finite faults and inverse theory with applications to the 1979 imperial valley earthquake abstract using a representation theorem from elastodynamics subsurface slip on a known fault is formulated as the solution to an inverse problem in which recorded surface ground motion is the data two methods of solution are presented the least squares method which minimizes the squared differences between theory and data and the constrained least squares method which simultaneously maintains a set of linear inequalities instabilities in the solution are effectively eliminated in both methods and the sensitivity of the solution to small changes in the data is quantitatively stated the inversion methodology is applied to 77 components of near field ground acceleration recorded during the 15 october 1979 imperial valley earthquake the faulting is constrained to propagate bilaterally away from the epicenter at an average velocity of 90 per cent of the shear wave speed on a vertical fault plane extending from the surface to 10 km depth inequality constraints are used to keep the faulting sequence physically reasonable by maintaining right lateral motion and positive slip velocity the preferred solution is stable and provides a good fit to the data it is also realistic and consistent with observed surface offsets and independent estimates of seismic moment

slip history of the 16 october 1999 mw 7 1 hector mine earthquake california from the inversion of insar gps and teleseismic data the slip distribution of the 16 october 1999 m w 7 1 hector mine earthquake california is investigated in space and time by jointly inverting geodetic data and broadband teleseismic data constrained by reported surface offsets the geodetic data consist of a dense network of global positioning system gps data and synthetic aperture radar sar interferograms from both ascending and descending satellite tracks considering the complexity of the earthquake rupture our fault model has four partially overlapping segments discretized into 3 3 km2 patches the seismic source parameters on each subfault are estimated using a nonlinear inversion scheme based on a simulated annealing method to explore the parameter space we allow a variable rupture velocity and slip to vary in amplitude direction and duration we first explore the space and time resolution of each data set and their combination with data synthetized from known slip distributions we estimate the slip distribution from the different data sets inverted separately and finally perform a joint inversion of the combined data sets the teleseismic data inversion exhibits a rather bad spatial resolution compared with the resolution power of the other data the geodetic data nearly completely map the coseismic deformation field of the hector mine earthquake and strongly constrain the spatial distribution of the final slip and the fault geometry the spatial resolution is expected to be best for the depth range of 0 to 10 km over the entire fault model the joint inversion of both geodetic and seismic data provides a robust estimate of slip history that simultaneously fits the independent data sets in space and time the hector mine earthquake is a right lateral strike slip event that presents a heterogeneous distribution of slip at shallow depth 12 km most of the seismic moment is released in the vicinity of the hypocenter over two overlapping segments the total seismic moment is 5 8 1019 n m our joint inversion with a peak displacement amplitude of about 6 m the velocity rupture is comprised between 2 and 2 5 km sec for a total duration of about 15 sec over an extent of about 50 km

mineralization of breccia pipes in northern arizona the paleozoic sedimentary rocks on the colorado plateau of northern arizona are host to hundreds ofbreccia pipes the uranium and copper deposits in these breccia pipes transgress formation boundaries from the mississippian redwall limestone to the triassic chinle formation they are not classic breccia pipes in that there is no volcanic rock associated with them in time or space they are the result of solution collapse within the redwall limestone and stoping of the overlying strata the karst development in the redwall limestone began in the mississippian and apparently either continued to the triassic or was at least once again active during that time the mineralization apparently occurred shortly thereafter sometime during the mesozoic mining activity in breccia pipes of the grand canyon region began during the nineteenth century and continues today with the operation of the hack i ii and iii mines although the exploited commodity has changed from cu to u although small in size these pipes contain samples with up to 55 percent u 3 o 8 and can yield ore averaging between 0 30 and 0 60 percent u 3 o 8 mineralization at the surface commonly occurs within nodules and concretions associated with pyrite and goethite and along fractures while the primary ore of the unoxidized zones is commonly within a comminuted sandstone matrix surrounding breccia fragments of overlying formations the ore mineral is uraninite although associated with it are sphalerite galena chalcopyrite tennantite millerite siegenite and molybdenite some of the surface nodules are encrusted with malachite and are exceptionally enriched in ag pyrite is abundant and the organic carbon content of some rocks is high enough to suggest that it along with the pyrite may be a reductant for uranium in contrast it is possible if uranium were transported as a bicarbonate or carbonate complex that only a conduit of brecciated rock was necessary to release co 2 thus disrupting the equilibrium and allowing uraninite to precipitate an extensive suite of elements is significantly enriched in the mineralized rock ag as ba cd co cr cs cu hg mo ni pb sb se sr u v zn and the rare earth elements of these cu pb zn ag and particularly as appear to be the best geochemical indicators of mineralized pipes at present the origin of the mineralizing fluids is not known the lack of extensive silification within the breccia along with the 80 degrees to 173 degrees c fluid inclusion filling temperatures on sphalerite dolomite quartz and calcite suggests relatively low temperature mineralizing fluids although heated in excess of what would be expected from the normal geothermal gradient on the colorado plateau with the exception of the u mineralized rock the mineral assemblage and geochemistry is similar to mississippi valley type deposits

