the 23 19 aftershock of the 15 october 1979 imperial valley earthquake more evidence for an asperity the well recorded strong ground motion data for the 23 19 aftershock of the 15 october 1979 imperial valley earthquake provide a good opportunity to study the high frequency source characteristics and the path effects at near source distances the best fitting point source model has a strike slip mechanism n40 w which is nearly identical to the main event the estimated stress drop is extremely high roughly 500 bars with a triangular time history 0 1 0 1 sec but with a moment of 1 0 10 24 dyne cm a double source model found by inversion fits the high frequency data better but indicates complex faulting the first source with strike n319 e dip 42 ne and slip angle 165 has a moment of 0 7 10 24 dyne cm the second source with strike n324 e dip 82 sw and slip angle 181 lies about 0 5 km to the north and has a seismic moment twice that of the first source source dimensions appear very small for this amount of energy release many of the anomalous behaviors observed at certain stations for the main event are also present in the aftershock data these features are examined in terms of path effects

source fault of the 2007 chuetsu oki japan earthquake the 2007 chuetsu oki japan earthquake is the world s first major earthquake upon a source fault that extends beneath a nuclear power plant and is also characterized by difficulty determining the source fault plane centroid moment tensor solutions indicate an m w 6 6 reverse faulting crustal earthquake with conjugate fault planes dipping to the northwest and southeast early results of aftershock locations suggest that either northwest dipping plane or southeast dipping plane can be the source fault plane of this earthquake we carried out source inversions and empirical green s function simulations of observed seismograms however they resulted in similar waveform residuals for the two fault planes we then determined the relative locations of earthquake asperities to the hypocenter using travel time differences of strong motion pulses and relocated the aftershocks observed by ocean bottom seismometers deployed in the source region these results imply that slips mainly occurred on the southeast dipping fault plane this implication was later confirmed by results of reflection surveys during the earthquake the kashiwazaki kariwa nuclear power plant experienced stronger ground motions than those anticipated at the time of design the ground motions consist of three seismic pulses that correspond to three asperities the first and second pulses arose from rupture propagation to the plant while the compact asperity on the distant southeast dipping fault plane and its s wave radiation pattern are responsible for the significant third pulse

laboratory earthquakes the sub rayleigh to supershear rupture transition we report on the experimental observation of spontaneously nucleated supershear rupture and on the visualization of sub rayleigh to supershear rupture transitions in frictionally held interfaces the laboratory experiments mimic natural earthquakes the results suggest that under certain conditions supershear rupture propagation can be facilitated during large earthquake events

electromagnetic surveying in current middle eastern archaeology application and evaluation since 1977 the smithsonian institution has had a major research program on the human biological history of the near east as part of this program electromagnetic em surveying methods have been extensively used to identify anomalies of potential archaeological significance below the surface an em 31 noncontacting terrain conductivity meter was used in jordan bahrain kuwait and egypt with excellent results in addition to the successful application of em equipment to archaeological problems we investigated the equipment s response to changing environmental and climatic conditions we have developed efficient methods for recording em data the following results were obtained recording accuracy is better than previously reported 0 97 percent repeatability error between two observers the degree of accuracy is primarily a function of operator error and less a function of equipment reliability and the em 31 produces helpful highly reproducible results in the arid and semiarid environment of the mi

geophysical remote sensing of historical aboriginal gravesites in southwestern western australia many suspected historical aboriginal gravesites are throughout southwestern western australia where individual burial locations remain unknown because of the cultural and historical importance of these heritage sites there is an increasing effort to identify such locations to enable better site preservation and appropriate commemoration gravesite reconnaissance routinely requires the investigation of large areas and it is inefficient and disrespectful to excavate large volumes in search of burials geophysical remote sensing offers a noninvasive alternative for identifying and delineating gravesites to these ends the university of western australia uwa society of exploration geophysicists seg student chapter has been working with the south west aboriginal land and sea council swalsc in a pilot study to acquire several near surface geophysical surveys at two historically documented aboriginal gravesites in quairading and toodyay western australia the resulting ground penetrating radar gpr magnetics conductivity mapping and resistivity profiling data sets identify subsurface anomalies that are consistent in location with historical documentation and elders recollections and with the expected geophysical signatures of historical burials and early development activities the geophysical survey results have been relayed to the swalsc and community decision makers to assist in upcoming preservation and commemoration efforts the pilot study could be helpful in identifying other aboriginal gravesites throughout western australia and would represent a positive step toward resolving key longstanding issues among different community interests surrounding the uncertainties of some sites of suspected aboriginal heritage

investigation of magnetic surveying data of buried grave jars in harmanoren necropolis turkey using linear transformations and analytic signal abstract harmanoren necropolis is the third biggest excavated necropolis in southwest anatolia dating back to 2500 b c the individual burials are composed of ceramic jars the dead bodies were placed in the fetal position in buried grave jars which were elongated eastwards buried burnt ceramics can be located by their own magnetic field directions thus magnetic surveying was used in the harmanoren necropolis in three different areas to locate buried grave jars ahead of archaeological excavation magnetic anomalies present some results but to identify these as buried grave jars advanced spectral methods were applied to the magnetic anomalies polarity orientations of magnetic anomalies are different from a north south direction due to remnant magnetization reduction to the pole transformation could not entirely remove disoriented polarities arising from the effect of remnant magnetization analytic signal transformation minimizes the disorientation caused by the effect of remanence magnetic susceptibility measurements of samples from the excavated jars indicate that the observed magnetic anomalies could be caused by them a good correlation was observed between the processed magnetic anomalies and excavation results

