regional scale co seismic landslide assessment using limit equilibrium analysis abstract traditionally regional assessment of seismic slope stability has been done using the infinite slope rigid sliding block analysis a major disadvantage of this approach is the resulting overestimation of the critical acceleration of the slope due to the underlying assumption of a predefined slope failure plane and consequently the underestimation of hazard areas prone to sliding in this paper we present a modified approach for assessing seismic slope instabilities using a model based on limit equilibrium analysis and circular slip surfaces with no restriction to any predefined slope failure plane for this purpose we conduct a parametric study to identify the relationship between the critical acceleration of the slope the slope angle and the slope shear strength parameters we model typical slopes in the rocscience software slide using bishop s limit equilibrium method to identify the critical accelerations that corresponds to a failure plane with factor of safety equal to one the critical accelerations were plotted against the variables in the parametric study and the best fit equations were obtained the proposed approach was developed for global application but it was tested using the well documented co seismic landslide database of the 1994 northridge ca earthquake the predicted sliding areas were compared to the inventory of landslides that were triggered in the val verde region in los angeles by the earthquake qualitative and quantitative assessments of the proposed model clearly show its advantages in predicting potential sliding areas

landslides triggered by the 22 july 2013 minxian zhangxian china mw 5 9 earthquake inventory compiling and spatial distribution analysis abstract on july 22 2013 an earthquake of ms 6 6 occurred at the junction area of minxian and zhangxian counties gansu province china this earthquake triggered many landslides of various types dominated by small scale soil falls slides and topples on loess scarps there were also a few deep seated landslides large scale soil avalanches and fissure developing slopes in this paper an inventory of landslides triggered by this event is prepared based on field investigations and visual interpretation of high resolution satellite images the spatial distribution of the landslides is then analyzed the inventory indicates that at least 2330 landslides were triggered by the earthquake a correlation statistics of the landslides with topographic geologic and earthquake factors is performed based on the gis platform the results show that the largest number of landslides and the highest landslide density are at 2400 m 2600 m of absolute elevation and 200 m 300 m of relative elevation respectively the landslide density does not always increase with slope gradient as previously suggested the slopes most prone to landslides are in s sw w and nw directions concave slopes register higher landslide density and larger number of landslides than convex slopes the largest number of landslides occurs on topographic position with middle slopes whereas the highest landslide density corresponds to valleys and lower slopes the underlying bedrocks consisting of conglomerate and sandstone of lower paleogene eb register both the largest number and area of landslides and the highest landslide number and area density values correlations of landslide number and landslide density with perpendicular and along strike distance from the epicenter show an obvious spatial intensifying character of the co seismic landslides the spatial pattern of the co seismic landslides is strongly controlled by a branch of the lintan dangchang fault which indicates the effect of seismogenic fault on co seismic landslides in addition the area affected by landslides related to the earthquake is compared to the relationship of area affected by landslides vs earthquake magnitude constructed based on earthquakes worldwide and it is shown that the area affected by landslides triggered by the minxian zhangxian earthquake is larger than that of almost all other events with similar magnitudes

a comparison and test of various site response estimation techniques including three that are not reference site dependent abstract we compare various site response estimation techniques using after shock data of the 1989 loma prieta earthquake collected in oakland california because of recent interest in comparing results from weak and strong motion to infer any nonlinearity and between direct s and coda waves we pay particular attention to the uncertainties first sediment to bedrock spectral ratio estimates between pairs of sites are compared with those obtained from various generalized inversion approaches where the source and site effects of multiply recorded events are solved for simultaneously we find that the site amplification factors are very similar among these approaches but that the uncertainties can be significantly different depending on how the data are weighted we also examine and test three site response estimation techniques that do not rely on a reference site to estimate source and path effects the first involves a parameterized source and path effects inversion even when the bedrock data are excluded from consideration this approach is found to reveal the frequency dependence of site response at each of the sediment sites the second technique involves taking horizontal to vertical component spectral ratios receiver function type estimates of shear wave aftershock data these are also found to reveal the frequency dependence of site response at the sediment sites and the results for the bedrock site are relatively flat and near unity the third estimate is formed by taking horizontal to vertical component ratios of ambient seismic noise and these are shown to reveal the fundamental resonant frequency of the sediment sites unfortunately discrepancies exist among all of the site response estimates and with one dimensional predictions with respect to a frequency independent scaling factor nevertheless the highly frequency dependent character of site response is well constrained and the fact that non reference site dependent methods are capable of revealing this is promising for site specific hazard assessments in regions that lack adequate reference sites

moment tensor solutions for small and moderate earthquakes in the ibero maghreb region 1 we applied time domain moment tensor inversion of local and regional waveforms to small and moderate mw 3 5 5 7 shallow earthquakes from the iberian peninsula northern morocco and northern algeria for the 6 years period from november 1995 to march 2002 and the previous network of autonomously recording seismograms nars experiment moment tensor solutions were obtained for 58 events considerably increasing the total number of available solutions in the study area for each event we performed a moment tensor inversion and a double couple grid search for simple faulting events the grid search is valuable as a quality test for its ability to reveal potential ambiguities of the solutions and to assess confidence limits of fault plane parameters or principal axes orientation the computed mechanisms show regional consistency a large part of the iberian peninsula is characterized by normal faulting mechanisms with sw ne oriented t axes thrusting and se nw compression is dominant in algeria in the alboran sea the westernmost part of the mediterranean and the transition between both regimes strike slip mechanisms dominate with approximately n s oriented p axes this pattern suggests a regional anomaly characterized by clockwise rotation of the principal horizontal stress orientations

lead isotope distribution in podzolic soil profiles on different types of bedrock in a formerly glaciated terrain oslo norway abstract lead has been exploited by man over thousands of years for a variety of metallurgical medicinal and industrial purposes the cumulative output of pb from mining is estimated to be 260 million metric tonnes and 85 of this has occurred over the last two centuries global annual production of pb from mining was about 3 million tonnes at the turn of the millenium terrestrial ecosystems all over norway have been contaminated moderately to strongly by pb and other trace elements from atmospheric deposition with the aim of developing a method for mapping the accumulated content of anthropogenic pb and how deep in the soil profile the atmospherically deposited pb has penetrated the concentration of pb and the 206pb 207pb ratio has been studied in podzolic forest soils at four locations with different lithology i e age and type of bedrock in the oslo area the concentrations of pb in the soil profiles are 6 6 38 1 mg kg median 10 3 the 206pb 207pb ratio ranges between 1 168 and 1 314 median 1 267 over the entire profile in the upper 5 cm the range is 1 168 1 191 similar to ratios determined in recent atmospheric deposition applying three different methods the amount of anthropogenically deposited pb is estimated at 1 6 t km2

