GLOBAL TRENDS IN EARTHQUAKE PREDICTION RESEARCH
INTRODUCTION
The objective of this note is to create awareness and to reawaken the scientific interest in precursor studies in Earthquake Prediction Research [EPR] and to impress on the policy and decision-makers to create a conducive atmosphere to achieve this objective.
Currently elaborate post-seismic event analysis exercise is being done rather than pre-seismic analysis in our country. So, far we are unable to give an early warning about imminent Earthquakes [EQs]. But scientists, especially in China [Li et al. 20031, Western World [Oei, 2004; van Genderen 20041, Russia and Japan, have taken up serious1 y the much-needed EPR and now this technology is fast deveIoping. This research endeavour encompasses rnultidiscipIinary integrated strategy [methods or a combination of methods] to predict the location of the epicenter of an imminent strong earthquake. The progress in this direction is satisfactory, yet much needs to be learnt and done.
Earthquake prediction, hitherto considered an impossibility due to the complexities involved, is now gaining its strength slowIy in the right direction due to the availability of emerging new technologies. In EPR, we need both ground and space-borne round the clock operational automated surveillance and warning systems to monitor the EQs precursors.
Earth's crust is in .a dynamic state with slowly moving [floating] sections of mobile continental and oceanic tectonic plates, resulting in Continental Drift. The motion is incredibly slow, at about the same speed as our fingernail grow with subduction and obduction zones, ocean fl oor-spreading etc. These plate movements cause earthquakes. Thus, earthquake-prone and volcanic zones are known. New seismic zones are emerging. EQs generate Primary [P or body or compressional] and Secondary [S or surface transverse] waves with velocit~es 6 and 3.5 krn/hr respectively. S-waves only cause the damage. EQs with Magnitude > 6 on Richter scale could be hazardous. The EQ distance is calculated for a given station based on time lag in the arrivals of P and S waves reaching that station. The epicenter is determined by drawing circles using the arrived EQ distance as radius for a given three stations and the intersection of these three circles [tri-junction] is the epicenter. From the seismogram of P and S waves the Time and Magnitude are determined.
PRINCIPLE MXTHODS IN EPR
Astronomical
Triggering of large EQs by Tidal Generation Force Resonance [TGFR] in a given strange astronomical constellation of Moon, a Celestial body and Earth in straight line. Turning points of the moon's relative motion to the earth, areas of compression and decompression wiII be developed by TGFR, which can be computed much in advance, as the stellar constellation [planets and stars] are known and could be precursors for imminent EQs. With TGFR technique one can predict EQs from 15 days to two months. Ancient Indian scholarly computation is practiced in China and their intermediate range of prediction [in conjunction], had a 40% success ratio.
Geomagnetic Field Change
The geomagnetic field starts changing 6 to 8 months and perceptible even just 10 to 20 hours before an
EQ.
The audio, video and EM spectral disturbances in TV reception, wireless communications and shift in radio frequency could be felt. The long-term changes also can be seen on telecommunications. eg: before Latur and Andarnans EQs, phone complaints increased, few months before. So telephone exchange data of Iand and mobile lines is useful.In Turkey, Japan and China, mobile phones malfunctioned 50 to 100 minutes prior to an EQ [no electrical, electronic or mechanical failures in telephone exchanges were reported].