magnetic mapping ground penetrating radar surveys and magnetic susceptibility measurements for the study of the archaeological site of serra di vaglio southern italy in this work we present the results of a multidisciplinary study for characterising the archaeological site of serra di vaglio basilicata region southern italy the site includes an ancient native settlement arisen between the 8th and the 3rd century bc the investigation has been performed by means of the integrated use of three different high resolution and no invasive geophysical techniques magnetic mapping ground penetrating radar profiling gpr and magnetic susceptibility measurements the integrated approach allows us to detect buried archaeological structures in particular our results helped to define spatial pattern of the buried remains to define the geometry of the anthropogenic settlements and to obtain detailed information about the composition and the manufacturing processes of different building materials the archaeological excavations carried out in one of the investigated sites confirm the usefulness and the reliability of the integrated employment of different geophysical techniques for the archaeological study of ancient buried structures

complexity of the mw 6 3 2009 l aquila central italy earthquake 2 broadband strong motion modeling 1 near fault strong ground motions 0 1 10 hz recorded during the mw 6 3 2009 l aquila earthquake exhibit great spatial variability modeling the observed seismograms allows linking distinct features of the observed wavefield to particular source and propagation effects and provides insights on strong motion complexity from this moderate magnitude event we utilize a hybrid integral composite approach based on a k square kinematic rupture model combining low frequency coherent and high frequency incoherent source radiation and providing omega squared source spectral decay several source model features proven to be stable by means of an uncertainty analysis in the preceding low frequency 2 hz

multiple fault slip triggered above the 2016 mw 6 4 meinong earthquake in taiwan rapid shortening in convergent mountain belts is often accommodated by slip on faults at multiple levels in upper crust but no geodetic observation of slip at multiple levels within hours of a moderate earthquake has been shown before here we show clear evidence of fault slip within a shallower thrust at 5 10 km depth in sw taiwan triggered by the 2016 mw 6 4 meinong earthquake at 15 20 km depth we constrain the primary coseismic fault slip with kinematic modeling of seismic and geodetic measurements and constrain the triggered slip and fault geometry using synthetic aperture radar interferometry the shallower thrust coincides with a proposed duplex located in a region of high fluid pressure and high interseismic uplift rate and may be sensitive to stress perturbations our results imply that under tectonic conditions such as high background stress level and high fluid pressure a moderate lower crustal earthquake can trigger faults at shallower depth

how fast is rupture during an earthquake new insights from the 1999 turkey earthquakes we report that during the two devastating 1999 earthquakes in turkey rupture propagated over a large part of the nearly 200km long fault zone at supershear speed approaching 5km s we present observations and modeling which confirm the original inference of supershear rupture during the izmit earthquake and we show that supershear rupture also occurred during the duzce earthquake we show that the rupture velocity measured about 2 times the shear wave velocity is the value predicted by theoretical studies in fracture dynamics we look for clues to explain these observations

diminishing high frequency directivity due to a source effect empirical evidence from small earthquakes in the abruzzo region italy the aim of this study is to investigate the directivity effects of 250 aftershocks magnitudes 3 5 5 of the mw 6 1 2009 l aquila earthquake central italy to this end we estimate the apparent source spectra at each station removing path and site effects inferred by standard generalized inversion technique then we evaluate the residuals between the apparent source spectra and the event mean source spectrum at selected frequencies we investigate azimuthal and frequency dependence of the residuals for 40 events with the best station coverage for most of events with the strongest directivity effect mw 3 4 4 0 we observe a remarkable decrease of the directivity amplification at high frequencies which has not yet been documented for such relatively small magnitude events since there is negligible distance dependence we ascribe this observation to a source phenomenon such as significant small scale rupture propagation complexity

rock and stiff soil site amplification dependency on vs30 and kappa κ0 abstract a ground motion prediction equation gmpe specific to rock and stiff soil sites is derived using seismic motion recorded on high v s 30 sites in japan this gmpe applies to events with 4 5 m w 6 9 and v s 30 ranging from 500 to 1500 m s stiff soil to rock sites the empirical site coefficients obtained and the comparison with the simulated site functions show that seismic motion on rock and stiff soil sites does not depend only on v s 30 but also on the high frequency attenuation site properties 0 the effects of the site specific 0 on site amplification are analyzed using stochastic simulations with the need to take into account both of these parameters for rock site adjustments adding the site specific 0 into the gmpes thus appears to be essential in future work the rock site stochastic ground motion simulations show that the site specific 0 controls the frequency corresponding to the maximum response spectral acceleration f amp 1 this observation is used to link the peak of the response spectral shape to 0 in this specific japanese dataset and then to add the effects of high frequency attenuation into the previous gmpe from the peak ground acceleration and up to periods of 0 2 s the inclusion of 0 allows the observed bias to be corrected for the intraevent residuals and thus reduces sigma however this 0 determination is limited to a minimum number of rock site records with m w 4 5 and to distances of less than 50 km

imaging the source region of the 2004 mid niigata prefecture earthquake and the evolution of a seismogenic thrust related fold 1 the velocity structure and accurate aftershock distributions of the 2004 mid niigata prefecture earthquake are elucidated by inverting the arrival times from 716 aftershocks using double difference tomography fourteen temporal seismic stations were immediately deployed in and around the source region within 46 h of the occurrence of mainshock the seismic velocities in a hanging wall are lower than those in a footwall and the velocity contrast extends to a depth of approximately 10 km the aftershocks associated with the mainshock are distributed around the clear boundary between the low and high velocity structures it is interpreted that the mainshock fault plane of the mid niigata prefecture earthquake was reactivated as a reverse fault since the crustal shortening initiated at 3 5 ma crustal stretching or shortening along the japan coastline has created complex structures such as low velocity zones which can potentially control the seismic activities around the source region