a model for repetitive cycles of large earthquakes the theory of the fusion of small cracks into large ones reproduces certain features also observed in the clustering of earthquake sequences by modifying our earlier model to take into account the stress release associated with the occurrence of large earthquakes we obtain repetitive periodic cycles of large earthquakes a preliminary conclusion is that a combination of the stress release or elastic rebound mechanism plus time delays in the fusion process are sufficient to destabilize the crack populations and ultimately give rise to repetitive episodes of seismicity

tectonic significance of the present relief of the betic cordillera abstract tortonian calcarenites of the betic cordillera were deposited in coastal or very shallow marine environments and represent an ideal marker for estimating vertical movements from the late miocene to the present a map showing the heights at which these tortonian marine rocks are situated has a clear correlation with the present relief indicating that today s relief has been formed since the tortonian there is also a good correlation between present relief and the bouguer anomaly distribution in the betic cordillera as well as with crustal thickness likewise the present relief is directly related to the geodynamic setting of a horizontal n s to nnw sse compression and an almost perpendicular extension along with isostatic readjustment existing in the betic cordillera from the tortonian as a result of these regional stresses faults and folds have produced notable vertical movements the highest rates of uplift of the betic cordillera coincide with large antiforms in particular those of the sierra nevada and the sierra filabres several subsiding sectors also exist for example the granada basin or the guadalquivir basin the foreland guadalquivir basin has a complex history because the uplift in its eastern sector and subsidence in the western sector coexisted during the late tortonian today the whole betic cordillera is characterized by differential regional uplift even in the aforementioned subsiding sectors

landslides caused by the m 7 6 tecoman mexico earthquake of january 21 2003 abstract the tecoman mexico earthquake also called the colima earthquake of january 21 2003 m 7 6 triggered several hundreds of landslides in the coastal cordilleras of colima state near the earthquake source and several thousands in the volcanic highlands north and northwest of colima city these landslides mostly shallow and disrupted failures caused minor damage to roads to a railroad and to irrigation systems in one area extensive post earthquake rock fall activity indicates a possible long term instability that could threaten dwellings and other infrastructure located nearby in the coastal cordilleras most of the landslides were generated by failures of artificially cut slopes especially along roads the rocks of the coastal cordilleras are generally well indurated and landslides occurred only where the rocks were made locally susceptible by weathering the presence of prominent discontinuities with unfavorable orientations or intense fracturing or shearing in contrast to the coastal cordilleras the volcanic rocks to the north were more susceptible to the occurrence of seismically triggered landslides the greatest number and concentrations of landslides occurred there and the landslides were larger than those in the coastal cordilleras even though this volcanic terrain was farther from the earthquake source here stretches of river bluffs several hundred meters long had been stripped of vegetation and surficial material by coalescing landslides and several days after the main shock thousands of small rock falls were still occurring each day indicating an ongoing hazard the high susceptibility of volcanic materials to earthquake generated landslides conforms to findings in other recent earthquakes

earthquake induced ground failures in italy abstract the national catalog of ground failures induced by strong earthquakes in italy cedit is described the catalog holds data on ground failures triggered by the earthquakes that occurred in italy in the last millennium and which had a nominal epicentral intensity equal to or greater than viii in the mercalli cancani sieberg mcs intensity scale the ground effects reported in the catalog are the following landslides fractures liquefaction surface faulting and topographic changes of the ground level subsidence settlements tilting and so on each effect is described in terms of seismological parameters of the triggering earthquake site coordinates and administrative code lithology and kinematic type of the ground failure the catalog represents a tool to assess the susceptibility of geologic materials to ground shaking and to validate predictive models of seismically induced ground displacements scenarios of earthquake induced geologic risks in the context of this study a simple statistical analysis of the database yielded useful relations between the parameters of the triggering earthquakes and the related effects

quantitative relations of seismic source parameters and a classification of earthquakes abstract relations between earthquake parameters moment m0 fault area s fault length l and width w stress drop time characteristics and magnitudes and faulting type dip slip ds and strike slip ss are quantitatively analyzed using a dataset of 240 events m 5 the analysis is carried further toward an earthquake systematization by introducing earthquake classes the results are 1 1 l w 2 1 for ds l w 2 30 for ss and l w 3 7 for giant m0 1029 dyne cm earthquakes respectively 2 2 log m0 1 5 log s 22 2 s in km2 and tentatively log m0 2 45 log s 17 49 for ds and ss and giant earthquakes respectively 3 3 the large scatter of data in m0 s dependences is the result of the combined effect of the variation in and l w 4 4 the concept of constant is replaced by variable to explain the large variations in relations between m0 s l and w for both ds and ss earthquakes and partly between body and surface wave magnitudes low intermediate and high stress drop gd 30 30 60 and 60 bar respectively earthquakes are defined 5 5 a relation of reciprocity exists between seismic slip fault length and width and stress drop 6 6 a saturation of s for some very large earthquakes is suggested from the interpretation of actual data on m0 s l w etc 7 7 the total source duration tsd increases with m0 in relation with earthquake type and tentatively log m0 2 16 log tsd 24 50 holds for ds earthquakes 8 8 log m0 1 5 mm 16 1 holds for mm brune engen mantle wave magnitude 8 5 8 75 9 9 more magnitudes of shorter or longer period on both body and surface wave basis are useful in constraining significant earthquake features 10 10 low and high frequency earthquakes can be distinguished using the gutenberg richter relation ms mb as a reference relation or a relation between ms and mmaxb 11 11 aki s similarity conditions are extended by adding two more conditions as to express more specifically four basic features geometry deformation frequency and time of the earthquake source 12 12 a reference earthquake is defined by criteria consistent with the similarity conditions 13 13 on this basis and in view of nonsimilarity of earthquakes in their totality a scheme for earthquake classification is proposed

a shallow fault zone structure illuminated by trapped waves in the karadere duzce branch of the north anatolian fault western turkey summary we discuss the subsurface structure of the karadere duzce branch of the north anatolian fault based on analysis of a large seismic data set recorded by a local passcal network in the 6 months following the mw 7 4 1999 izmit earthquake seismograms observed at stations located in the immediate vicinity of the rupture zone show motion amplification and long period oscillations in both p and s wave trains that do not exist in nearby off fault stations examination of thousands of waveforms reveals that these characteristics are commonly generated by events that are well outside the fault zone the anomalous features in fault zone seismograms produced by events not necessarily in the fault may be referred to generally as fault zone related site effects the oscillatory shear wave trains after the direct s arrival in these seismograms are analysed as trapped waves propagating in a low velocity fault zone layer the time difference between the s arrival and trapped waves group does not grow systematically with increasing source receiver separation along the fault these observations imply that the trapping of seismic energy in the karadere duzce rupture zone is generated by a shallow fault zone layer traveltime analysis and synthetic waveform modelling indicate that the depth of the trapping structure is approximately 3 4 km the synthetic waveform modelling indicates further that the shallow trapping structure has effective waveguide properties consisting of thickness of the order of 100 m a velocity decrease relative to the surrounding rock of approximately 50 per cent and an s wave quality factor of 10 15 the results are supported by large 2 d and 3 d parameter space studies and are compatible with recent analyses of trapped waves in a number of other faults and rupture zones the inferred shallow trapping structure is likely to be a common structural element of fault zones and may correspond to the top part of a flower type structure the motion amplification associated with fault zone related site effects increases the seismic shaking hazard near fault zone structures the effect may be significant since the volume of sources capable of generating motion amplification in shallow trapping structures is large