Triangular Network GPS Stations
With the help of Geodesy and Geodetic Engineering, one can predict the precursors 3 to 6 months before. The 3D positioning and Navigational Satellite System [24 in 6 orbital planes, with 4 per plane or 30 Satellites at an altitude of 24,000 km] can' cover the entire earth's surface. Simultaneous and continuous geodetic measurements and 3D analysis of large areas is possible. Earihquakeprediction usiizg
GPS
is a significant contributio,~ [Shunji Murai &Harunzi A mki, 20031, wherein, they had developed a teclziaique by which, the area change ratio is converted to annual change ratio [pprn]. If no crustal movements are involved then there could be an increase of 3 pprn. [in XY,
XZ
or YZ plane]. An early warnlng could be given in three stages:J stage 4-9 ppm I1 stage 10 pprn
111 stage >10 pprn and plus slgn [tension] suddenly changes to zero or mlnus [compression] or vrce versa, ind~cat~ng an EQ could take place in a few months
Differential SAR Interferrometry
With the help of Synthetic Aperture Radar Satelltte [SARI, 3D earth's surface extraction [length, w~dth and helght] by uslng the phase content of the complex radar s~gnals [dlg~tal Image] are posslble to predrct precursors befote 1 to 2 months Differential SAR ~nterferrometry [InSAR- topographic rnapplng of alr or space borne] facll~tates measurement of small elevation changes caused by the buckling of the earth's surface prlor to EQ The princ~ple concept envisages constructing of Interferrogram ~mages of slave and complex conjugate of master to accompl~sh thrs endeavor Amplitudes of the correspond~ng pixels have to be averaged and correspond~ng phases have to be d~fferenced at each Image polnt The elevation IS calculated at each polnt-using phase unwrapping [branch c u t t ~ n g , fringe detection, and cellurar-automata and knowledge lnjectlonj After several correct~ons the InSAR lmage qual~ty IS deflned by 'Degree of Coherence'
Dlfferentlal Interferometry [DTnSAR] provldes relatlve measurement, few cm or even less of movements tn vert~cal dlrectlon Small changes In vert~cal dlrnenslon are vltal, as these reflect buckllng of the earth's surface as a result of crustal stress precursor of EQs DInSAR ~rnage data generation IS ach~eved In two passes, wlth 2 Images and D~gltaI Elevation Model and In three passes w ~ t h 3 Images and 2 ~nterferograms [topographic p a r and deformatton pair having topography and deformation rnformatlon]
D~fferential radar Interferometry 1s a “double-differenced interferogram, a derlvat~ve of 2 correspond~ng Inter- ferograms For mon~tor~ng [pre, co & post sersmic] To cover entrre earth's surface, 4 satell~tes or more are needed NASA's 7 days repeat, L- band, InSAR of 4 satellites, w~th
10-meter resolution are okay Opt~mal repeat ttme would be 1 to 3 days Long-term measurements llke lnterselsmlc strat n accurnulatron [< 1 mmlyr resolut~on] and detarled maps of cosetsmlc deformation [fault ruptures, measurement of translent deforrnatlon llke postselsrnic relaxation and stress transfer, aselsmic creep and slow earthquakes are also possible]
Thermal InfraRed
The author hav~ng been saddened like all others, by the Kutch [Gujarat] 2001 EQ, had outllned a conceptual note / on "Forecast~ng Earthquakes and Volcanic Actrv~ty"
(Ramanamurthy, 20011, whereln, it was contemplated that the precursors could be In the form surface manifestation of a reg~onal thermal upwarp of the electromagnetic spectrum of the thermal regime, which IS detectable and mappable by satellite and computer ass~sted systems with perlod~c mon~tor~ng
Thrs realtty 1s reallzed In the R&D of EPR The concept is based on Thermal lR [Ground temperature increase prlor to EQ] The modern operationa1 space borne-sensors In the
thermal Infrared spectrum, employed In remote sens~ng and
meteorolog~cal satell~tes In m o n ~ tor~ng the earth's surface w~th hlgh spatla1 13 meters to 5 km] and high temporal resolut~ons, w~th MSS, twice a day to once p/hr are of great advantage In thls pursuit T h ~ s technology I S useful in predtcttng EQs before 1 day to 2 months in advance The themnodynamic and tens~on models, thermal measurements of soil rno~sture and gas content or composltlon, hydrodynamrcs and d~scharged water temperature change etc , are the key ~nputs The thermal spectral resolut~on of 0 12"
-
0 5' C degree IS hlgh enough for EQ precursordetectron A huge isolated temperature ~ncreaslng area appears far from epicenter before EQ [2" - 6°C degrees w~th respect to per] pherals] Magn~ tude IS a funct~on of anomalous area slze Increase of brightness values Temperature and Temperature Increas~ng Area [IBvT&TIA] are a direct funct~on of the magnitude Tlme 1s calculated based on BvT at peak anomaly [several to 60 days]
The IBvT&TIA ~ncrease over
P
