deposit from a giant wave on the island of lanai hawaii limestone bearing gravel the newly named hulopoe gravel blankets the coastal slopes on lanai the deposit which reaches a maximum altitude of 326 meters formerly was believed to have been deposited along several different ancient marine strandlines but dated submerged coral reefs and tide gauge measurements indicate that the southeastern hawaiian islands sink so fast that former worldwide high stands of the sea now lie beneath local sea level evidence indicates that the hulopoe gravel and similar deposits on nearby islands were deposited during the pleistocene by a giant wave generated by a submarine landslide on a sea scarp south of lanai

guyot and seamount morphology and tectonics of the hawaiian emperor elbow by multi beam sonar abstract five guyots and five seamounts are shown from the southernmost end of the emperor chain an area called the hawaiian emperor bend or the milwaukee seamount group in the north central pacific ocean the data are from the u s naval oceanographic office navoceano multi beam survey files the bend is shown to occur over an area encompassing 260 km questions are raised as to the relative proximity of different flat top depths and formational possibilities in the light of the differing geomorphology on the features in addition there are two new features taish and go shirakawa seamounts and four additional new names of features are introduced antoku guyot toba guyot and genji and go sanj seamounts

mass transport processes on amazon cone western equatorial atlantic three large mass transport deposits occur on the upper to middle amazon cone these slump debris flow complexes have been mapped from 3 5 khz echograms and cover approximately 75 000 sq km or about 10 of the cone the debris flows traveled down slopes with gradients as low as 1 90 to 1 165 0 3 to 0 6 for distances up to 300 km these deposits average 10 to 50 m in thickness and the total amount of sediments displaced may exceed 3 800 cu km the upslope parts of these complexes generally consist of hummocky slump or slide deposits which are commonly bounded by scarps of varying relief downslope from this zone of removal the deposits consist of thin the occurrence of such widespread mass movements on the amazon cone indicates that mass transport is probably an important sedimentation process on deep sea fans however most studies and models of modern deep sea fans have minimized or ignored the potential importance of mass transport processes in fan development we suggest that in the future both ancient and modern deep sea fans be more closely examined for mass transport deposits so that the importance of this process to overall fan development can be more accurately assessed

a multichannel seismic study of lithospheric flexure across the hawaiian emperor seamount chain existing models assume that the thickened crust beneath seamounts is the result of a surface volcanic load flexing an elastic plate new results suggest that flexed oceanic crust beneath the hawaiian emperor seamount chain is underlain by a 4 km thick deep crustal body we intepret the body as a deep crustal sill complex associated with the tholeiitic stage of volcano building along the chain

application of microseismic multiplet analysis to the basel geothermal reservoir stimulation events the stimulation of a geothermal well in basel switzerland produced a distribution of microseismic event locations with an overall alignment in the direction of the maximum horizontal stress fault plane solutions of individual larger events indicated movements on fracture planes at an angle to the maximum horizontal stress that could not be reliably interpreted from the event locations to obtain higher resolution images of the microseismic event locations events with similar waveforms have been identified by multiplet analysis a number of receivers were used in the multiplet processing to ensure each multiplet is represented by a unique group of waveforms the location accuracy within each multiplet has been significantly improved using cross correlation to refine the shear wave traveltime picks the distribution of events within each multiplet can be interpreted as being due to movements on a single fracture or a number of near parallel fractures it is shown that whilst the overall distribution of events is around the direction of the maximum horizontal stress the individual multiplets representing fracture planes have a variety of azimuths and dips

seismic wave attenuation from borehole and surface records in the top 2 5km beneath the city of basel switzerland summary we investigate attenuation q 1 of sediments of 2 5 3 5 km thickness underneath the city of basel switzerland we use recordings of 195 induced events that were obtained during and after the stimulation of a reservoir for a deep heat mining project in 2006 and 2007 the data set is ideally suited to estimate q as all events are confined to a small source volume and were recorded by a dense surface network as well as six borehole sensors at various depths the deepest borehole sensor is positioned at a depth of 2 7 km inside the crystalline basement at a mean hypocentral distance of 1 8 km this allows us to measure q for frequencies between 10 and 130 hz we apply two different methods to estimate q first we use a standard spectral ratio technique to obtain q and as a second measure we estimate q in the time domain by convolving signals recorded by the deepest sensor with a q operator and then comparing the convolved signals to recordings at the shallower stations both methods deliver comparable values for q we also observe similar attenuation for p and s waves qp qs as expected q increases with depth but with values around 30 50 it is low even for the consolidated permian and mesozoic sediments between 500 and 2700 m

the jura mountains an active foreland fold and thrust belt abstract recently completed in situ stress measurements using the borehole slotter at 33 new test sites within the swiss and french jura mountains combined with previously published stress data allow a detailed description of the contemporary state of stress in this fold and thrust belt and the adjacent foreland five stress provinces can be recognized with two different general orientations of maximum horizontal stress sh 1 the central and southwest provinces with a nnw sse to nne ssw orientation 2 the east northwest and southeast provinces with an e w to nw se orientation stress magnitudes are in general higher in the southern than in the northern jura mountains characteristic of the northern jura is an e w trending zone of low stress magnitudes which can be traced from the bresse depression south of besancon to the eastern end of the jura northwest of zurich boundaries of stress provinces show poor agreement with boundaries of tectonic units in the jura in addition stress provinces extend beyond the boundaries of the jura mountains into their foreland furthermore palaeo stress orientations show large discrepancies with respect to the contemporary stress orientation these findings are considered to indicate a termination of jura thin skinned foreland tectonics which probably took place some time between 9 and 4 ma according to palaeontological and tectonic evidence it is suggested that a new style of tectonics has commenced in the jura mountains deforming both the basement directly below the jura fold and thrust belt and the cover rocks in a similar mode