landslides and other surface effects induced by the 1997 umbria marche seismic sequence abstract this paper both describes and discusses landslides and other ground effects induced by the september october 1997 seismic sequence which struck the umbria and marche regions central italy three main events occurred on 26 september at 00 33 and 09 40 gmt and 14 october with magnitude m w equal to 5 8 6 0 and 5 4 respectively furthermore hundreds of minor but significant events were also recorded the authors examined an area of some 700 km 2 around the epicentre colfiorito primary and secondary effects were observed including surface faulting phenomena landslides ground fractures compaction and various hydrological phenomena surface evidence of faulting reactivation was found along the well known capable faults to a total length of ca 30 km landslides which were the most recurrent among the phenomena induced consisted mainly of rock falls and subordinately of rotational and translational slides which were generally mobilised by the inertia forces during the seismic motion the percentage of reactivated old landslides decreased as the distance from the epicentral zone increased a similar decrease had been observed for the 1980 irpinia earthquake southern italy the ground fracture distribution was consistent with the regional structural setting and the general pattern of macroseismic field numerous episodes of hydrological changes were observed within the most severely damaged area all this evidence confirms the relevance of the study of ground surface effects for achieving a more complete evaluation of seismic hazard

mechanism of induced seismicity at the geysers geothermal reservoir california the geysers reservoir is situated in a 60 80 km wide right lateral shear zone associated with the north american pacific plate boundary a small fraction of the shear may be occurring as permanent aseismic creep which is being converted to stick slip movement in the geysers reservoir due to steam production two mechanisms could be responsible for the induced seismicity a large 100 bars increase in effective rock pressure and an increase in the coefficient of friction the first mechanism requires that the initial state of the reservoir be predominantly liquid dominated the second mechanism is a consequence of dehydration of the reservoir causing both the hardening of clay and fault gouge and the precipitation of silica

topographic effects on the seismic response of steep slopes a frequency domain parametric study using generalized consistent transmitting boundaries has been performed to evaluate the significance of topographic effects on the seismic response of steep slopes the results show that the peak amplification of motion at the crest of a slope occurs at a normalized frequency h 0 2 where h is the slope height and is the wavelength of the motion the importance of the natural site frequency is illustrated by the analysis of a stepped layer over a half space it was found that the natural frequency of the region behind the crest can dominate the response relative to the topographic effect for the conditions studied moreover the effect of topography can be handled separately from the amplification due to the natural frequency of the deposit behind the crest of the slope this concept of separating the amplification caused by topography from that caused by the natural frequency is advantageous to the development of a simplified method to estimate topographic effects

deep structure of the mozumi sukenobu fault central japan estimated from the subsurface array observation of fault zone trapped waves summary in order to estimate the averaged fault zone structure i e the width shear wave velocity and qs of the mozumi sukenobu fault central japan we analysed the love wave type fault zone trapped waves recorded by a seismic array deployed in a subsurface survey gallery we selected the typical love wave type trapped waves based on the characteristics of dispersion amplitude apparent velocity and the polarization of wave trains following the direct shear wave we selected nine events showing typical love wave type trapped waves from 154 earthquakes epicentres of the events were located along the surface trace of the mozumi sukenobu fault the nine events showing trapped waves were found to be located in a plane dipping to the south at an angle of approximately 75 to 85 the duration of the fault zone trapped waves increase non linearly with the increase of hypocentral distance this result implies an increase in shear wave velocity of the fault zone with depth and or horizontal distance from the array in order to obtain averaged fault zone structure from hypocentre to receiver we assumed fault zone structure to be a 2 d uniform low velocity waveguide and modelled the dispersion curve and the waveform of trapped waves using an analytical solution the width shear wave velocity and qs of the fault zone were estimated to be 160 to 400 m 2 9 to 3 1 km s 1 and 60 to 90 respectively the width of the fault zone estimated in this analysis is consistent with the width of the extent of fault zone at the survey gallery we also conducted 3 d finite difference simulation 3 d fdm on fault zone trapped waves using depth dependent structure models referred to the 2 d averaged structure indicating the possible depth dependent structures the 2 d modelling is useful as an initial guide to the 3 d imaging of a fault zone

seismically induced rock slope failures resulting from topographic amplification of strong ground motions the case of pacoima canyon california abstract the 1994 northridge earthquake mw 6 7 triggered extensive rock slope failures in pacoima canyon immediately north of los angeles california pacoima canyon is a narrow and steep canyon incised in gneissic and granitic rocks peak accelerations of nearly 1 6 g were recorded at a ridge that forms the left abutment of pacoima dam peak accelerations at the bottom of the canyon were less than 0 5 g suggesting the occurrence of topographic amplification topographic effects have been previously suggested to explain similarly high ground motions at the site during the 1971 mw 6 7 san fernando earthquake furthermore high landslide concentrations observed in the area have been attributed to unusually strong ground motions rather than higher susceptibility to sliding compared with nearby zones we conducted field investigations and slope stability back analyses to confirm the impact of topographic amplification on the triggering of landslides during the 1994 earthquake our results suggest that the observed extensive rock sliding and falling would have not been possible under unamplified seismic conditions which would have generated a significantly lower number of areas affected by landslides in contrast modelling slope stability using amplified ground shaking predicts slope failure distributions matching what occurred in 1994 this observation confirms a significant role for topographic amplification on the triggering of landslides at the site and emphasises the need to select carefully the inputs for seismic slope stability analyses