digital image processing of airborne geophysical data for uranium mineralized breccia pipes exploration in northwestern arizona digital image processing and integration of data sets have been used to develop exploration models from airborne electromagnetics em magnetics and very low frequency electromagnetics vlf em data collected over an area in northwestern arizona the area has potential for the occurrence of uranium mineralized breccia pipes apparent resistivity and overburden thickness were derived from the em measurements using half space models digital image processing techniques applied to the geophysical data sets included 1 conversion of the data into gridded scale images 2 spatial filtering for noise removal 3 integration and analysis of the data sets and 4 modeling using various parameter combinations the general relationships between the geophysical variables parameters and their ability to detect metallic deposits were used as guides in selecting digital number ranges that were used as input into various models one of the best models incorporated apparent resistivity and total field magnetics t

evolution of a giant debris flow in the transitional mountainous region between the tibetan plateau and the qinling mountain range western china constraints from broadband seismic records abstract the catastrophic sanyanyu and luojiayu debris flows which were induced by heavy rainfall occurred at approximately midnight august 7th 2010 beijing time utc 8 and claimed 1 765 lives most seismic stations located within 150 km did not detect the debris flows except for the closest seismic station zhq indicating that the seismic signals generated by the debris flows decayed rapidly we analyzed broadband seismic signals from the zhq seismic station beginning approximately 20 min before the outbreak of the sanyanyu debris flow to rebuild its evolution processes seismic signals can detect development of the sanyanyu debris flow approximately 20 min after a heavy rain started falling in its initiation area this time was characterized by a gradual increase in seismic amplitude accompanied by a series of spike signals that were probably generated by rock collapses within the catchment the frequency contents and the characteristics of seismic signals before and after 23 33 15 t1 are distinctively different which we interpret as being generated by a large quantity of flowing material entering the main channel marking the formation of the sanyanyu debris flow we attribute seismic amplitude increases between 23 33 15 t1 and 23 34 26 t2 and between 23 35 40 t3 and 23 36 49 t4 to entrainment of the deposit material after initiation of the debris flow and to its flow through a colluvial deposit area respectively the main frequency band broadening of seismic signals after 23 37 30 t5 is believed to have been induced by impacts between the flowing material and check dams

earthquake induced chains of geologic hazards patterns mechanisms and impacts large earthquakes initiate chains of surface processes that last much longer than the brief moments of strong shaking most moderate and large magnitude earthquakes trigger landslides ranging from small failures in the soil cover to massive devastating rock avalanches some landslides dam rivers and impound lakes which can collapse days to centuries later and flood mountain valleys for hundreds of kilometers downstream landslide deposits on slopes can remobilize during heavy rainfall and evolve into debris flows cracks and fractures can form and widen on mountain crests and flanks promoting increased frequency of landslides that lasts for decades more gradual impacts involve the flushing of excess debris downstream by rivers which can generate bank erosion and floodplain accretion as well as channel avulsions that affect flooding frequency settlements ecosystems and infrastructure ultimately earthquake sequences and their geomorphic consequences alter mountain landscapes over both human and geologic time scales two recent events have attracted intense research into earthquake induced landslides and their consequences the magnitude m 7 6 chi chi taiwan earthquake of 1999 and the m 7 9 wenchuan china earthquake of 2008 using data and insights from these and several other earthquakes we analyze how such events initiate processes that change mountain landscapes highlight research gaps and suggest pathways toward a more complete understanding of the seismic effects on the earth s surface