decollement tectonics in the jura forelandfold and thrust belt abstract interpretation of more than 1500 km of industry seismic reflection lines from theswiss and french jura mountains and the western swiss molasse basin demonstrates that themesozoic and cenozoic cover of the jura fold and thrust belt has been deformed over a veryweak basal decollement and displaced for many kilometers toward the nw and that thebasement is not involved a depth to the basement map derived from depth conversion of theseismic lines shows a rather smooth flat basement dipping 1 3 to the s se the low amplitudebroad folds of the molasse basin and the external plateau jura are controlled by evaporitepillows or anticlines of middle triassic age the high amplitude folds of the haute chaine jura however are related to nw or se vergent thrusts with at least kilometric dipslip displacementthat has doubled the entire jurassic sequence the plateau jura evaporite related folds located in the foreland are interpreted as early stage buckle folds with further deformation afault ramp nucleates and develops into thrust related folds as observed in the haute chaine thus within the fold and thrust belt deformation increases toward the hinterland in the molassebasin however low amplitude folds represent an early deformation stage which could notdevelop further owing to the load of the overlying thick tertiary clastic wedge

near surface attenuation and site effects from comparison of surface and deep borehole recordings abstract near surface attenuation and site effects are investigated using the seismograms of 17 local earthquakes recorded at depths of 0 0 3 1 5 2 5 and 2 9 km in the cajon pass borehole southern california the borehole penetrates 500 m of miocene sandstone and then crystalline granitic basement rock previous estimates of site response have been limited to shallower holes where the surface reflection interferes with the upgoing direct wave and the deepest sensor is not below the severe near surface effects in bedrock spectral ratios of the direct p and s waves for each earthquake between the different recording levels are well modeled with frequency independent q and amplification at the borehole q p 27 8 and q s 21 7 in the upper 2 9 km increasing from q p 26 and q s 15 in the upper 300 m to q p 133 and q s 47 between 1 5 and 3 km one event was also recorded at a surface granite site less than 1 5 km from the wellhead comparison of the 2 9 km recording with that at this granite site gives q p 50 and q s 23 the similarity of these values with those of previous studies at a wide range of sites suggests that q is very low in the near surface independent of rock type near surface amplification appears considerably more site dependent at the wellhead the amplifications at 1 hz of the direct p and s waves are 12 7 and 13 7 respectively these values include the free surface effect and are in reasonable agreement with the impedance contrast from the borehole logs at the granite site amplification of both p and s waves is less than four direct wave amplification at the wellhead is therefore at least three times that of the granite site the spectra of the direct and coda waves of the one earthquake recorded at both the wellhead and granite sites are compared with the corresponding 2 9 km recording coda wave amplification is in good agreement with the direct wave at the rock site but at the borehole the coda wave amplification factor overestimates the direct wave amplification by a factor of 3

the off shore continuation of an active basaltic volcano piton de la fournaise reunion island indian ocean structural and geomorphological interpretation from sea beam mapping abstract in 1984 a sea beam survey of the submarine east flank of piton de la fournaise was performed with r v jean charcot three main types of volcanic or volcano tectonic features have been identified 1 1 the subaerial ne and se volcanic rift zones of piton de la fournaise do not extend more than about five kilometers offshore unlike typical hawaiian rift zones which form narrow 2 4 km ridges extending tens of kilometers from the summit the active rift zones of piton de la fournaise widen downslope attaining more than 10 km at their front 2 2 the submarine extension of the grand brule slide is larger than the subaerial portion the entire slide forms a 7 24 km scar bounded by two ramparts to the north and south the slumped material may have moved as a debris flow forming a large talus downslope of the slide however the submarine counterpart of the south area of the grand brule seems to be composed by a slumped block whose structure is apparently not disturbed 3 3 another prominent feature is a conspicuous topographic high that occupies nearly all the center of the surveyed zone this cast flank submarine plateau cannot be associated with any active structure of piton de la fournaise its surface generally dips gently 2 3 and its northern and southern flanks are extensively cut by landslides cones of variable dimensions are observed on the plateau and farther to the east three hypotheses are examined to account for the origin of this morphology a remnant flank of an ancestral fournaise volcano associated with a large buried intrusion found by drilling beneath the grand brule b distinct volcanic massif or c material of a huge and ancient landslide the geophysical data show that the western part of this submarine plateau is reversely magnetized and associated with a moderate positive gravity anomaly this confirms that as suggested by the bathymetric analysis this part of the plateau is relatively coherent conversely the eastern portion of the plateau appears to be poorly magnetized and composed of low density material probably chaotic materials derived from landslides the reversed magnetization of the western part shows that the whole structure is older than 0 7 ma these results show that the volcanic history of piton de la fournaise is more complex than previously thought

antiquity of the continental slope along the middle atlantic margin of the united states a detailed high resolution geophysical study of part of the continental slope along the mid atlantic margin of the united states indicates that it is an ancient relict landscape largely unmodified by modern slope processes the slope morphology is heavily influenced by bedrock outcrops including joints and bedding planes rather than by any single degradational process a pelagic drape averaging 3 to 5 meters in thickness blankets the slope carbon 14 dates from eight drop cores show that the drape was deposited in late pleistocene and holocene times the holocene part of the drape comprising the uppermost 1 meter was deposited at a continuous rate of 10 centimeters per 1000 years most features on the slope predate the drape cover