geophysical surveys of burial sites a case study of the oaro urupa a maori family burial site was surveyed using shallow electromagnetic em magnetometer gradiometer and ground penetrating radar gpr techniques the locations of some older graves are no longer known partly through the loss of markers and partly through the loss of the oral record there are at least 150 such burial sites throughout new zealand and similar problems occur elsewhere in the world the knowledge that maori graves are traditionally set out facing east made survey design easier background trends are removed and possible anomalous features are identified despite the complicating presence of metal fencing the em in phase response the vertical gradient of the total magnetic field and the gpr response were particularly useful in combination gpr surveys were carried out using two frequencies 450 and 200 mhz the higher frequency radar surveys were limited in extent because these data had a limited depth of penetration and were prone to signal ringing in the surficial clay the lower

joint vp and vs tomography of taiwan implications for subduction collision orogeny abstract the taiwan orogen sitting at the pre rifted eurasian margin and bracketed by two sub orthogonal subduction systems is subject to complicated geotectonics motivating numerous seismic tomographic studies in local and regional scale most of them obtained p wave velocities vp or with vp vs ratio jointly but few were for s wave velocities vs with unprecedented amount of s wave data in this study a new set of well tuned vp vs and vp vs models were determined by an elaborate joint inversion scheme integrating the data of p and s wave travel times s p times and the borehole logging data for near surface correction into one system this allowed us to revisit the subduction collision process in detail by comparing vp vs and vp vs ratio simultaneously with enhanced slab imaging of philippine sea plate psp under northeast taiwan we are able to discriminate the plausible missing luzon forearc basement along the plate boundary and propose a skateboarding edge model in which the westernmost psp rides on the east subducted forearc basement and subducts northward underneath the eurasian lithosphere the underlain forearc basement along with the psp subduction then results in the anomalous shallow double seismic zone observed only near taiwan island meanwhile at around 121 e the north subducting psp seems dipping west to collide with the deep eurasian lithosphere shaping an irregular corner wedge structure in addition we evaluate our model with previous ones by waveform modeling approach and show the current performance of travel time tomography in taiwan region

images of buried graves in bayat afyon turkey from high resolution magnetic data and their comparison with preliminary excavations dedemezari necropolis the site of our study is located in the west of turkey near afyon archaeologists think that it belongs to the middle bronze age a high resolution magnetic survey identified buried material highly accurately in particular anomalies which are transformed by the analytic signal method clarify the observed magnetic anomalies magnetic surveying was applied in three different areas in this study the map of analytic signal transformed anomalies presented good results on preliminary excavation in trenches a and b two types of graves are found in the study area one is made of clay and the second is carved in the rocks shapes of the buried graves are mainly cylindrical and elliptical most of the magnetic anomalies are elliptical and reflect the shape of the buried materials future excavations in dedemezari necropolis will be able to be carried out more easily due to the known locations of the buried graves

rupture processes of the 2004 chuetsu mid niigata prefecture earthquake japan a series of events in a complex fault system 1 we relocated the hypocenters of the 2004 chuetsu earthquake sequence niigata japan using the double difference method the distribution of aftershocks reveals a complex fault system consisting of five different fault planes inversions of strong motion records for the five major events within the sequence indicate that the mainshock mw 6 6 and the largest aftershock mw 6 3 occurred on parallel wnw dipping fault planes the zones of large slip asperities of these two events are located near the hypocenters in contrast the three other large earthquakes mw 5 9 5 7 and 5 9 occurred on east dipping fault planes oriented perpendicular to the fault plane of the mainshock we used slip distributions deduced from waveform inversions to estimate the coulomb failure stress changes that occurred immediately prior to each event cff values were positive at the hypocenters and within the asperities of the major aftershocks these results suggest that stress changes resulting from individual earthquakes led directly to the occurrence of subsequent earthquakes within the complex fault system

supershear rupture of the 5 january 2013 craig alaska mw 7 5 earthquake supershear rupture in which a fracture s crack tip expansion velocity exceeds the elastic shear wave velocity has been extensively investigated theoretically and experimentally and previously inferred from seismic wave observations for six continental strike slip earthquakes we find extensive evidence of supershear rupture expansion of an oceanic interplate earthquake the 5 january 2013 mw 7 5 craig alaska earthquake this asymmetric bilateral strike slip rupture occurred on the queen charlotte fault offshore of southeastern alaska observations of first arriving sn and sg shear waves originating from positions on the fault closer than the hypocenter for several regional seismic stations with path calibrations provided by an empirical green s function approach indicate a supershear rupture process several waveform inversion and modeling techniques were further applied to determine the rupture velocity and space time distribution of slip using regional seismic and geodetic observations both theoretical and empirical green s functions were used in the analyses with all results being consistent with a rupture velocity of 5 5 to 6 km s exceeding the crustal and upper mantle s wave velocity and approaching the crustal p wave velocity supershear rupture occurred along 100 km of the northern portion of the rupture zone but not along the shorter southern rupture extension the direction in which supershear rupture developed may be related to the strong material contrast across the continental oceanic plate boundary as predicted theoretically and experimentally the shear and surface wave mach waves involve strongly enhanced ground motions at azimuths oblique to the rupture direction emphasizing the enhanced hazard posed by supershear rupture of large strike slip earthquakes