the alhama de murcia fault se spain a seismogenic fault in a diffuse plate boundary seismotectonic implications for the ibero magrebian region received 20 december 2002 revised 15 september 2003 accepted 26 september 2003 published 2 january 2004 1 the shortening between the african and the iberian plates is absorbed by a number of faults distributed over a very wide zone with very low slip rates and long periods of seismic loading thus a seismotectonic map based only on faults associated with seismicity or with expressive geomorphic features is incomplete it is possible to characterize seismogenic faults using paleoseismology first paleoseismological results based on trenching analysis in the eastern betics lorca totana segment of the alhama de murcia fault are presented the main paleoseismic parameters of this fault segment are 1 a minimum of two to three mw 6 5 7 earthquakes in the last 27 kyr shortly before 1650 a d between 830 and 2130 b c and shortly before 16 7 ka respectively with a mean recurrence period of 14 kyr and a very short elapsed time and 2 a net slip rate of 0 07 0 6 mm yr during the last 30 kyr these results were extrapolated to the rest of the known active faults in the eastern betics and were added to the slip rates of the active faults at the african margin the total slip rate of the transect which crosses de alhama de murcia fault in spain and reaches the cheliff basin algeria would represent 21 82 of the total shortening between africa and eurasia estimated from plate motion models and seismic moment summation a number of factors could account for this discrepancy 1 hidden seismogenic faults in the emerged areas 2 absence of correlation between current and late pleistocene slip rates 3 extensive small faults that are undetected and that absorb a significant amount of the deformation and 4 possible overestimation of the convergence rates index terms 7221 seismology paleoseismology 7230 seismology seismicity and seismotectonics 7215 seismology earthquake parameters 8150 tectonophysics plate boundary general 3040 keywords eastern betics alhama de murcia fault paleoseismology trenching seismotectonics plate boundary

database and spatial distribution of landslides triggered by the lushan china mw 6 6 earthquake of 20 april 2013 abstract on 20 april 2013 an earthquake with mw 6 6 ms 7 0 hit lushan county sichuan province of china 30 3 n 103 e only 85 km southwest of the 2008 wenchuan mw 7 9 event the lushan shock triggered a large number of landslides with various types including highly disrupted shallow slides and rock falls deep seated landslides and large scale rock avalanches post earthquake high resolution aerial photographs and satellite images as well as a series of pre earthquake high resolution satellite images were collected to construct a detailed accurate objective and complete coseismic landslide database inventory which was validated by field investigation in selected areas based on the aerial photographs 0 2 or 0 6 m resolution that partly cover the affected area and pre earthquake satellite images 14 580 coseismic landslides were recognized and mapped in those areas without post earthquake aerial photographs coverage we mapped 7 948 more coseismic landslides based on post earthquake satellite images rapideye images with 5 m resolution and zy 3 images including panchromatic images with 2 1 m resolution and multi spectral images with 5 8 m resolution and pre earthquake satellite images the 22 528 coseismic landslides with a horizontal projection area of 18 88 km 2 and an estimated total volume of 41 56 10 6 m 3 were distributed in a nearly elliptic area of about 5 400 km 2 correlations between coseismic landslide abundances and topographic geologic and seismic factors were analyzed on 15 546 landslides of area 100 m 2 scatter plots between regional slope angle and landslide abundances in generalized homogeneous lithology combinations show no obvious relationship is present between them which challenges the conclusions of previous studies combining the lushan earthquake triggered landslides with other events on reverse and or thrust faults such as the 1999 chi chi and 2008 wenchuan shocks we found that coseismic landslides tend to occur in areas enveloped by two or more imbricated reverse and or thrust faults rather than only along the seismogenic fault the lushan event shows a higher ability of triggering landslides compared with other earthquakes of similar magnitudes which is likely due to the steep and rugged topography and fractured and densely jointed lithology resulted from long term tectonic activity the blind reverse seismogenic fault is likely also another significant factor based on detailed coseismic landslide inventory maps and databases of several recent major earthquakes such as the 2008 wenchuan 2010 haiti 2010 yushu and 2013 lushan temblors we suggest that the empirical correlations between earthquake magnitude and coseismic landslides need to be updated

depth dependent structure of the landers fault zone from trapped waves generated by aftershocks we delineate the internal structure of the johnson valley and kickapoo faults landers southern rupture at seismogenic depth using fault zone trapped waves generated by aftershocks trapped waves recorded at the dense linear seismic arrays deployed across and along the surface breaks of the 1992 m7 5 landers earthquake show large amplitudes and dispersive wave trains following the s waves group velocities of trapped waves measured from multiple band pass filtered seismograms for aftershocks occurring at different depths between 1 8 km and 8 2 km show an increase in velocity with depth velocities range from 1 9 km s at 4 hz to 2 6 km s at 1 hz for shallow events while for deep events velocities range from 2 3 km s at 4 hz to 3 1 km s at 1 hz coda normalized amplitude spectra of trapped waves peak in amplitudes at 3 4 hz for stations located close to the fault trace the amplitude decays rapidly with the station offset from the fault zone normalized amplitudes also decrease with distance along the fault giving an apparent q of 30 for shallow events and 50 for deep events we evaluated depth dependent fault zone structure and its uncertainty from these measurements plus our previous results from near surface explosion excited trapped waves li et al 1999 in a systematic model parameter searching procedure using a three dimensional 3 d finite difference computer code graves 1996 our best model of the landers fault zone is 250 m wide at the surface tapering to 100 150 m at 8 2 km depth the shear velocity within the fault zone increases from 1 0 to 2 5 km s and q increases from 20 to 60 in this depth range fault zone shear velocities are reduced by 35 to 45 from those of the surrounding rock and also vary along the fault zone with an increase of 10 near ends of the southern rupture zone

a seismologically consistent expression for the total area and volume of earthquake triggered landsliding we present a new seismologically consistent expression for the total area and volume of populations of earthquake triggered landslides this model builds on a set of scaling relationships between key parameters such as landslide spatial density seismic ground acceleration fault length earthquake source depth and seismic moment to assess the model we have assembled and normalized a catalog of landslide inventories for 40 shallow continental earthquakes low landscape steepness causes systematic overprediction of the total area and volume of landslides when this effect is accounted for the model predicts the total landslide volume of 63 of 40 cases to within a factor 2 of the volume estimated from observations r2 0 76 the prediction of total landslide area is also sensitive to the landscape steepness but less so than the total volume and it appears to be sensitive to controls on the landslide size frequency distribution and possibly the shaking duration some outliers are likely associated with exceptionally strong rock mass in the epicentral area while others may be related to seismic source complexities ignored by the model however the close match between prediction and estimate for about two thirds of cases in our database suggests that rock mass strength is similar in many cases and that our simple seismic model is often adequate despite the variety of lithologies and tectonic settings covered this makes our expression suitable for integration into landscape evolution models and application to the anticipation or rapid assessment of secondary hazards associated with earthquakes