image processing of aeromagnetic data and integration with landsat images for improved structural interpretation digital image processing of aeromagnetic data from three mineral prospects significantly improved the existing structural interpretations that were made from contour maps of the aeromagnetic data useful image processing techniques include 1 presentation as small scale gray level images 2 local contrast enhancement 3 artificial illumination and 4 directional filtering digital processing also enables direct comparison between landsat data and aeromagnetic data interpretations were improved by the study of the integrated data sets images of aeromagnetic data from one prospect in a precambrian granite greenstone terrane show major folds and faults that were not previously recognized from contour maps of the aeromagnetic data a landsat multispectral scanner mss image shows the subtle surface expression of two folds the newly identified structures point to additional prospective ground in the search for volcanogenic massive sulfide deposits in the area aeromagnetic data from a second prospe

present day crustal motion within the tibetan plateau inferred from gps measurements 1 using the measurements of 726 gps stations around the tibetan plateau we determine the rigid rotation of the entire plateau in a eurasia fixed reference frame which can be best described by an euler vector of 24 38 0 42 n 102 37 0 42 e 0 7096 0 0206 ma the rigid rotational component accommodates at least 50 of the northeastward thrust from india and dominates the eastward extrusion of the northern plateau after removing the rigid rotation to highlight the interior deformation within the plateau we find that the most remarkable interior deformation of the plateau is a glacier like flow zone which starts at somewhere between the middle and western plateau goes clockwise around the eastern himalayan syntaxis ehs and ends at the southeast corner of the plateau with a fan like front the deformation feature of the southern plateau especially the emergence of the flow zone could be attributed to an eastward escape of highly plastic upper crustal material driven by a lower crust viscous channel flow generated by lateral compression and gravitational buoyancy at the later developmental stage of the plateau the first order feature of crustal deformation of the northeastern plateau can be well explained by a three dimensional elastic half space dislocation model with rates of dislocation segments comparable to the ones from geological observations in the eastern plateau although gps data show no significant convergence between the eastern margin of the plateau and the sichuan basin a small but significant compressional strain rate component of 10 5 2 8 nstrain yr exists in a relatively narrow region around the eastern margin in addition a large part of the eastern plateau northeast of the ehs is not undergoing shortening along the northeastward convergence direction of the ehs but is stretching

the seismic signatures of the surge wave from the 2009 xiaolin landslide dam breach in taiwan the catastrophic xiaolin landslide occurred on 9 august 2009 after typhoon morakot struck taiwan this landslide formed a dam that subsequently breached burying and flooding the village of xiaolin seismic signals were induced by the landslide and dam breaching and recorded at the jiaxian broadband seismic station in taiwan the time frequency spectra for the data from this station were analysed to extract the seismic characteristics of the landslide and to deduce the timing of processes associated with the landslide dam break flooding the duration of the river blockage the time of the dam breach the duration of the surge wave and the mean speed of the surge wave were estimated and the hydrological implications of the flood behaviour were interpreted the spectral characteristics of the different stream discharges were also studied stream water level discharge is closely related to the frequency of the seismic signals the broadband stations are particularly useful for flood monitoring due to their ability to continuously record measurements and their high sensitivity copyright 2011 john wiley sons ltd

rupture history of the 2010 ms 7 1 yushu earthquake by joint inversion of teleseismic data and insar measurements abstract we applied a joint inversion of teleseismic data and insar measurements aiming at obtaining a robust rupture process and slip distribution of the 2010 yushu earthquake through reducing the trade off between slip timing and location with the condition of the final static deformation of insar measurements the rupture history can be achieved with more confidence surface offset constraint is also applied to our inversion through synthetic data inversion we find that insar data can resolve better fault slip at near surface depth range of 0 15 km than teleseismic data yet it has much poorer resolution at near hypocenter area where teleseismic data has a relatively better resolution our final joint inversion results show that the 2010 yushu earthquake has an essential rupture time around 20 s during which 90 of the seismic moment has been released two peak energy releasing moments occur at 8 and 12 s after the earthquake initiation respectively the fault slip breaks the surface at most segments of the total 76 km fault model and the maximum slip reaches 2 2 m we also find two peak slip asperities one at near hypocentral area mainly distributed at depth around 10 15 km the other distributed in a large area at the eastern segments at near surface our most robust estimation of the seismic moment reaches 2 30 1019 n m equivalent to a moment magnitude of mw 6 9