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

unveiling the prehistoric landscape at stonehenge through multi receiver emi abstract archaeological research at stonehenge uk is increasingly aimed at understanding the dynamic of the wider archaeological landscape through the application of state of the art geophysical techniques unprecedented insight is being gathered into the buried archaeological features of the area however applied survey techniques have rarely targeted natural soil variation and the detailed knowledge of the palaeotopography is consequently less complete in addition metallic topsoil debris scattered over different parts of the stonehenge landscape often impacts the interpretation of geophysical datasets the research presented here demonstrates how a single multi receiver electromagnetic induction emi survey conducted over a 22 ha area within the stonehenge landscape offers detailed insight into natural and anthropogenic soil variation at stonehenge the soil variations that were detected through recording the electrical and magnetic soil variability shed light on the genesis of the landscape and allow for a better definition of potential palaeoenvironmental and archaeological sampling locations based on the multi layered dataset a procedure was developed to remove the influence of topsoil metal from the survey data which enabled a more straightforward identification of the detected archaeology the results provide a robust basis for further geoarchaeological research while potential to differentiate between modern soil disturbances and the underlying sub surface variations can help in solving conservation and management issues through expanding this approach over the wider area we aim at a fuller understanding of the human landscape interactions that have shaped the stonehenge landscape

supershear rupture on multiple faults for the mw 8 6 off northern sumatra indonesia earthquake of april 11 2012 1 we perform a back projection method to image the rupture propagation and short period energy release of the 2012 off northern sumatra earthquake mw8 6 using hi net data recorded in japan the results show a complex pattern of four conjugate faults over about 180 sec there is a striking correspondence between the lengths and orientations of our rupture pattern with the distribution of aftershocks each of the first three stages of the rupture corresponds to a clear lineation in the aftershocks with lengths of 200 to 400 km rupture speeds for several of the fault segments were very high about 5 km s and exceed the local s wave velocity this is the first example of an oceanic earthquake with supershear rupture speed

progression of spontaneous in plane shear faults from sub rayleigh to compressional wave rupture speeds we investigate numerically the passage of spontaneous dynamic in plane shear ruptures from initiation to their final rupture speed using very fine grids by carrying out more than 120 simulations we identify two different mechanisms controlling supershear transition for relatively weaker faults the rupture speed always passes smoothly and continuously through the range of speeds between the rayleigh and shear wave speeds the formerly considered forbidden zone of rupture speeds this however occurs in a very short time before the ruptures reach the compressional wave speed the very short time spent in this range of speeds may explain why a jump over these speeds was seen in some earlier numerical and experimental studies and confirms that this speed range is an unstable range as predicted analytically for steady state singular cracks on the other hand for relatively stronger faults we find that a daughter rupture is initiated by the main mother rupture ahead of it the mother rupture continues to propagate at sub rayleigh speed and eventually merges with the daughter rupture whose speed jumps over the rayleigh to shear wave speed range we find that this daughter rupture is essentially a pseudorupture in that the two sides of the fault are already separated but the rupture has negligible slip and slip velocity after the mother rupture merges with it the slip the slip velocity and the rupture speed become dominated by those of the mother rupture the results are independent of grid sizes and of methods used to nucleate the initial rupture

determining geophysical responses from burials in graveyards and cemeteries abstractgraveyards and cemeteries around the world are increasingly designated as full therefore there is a requirement to identify vacant spaces for new burials or to identify existing ones to exhume and then reinter if necessary geophysical methods offer a potentially noninvasive target detection solution however there has been limited research to identify optimal geophysical detection methods against burial age we have collected multifrequency 225 900 mhz ground penetrating radar gpr electrical resistivity and magnetic susceptibility surface data over known graves with different burial ages and soil types in three uk church graveyards results indicate that progressively older burials are more difficult to detect but this decrease is not linear and is site specific medium to high frequency gpr and magnetic susceptibility was optimal in clay rich soils medium to high frequency gpr and electrical resistivity in sandy soils and electrical resistivity and low frequency gpr in coarse sand

determining magnetic susceptibility of ancient and modern potsherds using a fast cheap and portable probe archaeometry is the application of scientific techniques to archaeology the general perception is that it consists of the use of a number of geophysical techniques that were originally developed to explore for mineral deposits in order to delineate anthropological remains in the subsurface without disturbing them such techniques include resistivity tomography e g saey et al 2012 glover 2010 papadopoulos et al 2006 proton spin magnetometry e g buyuksaraca et al 2006 ground penetrating radar e g dabas et al 2000 neubauer et al 2002 and electromagnetic measurements e g bigman 2012 the perception has been fed by television series such as the time team and now many university based geophysicists spend at least some of their time applying their techniques to archaeological remains however these techniques are only one part of archaeometry which also covers the use of physical and chemical methods to understand how archaeological remains were made and used e g lima et

inside a mound applied geophysics in archaeological prospecting at the kings mounds gamla uppsala sweden a combined geophysical prospection with slingram gradiometer and ground penetrating radar is described the prospection is carried out at the eastern mound and the thing mound gamla uppsala middle sweden in an attempt to detect the internal structure of the mounds at the eastern mound we were able to identify the fossil ground surface a centre cairn a possible older grave under the mound and a few other anomalies some of them most possibly depending on historical activities and some more likely on prehistoric human activities the thing mound was found being of geological origin and only prepared to become a grave the project shows that a combined use of several geophysical methods improves and simplifies the interpretation

evidence for ascending upper mantle derived melt beneath the cheb basin central europe 1 we present new 3he 4he data of co2 rich gas exhalations of three presently nonvolcanic areas in europe the 3he 4he ratios from the cheb basin czech republic are clearly higher than data obtained ten years ago whereas the 3he 4he ratios from the other areas laacher see germany and marianske lazn cr have remained nearly constant no other locality showing such high 3he 4he ratios in free gases supplied by continental mantle degassing is known in the european cenozoic rift system at the northeastern edge of the cheb basin swarm earthquakes repeatedly occur in the context of contemporaneous periods of seismicity the increased 3he 4he ratios are interpreted as the first geochemical evidence for ascending mantle derived melt beneath the cheb basin which is related to the triggering of earthquake swarms