earthquake source scaling relationships from 1 to 5 ml using seismograms recorded at 2 5 km depth the scaling relationships of earthquake sources less than about magnitude 3 have been the subject of considerable controversy over the last two decades studies of such events have shown a tendency for the constant stress drop self similarity of larger earthquakes to breakdown at small magnitudes and an apparent minimum source dimension of about 100 m has been observed other studies showed that this apparent breakdown in scaling could be an artifact of severe near surface attenuation limiting the spatial resolution of surface data in this study source parameters are determined for over 100 nearby tectonic earthquakes from recordings at a depth of 2 5 km in granite in the cajon pass scientific drill hole southern california comparison of the seismograms recorded at this depth with those at the wellhead clearly demonstrates the effect of the severe attenuation in the upper kilometers of the earth s crust source parameters are calculated by spectral modeling of three component p and s waves assuming four source models based on the brune 2 n 2 model in model l n 2 is fixed and q of p and s waves is determined to be 912 581 1433 and 1078 879 1323 respectively the numbers in parentheses are 1 standard deviation in model 2 qp qs 1000 is assumed and n is allowed to vary the 2 model is a good average for the data set but there is some real scatter supported by the data in model 3 qp qs 1000 is also assumed and 2 is constrained and in model 4 attenuation is ignored and n is allowed to vary source dimensions of less than 10m are observed for all four models 10 times smaller than the proposed minimum no breakdown in constant stress drop scaling is seen in the downhole data approximately ml 1 to 5 5 m0 109 1016 nm the ratio between radiated seismic energy estimated by integrating the velocity squared spectra with adequate signal bandwidth and seismic moment appears to decrease gradually with decreasing moment in the magnitude range 1 to 7 this is not incompatible with a constant stress drop but could result from errors in calculating energy the ratio of the s wave energy to that radiated by the p waves is about 14 after correction for attenuation this low value is consistent with the corner frequency shift of about 1 3 this corner frequency shift is observed for all four source models and therefore is interpreted as being source controlled

ground motion and macroseismic intensities of a seismic event related to geothermal reservoir stimulation below the city of basel observations and modelling summary to stimulate a geothermal reservoir below the city of basel switzerland fluid was injected in december 2006 at high pressure into a 5 km deep borehole this stimulation led to an increase in local seismicity with the largest seismic event ml 3 4 occurring on 2006 december 8 the event was widely felt by the local population slight non structural damage to buildings was reported and ultimately this event was the cause to put the geothermal project on hold in this study we present recorded ground motion and determinations of macroseismic intensity of the ml 3 4 event as well as simulations of seismic wave propagation and a model to predict macroseismic intensities as the two models are based on different simplifying assumptions and different underlying physical processes the predicted intensity distributions exhibit differences in their details however the first order characteristics of the observed macroseismic intensity distribution are well matched based on this result we compute intensities also for hypothetical scenarios of earthquakes with larger magnitudes

attenuation of seismic shear wave energy in switzerland summary modelling the attenuation of shear wave energy is an important component of seismic hazard analysis previous studies have shown how attenuation particularly in the uppermost layers of the crust is regionally dependent the impact of this is that the decay of energy radiating from an earthquake will vary from place to place to quantify the regional attenuation in switzerland we model the fourier spectral amplitude of small to moderate earthquakes recorded on the local seismic networks high frequency decay is parametrized by q and while apparent geometrical spreading models account for the frequency independent decay of energy we analyse ground motion encompassing the significant duration of shaking to provide models that are useful for the purpose of seismic hazard analysis two methods are used to estimate the whole path attenuation parameter t first a simultaneous fit of the source model and attenuation effects across the entire spectral bandwidth for earthquakes with m 2 and secondly a linear fit of an attenuation model to the high frequency part of the spectrum for earthquakes with m 3 5 the t parameter is found to vary with hypocentral distance consistent with a weakly attenuating crust and strongly attenuating uppermost layer 1 d tomographic inversions indicate a profile of increasing q with depth down to the moho frequency independent decay is parametrized using a three part model which allows for the inclusion of moho reflection phases in the spectrum in the range of 20 140 km in the swiss foreland and from 70 to 140 km in the swiss alps

the southeastern border of the upper rhine graben a 3d geological model and its importance for tectonics and groundwater flow a 3d geological model of the area east of basel on the southeastern border of the upper rhine graben consisting of 47 faults and six stratigraphic horizons relevant for groundwater flow was developed using borehole data geological maps geological cross sections and outcrop data this model provides new insight into the discussions about the kinematics of the area between the southeastern border of the upper rhine graben and the tabular jura east of basel a 3d analysis showed that both thin skinned and thick skinned tectonic elements occur in the modeled area and that the anticline and a series of narrow graben structures developed simultaneously during an extensional stress field varying from e w to sse nnw which lasted from the middle eocene to late oligocene in a new approach the faults and horizons of the 3d geological model were transferred into discrete elements with distributed hydrogeological properties in order to simulate the 3d groundwater flow regime within the modeled aquifers a three layer approach with a horizontal regularly spaced grid combined with an irregular property distribution of transmissivity in depth permitted the piezometric head of the steady state model to be automatically calibrated to corresponding measurements using more than 200 piezometers groundwater modeling results demonstrated that large scale industrial pumping affected the groundwater flow field in the upper muschelkalk aquifer at distances of up to 2 km to the south the results of this research will act as the basis for further model developments including salt dissolution and solute transport in the area and may ultimately help to provide predictions for widespread land subsidence risks

microseismic imaging of a geothermal reservoir stimulation exploitation of geothermal heat energy from rocks at depths of several km has been the goal of vari ous projects since the mid 1970s to exploit the energy in these deep rocks poses technical challenges in drilling well completion creation of the heat exchange reservoir at depth and control of seismicity in spite of the difficulties what are now known as enhanced engineered geothermal systems egs offer almost limitless clean energy so it is not surprising that this technology continues to attract investors however commercial energy production from the greatest potential resource hot rock at depths 5 km or temperatures 200 c remains elusive