the 14 november 2001 kokoxili tibet earthquake high frequency seismic radiation originating from the transitions between sub rayleigh and supershear rupture velocity regimes seismic array based analysis of the major kokoxili earthquake tibet 14 november 2001 yields an unambiguous reconstruction of the seismic rupture history and relates it to the generated seismic radiation we demonstrate that after a classical sub rayleigh velocity stage the rupture speed has jumped to supershear values close to compressional wave velocity over a 175 km long fault segment before abruptly slowing down in the late part of the earthquake the transition locations between these three phases are correlated with the fault geometry and are associated with the most energetic radiation this observation proves that the rupture velocity changes as theoretically predicted are a primary source of high frequency seismic radiation this result requires reconsidering the origins of seismic damage generally attributed to slip variations

fault source modeling of the 2008 wenchuan earthquake based on alos palsar data abstract we use crustal deformation data sets derived from satellite based synthetic aperture radar sar to develop a fault source model of the 2008 m w 7 9 wenchuan earthquake china that occurred at the longmen shan fault zone the data sets include interferometric sar insar range offset and azimuth offset data acquired at seven ascending paths the range and azimuth offset data are particularly important exhibiting a single major rupture to the northeast ne and multiple ruptures to the southwest sw our preferred model consists of six segments four follow the previously mapped traces of the beichuan fault bf and its ne extension one corresponds to the pengguan fault pf to the sw and the other is included to represent a conjugate fault to the sw fixing the location and geometry of those segments we solve the variable slip distribution whose patch size increases toward the greater depth we use a nonnegative least squares method with a smoothing constraint on the distributed slip the geodetically estimated moment is 1 05 10 21 n m m w 7 9 which is close to the seismological estimate and suggests that there are insignificant postseismic signals in the data maximum slip of 10 m consisting of both thrust and right lateral slip components is identified at the shallowest patches to the ne along the bf the multiple fault segments to the sw show that the thrust slip component initially dominates and the strike slip becomes significant toward the ne examining the sensitivity of the predicted azimuth offset data to the assumed dip angle we found that the dip angle changed significantly from 35 45 at the sw fault segment for the pf to 80 90 at the ne extension of the bf

detection of landslides and submarine slumps using broadband seismic networks 1 we detected 52 seismic events associated with landslides and submarine slumps on 8 august 2009 when typhoon morakot hit taiwan these events were neither felt nor reported because their seismic energy was primarily in the long period band 20 50 s most of these events were located in mountain areas where the accumulated rainfall was extremely high though some were found offshore southern taiwan among all events the fatal landslide earthquake was located at hsiaolin village where 474 people were buried inversion modelling of the seismic waveforms generated by the hsiaolin landslide shows that the seismic source was represented by single force consistent with downhill sliding some offshore seismic events indicate that submarine slumps probably occurred along submarine canyons and steep slopes our study shows that broadband seismic monitoring can be used to issue early warnings for mitigating disasters generated by inland and offshore landslides

fault slip in the 1997 manyi tibet earthquake from linear elastic modelling of insar displacements summary the mw 7 6 1997 manyi earthquake occurred in an area of central northern tibet where sparse vegetation coverage and a lack of human habitation provide excellent conditions for interferometric synthetic aperture radar insar studies we use coseismic pairs of radar images acquired by the esa ers 2 satellite to construct interferograms of the surface displacement field due to the earthquake the location and extent of the coseismic fault rupture are mapped using a combination of optical satellite imagery high resolution digital topography interferometric correlation and azimuth offset measurements in so doing we are able to relate prominent geomorphic features in the fault zone to bends in the fault using elastic dislocation models consistent with this mapped fault trace we then test a range of fault geometries and slip conditions to find the combination which best explains the insar displacements our favoured model contains a reversal in fault dip approximately halfway along its length occurring at the location of a restraining bend slip on this model fault is heterogeneous with two areas of peak slip of 7 m or greater and components of dip slip displacement which vary significantly along strike the success of this model in fitting the data implies that an observed asymmetry in the coseismic interferograms can be explained in terms of the local fault geometry rather than by using non linear elastic rheologies as suggested by earlier authors