imaging skeletal remains with ground penetrating radar comparative results over two graves from viking age and medieval churchyards on the stora seyla farm northern iceland detailed ground penetrating radar surveys were conducted at separate viking age and medieval churchyards on the stora seyla farm in skagafjor ur northern iceland surveying over a previously unknown site ca ad 1000 that is located just a few meters above the skagafjor ur valley bottom delineated the remnants of a buried circular turf wall that encloses a church structure and several graves the radar profiles over the graves contain strong hyperbolic reflections that emanated from the skeletal remains over one of the graves an air filled void within the chest cavity had been detected as noted by reflections with normal polarity which indicated a boundary towards increasing microwave velocity during excavation the soil surrounding an intact rib cage collapsed thus confirming the presence of the void in general the skeletal remains were very well preserved and yielded strong reflections which permitted the orientation of the body to be determined conversely the radar profiles over a grave from a more recent churchyard ca ad 1200 show ground disturbance but lack hyperbolic reflections upon excavation only teeth were recovered the poor preservation of the skeletal remains is attributed to increase contact with infiltrating groundwater from an overlying gravel layer interpretations were aided by time slice overlay imaging forward modeling and analysis of the reflection coefficient

seismic imaging of the 1999 izmit turkey rupture inferred from the near fault recordings we use near fault accelerograms to infer the space time history of rupture on the fault during the izmit earthquake the records show that the ground displacement and velocity near the fault were surprisingly simple rupture propagated toward the west at a velocity of about 3 km s and toward the east at a remarkably high average velocity of 4 7 km s over a distance of about 45 km before decelerating to about 3 1 km s on the eastern segment slip on the fault is particularly large down to a depth of 20 km on the central portion of the fault where it reaches about 7 m slip is large also below 10 km on the eastern fault segment and this may have contributed to the loading of shear stress on the duzce fault on the western fault segment large slip seems confined to shallow depths

detection and characterisation of black death burials by multi proxy geophysical methods the construction of the new crossrail railway discovered 25 well preserved skeletons shallowly buried in central london in 2013 subsequent carbon dating and adna analysis confirmed the archaeological age and presence of the yersinia pestis black death plague epidemic strain here we present the non invasive multi proxy geophysical survey of the adjacent charterhouse square rapidly undertaken to detect any further burials and characterise the site historical records suggested the area was a burial ground for black death plague victims before subsequent cemetery and urban land use following initial trial surveys surveys imaged 200 isolated and similar sized burials in the south west of the site there were also two contrasting burial orientations present at various depths which suggested a series of controlled phased burials a well defined eastern burial boundary taking the form of a ditch and bank was also discovered geophysical surveys also identified a subsequent complex site history with multiple aged features this study revises knowledge of black death aged burials and provides important implications for successful geophysical burial detection with significant time and space limited site constraints

faulting characteristics of supershear earthquakes article i nfo recent observations of large continental strike slip earthquakes show that different fault segments may rupture at different speeds and that rupture may propagate faster than the shear wave velocity of surrounding rocks we report that all the documented occurrences of supershear rupture are associated with faults which have simple geometry the surface trace of these faults is described in the field or seen on satellite images as remarkably linear continuous and narrow segmentation features along these segments are small or absent and the deformation is highly localized as theoretically predicted supershear is clearly associated with mode ii rupture

near source ground motion from steady state dynamic rupture pulses 1 ground motion from two dimensional steady state dynamic ruptures is examined for both subshear and supershear rupture velocities synthetic seismograms demonstrate that coherent high frequency information about the source process rapidly attenuates with distance from the fault for subshear ruptures such records provide almost no resolution of the spatial extent of the stress breakdown zone at supershear speeds s waves radiate away from the fault preserving the full source spectrum and carrying an exact history of the slip velocity on both the fault parallel and fault normal components of motion whose amplitudes are given by a function of rupture speed that vanishes at times the s wave speed the energy liberated from the strain field by the passage of a supershear rupture is partitioned into fracture energy dissipated within the fault zone and far field s wave radiation the partition depends on both the rupture velocity and the size of the breakdown zone

the aftershock signature of supershear earthquakes recent studies show that earthquake faults may rupture at speeds exceeding the shear wave velocity of rocks this supershear rupture produces in the ground a seismic shock wave similar to the sonic boom produced by a supersonic airplane this shock wave may increase the destruction caused by the earthquake we report that supershear earthquakes are characterized by a specific pattern of aftershocks the fault plane itself is remarkably quiet whereas aftershocks cluster off the fault on secondary structures that are activated by the supershear rupture the post earthquake quiescence of the fault shows that friction is relatively uniform over supershear segments whereas the activation of off fault structures is explained by the shock wave radiation which produces high stresses over a wide zone surrounding the fault

supershear transition due to a free surface in 3 d simulations of spontaneous dynamic rupture on vertical strike slip faults supershear rupture propagation has been inferred from seismic observations for natural faults and observed in laboratory experiments we study the effect of the free surface on the transition of earthquake rupture from subshear to supershear speeds using simulations of spontaneous dynamic rupture on vertical strike slip faults we find that locally supershear rupture near the free surface can occur due to i the generalized burridge andrews mechanism that is a supershear loading field between p and sv wave arrivals generated by the main rupture front at depths and ii the phase conversion of sv to p diffracted waves at the free surface weaker supershear slip due to the generalized burridge andrews mechanism is caused by the low strength at shallow portions of the fault relative to deeper ones dominant supershear rupture is supported by the additional supershear loading field produced by phase conversion locally supershear propagation at the free surface occurs regardless of the level of prestress and can cause transition to supershear propagation over the entire seismogenic depth such global supershear transition which depends on prestress can occur under prestress levels lower than the theoretical estimates for models with no free surface although the effectiveness of supershear transition due to the free surface can be diminished by several potentially important factors it may play an important role on natural faults at least in those strike slip earthquakes that accumulate significant surface slip