landslides triggered by the 1994 northridge california earthquake abstract the 17 january 1994 northridge california earthquake m w 6 7 triggered more than 11 000 landslides over an area of about 10 000 km 2 most of the landslides were concentrated in a 1000 km 2 area that included the santa susana mountains and the mountains north of the santa clara river valley we mapped landslides triggered by the earthquake in the field and from 1 60 000 nominal scale aerial photography provided by the u s air force and taken the morning of the earthquake these mapped landslides were subsequently digitized and plotted in a gis based format most of the triggered landslides were shallow 1 to 5 m thick highly disrupted falls and slides within weakly cemented tertiary to pleistocene clastic sediment average volumes of these types of landslides were less than 1000 m 3 but many had volumes exceeding 100 000 m 3 the larger disrupted slides commonly had runout paths of more than 50 m and a few traveled as far as 200 m from the bases of steep parent slopes deeper 5 m thick rotational slumps and block slides numbered in the tens to perhaps hundreds a few of which exceeded 100 000 m 3 in volume most of these were reactivations of previously existing landslides the largest single landslide triggered by the earthquake was a rotational slump block slide having a volume of 8 10 6 m 3 analysis of the mapped landslide distribution with respect to variations in 1 landslide susceptibility and 2 strong shaking recorded by hundreds of instruments will form the basis of a seismic landslide hazard analysis of the los angeles area

recurrence models and parkfield california earthquakes main shocks of the earthquake sequences that occurred on the parkfield section of the san andreas fault in central california in 1922 1934 and 1966 are characterized by southeast rupture expansion over the same 20 to 30 km long section of the fault whereas the seismic moments for the 1922 and 1934 events are identical to within a precision of 10 the seismic moment for 1966 is 20 greater than for the earlier events to within a precision of 20 the parkfield area seismicity in general seems well described by a recurring moderate size characteristic earthquake repeating the same epicenter magnitude seismic moment rupture area and southeast direction of rupture expansion an unexplained 10 year advance of the 1934 event is the only discrepancy in the hypothesis that the parkfield earthquakes in 1857 1881 1901 1922 1934 and 1966 represent a strictly periodic process assuming the strictly periodic model and the absence since 1966 of the perturbations hypothesized for the 1922 to 1934 period the next characteristic parkfield earthquake should occur between 1983 and 1993

seismically induced landslides by a low magnitude earthquake the mw 4 7 ossa de montiel event central spain this work has been funded by spanish ministry of economy and competitiveness research project cgl2011 30153 c02 02 and by the research groups rnm 374 junta de andalucia tectac ucm 910368 and vigrob 184 universidad de alicante mr loffredo acknowledges funding of the universita di roma la sapienza post graduate grant concorso a n 480 area cun 04

simplified frequency content estimates of earthquake ground motions it is often useful in earthquake engineering practice to characterize the frequency content of an earthquake ground motion with a single parameter three simplified frequency content parameters are examined mean period t m predominant period t p and the smoothed spectral predominant period t o these frequency content parameters are calculated for 306 strong motion recordings from 20 earthquakes in active plate margin regions these data are used to develop a model that describes the magnitude distance and site dependence of these frequency content parameters nonlinear regression analyses are performed to evaluate model coefficients and standard error terms the results indicate that the traditional t p parameter has the largest uncertainty in its prediction and that previous relationships proposed to predict t p are inconsistent with the current data set moreover t m is judged to be the best simplified frequency content characterization parameter and it can be reliably estimated

a global empirical model for near real time assessment of seismically induced landslides earthquake triggered landslides are a significant hazard in seismically active regions but our ability to assess the hazard they pose in near real time is limited in this study we present a new globally applicable model for seismically induced landslides based on the most comprehensive global dataset available we use 23 landslide inventories that span a range of earthquake magnitudes and climatic and tectonic settings we use logistic regression to relate the presence and distribution of earthquake triggered landslides with spatially distributed estimates of ground shaking topographic slope lithology land cover type and a topographic index designed to estimate variability in soil wetness to provide an empirical model of landslide distribution we tested over 100 combinations of independent predictor variables to find the best fitting model using a diverse set of statistical tests blind validation tests show the model accurately estimates the distribution of available landslide inventories the results indicate that the model is reliable and stable with high balanced accuracy correctly vs incorrectly classified pixels for the majority of test events a cross validation analysis shows high balanced accuracy for a majority of events as well by combining near real time estimates of ground shaking with globally available landslide susceptibility data this model provides a tool to estimate the distribution of coseismic landslide hazard within minutes of the occurrence of any earthquake worldwide for which a u s geological survey shakemap is available

onshore and offshore compressional tectonics in the eastern betic cordillera se spain abstract this study concerns the northern terminal splay of the eastern betic shear zone betic cordillera se spain where the bajo segura basin lies and its offshore prolongation along the western mediterranean margin we have integrated seismic reflection profiles with gravimetry seismicity wells and outcrop data from the bajo segura basin and the alicante shelf in order to determine the current geodynamic setting of the area the results indicate that the same compressional structures in upper miocene quaternary rocks are observed both on and offshore in the onshore bajo segura basin there are ene wsw growth folds related to reverse faults in the basement in the alicante shelf the main structure is an ene wsw anticlinorium which deforms upper miocene quaternary syntectonic deposits these compressional structures are still active at present as shown by the offshore seismicity from the structural analysis and focal mechanisms of the earthquakes we conclude that the bajo segura basin and its adjacent shelf have been subject to nnw sse compression since late miocene until the present folding and reverse faulting of the upper miocene quaternary sedimentary cover and of its basement have accommodated this compression the main active structures onshore located in the bajo segura basin extend eastwards into the mediterranean sea this fact is interpreted as the eastern betic shear zone continues offshore to the east

lunar solar periodicities of large earthquakes in southern california large earthquakes in southern california with epicentres between 33 and 36 n have statistically significant 12 hourly lunar fortnightly and 18 6 yr periodicities smaller earthquakes in the same region do not display these periodicities a search for tidal effects associated with these periodicities shows that large earthquakes have significant correlations with the times and orientations of daily semi daily tidal stresses while the lunar fornightly term is associated with the ocean tides along the southern californian coast

seismic performance of loess mudstone slope in tianshui centrifuge model tests and numerical analysis abstract dynamic behavior and failure mechanism of slope during earthquake are hot topics in geotechnical engineering community in tianshui area northwest of china the deformation features of loess mudstone slopes induced by earthquakes are still not well understood the current study aims to discuss the dynamic behavior of the slope under earthquake by performing a series of centrifuge shaking table tests and numerical simulations the results are processed for pga amplificatory effect study and to evaluate the earthquake induced deformation mechanism better agreement is obtained between the results of numerical simulations and centrifuge tests the results indicated that the acceleration response of the loess mudstone slope showed several amplifying characteristic the height effect lithologic effect and surface effect it also proves that the displacements in the loess layer are much larger than mudstone as the input amplitude increased the shear plastic zone developed along a further slide surface tension plastic zone mainly occurred at the crest roughly the regions of earthquake induced deformation state increased with the increase in amplitude of earthquake wave deformations occurred at the upper part of the slope tensile cracks evolved on the crest and the upper part of slope in loess layer moreover failures occurred at slope surface and only slight deformation at slope toe deformations with continuous shear cracks and slope surface upheavals developed at the middle part of slope