determination of displacements in the upper rhine graben area from gps and leveling data the upper rhine graben is a north northeast trending rift system which belongs to the european cenozoic rift system today the southern part of the graben is seismically still active earthquakes of magnitude 5 have a recurrence time of approximately 30 years in order to monitor and to determine the displacements in the study area gps measurements have been carried out in two campaigns 1999 and 2000 and observations of the available permanent stations have been processed in 2002 owing to the small size of deformations expected high accuracy requirements must be met by the gps processing in order to achieve these requirements precise antenna modeling has been introduced into the processing as expected the short time span has not enabled to detect significant displacements from the gps measurements the deformation analysis shows that the horizontal displacement rates do not exceed 1 mm year which is compatible with the geological information owing to the fact that the accuracy of positioning with gps for the vertical coordinates is lower than for the horizontal coordinates the determination of vertical displacements has been carried out using the leveling technique in the area of freiburg first order and second order leveling lines have been chosen for the detection of local displacements on the weinstetten on the lehen schonberg and on the main border fault mbf some sections of these faults are still active today significant vertical displacements have been observed at the weinstetten fault in the area of bad krozingen and on the mbf in freiburg the displacement rates 1925 1984 are 0 17 0 01 mm year and 0 25 0 02 mm year respectively the results agree very well with the results of seismotectonic investigations and show that ongoing displacements can be found on the northern part of the lehen schonberg fault in the vicinity of eichstetten and on the mbf in the vicinity of freiburg

recent stress field and neotectonics in the eastern jura mountains switzerland the regional stress field and its local variation were determined for the northern part of central switzerland fig 1 by using overcoring techniques doorstopper triaxial strain cell and observations of breakouts in deep boreholes the results are compared with fault plane solutions of earthquakes and with the orientation of horizontal stylolites in the northern part of central switzerland the nw se orientation of the maximum horizontal stress sh which is characteristic for central europe was observed only in the crystalline basement in the folded jura and south of it in one well the greatest principal horizontal stress above the triassic decollement horizon is oriented approximately in a n s to nne ssw direction this direction persists into the western tabular jura and the southernmost rhine graben only in the eastern part of the tabular jura the greatest principal horizontal stress shows a nnw sse to nw se orientation comparison of the near surface stress field as determined by in situ stress measurements and borehole breakouts with the directions of horizontal stylolites generated during the evolution of the folded jura indicates that the orientation of the recent stress field near the earth s surface is the same as that which prevailed during the upper miocene to lower pliocene the central part of northern switzerland is therefore the first area in central europe where it is possible to demonstrate that the near surface stress field is decoupled from that in the crystalline basement the difference in the orientation of the greatest principal horizontal stress is about 50

diatoms as bioindicators of site use locating turf structures from the viking age diatoms recovered from archaeological features on a viking age farmstead excavation in the mosfell valley in southwestern iceland are utilized as microscopic indicators of turf based structures eroded turf can be difficult to distinguish macroscopically from naturally occurring sediments because turf foun dations erode and melt into the landscape over time leaving minimal evidence of site use turf was a principle building component in iceland until the early 20th century turf strips and blocks were harvested from lowlands where organically rich peat and abundant water contributed to the develop ment of bog plants with thick root mats that produced premium turf diatoms embedded in turf reflect the ecological conditions of the peat bog at the time of deposition turf was cut from the bog and transported to higher elevations where drainage was more conducive to house construction siliceous diatom frustules are resistant to decay and preserve well archaeologically the presence of diatoms in archaeological sediments is considered a marker of sediment provenience and an indication of human site use and anthropogenic modification of natural substrates this paper demonstrates how diatom analysis can determine the presence and delimitation of archaeological features otherwise difficult to distinguish with the naked eye

determination of earthquake energy release and ml using terrascope we estimated the energy radiated by earthquakes in southern california using on scale very broadband recordings from terrascope the method we used involves time integration of the squared ground motion velocity and empirical determination of the distance attenuation function and the station corrections the time integral is typically taken over a duration of 2 min after the p wave arrival the attenuation curve for the energy integral we obtained is given by q r cr n exp kr r 2 2 h ref 2 with c 0 49710 n 1 0322 k 0 0035 km 1 and h ref 8 km where is the epicentral distance a similar method was used to determine m l using terrascope data the station corrections for m l are determined such that the m l values determined from terrascope agree with those from the traditional optical wood anderson seismographs for 1 5 6 5 m l saturates the ratio e s m 0 m 0 seismic moment a measure of the average stress drop for six earthquakes the 1989 montebello earthquake m l 4 6 the 1989 pasadena earthquake m l 4 9 the 1990 upland earthquake m l 5 2 the 1991 sierra madre earthquake m l 5 8 the 1992 joshua tree earthquake m l 6 1 and the 1992 landers earthquake m w 7 3 are about 10 times larger than those of the others that include the aftershocks of the 1987 whittier narrows earthquake the sierra madre earthquake the joshua tree earthquake and the two earthquakes on the san jacinto fault the difference in the stress drop between the mainshock and their large aftershocks may be similar to that between earthquakes on a fault with long and short repeat times the aftershocks which occurred on the fault plane where the mainshock slippage occurred had a very short time to heal hence a low stress drop the repeat time of the major earthquakes on the frontal fault systems in the transverse ranges in southern california is believed to be very long a few thousand years hence the events in the transverse ranges may have higher stress drops than those of the events occurring on faults with shorter repeat times such as the san andreas fault and the san jacinto fault the observation that very high stress drop events occur in the transverse ranges and the los angeles basin has important implications for the regional seismic potential the occurrence of these high stress drop events near the bottom of the seismogenic zone strongly suggests that these fault systems are capable of supporting high stress that will eventually be released in major seismic events characterization of earthquakes in terms of the e s m 0 ratio using broadband data will help delineate the spatial distribution of seismogenic stresses in the los angeles basin and the transverse ranges