0 1 to 0 3 m11lion sq km is ~ndicat~ve of EQ of Ms > 5P 0 4 to 0 7 milllon sq km is ~ndtcat~ve of EQ of M s > 6
P 0 7 rn~ll~on sq km 1s ~ndicattve of EQ Ms
>
7The concept of thermal clouds [hot gases released from fracture zones prror to quakes condense In atmosphere to form clouds] needs careful evaluat~on In terms of detectabillty and measurability
Abnormal Animal Behaviour
On a horizontal rod, a budger~gar [a k ~ n d of parrot] couple IS caged and the cage 1s connected with a sensor and a counter The normal jump frequency of budgerrgars is around 600 to 700 plday But before an tmmlnent EQ the jump frequency 1s more than 2000 p/day, This informat~on is only about an imminent EQ and 1s a good EQ precursor But no other ~nformatlon could be obtained on drrection, epicenter, magnitude and tlme Based on this method an EQ can be predicted before 7 to 13 days In Kangra EQ
[1905], where the magnitude was >8, a day before, all zoo animals were highly disturbed [a recorded fact].
Gravity Method
Tectonic plates when crushed against each other, subjected to compressional forces, suffer deformation or strain, before the rock fractures. In deformation zone, on earth's surface, read as displacement or relative movement of the earth's gravitational center, a precursor in advance of an imminent EQ in 5 to 6 days. Given, at least 3 measuring points of earth's gravity force, a triangulation procedure allows locating the epicenter.
Crustal Stress Measurehent
Crustal strain pulse signals are generated before an EQ.
Relative change of crustal stress reflects seismicity, hence crustal stress value is adopted instead of absolute value. The crustal stress is measured by a crustal stress transducer, the strain in 3 directions on a level underground.
Principal stress can be calculated [crustal stress = crustal strain
*
elastic modulus]. Its direction is towards epicenter. Prediction is possible by 1 to 3 days before an EQ.Infrasound Waves [ISW]
Imminent EQ precursors are having abnormal Infrasonic wave signals which are measurable in 1 to 9 days in advance [van Helvoist, 20041, ISW are ultra low frequency, longitudinal vibrations in the air, they propagate very long distances, without significant attenuation and distortion. Since, they are normal sound waves of 1ongitudinaI nature, there is no polariz?tion. Human audible frequency range is 20
Hz
to 20kHz.
The ISW frequency ranges from 0 to 20 Hz, hence, they are human inaudible. ISW wave length ranges from 17 meters to thousands of kilometers. In nature strong ISW are produced by meteors, volcanic eruptions [0.5-10 Hz], sonic booms [0.5 to 6 Hz], ocean waves. EQs ISW frequency range is from 5 to 12 Hz, but whereas, EQs precursor frequency range is < 1 Hz. Wind pressure variations and ISW are separable, in later case signals are coherent over several kilometers. Atmospheric components are relatively dynamic than solid earth's static nature. ISWs increases with wind velocity, but seismic velocity has little or no dependency. Seismicity ISWs are discernable. Un- natural ISWs produced by explosions, nuclear tests, rocket launchers, super sonic planes / space shuttles etc., are discriminatable, range being 0.5 to 6 Hz. ISWs released from fault fractures [rock destruction] prior to large EQs at epicenter, the range being 0.004 to 0.1 Hz. Infrasonic sound measured in a star topology with optimum array configuration using low frequency microphone or by highfrequency barometer sensors. A high value of 1.250 rnV
[lOPa sonic P] is a manifestation of an EQ's magnitude of Ms >7 to 7.5
Signal Processing [SP]
Digital Signal Processing [DSP] is a branch of Electrical Engineering. In EPR st signal is a function of time. Advent
of hybrid computer technology has made real time
DSP,
a reality. DSP manipulates information-bearing analog-signals in the digital domain. In doing so, it harnesses the power of modern computing to perform complex tasks at very low costs. The DSP, unlike classical computers, which use the serial von Neumann architecture, are specialized computers called Digital Signal Processors, employs Harvard architecture to process data faster. In earlier times, expensive hardware noise filters, amplifiers and suppressors were used to improve the quality of received signal. Today sophisticated mathematical algorithms are available to remove the unwanted artifacts, noise etc., [wisdom should prevail in design and operation] from the digital signal. Now DSP techniques are available on DSP chips, which are significantly enhancing the data throughput.The SP is meant for events and non-events detection by discrimination. ISWs produced for an imminent EQs as Precursors are in the range of 0.004 to 0.1 Hz and EQs themselves produce 5 to 12 Hz. Fisher Statistics is adopted in time and frequency domain for prediction.