catastrophic landslide induced by typhoon morakot shiaolin taiwan abstract typhoon morakot induced the catastrophic and deadly shiaolin landslide in southern taiwan on 9 august 2009 resulting in more than 400 casualties we undertook a geological and geomorphological investigation with the aim of reconstructing the events leading up to this landslide and to clarify factors that contributed to its development cumulative rainfall reached up to 1676 5 mm in about three days under the influence of the typhoon and the shiaolin landslide with a volume of 25 106 m3 occurred one day after the peak in rainfall intensity the landslide occurred on a dip slope overlying late miocene to early pliocene sedimentary rocks consisting of silty shale massive mudstone and sandstone it started as a rockslide in the upper third of the landslide area and transformed into a rock avalanche that crossed a series of terraces and displaced or buried the village below it buried the riverbed of the chishan river and ran up the opposite slope creating a landslide dam 60 m high which was breached about 1 h and 24 min later flooding the village the velocity of the landslide is estimated to have been 20 4 to 33 7 m s 1 and its apparent friction angle was 14 which indicates its high mobility the detachments in the source area consist of combinations of bedding planes and joints or faults the landslide was preceded by gravitational deformation which appeared as hummocky landforms before the landslide and as buckle folds exposed after the event the landslide deposits consist of fragments of mudstone shale and sandstone as well as clayey material at its base this clayey material consisting of illite chlorite quartz feldspar and calcite is assumed to have strongly influenced the long rapid runout

geochemical exploration for mineralized breccia pipes in northern arizona u s a abstract thousands of solution collapse breccia pipe crop out in the canyons and on the plateaus of northern arizona over 80 of these are known to contain u or cu mineralized rock the high grade u ore associated with potentially economic concentrations of ag pb zn cu co and ni in some of these pipes has continued to stimulate mining and exploration activity in northern arizona despite periods of depressed u prices large expanses of northern arizona are comprised of undissected high plateaus recognition of pipes in these areas is particularly important because mining access to the plateaus is far better than to the canyons the small size of the pipes generally less than 600 ft 200 m in diameter and limited rock outcrop on the plateaus compounds the recognition problem although the breccia pipes which bottom in the mississippian redwall limestone are occasionally exposed on the plateaus as circular features so are unmineralized near surface collapse features that bottom in the permian kaibab and toroweap formations the distinction between these two classes of circular features is critical during exploration for this unique type of u deposit various geochemical and geophysical exploration methods have been tested over these classes of collapse features because of the small size of the deposits and the low level geochemical signatures in the overlying rock that are rarely dispersed for distances in excess of several hundred feet most reconnaissance geochemical surveys such as hydrogeochemistry or stream sediment will not delineete mineralized pipes several types of detailed geochemical surveys made over collapse features located through examination of aerial photographs and later field mapping have been successful at delineating collapse features from the surrounding host rock 1 rock geochemistry commonly shows low level ag as ba co cu ni pb se and zn anomalies over mineralized breccia pipes 2 soil surveys appear to have the greatest potential for distinguishing mineralized breccia pipes from the surrounding terrane although the soil anomalies are only twice the background concentrations for most anomalous elements traverses made over collapse features show consistent enrichment inside of the feature as compared to outside 3 b cereus surveys over a known mineralized pipe show significantly more anomalous samples collected from within the ring fracture than from outside of the breccia pipe 4 helium soil gas surveys were made over 7 collapse features with discouraging results from 5 of the 7 features geophysical surveys indicate that scaler audio magnetotelluric amt and e field telluric profile data show diagnostic conductivity differences over mineralized pipes as compared to the surrounding terrane these surveys coupled with the geochemical surveys conducted as detailed studies over features mapped by field and aerial photograph examination can be a significant asset in the selection of potential breccia pipes for drilling

slip distribution on a thrust fault at a plate boundary the 2003 chengkung earthquake taiwan summary the 2003 chengkung earthquake mw 6 8 occurred on the east dipping chihshang fault of eastern taiwan a listric fault with dominant reverse motion a joint inversion taking into account geodetic gps and seismological accelerometric and teleseismic data is performed this modelling highlights the rupture process behaviour on the fault plane at depth the coseismic rupture developed essentially between 12 and 26 km depth expanding laterally by about 30 km towards the ssw two slip patches dominated with slip values exceeding 1 5 m during the 30 s of the whole process the rupture propagation decelerated with time starting at 3 4 0 3 km s 1 in the two main slip patches and ending with velocities below 1 6 0 1 km s 1 the 48 hr of aftershocks that followed the main shock are distributed essentially inside the coseismic slip patches on the fault surface except in the deepest southern part of the fault where slip is less resolved the results of our modelling illustrate the particular behaviour of the 2003 chengkung earthquake where the coseismic slip rapidly diminished towards the surface in good agreement with the observation of fast post seismic slip followed by interseismic creep along the chihshang fault