focal mechanisms and locations of earthquakes in the vicinity of the 1975 kalapana earthquake aftershock zone 1970 1979 implications for tectonics of the south flank of kilauea volcano island of hawaii the november 29 1975 kalapana earthquake of magnitude 7 1 on the south flank of kilauea volcano hawaii represents a major rift tectonic event it is generally understood that the earthquake resulted from movement on a nearly horizontal fault plane with the crustal block south of kilauea s east rift zone moving south southeastward up to several meters well recorded earthquakes on the south flank of kilauea from 1970 to 1979 were analyzed and focal mechanisms determined to obtain a better understanding of the details of south flank tectonics included are a large number of earthquakes from the aftershock sequence of the 1975 earthquake hypocenters are distributed in a subplanar zone that dips 2 to 3 to the west at a depth of about 8 9 km depth we interpret this pattern to coincide with a portion of the slip plane of the kalapana earthquake and to be consistent with the notion of the slip plane occurring in a weak layer at the top of the old oceanic crust focal mechanisms are remarkably constant throughout this time period both before and after the 1975 event and closely agree with the mainshock mechanism p axis azimuths and slip vectors for the low angle fault planes are normal to the middle and lower east rift zones of kilauea there is suggestion of a change in the orientation of p axes from shallower to steeper plunge at the time of the kalapana earthquake such a change is consistent with a general reduction in the horizontal compressional stress normal to the rift zone at the time of the large earthquake no other evidence of precursory reorientation of the stress field was found and the precise predictability of this event remains in doubt however a general model of the tectonics of the volcanic rift system is now available that satisfies a number of geological and geophysical observations

deterministic earthquake scenario for the basel area simulating strong motions and site effects for basel switzerland 1 the basel earthquake of 18 october 1356 is considered one of the most serious earthquakes in europe in recent centuries i0 ix m 6 5 6 9 in this paper we present ground motion simulations for earthquake scenarios for the city of basel and its vicinity the numerical modeling combines the finite extent pseudodynamic and kinematic source models with complex local structure in a two step hybrid three dimensional 3 d finite difference fd method the synthetic seismograms are accurate in the frequency band 0 2 2 hz the 3 d fd is a linear explicit displacement formulation using an irregular rectangular grid including topography the finite extent rupture model is adjacent to the free surface because the fault has been recognized through trenching on the reinach fault we test two source models reminiscent of past earthquakes the 1999 athens and the 1989 loma prieta earthquake to represent mw 5 9 and mw 6 5 events that occur approximately to the south of basel to compare the effect of the same wave field arriving at the site from other directions we considered the same sources placed east and west of the city the local structural model is determined from the area s recently established p and s wave velocity structure and includes topography the selected earthquake scenarios show strong ground motion amplification with respect to a bedrock site which is in contrast to previous 2 d simulations for the same area in particular we found that the edge effects from the 3 d structural model depend strongly on the position of the earthquake source within the modeling domain

diverse basalt types from loihi seamount hawaii loihi seamount is the southeasternmost active volcano in the hawaiian emperor volcanic chain the seamount is considered representative of the early phase of hawaiian volcanism because of its youth small size and location near the melting anomaly seventeen dredge stations recovered transitional basalt alkalic basalt and basanite in addition to the expected tholeiitic basalt four flows of alkalic basalt contain common small dunite xenoliths the recovered samples have thin palagonite rinds and almost no manganese on the glassy surfaces we estimate that the lavas are less than about 4 000 yr old and many are less than 1 000 yr old loihi seamount is apparently in a transitional growth phase between the early eruption of alkalic lavas and the commonly observed subaerial tholeiitic eruptive phase previously thought to dominate hawaiian volcanism from inception until the postcaldera collapse alkalic stage

seismic energy release in mexican subduction zone earthquakes we estimated radiated seismic energy es from 18 shallow thrust mexican subduction zone earthquakes 4 1022 m 1 1 1028 dyne cm 11 h 37 km using digital accelerograms from the guerrero accelerograph array and neglecting stations with large site effects es is computed by integrating squared velocity spectra after applying geometrical spreading and q corrections we discarded epicentral recordings for the largest michoacan event we find that log es m 4 152 0 275 which gives a median value of es m and apparent stress a of 7 1 10 5 and 24 bars respectively the median es m value is in accordance with gutenberg and richter s g r 1956 formula for es in which es m 5 10 5 is implicit worldwide es m data where es is computed from local records mostly fall between 5 10 5 and 5 10 4 for events with m 1022 dyne cm on the other hand es m values generally lie between 5 10 6 and 5 10 5 if es is estimated from teleseismic records especially anomalous are the es m data from kikuchi and fukao 1988 for large and great earthquakes which fall near 5 10 6 thus while es from local data suggests that the g r relation seldom overestimates seismic energy release the teleseismic data point to the contrary the cause of this discrepancy may lie in the difficulty of resolving incoherent radiation from the fault and inappropriate choice of t in the analysis of teleseismic data