Time Domain Detection
The data correlation is attempted with different and within the channels itself. A complex formula calculates the Fisher value [F] and F value > 4 is considered due to EQs precursor. Higher F denotes more coherent in different channels [high F ratio indicates greater chances of an event]. Time domain processing is speedier than frequency domain. In fast scan peak detection timefisher algorithm, the significant threshold of 5*SD criterion equals a confidence interval of 99.9999 %.
Frequency Domain Detection
from atmospheric models, where the speed of sound and orthogonal wind speed are functions of the height] etc., are used for source location accuracy. Pre-filtering is applied to enhance the signal to get better results [some characteristics are enhanced and others are attenuated]. Removal of noise from total frequency spectrum is achieved to get acceptable signal-to-noise ratio. The procedure involves that the original signal is transferred into frequency domain, filtering by selective window [sliding], spectrum of the signal multiplied with pre-filter and resulted signal is transformed back to the time domain. The real part of this signal is used as the filtered signal. This results in truncated frequency spectrum, in which only desired [real signal] frequencies are passed. In sIiding filter the signal is transformed to the frequency domain via FFT, by baseline wandering correction in time domain via a polynomial linear curve fit. This corrected signal is fitted again with 10' order polynomial, high and low cutoff frequencies determined from the top of the polynomial [threshold 50% of the top value], a band pass filter is created [rectangular window in frequency domain], then signal is filtered with this filter, resulted signal is transferred back to time domain by taking the real part of the inverse FFT, this result goes to timefisher algorithm. Sliding filter adopts total energy spectrum of the signal and removes noise without loosing real signal. One must exercise great care. The down sampling, reduces the data storage space, but reduces accuracy too. So, high F- ratio is an indicator of high event detection [good signal strength, signal-lo-nolse ratio and coherency].
Geoeiectric Pulses
A normal pulse is seen as a smoothly round curve, but before an EQ these curves depict abnormal picture, Amplitude of the abnormal signal determines the magnitude. ,Procedures are same as of ISW. With the help of geoelectric
pulses one can predict an EQ 1 to 9 days in advance.
Cost Benefit Pnalysis
Cost Benefit Analysis envisaged in this R&D endeavour is beneficial. India too can afford to participate and gain patent rights, when compared with high damages vs low EPR investment on R&D.
A four year collaborative robust globally predictive R&D +
and implementation endeavour between the International Institute for Geo-information Sciences and Earth Observation [itc] of the Netherlands and Chinese Institute of Earthquake Pred~ction Research, Beijing, University of Technology is estimated around Euro 273,000 [US $0.35 million or Rs 1.5 crore]. This cost could be further reduced in our country, because of low socio-economic costs.
US Global Earthquake Satellite System [GESS] is a 20 years SAR based project. With InSAR capable of providing repetitive coverage of 36 hours vs the present 35 days is estimated around $ 400-500 million. Five years of R&D and 15 years of mission operation is planned. India can purchase the data products, instead of taking up such expensive missions, to start with.
The other plan of GESS is a constellation of a Geosynchronous Satellite System. At present this is too expensive and not within the range. The total cost of first satellite is in the range of $ 1 - 2 billion [5 years R&D and 15 years of mission operation]. A 10-satellite constellation wills costs roughly $ 8 - 10 billion.