upper crustal stresses and vertical stress migration in eastern canada diversified phenomena are contributing to our knowledge of various aspects of the stress field and the origin of the crustal stresses in eastern canada both in situ stress measurements to 2100 m and earthquake fault plane solutions in the upper crust 5 20 km indicate that the maximum horizontal stress is greater than the vertical absence of earthquakes in the lower crust 20 km implies a comparatively lower deviatoric horizontal stress in this layer stress directions as determined from both in situ measurements and earthquake fault plane solutions indicate an overprint confined to the ene octant which correlates with the direction predicted by modeling of plate tectonic stresses thus spreading mid atlantic ridge stress is considered to be one of the important contributors to the stress field in eastern canada viscoelastic relaxation of this stress is considered to enhance the deviatoric stress level in the upper crust while simultaneously reducing that in the lower crust the crust acts as a stress guide within which stresses in the upper crust that are lost through brittle failure i e earthquake stress drop can be replenished from the lower crust moreover the directionality predicted by modeling of spreading mid atlantic ridge stress is maintained incomplete postglacial rebound also contributes to deviatoric compression other possible contributors to the upper crustal stress field are basal drag and membrane stress but the relative contributions from these sources are not properly understood

regularity patterns and zones of seismic potential for future large earthquakes in the mediterranean region large earthquakes m 6 75 in the mediterranean region from iran to the azores were investigated with the aim of establishing possible regularity patterns in their occurrence and identifying regions of seismic potential the earthquakes investigated occurred along the complex boundaries in the zone of convergence between the eurasian and african arabian plates for both historic and modern times the magnitudes of some larger earthquakes were reconsidered the relatively complete record over a long period of time together with space time magnitude diagrams suggest the following patterns 1 1 an alteration of active and quiet seismic periods along the whole region 2 2 a cyclic eastward migration in the hellenic arc 3 3 average recurrence times of 100 150 yr for stress accumulation greece italy and 4 4 the triggering of the largest events at the eastern end of the north anatolian fault by stress transfer resulting from indentation of the arabian plate this has also been used as a hypothesis to explain the main features of space time earthquake evolution before the large 1939 earthquake finally using the observed regularities and some additional criteria e g the time elapsed since the last occurrence dimensions of rupture zones the following zones have been specially investigated with respect to their seismic potential 1 1 the eastern part of the north anatolian fault zone 2 2 northern marmara region 3 3 northeast of crete 4 4 south peloponnesus 5 5 southeastern sicily and central italy 6 6 west of gibraltar

presentation and analysis of a worldwide database of earthquake induced landslide inventories earthquake induced landslide eqil inventories are essential tools to extend our knowledge of the relationship between earthquakes and the landslides they can trigger regrettably such inventories are difficult to generate and therefore scarce and the available ones differ in terms of their quality and level of completeness moreover access to existing eqil inventories is currently difficult because there is no centralized database to address these issues we compiled eqil inventories from around the globe based on an extensive literature study the database contains information on 363 landslide triggering earthquakes and includes 66 digital landslide inventories to make these data openly available we created a repository to host the digital inventories that we have permission to redistribute through the u s geological survey sciencebase platform it can grow over time as more authors contribute their inventories we analyze the distribution of eqil events by time period and location more specifically breaking down the distribution by continent country and mountain region additionally we analyze frequency distributions of eqil characteristics such as the approximate area affected by landslides total number of landslides maximum distance from fault rupture zone and distance from epicenter when the fault plane location is unknown for the available digital eqil inventories we examine the underlying characteristics of landslide size topographic slope roughness local relief distance to streams peak ground acceleration peak ground velocity and modified mercalli intensity also we present an evaluation system to help users assess the suitability of the available inventories for different types of eqil studies and model development

active faulting offshore se spain alboran sea implications for earthquake hazard assessment in the southern iberian margin the southern margin of the iberian peninsula hosts the convergent boundary between the european and african plates the area is characterised by low to moderate magnitude shallow earthquakes although large historical events have also occurred in order to determine the possible sources of these events we recently acquired swath bathymetry tobi sidescan sonar and high resolution seismic data on the almeria margin eastern alboran sea the new dataset reveals the offshore continuation of the ne sw trending carboneras fault a master fault in the eastern betic shear zone and its associated structures n150 and ns faults these structures are active since they cut the late quaternary sedimentary units the submarine carboneras fault zone is 100 km long 5 10 km wide and is divided into two n045 and n060 segments separated by an underlapping restraining stepover geomorphic features typically found in subaerial strike slip faults such as deflected drainage water gaps shutter ridges pressure ridges and ben echelonq folds suggest a strike slip motion combined with a vertical component along the submarine carboneras fault considering the nnw sse regional shortening axis a left lateral movement is deduced for the carboneras fault whereas right lateral and normal components are suggested for the associated n150 and ns faults respectively the offshore portion of this fault is at least twice as long as its onshore portion and together they constitute one of the longest structures in the southeastern iberian margin despite the fact that present day seismicity in the almeria margin seems to be associated with the n150 to ns faults the carboneras fault is a potential source of large magnitude mw 7 2 events hence the carboneras fault zone could pose a

landscape response to strike slip faulting linked to collisional settings quaternary tectonics and basin formation in the eastern betics southeastern spain abstract neotectonic behaviour of the eastern betics southeastern spain has been controlled by the presence of a large left lateral shear zone this is an intraplate transcurrent zone probably decoupled by a mid crustal detachment horizon the morphological expression of this crustal structure is a sigmoidal corridor in which the main quaternary basins are located three types of morphostructural domains can be distinguished in the sigmoidal corridor the central segment and the northern and southern terminal splays the central segment is characterized by wrench tectonics whilst the southern and northern terminal splays are controlled by transtensional and transpressional tectonics respectively the quaternary morphostructural pattern is only the more recent picture of the tectonic processes that have controlled the late orogenic evolution of the eastern betics the indentation of the aguilas arc accompanied by thin skinned thrusting and tectonic escape in its easternmost sector and extensional collapse accompanied by thin skinned stretching in its westernmost sector