morphology and structure of loihi seamount based on seabeam sonar mapping loihi seamount has been mapped using seabeam multibeam sonar and the resulting data have been processed to produce bathymetric maps with a 10 m contour interval and shaded relief perspective images analysis of morphological and structural data recorded in the maps and images indicates that constructional volcanism on loihi has been localized predominantly along its southern and northern rift zones and that these rifts have been active since early in the seamount s history the distinct asymmetry between loihi s eastern and western slopes the eastern slopes are steeper is attributed to mass wasting of large sections of the volcano s west flank two large amphitheater valleys on the seamount s west flank are believed to have resulted from repeated mass wasting events triggered by earthquakes associated with an early rift zone whose core now lies buried beneath the block feature present on loihi s southwest flank the prominent kink in the present south rift zone of loihi may represent a fundamental readjustment of along rift magma conduits that was caused by gravitational slumping on the southwest flank of the volcano lava cones and constructional volcanic ridges are present along the rims of summit pit craters and form a continuous chain of volcanic constructs around the periphery of the summit platform the concentric arrangement of young eruptive vents pn loihi s summit may be caused by ring dikes the morphology and structural interrelationships of pit craters on loihi s summit suggest that the southeastern pit is the youngest the formation of a summit platform on loihi may have been caused by repeated collapse of pit craters and the southward migration of primary magma conduits that underlie the pits this model predicts a north to south age progression for volcanism on loihi s summit

seismic wave propagation in shallow layers at the gonaf tuzla site istanbul turkey using the first dataset available from the downhole geophysical observatory of the north anatolian fault we investigated near surface seismic wave propagation on the tuzla peninsula istanbul turkey we selected a dataset of 26 seismograms recorded at tuzla at sensor depths of 0 71 144 215 and 288 m to determine near surface velocities and attenuation structures the waveforms from all sensors were pairwise deconvolved and stacked this produced low noise empirical green s functions for each borehole depth interval from the green s functions we identified reflections from the free surface and a low velocity layer between 90 and 140 m depth the presence of a low velocity zone was also confirmed by a sonic log run in the borehole this structure plus high near surface p and s wave velocities of 3600 4100 and 1800 m s lead to complex interference effects between upgoing and downgoing waves as a result the determination of quality factors q with standard spectral ratio techniques was not possible instead we forward modeled the green s functions in the time domain to determine effective q values and to refine our velocity estimates the effective q p values for the depth intervals of 0 71 0 144 0 215 and 0 288 m were found to be 19 35 39 and 42 respectively for the s waves we obtained an effective q s of 20 in the depth interval of 0 288 m considering the assumptions made in our modeling approach it is evident that these effective quality factors are biased by impedance contrasts between our observation points our results show that even after correcting for a free surface factor of 2 the motion at the surface was found to be 1 7 times greater than that at 71 m depth our efforts also illustrate some of the difficulties of dealing with site effects in a strongly heterogeneous subsurface online material plots of resistivity and caliper logs and the spectra of all 26 events

global patterns of radiated seismic energy and apparent stress radiated energies from shallow earthquakes with magnitudes 5 8 that occurred between 1986 and 1991 are used to examine global patterns of energy release and apparent stress in contrast to traditional methods which have relied upon empirical formulas these energies are computed through direct spectral analysis of broadband seismic waveforms velocity squared spectra of body waves are integrated after they have been corrected for effects arising from depth phases frequency dependent attenuation and focal mechanism the least squares regression fit of energy es to surface wave magnitude ms for a global set of 397 earthquakes yields log es 4 4 1 5ms which implies that the gutenberg richter relationship overestimates the energies of earthquakes the least squares fit between es and seismic moment m0 is given by the relationship es 1 6 10 5 m0 which yields 0 47 mpa as the average global value of apparent stress however the regression lines of both es ms and es m0 yield poor empirical predictors for the actual energy radiated by any given earthquake the scatter of data is more than an order of magnitude about each of the regression lines on the other hand global variations between es and mo while large are not random when subsets of es m0 are plotted as a function of seismic region and faulting type the scatter in data is substantially reduced the es m0 fits for many seismic regions and tectonic environments are very distinctive and a characteristic apparent stress c can be derived the lowest apparent stresses 3 0 mpa are associated with strike slip earthquakes that occur at oceanic ridge ridge transforms and in intraplate environments seaward of island arcs intermediate values of apparent stress 1 5 a 3 0 mpa are associated with strike slip earthquakes at incipient or transitional plate boundaries in general the dominant mode of failure for a tectonic environment is associated with the faulting type that has the lowest apparent stress an energy magnitude me can complement moment magnitude mw in describing the size of an earthquake me being derived from velocity power spectra is a measure of seismic potential for damage mw being derived from the low frequency asymptote of displacement spectra is more physically related to the final static displacement of an earthquake when earthquake size is ranked by moment a list of the largest events is dominated by earthquakes with thrust mechanisms when earthquake size is ranked by energy the list of the largest events is dominated by strike slip earthquakes

a summary of attenuation measurements from borehole recordings of earthquakes the 10 hz transition problem earthquake seismograms recorded by instruments in deep boreholes have low levels of background noise and wide signal bandwidth they have been used to extend our knowledge of crustal attenuation both in the near surface and at seismogenic depths site effects are of major importance to seismic hazard estimation and the comparison of surface shallow and deep recordings allows direct determination of the attenuation in the near surface all studies to date have found that q is very low in the near surface 10 in the upper 100 m and increases rapidly with depth unlike site amplification attenuation at shallow depths exhibits little dependence on rock type these observations are consistent with the opening of fractures under decreasing lithostatic pressure being the principal cause of the severe near surface attenuation seismograms recorded in deep boreholes are relatively unaffected by near surface effects and thus can be used to measure crustal attenuation to higher frequencies 100 hz than surface recordings studies using both direct and coda waves recorded at over 2 km depth find q to be high 1000 at seismogenic depths in california increasing only weakly with frequency between 10 and 100 hz intrinsic attenuation appears to be the dominant mechanism these observations contrast with those of the rapidly increasing q with frequency determined from surface studies in the frequency range 1 to 10 hz further work is necessary to constrain the factors responsible for this apparent change in the frequency dependence of q but it is clearly unwise to extrapolate q estimates made below about 10 hz to higher frequencies