A worldwide Infrasound system is relatively cheap and could be around $ 0.1 million [Rs. 0.5 crore]. The most ideal, cheapest and economically viable system is to use the present system of sixty existing infrasound stations located around the world of the Comprehensive Nuclear Test Ban Treaty [CNTBT] for the purpose of predicting and locating imminent earthquakes. In this case, one would need to budget the incremental costs and annual operating costs, as the network is already established and in place.
Thus, it is clear by adding all the costs [R&D and implementation] of these methods and adding an extra ten + million dollars per year in establishing and running the global network to include all other precursor methods that were discussed as above, the annual costs are still less than a tenth of the annual losses [material] resulting from earthquakes. Of course, this excludes the invaluable human life loss, because no one can ever estimate the human value.
The Prospect
Today by utilizing the modern convergent technological +
developments, seismoIogists and seismic engineers are accomplishing the envisaged objectives by adopting a multidisciplinary comprehensive integrated strategy to predict the precursors of imminent EQs, with the help of space, air and ground systems.
Computerized image processing involving data enhancement and feature extraction techniques [geometrical, structural, spectral, stat~stical], integration of multiple data sets and composite digital image generation are novel attempts, but should be done with great care, clarity and wisdom. Image data fusion with two or more images, based
on [pixel, feature, decision], algorithm should be in line with scientific doctrine. The data integration and synthesis is a continuous process to refine and improve the visual image exploitation by human image interpreters. Decision levels on fusion techniques are knowledge [logical, syntactical, and contextual] and identlty [statistical inferences] based.
The R&D encompasses detarl study of EQs Geology, Physics and Eng~neerlng, so that EQs Predictive Technology wlll emerge by Global Team Effort, with an Integrated Global strategy Ind~a should participate In this endeavour with innovative contributions and to g a ~ n patents
The tnnovatlve efforts of the Chinese in, rnultlple methods and comprehensive studies in imminent EQs precursors predictlon IS worth emulating The~r seismologists
had pred~cted seven EQs from 1966 to 2003 and their predlctrons are notably accurate In terms of time, magnitude and place and the error range IS [znslgnzficnnr or very small] well within thew expectation They were honored w~th "success certificat~on of predictlon" for thelr excellent accuracy In prediction (LI et al, 2003)
Global Earthquake Satellite System [GESS] of NASA is a global example DEMElER [Detect~on of Electro- Magnetlc Ern~ssrons Transmitted from Earthquake Reg~ons],
IS a mrcrosatelllte launched by France on 29 June 2004 In
their serles The sclent~fic purpose of the misslon is to study the ionospheric disturbances related to seismic actlvlty, study the ionospheric drsturbances related to human activity, study the pre- and post-seism~c effects in the lonosphere, contribute to understand the mechanisms generating those dlstutbances, glve global information on the earth's electromagnetlc environment and Pre, Co & Post [seism~c] study, at the satellite altitude
Global and national seisrnlc pollcy, publlc educat~on on EQs and especially on precursors, selsmic proof & tsunamr safe planning and constructions, early warnrng communrcatrons networks, real time emergency services, d~saster rellef and management, selsmlc audlt, construction
codes and other related issues needs immediate attention of all concerned
The Pred~ction Precursor Techniques conslsts of a three-t~re system
1 Macro [large] range
Astronom~cal years before
+ Geornagnet~c f~eId change 6-8 months
+ GPS [Geodesy & Geodetlc
measurements] 3-6 months
2 Meso [medium] range Radar1 - 2 months
Thermal IR 1 day-2 months
Tidal Generation Forces
Resonance 15 days-2 months
1 Mrcro [small] range
Budgerigars Jump frequency 7- 13 days
+ Gravity 5-6 days
Infrasound 1-9 days
Geoelectr~cal pulse 2-9 days Crus tral strain 1-3 days Geomagnet~c field change 50- 100 mtnutes affects tele&w~reless comm to few hours and [TV, Ph land & cell] months