the relationship between late cenozoic tectonic events and stress field and basin development in northeast japan the regional tectonic stress field basin development and crustal deformation of the ne japan arc in the interval between 32 ma to the quaternary can be synthesized based on dike vein and fault orientation data as well as on the compilation of the regional geology an extensional stress field became prevalent from 32 ma and major normal faulting started at 25 20 ma which resulted from back arc rifting normal faulting trending nearly parallel to the arc propagated from the present japan sea coast to the forearc side following the trenchward migration of the main volcanic field from 20 to 15 ma normal faults with an oblique trend to the arc developed due to the counterclockwise rotation of ne japan the rapid clockwise rotation of sw japan since 16 ma produced a nw se directed transtensional stress regime in the ne japan arc due to crustal stretching associated with this pull apart movement the back arc side of the ne japan arc subsided rapidly to middle bathyal environments after the termination of the opening of the japan sea at about 14 ma a neutral stress regime prevailed which included phases of both weak extension and compression lithospheric cooling eventually led to thermal subsidence of the back arc region and igneous underplating caused uplift of the axial zone of the volcanic arc the increase in velocity of the westward motion of the pacific plate at around 4 ma produced strong compression across the arc reactivating most of the miocene normal faults and uplifting the volcanic arc the greatest crustal shortening occurred in areas that were stretched the most in the miocene within the volcanic arc which implies tectonic inversion

spatial and temporal distribution of slip for the 1992 landers california earthquake we have determined a source rupture model for the 1992 landers earthquake m w 7 2 compatible with multiple data sets spanning a frequency range from zero to 0 5 hz geodetic survey displacements near field and regional strong motions broadband teleseismic waveforms and surface offset measurements have been used explicitly to constrain both the spatial and temporal slip variations along the model fault surface our fault parameterization involves a variable slip multiple segment finite fault model which treats the diverse data sets in a self consistent manner allowing them to be inverted both independently and in unison the high quality data available for the landers earthquake provide an unprecedented opportunity for direct comparison of rupture models determined from independent data sets that sample both a wide frequency range and a diverse spatial station orientation with respect to the earthquake slip and radiation pattern in all models consistent features include the following 1 similar overall dislocation patterns and amplitudes with seismic moments of 7 to 8 10 26 dyne cm seismic potency of 2 3 to 2 7 km 3 2 very heterogeneous unilateral strike slip distributed over a fault length of 65 km and over a width of at least 15 km though slip is limited to shallower regions in some areas 3 a total rupture duration of 24 sec and an average rupture velocity of 2 7 km sec and 4 substantial variations of slip with depth relative to measured surface offsets the extended rupture length and duration of the landers earthquake also allowed imaging of the propagating rupture front with better resolution than for those of prior shorter duration strike slip events our imaging allows visualization of the rupture evolution including local differences in slip durations and variations in rupture velocity rupture velocity decreases markedly at shallow depths as well as near regions of slip transfer from one fault segment to the next as rupture propagates northwestward along the multiply segmented fault length the rupture front slows as it reaches the northern limit of the johnson valley landers faults where slip is transferred to the southern homestead valley fault an abrupt acceleration is apparent following the transfer this process is repeated and is more pronounced as slip is again passed from the northern homestead valley fault to the emerson fault although the largest surface offsets were observed at the northern end of the rupture our modeling indicates that substantial rupture was also relatively shallow less than 10 km in this region

rupture process of the 1944 tonankai earthquake ms 8 1 from the inversion of teleseismic and regional seismograms 1 we digitized teleseismic and regional records of the 1944 tonankai earthquake we used the multiple time window method to invert these records for the spatial and temporal distribution of slip and rake we assume a 220 140 km fault with a spacing of 20 20 km and a maximum rupture velocity of 2 5 km s the inversion resolved an asperity along the accretionary wedge and under the shima and atsumi peninsulas the rupture propagated from southwest to northeast and there was little slip near the hypocenter consistent with the absence of uplift in the overlying submarine forearc basin the peak slip is 2 3 m and the total seismic moment is 2 4 1028 dyn cm mw 8 2 we compared the predicted and observed vertical geodetic displacements and inferred that the limit of rupture is consistent with the change from subsidence to uplift west of the atsumi peninsula this suggested that the earthquake did not rupture the plate interface in the tokai gap we modeled the tsunami using sea bottom displacements generated from this slip model the tide gauge amplitudes and frequency content are consistent with those predicted resolution tests from inverting synthetic seismograms computed using a simplified slip model indicated that the combination of teleseismic and regional data sets best recovers the asperity locations and peak slips given similar station geometry and degrees of freedom an inversion of the synthetic regional data set indicates that slip artifacts can occur early in the rupture process due to many clipped records while the inversion of synthetic teleseismic data set had less resolution and recovered only 50 of the peak slip

source complexity of the 4 march 2010 jiashian taiwan earthquake determined by joint inversion of teleseismic and near field data abstract the jiashian earthquake m l 6 4 occurred on 4 march 2010 it was the largest inland event in southern taiwan of 2010 the mainshock location was unexpected since it occurred in an area with relatively low background seismicity in addition reports of earthquake focal mechanisms do not fit with any known active fault geometry in order to understand the origin of this earthquake especially its rupture process we perform a joint source inversion by using teleseismic body wave gps coseismic displacements and near field ground motion data in this study we considered a northwest southeast trending fault with a northeast dip retrieved from gps coseismic data and aftershocks distribution to analyze the detailed slip distribution in space and time we used near field 3d green s functions provided by spectral element method and a full time space inversion technique we find a complex rupture process with several slip patches distributed inside two main asperities the slip map reveals a mean slip of 12 9 cm for a maximum slip of 27 3 cm leading to a m w 6 47 for this event the rupture initiates in the deepest portion of the fault at 20 km depth and propagated upward up to 2 km depth to form the two asperities the source time function of this event revealed two pulses corresponding to the two asperities for a total duration time of about 16 s most aftershocks occurred near the upper boundary of the deepest asperity while no aftershocks are located close to the shallowest one we infer that the locations of these slip patches are related to the surrounding fault systems that may have restricted the rupture propagation during the earthquake