microearthquake s wave observations from 0 to 1 km in the varian well at parkfield california abstract high gain three component seismometers from 0 to 1 km deep along the varian a 1 well at parkfield california were used to record the waveforms of nearby microearthquakes despite being in the thick tertiary sediments of the parkfield syncline the s wave amplification at this site is only about a factor of 3 the spectral content and spectral ratios of s waves along the well show that the average qs in the top 1 km at this site is 37 with the qs in different subintervals varying between 8 and 65 based on initial s wave polarizations a complex s wave velocity structure must exist at and below the varian site this structure appears to include position dependent anisotropy as well as steep lateral velocity gradients at a depth of 1 km s wave splitting parallel and normal to the san andreas fault zone is consistently observed this splitting scales at roughly 0 01 sec km subsequent to the split s waves the particle motion seems to be controlled by event focal mechanism above 1 km the upgoing s waves attenuate and change directions of polarization with a new splitting rate of 0 1 sec km uniquely for some events on the san andreas fault immediately below the varian site large post s wave signals with normal dispersion are present we propose that these phases are fault zone guided waves channeled from the san andreas fault to the varian site along the gold hill fault

a single force model for the 1975 kalapana hawaii earthquake a single force mechanism is investigated as the source of long period seismic radiation from the 1975 kalapana hawaii earthquake m s 7 1 the observed love wave radiation pattern determined from the spectra of world wide standard seismograph network and high gain long period records at 100 s is two lobed with azimuth consistent with a near horizontal single force acting opposite strike 330 to the observed displacement direction of the earthquake this pattern is inconsistent with the expected double couple pattern assuming a form of the force time history of a one cycle sinusoid the total duration of the event estimated from rayleigh waves at two international deployment of accelerometers stations is approximately 180 s the peak amplitude f o of the time function is 1 10 15 n from amplitudes of love and rayleigh waves the interpretation is that the bulk of the seismic radiation was produced by large scale slumping of a large area of the south flank of kilauea volcano the single force is a crude representation of the effect on the earth of the motion of a partially decoupled large slide mass using the mass estimated from the tsunami generation area 10 15 10 16 kg the peak acceleration of the slide block 0 1 1 m s 2 inferred from the seismic force is comparable with the acceleration due to gravity on a gently inclined plane the slump model for the kalapana earthquake is also more qualitatively consistent with the large horizontal deformation 8 m on land and tsunami associated with the earthquake which are difficult to explain with the conventional double couple source model the single force source has been used previously to model the long period seismic waves from the landslide accompanying the eruption of mount st helens volcano and may explain other anomalous seismic events as being due to massive slumping of sediments or unconsolidated material and not to elastic dislocation

the storegga slides evidence from eastern scotland for a possible tsunami abstract the second storegga slide on the continental slope off western norway has been dated at between 8000 and 5000 yrs b p a prominent sand layer in flandrian holocene deposits along the coast of eastern scotland and dated at approximately 7000 yrs b p may have been deposited by a tsunami generated by the slide the altitude and stratigraphy of the layer allow estimates to be made of the magnitude of the earthquake which initiated the slide

the 1356 basel earthquake an interdisciplinary revision summary within historical times one of the most damaging events in intra plate europe was the 1356 basel earthquake given its significance for assessing regional seismic hazard in central europe an interdisciplinary project was launched in 2005 to re explore this event our effort aimed to incorporate techniques from history seismology archaeology paleoseismology and engineering new and reinterpreted historical data from basel and its surroundings plus archaeological findings on buildings that survived the event and still exist enabled this macroseismic assessment palaeoseismological studies combined with historical evidence provided additional data for the surrounding areas archaeology offers sparse information on some castles and churches sometimes supported by historical records a contemporary source allows some reconstruction of the stronger fore and aftershocks this expanded information base improves our sense of the event s damage and consequences for the city of basel the relatively abundant archaeological data allowed us to assess statistically the macroseismic intensity at ix although the pattern of damage was scattered data points for the expected area of damage around basel are not distributed regularly the absence of historical and archaeological findings for southern germany might be due to archival problems future investigation may improve this situation our results confirm that the basel earthquake was the most destructive known for central europe intensities up to viii are found within a radius of about 30 km analysing the macroseismic field confirms our former assessment of the event and shows an epicenter located about 10 km south of basel the most probable range for the moment magnitude mw is between 6 7 and 7 1

surface and near surface effects on seismic waves theory and borehole seismometer results a simple plane wave model is adequate to explain many surface versus borehole seismometer data sets using such a model we present a series of examples which demonstrate the effects of the free surface near surface velocity gradients and low impedance surface layers on the amplitudes of upcoming body waves in some cases these amplitudes are predictable from simple free surface and impedance contrast expressions however in other cases these expressions are an unreliable guide to the complete response and the full plane wave calculation must be performed large surface amplifications are possible even without focusing due to lateral heterogeneities or nonlinear effects both surface and borehole seismometer site responses are almost always frequency dependent ocean bottom versus borehole seismic data from the 1983 ngendei seismic experiment in the southwest pacific are consistent with both a simple plane wave model and a more complete synthetic seismogram calculation the borehole seismic response to upcoming p waves is reduced at high frequencies because of interference between the upgoing p wave and downgoing p and sv waves reflected from the sediment basement interface however because of much lower borehole noise levels the borehole seismometer enjoys a p wave signal to noise advantage of 3 to 7 db over nearby ocean bottom instruments