Early tsunam~ Warnlng Systems [EtsWS] are debatable in terms of "truth or fictron7" Hence, the relevance of EtsWS, becomes questionable? The debate can cont~nue Meanwhile, an ~ndigenous EtsWS of d e s ~ g n ~ n g and development can be undertaken as ~t scores over foreign systems In terms technocommerclal viab~lity, customlzation, updates etc , more so we can get technical competency and poss~bIe patent r~ghts
It IS worth rnention~ng here that studles tn respect of
Dlsease Precursor Detection In Medical sciences IS also In progress Abnormal ceIl growth precursor by Pos~tron Emlssron Tomography - Computer~zed Tomography [PET-
CT] is a realrty today Signal Process~ng Doctrrne principles are same in any sclentifrc pursu~t, In fact slgnal-processing technique is adopted in medical applications by automatic processing of the foetal MCG and cardlac diseases est~mate
It IS the authors percept~on that it is posslble in near future that a precursor sensor [I~ke a wristwatch] on human body can be placed to rnonltor on selected ~ntervals the v~tal organs functlon~ng and connected to a central~zed computerized database, w h ~ c h constantly and continuously compares with the healthy or accepted updated signature of the patlent, wh~ch can grve warn~ng s~gnals i n case of
departures T h ~ s techn~que may replace the exlsting periodical preventive medlcal checkups, In the hospitals The author feels that s~mrlar system can be env~saged to detect body cell level chem~cal actlvlty to detelmlne abnormal~ties, very much in advance
Following Steps are Suggested to Foster EPR-Studies
1 It 1s evrdent that the above research trends do amply ~ n d l c a t e the need for A c a d e m ~ c Inst~tutlons, Professional and Research Institutes In our country should rise to the occaslon and joln the globdl EPR research effort in a more purposeful and active fashion to contribute then due share
2 In order to accompl~sh the env~saged EPR endeavour, ~t is needless to state that we need a deeper lnsrght Into the problem and the tenaclty to pursue the goal As of now, many countr~es do not have the requ~slte know- how As, such, they must get exposed to thls field by way of traln~ng and undertake collaborative projects wlth centres where such know-how exlsts
3 The author ident~fies ITC, Netherlands as one such
centre. Interested researchers may contact: International I n s t ~ t u t e For Geo-information Science and Earth Observation [I tc], P.O.Box 6,7500 AA Enschede, The Netherlands. Tel: +3 1-53-4874254. fax: + 3 1-53- 4874466. http: www.itc.nl or Professor Dr.J.L.van Genderen, Department of Earth Observation Science, Email: genderen @i tc.nl,
4. E s t a b l ~ s h m e n t o f United N a t i o n s U n i v e r s ~ t y ' s associated institutions of EQs Prediction Research
Centers of Global Scientific Excellence in various countries are needed In this effort.
Student participat~on by way of Masters and Doctoral programs should b e a n ~ n t e g r a l part of the EPR
endeavour
UN, World Human Rights Commission and NGOis to contrrbute thelr bit in this endeavour.
5. A false alarm can cause panic, hence special care IS
needed.
6. It appears that the EPR is on sound foundat~on and it is in the rxght direction, wherein the cardinal aim is
narrowing down the event predictive process [time,
location, magnitude] by employrng the Prediction Precursor Techniques of a three-tire system [macro,
meso and micro] involving space and ground-borne systems and data processing and evaluation by successive progressive approximations. By knowledge integration one can brlng the envisaged endeavour nearer to the truth.
7. WhrIe taking advantage of the symptomatic approach In the applrcation of EPR research, the sc~entific r a t ~ o n a l e if a n y behlnd s o m e popular b e l ~ e f s / superstitrons etc should be parallely ~nvest~gated.
Acknowledgements: The prlmary source for preparation of this note has been the materlal suppl~ed by Professor Dr.J.L.van Genderen, ITC, the Netherlands, as rnent~oned under references, for whlch the author is immensely grateful. The Editor of the Journal is thanked for some helpful suggestions in improving the manuscript.
68-I-3/1, Netajz Street M.V. RAMANAMURTMY
Ashok Nagar Kakinada - 533 003
D E S ~ . East Gudavari Andhra Pradesh
Ernail: rmyjranav @sa~zcharnet, in
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