joint inversion of seismic and geodetic data for the source of the 2010 march 4 mw 6 3 jia shian sw taiwan earthquake

near fault broadband ground motion simulations of the 2016 meinong taiwan earthquakenear fault broadband ground motion simulations of the 2016 meinong taiwan earthquake

near source ground motions from simulations of sustained intersonic and supersonic fault ruptures we examine the long period near source ground motions from simulations of m 7 4 events on a strike slip fault using kinematic ruptures with rupture speeds that range from subshear speeds through intersonic speeds to supersonic speeds the strong along strike shear wave directivity present in scenarios with subshear rupture speeds disappears in the scenarios with ruptures propagating faster than the shear wave speed furthermore the maximum horizontal displacements and velocities rotate from generally fault perpendicular orientations at subshear rupture speeds to generally fault parallel orientations at supersonic rupture speeds for rupture speeds just above the shear wave speed the orientations are spatially heterogeneous as a result of the random nature of our assumed slip model at locations within a few kilometers of the rupture the time histories of the polarization of the horizontal motion provide a better diagnostic with which to gauge the rupture speed than the orientation of the peak motion subshear ruptures are associated with significant fault perpendicular motion before fault parallel motion close to the fault supershear ruptures are associated with fault perpendicular motion after significant fault parallel motion consistent with previous studies we do not find evidence for prolonged supershear rupture in the long period 2 sec ground motions from the 1979 imperial valley earthquake however we are unable to resolve the issue of whether a limited portion of the rupture approximately 10 km in length propagated faster than the shear wave speed additionally a recording from the 2002 denali fault earthquake does appear to be qualitatively consistent with locally supershear rupture stronger evidence for supershear rupture in earthquakes may require very dense station coverage in order to capture these potentially distinguishing traits

the search for graves with ground penetrating radar in connecticut the search for unmarked and clandestine graves is a labor intensive time consuming and often frustrating task several geo physical methods are available which can be expediently used with little or no disturbances to sites among which ground penetrating radar gpr is often considered the most useful tool to delineate possible graves this paper is the result of many years of gpr testing for unmarked graves in connecticut natural and cultural conditions are considered in the failure and or success of detection and the use of gpr in archaeological studies

distortion of the apparent s wave radiation pattern in the high frequency wavefield tottori ken seibu japan earthquake of 2000 summary the distortion properties of the apparent s wave radiation pattern in the high frequency seismic wavefield of over f 2 hz is investigated using a large number of waveform records of the main shock and 29 aftershocks of the tottori ken seibu japan magnitude mw 6 6 earthquake in 2000 the dense seismic records from the kik net strong motion network show a clear four lobe pattern in the apparent s wave radiation pattern in the low frequency wavefield of f 2 hz and shows an almost isotropic distribution in all directions as the frequency increases above 5 hz the distortion of the apparent s wave radiation pattern in the high frequency wavefield increases as travel distance increases therefore the path effect caused by the scattering of seismic waves due to small scale heterogeneities in the crust is a major cause of distortion of the radiation pattern this hypothesis is examined by a 2 d finite difference method simulation of seismic waves in heterogeneous structure models the results of simulations clearly demonstrate the collapse of the s wave front due to seismic wave scattering in the heterogeneous structure by comparing the observed wavefield and the results of simulations using different sorts of stochastic heterogeneous models the most preferable model that can explain the observation is described by a von karman autocorrelation function with correlation distance of a 3 5 km order of 0 5 and rms value of e 0 07 however our simple stochastic random heterogeneity model proposed herein somewhat overestimates the scattering of low frequency signals below 2 hz

the 2010 qinghai china earthquake a moderate earthquake with supershear rupture abstract from analyses using near field and teleseismic data we estimate the rupture speed of the 2010 qinghai china earthquake m w 6 9 comparisons of model calculations of the initiations to the observed near field seismogram at station yus indicate a fast supershear rupture propagation of about 5 0 km s from the teleseismic analyses using an envelope deconvolution method with an empirical green s function event two high frequency pulses are identified at 6 5 km and 41 8 km southeast of the epicenter indicating two subevents the location and timing of the high frequency events also show a supershear rupture velocity of 4 7 to 5 8 km s the supershear speed of the rupture likely contributed to the severe damage caused in the forward direction of the rupture toward the town of yushu

the search for graves over the decades grave markers in old cemeteries have been lost geophysical exploration can sometimes locate the unmarked burials the two techniques which may be best for this search are a ground penetrating radar survey and a soil conductivity survey a ground penetrating radar survey with its capability for estimating the depth and shape of buried objects is particularly suitable with an electromagnetic induction survey the disturbed soil in the grave shaft can sometimes be detected as a change in electrical conductivity both of these surveys also can locate large metal objects these surveys have limitations at some sites the radar cannot profile deeply enough at others the soil strata are so complex that graves cannot be distinguished a conductivity survey can be degraded by metallic trash and other small objects in the topsoil it can give the best results where the earth is distinctly stratified results from nine surveys are illustrated here the sites are all in the u s a and the gra