digital image processing applied to analysis of geophysical and geochemical data for southern missouri linear gravity low across southern missouri underlain by low amplitude low gradient aeromagnetic anomalies due to variations in basement structures of rock types smoothed estimates of u th and k derived from aerial gamma ray data covering the rolla quadrangle were color coded and digitally overlaid onto a landsat image a shaded relief image of topography and the geologic map of missouri cambrian lamotte sandstone and bonneterre dolostone which crop out adjacent to the precambrian exposures have higher values than the younger cambrian and ordovician carbonates sandstones and shales enrichment within the interfluvial plains probably due to presence of a clay rich residuum modified journal abstract

coseismic deformation from the 1999 mw 7 1 hector mine california earthquake as inferred from insar and gps observations we use interferometric synthetic aperture radar insar and global positioning system gps observations to investigate static deformation due to the 1999 m w 7 1 hector mine earthquake that occurred in the eastern california shear zone interferometric decorrelation phase and azimuth offset measurements indicate regions of surface and near surface slip which we use to constrain the geometry of surface rupture the inferred geometry is spatially complex with multiple strands the southern third of the rupture zone consists of three subparallel segments extending about 20 km in length in a n45 w direction the central segment is the simplest with a single strand crossing the bullion mountains and a strike of n10 w the northern third of the rupture zone is characterized by multiple splays with directions subparallel to strikes in the southern and central the average strike for the entire rupture is about n30 w the interferograms indicate significant along strike variations in strain which are consistent with variations in the ground based slip measurements using a variable resolution data sampling routine to reduce the computational burden we invert the insar and gps data for the fault geometry and distribution of slip we compare results from assuming an elastic half space and a layered elastic space results from these two elastic models are similar although the layered space model predicts more slip at depth than does the half space model the layered model predicts a maximum coseismic slip of more than 5 m at a depth of 3 to 6 km contrary to preliminary reports the northern part of the hector mine rupture accommodates the maximum slip our model predictions for the surface fault offset and total seismic moment agree with both field mapping results and recent seismic models the inferred shallow slip deficit is enigmatic and may suggest that distributed inelastic yielding occurred in the uppermost few kilometers of the crust during or soon after the earthquake

frequency characteristics and numerical computation of seismic records generated by a giant debris flow in zhouqu western china the catastrophic sanyanyu and luojiayu debris flows which were induced by heavy rain struck zhouqu county in gannan prefecture gansu province at approximately midnight 7 august 2010 beijing time utc 8 causing 1765 fatalities and huge economic loss the zhq seismic station is located approximately 170 m west of the outlet of the sanyanyu gully and its power system was destroyed by the sanyanyu debris flow when its leading edge reached the vicinity of the seismic station in this paper seismic signals recorded approximately 10 min before its termination are collected and analyzed to study the sanyanyu debris flow a double exponential model is first proposed to quantitatively characterize seismic energy distributions in the frequency domain which reveals that the peak frequency of seismic signals is around 5 hz influenced by the doppler effect the peak frequency of the n s component is the highest and the u d component is the lowest time frequency analysis is applied to the seismic signals from the spectrogram it is easily observed that the formation time of the sanyanyu debris flow is around 23 33 10 the entire debris flow is divided into three phases with distinct frequency characteristics using 23 36 20 and 23 37 35 as crucial times the frequency energy distributions in the first two phases are relatively stable and are constrained in 0 8 8 hz and 0 17 8 hz respectively for the third phase the upper boundary of frequency energy increases in a nearly linear manner reaching approximately 35 hz at the end we calculate synthetic seismograms of the sanyanyu debris flow generally synthetic seismograms have morphological features and characteristics in key stages similar to those of the actual seismic records and their maximum values are of the same magnitude our results suggest that the seismic source of a debris flow can be represented by a single force model and reveal that real time monitoring and rapid identification of potential debris flows using broadband seismic network records is possible which can provide approximately 15 min of pre event warning for local residents and hopefully save many lives