pseudo static failure modes and yield accelerations in rock slopes abstract earthquake induced landslide databases indicate that failure modes observed in the field following earthquakes include sliding toppling and slumping methods based on simplified discrete single block models are limited to rectangular blocks on a plane or wedge blocks that restrict the potential failure modes to sliding or toppling this paper expands the geometry assumptions so that additional failure modes will be kinematically admissible a simple yet broadly applicable two dimensional 2d single block framework is introduced that does not restrict the geometry to orthogonal fracture sets this framework allows for the slumping failure mode to naturally occur and can identify a new failure mode confined toppling using simple failure mode charts this framework can be easily applied to a wide range of analysis and design applications in addition to the identification of new failure modes seismic yield acceleration equations are presented for all four modes of failure sliding toppling slumping and confined toppling the equations for slumping and confined toppling are derived for the first time although the model may be simple in its formulation and implementation it is quite powerful allowing for significant implications to be developed complex shaped blocks can be easily evaluated knowing just their centers of mass and contact points with supporting fractures the failure mode of a discrete rock block is shown to be independent of the primary fracture inclination on which the block rests upon and the scale of the block itself seismic failure modes are demonstrated to be different from those induced by static forces alone and can even change modes depending on the amount of displacement during the ground motion in addition it is shown that the characteristics of an earthquake ground motion acting on these blocks in combination with geometric variability can influence the abundance of failure types observed in the field finally an example mode and yield acceleration evaluation of alaskan rock slope is presented

a global slope unit based method for the near real time prediction of earthquake induced landslides abstract rapid assessment of spatial distribution of earthquake induced landslides could provide valuable information in the emergency response phase previous studies proposed global analyses with the aim of predicting earthquake induced landslide distributions in near real time however in all those studies mapping units are constituted by pixels which do not reflect homogeneously distributed physical property for a given terrain unit and whose size do not match the resolution of existing thematic data at global scale moreover none of the existing analyses considers sampling balance between different inventories or categorizing the inventories to construct a training set with higher statistical representativeness we develop an improved global statistical method to address these drawbacks we use slope units which are terrain partitions attributed to similar hydrological and geomorphological conditions and to processes that shape natural landscapes a set of 25 earthquake induced landslide events are selected and categorized based on the similarity between causal factors to determine the most relevant training set to make a prediction for a given landslide event as a result we develop a specific model for each category we sample an equal number of landslide points from each inventory to overcome the dominance of some inventories with large landslide population we use seven independent thematic variables for both categorizing the inventories and modeling based on logistic regression the results show that categorizing landslide events introduces a remarkable improvement in the modeling performance of many events the categorization of existing inventories can be applied within any statistical global approach to earthquake induced landslide events the proposed categorization approach and the classification performance can be further improved with the acquisition of new inventory maps

attenuation of peak horizontal acceleration and velocity from italian strong motion records italian strong motion data were used to study attenuation characteristics of horizontal peak ground acceleration and velocity the data base consisted of 190 horizontal components of accelerograms recorded in italy since 1976 from 17 earthquakes of magnitudes 4 6 to 6 8 the resulting equations are log a 1 562 0 306 m log r 2 5 8 2 1 2 0 169 s log v 0 710 0 455 m log r 2 3 6 2 1 2 0 133 s where a is peak horizontal acceleration in g v is peak horizontal velocity in centimeters second m is magnitude r is the closest distance to the surface projection of the fault rupture in kilometers and s is a variable taking the values of 0 and 1 according to the local site geology peak acceleration and velocity were found to be lognormally distributed with a standard error representing respectively a 49 and 64 per cent increase in the median estimate we considered a magnitude dependent shape of the attenuation curves but we found no basis for it in the data attenuation relationships developed using epicentral distance in place of fault distance gave similar results with higher standard errors and higher predicted values for short distances and high magnitudes sensitivity studies performed with the analysis of the residuals showed that predictions based on our relatiaons are stable with respect to reasonable variations of the model and the seismic areas providing the data comparisons with attenuation relationships proposed for western north america showed differences of the same order of magnitude as the statistical prediction uncertainty

analysis of topographic amplification of inclined shear waves in a steep coastal bluff abstract the effect of inclined shear waves on the seismic response of a steep bluff is analyzed using generalized consistent transmitting boundaries the results of the frequency domain analysis of a stepped half space subjected to incident shear waves inclined from 0 to 30 show that the motion at the crest of the slope is amplified for waves traveling into the slope and attenuated for waves traveling away from the slope as compared to the motion in the free field behind the crest of the slope this amplification can be as much as twice that observed for vertically propagating waves a time domain analysis of bluffs at seacliff state beach california is used to estimate the effect of topography using realistic conditions taking into account wave inclination and site effects the analysis of the site shows that although topographic amplification does in fact nearly double the amplitude of the motion in some cases this amplification is offset by reduced site amplification and by wave splitting at material interfaces thus the actual peak acceleration occurring at the crest of the slope changes little with incident angle as compared to the amplification of the free field motion and actually decreases in many cases though a more general study is recommended these results suggest that wave orientation and inclination substantially increase topographic amplification however it may be adequate to only account for vertically propagating waves for site response and slope stability analyses where only the magnitude of acceleration is considered

the earthquake cycle in subduction zones lithospheric plates are subducted episodically a few meters at a time during earthquakes these earthquakes recur over intervals ranging from decades to centuries within weeks to perhaps years after such an earthquake elastic stresses induced in the asthenosphere relax allowing displacement and stress to propagate away from the subduction zone into the adjacent plates finite element modelling of this process has shown that the propagation is asymmetric the subducted slab serves to buffer the subducting plate against extensive motion we have constructed a simple analytic model which incorporates the effect of he subducted slab in a fundamental way the slab s effect is modelled by a maxwell viscoelastic element which is attached to the subducting plate both plates obey elsasser s displacement propagation equations the elastic response of the maxwell element at first restrains the motion of the subducted plate the plate eventually moves on the timescale of stress relaxation in the mesosphere hundreds to thousands of years the model predicts that the trench moves toward the subducting plate at an average speed of one half of the convergence rate a strong extensional pulse is propagated into the overthrust plate shortly after the earthquake whereas the stress pulse is small in the subducting plate although this extension changes into compression before the next earthquake in the cycle the period of strong extension following the earthquake may be responsible for extensional tectonic features in the back arc region

the interaction of seismic waves with step like slopes and its influence on landslide movements abstract the interaction of seismic waves with slopes is a major factor influencing landslide movements that involve slope stability local site seismic amplification and topographic effects affecting ground motion the results of a numerical study of landslide movements induced by the interaction of seismic waves with step like slopes are presented here to investigate this input slope interaction a dynamic analysis was performed using the finite difference stress strain numerical code flac 6 0 under visco plastic conditions the dynamic signals were selected to be representative of different peak ground accelerations pgas arias intensities and frequency contents and they were used in a parametric study of different step like slopes with different geometrical configurations in terms of dip height and thickness of geological strata the derived outputs were processed for a seismic amplification analysis and to evaluate the induced stress strain effects in terms of progressive failure and resulting displacements the obtained results i describe a fundamental role of topography in amplifying or de amplifying the seismic ground motion ii demonstrate that the progressive failure of unsheared slopes influences the seismic amplification iii show that the strain effects on unsheared slopes in terms of progressive failure are more intense with increasing arias intensity and slope dip iv prove that amplification or de amplification processes can justify the values of displacements involving pre existing landslide masses which are significantly different with respect to those expected on the basis of sliding block approaches i e newmark s and flexible sliding block methods v highlight that in the geological setting considered here the seismically induced displacements arising from the reactivation of pre existing landslide masses can be significantly underestimated by sliding block approaches in the case of low angle slopes characterised by high k values i e the ratios between the critical pseudostatic threshold ky of the landslide and pgas of the applied seismic input