up dip directivity in near source during the 2009 l aquila main shock s u m m a r y in this study we have investigated the directivity associated with the initial up dip rupture propagation during the 2009 april 6 mw 6 1 l aquila normal faulting earthquake the objective is the understanding of how the peculiar initial behaviour of rupture history during the main shock has affected the near source recorded ground motions in the l aquila town and surrounding areas we have modelled the observed ground velocities at the closest near source recording sites by computing synthetic seismograms using a discrete wavenumbers and finite difference approach in the low frequency bandwidth 0 02 0 4 hz to avoid site effects contaminations we use both the rupture model retrieved by inverting ground motion waveforms and continuous high sampling rate gps time series as well as uniform slip constant rupture speed models our results demonstrate that the initial up dip rupture propagation characterizing the first 3 s of the rupture history during the l aquila main shock and releasing only 25 per cent of total seismic moment controls the observed ground motions in the near source this initial stage of the rupture is characterized by the generation of ground velocity pulses which we interpret as a forward directivity effect our modelling results confirm a heterogeneous distribution of rupture velocity during the initial up dip rupture propagation since uniform rupture speed models overestimate up dip directivity effects in the footwall of the causative fault the up dip directivity observed in the near field during the 2009 l aquila main shock is that expected for a normal faulting earthquake but it differs from that inferred from far field observations that conversely provide evidence of along strike directivity this calls for a careful analysis as well as for the realistic inclusion of rupture directivity to predict ground motions in the near source

continuous gps array and present day crustal deformation of japan a gps array with about 1 000 permanent stations is under operation in japan the gps array revealed coseismic deformations associated with large earthquakes and ongoing secular deformation in the japanese islands based on daily coordinate data of the gps stations strain rate distribution is estimated most regions with a large strain rate are related to plate boundaries and active volcanoes in addition the niigata kobe tectonic zone nktz is recognized as a region of large strain rate along the japan sea coast and in the northern chubu and kinki districts this newly found tectonic zone may be related to a hypothetical boundary between the eurasian or amurian and the okhotsk or north america plates precise observation of crustal deformation provides important boundary conditions on numerical modeling of earthquakes and other crustal activities appropriate computation methods of continuous deformation field are directly applicable to data assimilation for such numerical simulations

a faulting model for the 1979 imperial valley earthquake by comparing synthetic particle velocities with the near source strong motion data we have constructed by trial and error a faulting model for the 1979 imperial valley earthquake the calculation of the synthetic seismograms takes into account the vertical inhomogeneity of the elastic parameters in the imperial valley and the spatial variation of the slip rate parameters on the fault plane the independent slip rate parameters are 1 the strike slip rate amplitude 2 the dip slip rate amplitude 3 the duration that slip rate is nonzero the rise time of the slip function and 4 the rupture time which determines when the slip rate is initiated our faulting model has the following principal features 1 faulting occurred on the imperial fault and on the brawley fault rupture on the brawley fault being triggered by rupture on the imperial fault 2 the imperial fault is a plane 35 km long and 13 km wide with a strike of 323 measured clockwise from north and a dip of 80 ne the brawley fault is a 10 km long and 8 km wide plane with a strike of 360 and a dip of 90 3 faulting on the imperial fault is primarily right lateral strike slip with a small component of normal dip slip in the sediments at its northern end the larger strike slip rates are generally confined between depths of 5 and 13 km with maximum values of about 1 0 m s the duration varies on the fault with a maximum of 1 9 s which is considerably shorter than the total time for the rupture to take place 4 the rupture velocity on the imperial fault is highly variable locally it exceeds the shear wave velocity and in one instance the compressional wave velocity the average rupture velocity though is less than the shear wave velocity 5 although the slip on the brawley fault contributes only about 4 of the total moment it greatly affects the ground motion at nearby stations 6 the total seismic moment is 6 7 1018 n m where the imperial fault contributes 6 4 1018 n m and the brawley fault contributes 2 7 1017 n m in the process of trying almost 300 faulting models we found that given the elastic parameters of the medium the synthetic seismograms were most sensitive to the specification of the rupture time although the slip rate amplitudes are linearly related to the data the rupture time and the duration are not the parameterization of the nonlinear variables has a strong effect on the generation of synthetic seismograms from a finite fault

evidence for a supershear transient during the 2002 denali fault earthquake elastodynamic considerations suggest that the acceleration of ruptures to supershear velocities is accompanied by the release of rayleigh waves along the fault from the stress breakdown zone these waves generate a secondary slip pulse trailing the rupture front but manifest almost entirely in ground motion perpendicular to the fault in the near source region we construct a spontaneously propagating rupture model exhibiting these features and use it to explain ground motions recorded during the 2002 denali fault earthquake at pump station 10 located 3 km from the fault we show that the initial pulses on both the fault normal and fault parallel components are due to the supershear stress release on the fault whereas the later arriving fault normal pulses result from the trailing subshear slip pulse on the fault online material mpeg movies of rupture history and ground motion

seismic characteristics of supershear and sub rayleigh earthquakes implication from simple cases numerous investigations of supershear earthquakes make a conclusion that a supershear earthquake produces a seismic shock wave on the ground that may increase the resulting destruction we investigate a supershear rupture promoted by the free surface and find out that although the seismic energy of a supershear earthquake can be transmitted further with large amplitudes the peak slip velocity on a fault near the free surface is smaller than that caused by a subshear rupture earthquake our results show that the free surface induced supershear rupture mitigates the amplitudes of ground motions near the fault plane compared with the subshear rupture the coulomb failure change derived from dynamic modeling further suggests that this free surface induced supershear reduces aftershock potential compared to a subshear rupture both ground motion at near fault and aftershock possibility show low risk for the free surface induced supershear rupture earthquake than subshear earthquake contrary to the traditional concept