, but does not inform other hosts, routers, or Remote Annexes that it has this capability. Other hosts and routers on the same network must be told about the route before they can use it.
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During the past two decades, satellite gravity missions (CHAMP, GRACE and GOCE) increased the accuracy, spatial resolution, and temporal resolution of the Earth’s gravity potential models (Elsaka et al., 2014). In the future, we may have access to improved data if better scenarios are launched in different configurations. In order to obtain optimum scenarios, different studies have been published during the last decades and they are all included in (Elsaka et al., 2014). They have revealed a substantial increase in the accuracy and sensitivity. After the Sumatra-Andaman earthquake and the analysis of GRACE data, the application of GRACE data to detect coseismic effects was found to be feasible [e.g., Han et al., 2006 ; Chen et al., 2007; Han et al., 2010;Heki & Matsuo, 2010; Han et al., 2011; Kobayashi et al., 2011;Matsuo & Heki, 2011; Cambiotti & Sabadini, 2012; Wang et al., 2012a; Zhou et al., 2012; Han et al., 2013; Dai et al., 2014]. The modern geodetic techniques will enable us to have a better detection of the coseismic deformations such as displacement, gravity changes, etc. [e.g., Han et al., 2006; Chang & Chao, 2011; Hayes, 2011; Ito et al., 2011;Kobayashi et al., 2011; Sato et al., 2011; Shao et al., 2011; Suito et al., 2011; Sleep, 2012; Suzuki et al., 2012; Wang, 2012; Wang et al., 2012b; Li & Shen, 2015].
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A similar intragranular deformation mechanism is operat- ing in all of the tested metals, i.e. straightly aligned dislocation arrays without any tangled dislocations. Although several slip systems are observed in each specimen, it is important that only one slip system (planar slip) is activated inside of each grain. Other slip systems might not be activated in each grain because the h.c.p. structure possesses a low crystalline symmetry. Because few tangled dislocations give a low work-hardening exponent, creep deformation proceeds.
Our results from the Central Italy seismic sequence provide im- portant real-world constraint on this problem, simply because we can consider the sequence as a failed multi-segment earthquake. As the different fault segments in our case were necessarily all near-critically stressed at the beginning of the sequence, our study clearly demonstrates the importance of pre-existing structure in stopping small earthquakes from becoming larger ones. Since the static stresses involved in eventual triggering of the Norcia earth- quake are signiﬁcantly smaller than stresses at the crack tip during dynamic rupture, it is likely that the Laga–Vettore fault system would have ruptured in a single large earthquake if pre-existing structure had not arrested slip. However, it is also important to note that despite this clear structural control for most of the seis- mic sequence, the Norcia earthquake appears to have ruptured through a barrier that halted the Amatrice earthquake. Our study therefore highlights that structural barriers appear to play a vital but enigmatic role in determining whether a large earthquake or a seismic sequence occurs on a segmented, critically stressed fault system.
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An analysis has been carried out to study the heat trans- fer characteristics of a water-based nanofluid over a stretching/shrinking sheet with second-order slip flow model. The basic boundary-layer non-linear partial dif- ferential equations have been converted into a set of non-linear ordinary differential equations by using scal- ing transformations. An exact solution to the momen- tum equation is obtained and the solution of energy equation is obtained in terms of a hypergeometric func- tion for different water-based nanofluids containing Au, Ag, Cu, Al, Al 2 O 3 and TiO 2 nanoparticles, and the ana-
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We have processed GNSS time series data to extract total electron content (TEC) perturbations in the ionosphere due to the Kaikoura earthquake. We used ray-based modeling to infer which part of the Earth’s surface coupled significant energy from the solid Earth into the atmosphere. We compared modeled TEC data to the observed time series data and determine that significant coupling occurred northeast of the initial slip. This work corroborates existing analysis made with geodetic and InSAR data. The TEC data suggested that the initial rupture coupled little energy into the atmosphere and only after significant surface displacements (∼60 s after the initiation) caused ionospheric perturbations. Using an array of GNSS stations, we were able to track the moveout of the acoustic wave through the ionosphere. We used a method commonly used in seismological studies called backprojection to estimate the exact location of the source of the TEC perturbation. This is the first time that this method has been applied to TEC data and the results are quite promising. The backprojection results are slightly shifted in space from the known area of maximum uplift, and we attribute this small discrepancy to the fact that we did not account for horizontal winds in the atmosphere in our travel-time modeling.
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The results prove that the proposed method can provide a better description of coseismic landslides spatial distribution. Based on the model, there are four distinctive CLSL: negli- gible, low, moderate, and medium zones. The negligible zone of CLSL are defined as the most stable and safe areas, which have value range between 0 and 6. These zones are usually located on flat—gentle slope areas (0–8%). Most of them are associated with an alluvial plain, colluvium- alluvium foot slopes and natural levees. The low zones of CLSL are associated with the border areas between moun- tainous and flat areas in the eastern research area. Most of them are located on sloping areas (8–15%) and very close to rivers. The moderate zones of CLSL are mainly located on the middle slope of the strong and weak eroded denudation hills of the Semilir Formation, which consists of interbedded tuff-breccia, pumice breccia, dacite tuff and andesite tuffs and tuffaceous claystone. The medium zones of CLSL is de- fined as the most unstable and susceptible to coseismic landslides in the study area. These zones are often associated with the upper slope of the Baturagung Escarpment, which are mainly located on the steep to very steep slopes (>30%). There is still a need improvement for further, which focus on the coseismic landslide data inventory and statistical ana- lysis of coseismic landslide in order to obtain the better re- sults of coseismic landslides hazard zonation.
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acceleration coefficients. In case 1, the factor-of-safety map indicates that the whole study area is in stable state without seismic loading and only very limited areas, i.e., the Tomisato sliding area and the eastern boundary of the study area, have high possibility for slope failure (Fig. 10a). Case 2 to case 8 illustrate that slope instability increases with the increase of horizontal pseudo- acceleration coefficients. A horizontal pseudo- acceleration coefficient of 0.5 (case 8) will result in that more than half of the whole study area is in unstable state. In order to quantitively evaluate to calculation re- sults, landslide points distributed in each stability classes were extracted and areas of slope stability classes were calculated for eight cases. Figure 11 displays the cumula- tive landslide point percentage of the slope stability clas- ses. For case 1, no landslide is distributed in the very unstable class and 99.8% of the coseismic landslides are Table 5 Classifications of slope stability and instability based on
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For coseismic displacements induced by the 2011 Tohoku earthquake, the RMS error of east component (4.0 mm) is high abnormally compared with that of north component (0.7 mm) due to DAEJ site (Table 3). DAEJ site is located about 1300 km west of the epicenter and perpendicular to the subducting slab so that the coseismic and postseismic slip is heavily influenced from the event. Fig. 3 (east component of DAEJ) shows that the coseismic offset is overestimated due to effect of postseismic slip that more clearly appeared after about two weeks at this site. If the RMS error is calculated without DAEJ, its horizontal component will be only 1.0 mm. It is no significant difference between the predicted and observed coseismic displacements. Thus, the results imply that both numerical rupture models of earthquakes adequately explain the far-field coseismic displacements in Vietnam.
the surface of the cylinder. This shows the consequences of the geometry-dependence of slip: there is up to a 2.1% difference in the calculation of slip at the wall between simula- tions using general Maxwell slip (1) and con- ventional slip (2). This accumulating error be- tween the different velocity slip solutions is likely to have consequences in predictions of the trailing edge flow, or in the simulation of any aerodynamic surfaces beyond the right hand boundary of Figure 2.