prodigious submarine landslides on the hawaiian ridge the extensive area covered by major submarine mass wasting deposits on or near the hawaiian ridge has been delimited by systematic mapping of the hawaiian exclusive economic zone using the side looking sonar system gloria these surveys show that slumps and debris avalanche deposits are exposed over about 100 000 km2 of the ridge and adjacent seafloor from kauai to hawaii covering an area more than 5 times the land area of the islands some of the individual debris avalanches are more than 200 km long and about 5000 km3 in volume ranking them among the largest on earth the slope failures that produce these deposits begin early in the history of individual volcanoes when they are small submarine seamounts culminate near the end of subaerial shield building and apparently continue long after dormancy consequently landslide debris is an important element in the internal structure of the volcanoes the dynamic behavior of the volcanoes can be modulated by slope failure and the structural features of the landslides are related to elements of the volcanoes including rift zones and fault systems the landslides are of two general types slumps and debris avalanches the slumps are slow moving wide up to 110 km and thick about 10 km with transverse blocky ridges and steep toes the debris avalanches are fast moving long up to 230 km compared to width and thinner 0 05 2 km they commonly have a well defined amphitheater at their head and hummocky terrain in the lower part oceanic disturbance caused by rapid emplacement of debris avalanches may have produced high level wave deposits such as the 365 m elevation hulopoe gravel on lanai that are found on several islands most present day submarine canyons were originally carved subaerially in the upper parts of debris avalanches subaerial canyon cutting was apparently promoted by the recently steepened and stripped slopes of the landslide amphitheaters

a stochastic ground motion model for switzerland abstract we present a stochastic ground motion model for switzerland a model for the far field fourier amplitude spectra of earthquakes is first proposed constrained by ground motions observed from small local and regional earthquakes in addition to macroseismic intensities observed from large damaging events in switzerland we then use this model in a stochastic simulation technique to generate predictions of peak ground acceleration and velocity and 5 damped response pseudo spectral acceleration we facilitate the prediction of ground motions from finite fault sources through the use of the r eff distance metric and show that magnitude and distance scaling behavior of events up to m w 7 5 is broadly consistent with next generation attenuation and japanese models ground motion prediction uncertainty is described in terms of between and within event uncertainties through residual analysis of response spectra finally single station sigma is derived accounting for the prediction uncertainty at a given site without the ergodic assumption consistency of the model is emphasized through its compatibility with other seismic hazard products the model is referenced to a generic rock profile that was developed by utilizing velocity profiles of the sites of seismic stations and is calibrated at higher magnitudes to the swiss regional macroseismic intensity prediction model furthermore the model is based on moment magnitudes from the recently developed earthquake catalogue of switzerland 2009 ecos09 the well defined reference for the model means that it can easily be adapted for a site specific application for instance through the use of proxies such as quarter wavelength velocity and travel time average shear wave velocity in the upper 30 m v s 30

evidence for non constant energy moment scaling from coda derived source spectra 1 we present two lines of evidence showing the ratio of seismically radiated energy er to seismic moment mo increases with increasing moment for crustal events spanning 5 orders in seismic moment this ratio often referred to as the scaled energy er m0 has been elusive and the subject of recent debate within the seismological community because significant frequency dependent corrections must be made to account for source and path heterogeneity it is not uncommon that energy estimates of the same event by different researchers have significantly different values to minimize some of the potential problems we used the regional coda methodology outlined by mayeda et al 2003 on 4 large earthquake sequences mw 7 4 and 7 2 izmit duzce mw 7 2 gulf of aqaba mw 7 3 landers and mw 7 2 hector mine this methodology has been shown to provide the lowest variance estimate of the source spectrum when compared against traditional direct wave estimates in our first approach we made energy estimates from coda derived spectra and observed that increases with increasing moment for 3 7 mw 7 4 in our second approach we used the simple idea outlined by prieto et al 2004 to directly test for self similarity under self similarity earthquake source spectra scaled by 3 should have the same shape to test this one needs very stable spectra either through spectral stacking of direct wave spectra or by the use of stable coda derived spectra for all sequences we found that the mainshocks and larger aftershocks had significantly different spectral shapes than the smaller events the scaled 3 spectra of the larger events represented an upper bound having larger amplitudes near the corner frequency in fact an 3 5 scaling moved the larger events closer to the mean of the spectral population though the spectral shape differences persisted these results strongly suggest that earthquakes are not scaling self similarly and that complexities in the rupture process such as variable slip velocity exist between small and large events

high frequency borehole seismograms recorded in the san jcinto fault zone southern california part 2 attenuation and site effects we examine surface and downhole p and s wave spectra from local earthquakes recorded at two borehole seismometer arrays knw bh and pfo bh installed in the southern california batholith region of the san jacinto fault zone by the u s geological survey to assess the influence of the weathered layer on the spectral content of high frequency 2 to 200 hz seismic signals earthquake signals recorded downhole at both sites show significantly improved seismic bandwidth due to both a reduction in ambient noise levels and especially to dramatically increased levels of high frequency signal significant seismic signal is observed up to approximately 190 hz for p waves at knw bh stacked spectral ratios from these signals indicate that the highly weathered near surface between 0 and 150 m at knw bh and pfo bh exerts a much larger influence on seismic signals than deeper between 150 and 300 m material modeling of uphole downhole spectral ratio data suggests q 6 5 and q 9 between 0 and 150 m increasing to q 27 and q 26 between 150 and 300 m an outcrop mounted anza network station deployed approximately 0 4 km from knw bh displays roughly similar high frequency content to the knw bh downhole sensors but it exhibits spectra that are significantly colored by directional resonances low q and low velocity near surface material forms a lossy boundary layer at these borehole sites that is advantageous to the high frequency downhole environment not only are noise levels reduced but reflections from the surface and near surface are greatly attenuated as a result high frequency recordings from below the weathered zone more nearly resemble those recorded in a whole space than would otherwise be expected