topography and its isostatic compensation as a cause of seismicity a revision abstract the maximum shear stress mss generated in a spherical shell by the load of a mountain range and the buoyancy of its isostatic compensation has been computed in a previous paper caputo et al 1984 by simulating the effect of the buoyant body force with a surface force applied to the inner surface of the shell in this paper the buoyant force is modeled more exactly with a body force in a multilayered earth model the results show that the previous model is only accurate when the load is above the buoyant mass case a and not when the two are displaced case b the more accurate modelling of this paper shows that in case a the mss is reduced to less than 25 of the load by half way down in the second layer while in case b the mss extends to a much greater depth for example for a surface load of 350 bar isostatically compensated with a second layer 80 km thick the mss is less than 70 bar at a depth of 70 km from the surface in case a in case b this depth is close to 210 km also the very large mss found for case b in the model of the previous paper caputo et al 1984 is greatly reduced with the more accurate model of this paper

analysis of near source static and dynamic measurements from the 1979 imperial valley earthquake gross features of the rupture mechanism of the 1979 imperial valley earthquake ml 6 6 are inferred from qualitative analysis of near source ground motion data and observed surface rupture a lower bound on the event s seismic moment of 2 5 1025 dyne cm is obtained by assuming that the average slip over the whole fault plane equals the average surface rupture 40 5 cm far field estimates of moment suggest an average slip over the fault plane of 105 cm from which a static stress drop of 11 bars is obtained an alternative slip model consistent with the far field moment has 40 5 cm of slip in the upper 5 km of the fault and 120 cm of slip in the lower 5 km this model suggests a static stress drop of 39 bars from the lower estimate of 11 bars an average strain drop of 32 strain is derived this strain drop is four times greater than the strain that could have accumulated since the 1940 el centro earthquake based on measured strain rates for the region hence a major portion of the strain released in the 1979 main shock had been accumulated prior to 1940 unusually large amplitude 500 to 600 cm sec2 vertical accelerations were recorded at stations e05 e06 e07 e08 eda of the ei centro array and the five stations of the differential array near eda although the peak acceleration of 1705 cm sec2 at e06 is probably amplified by a factor of 3 due to local site conditions these large amplitude vertical accelerations are unusual in that they are evident on only a few stations all of which are near the fault trace and at about the same epicentral range two possible explanations are considered first that they are due to a direct p wave generated from a region about 17 km north of the hypocenter or second that they are due to a pp phase that is unusually strong in the imperial valley due to the large p wave velocity gradient in the upper 5 km of the imperial valley based on the distribution of both the horizontal and vertical offsets it is likely that the rupture went beyond stations e06 and e07 during the main shock by exploiting the antisymmetry of the parallel components of particle velocity between e06 and e07 and by examining polarization diagrams of the particle velocity at e06 and e07 an average rupture velocity in the basement of 2 5 to 2 6 km sec between the hypocenter and station e06 is obtained in addition several lines of evidence suggest that the imperial fault dips about 75 to the ne

regression models for estimating coseismic landslide displacement newmark s sliding block model is widely used to estimate coseismic slope performance early efforts to develop simple regression models to estimate newmark displacement were based on analysis of the small number of strong motion records then available the current availability of a much larger set of strong motion records dictates that these regression equations be updated regression equations were generated using data derived from a collection of 2270 strong motion records from 30 worldwide earthquakes the regression equations predict newmark displacement in terms of 1 critical acceleration ratio 2 critical acceleration ratio and earthquake magnitude 3 arias intensity and critical acceleration and 4 arias intensity and critical acceleration ratio these equations are well constrained and fit the data well 71 br 2 b88 but they have standard deviations of about 0 5 log units such that the range defined by the mean one standard deviation spans about an order of magnitude these regression models therefore are not recommended for use in site specific design but rather for regional scale seismic landslide hazard mapping or for rapid preliminary screening of sites 2007 elsevier b v all rights reserved

landslides triggered by the avaj iran earthquake of june 22 2002 abstract the 2002 avaj iran earthquake mw 6 5 triggered many landslides over an area of about 3600 km 2 in this paper we describe a ground based field study conducted during several days immediately after the earthquake and pre and post earthquake landslide inventory maps that were prepared the landslides due to earthquake include 47 fall and topple zones 9 slides and 3 lateral spreads the largest slide is a rockslide 150 100 m which occurred southeast of the village of changureh the main results of this study are the density of earthquake triggered landslides decreases away from the fault zone in a manner that is asymmetric with respect to direction although several slides and lateral spreads were seen the most common types of triggered landslides are falls and topples the area throughout which landslides occurred and maximum epicentral and fault zone distances of landslides are comparable to similar data from other historical earthquakes landslides mostly occurred in the most susceptible geologic units in which there were many landslides before the earthquake new disrupted slides and falls generally occurred in ancient fall zones but no information about reactivation of coherent slides is available

stochastic slip predictable model for earthquake occurrences recent geophysical studies have indicated that an earthquake recurrence interval and the size of the preceding event are positively correlated this observation is the basis for the deterministic time predictable recurrence model of shimazaki and nakata using the basic assumptions of the time predictable recurrence model we develop a stochastic model of earthquake occurrence that incorporates temporal dependence this paper discusses the formulation of the model and the effect of including temporal dependence hazard estimates for a section of the san andreas fault near parkfield where data has suggested time predictable behavior are obtained for illustrative purposes comparisons are made with the poisson model results indicate that currently used poisson models may give lower estimates of the seismic hazard when there has been a seismic gap of the various sensitivity analyses performed it is observed that slip rate has the largest effect on exceedence probabilites computed from the stochastic time predictable model therefore accurate determinations of slip rates both seismic and aseismic can substantially reduce the uncertainty in seismic hazard estimates

structure and permeability geologic controls on induced seismicity at nurek reservoir tadjikistan ussr induced seismicity at nurek tadjik s s r is occurring within the upper plate of the ionakhsh thrust which passes at depth directly beneath the reservoir within the immediate vicinity of the reservoir one can contrast two distinct areas one seismic and the aseismic both consist of rocks that can be shown to have a highly anisotropic permeability due to alternating permeable and impermeable strata water flow is favored along bedding while essentially prohibited across bedding however because the two areas differ in structure they also differ in their vertical component of permeability as a direct result of the different attitudes of the bedding in the aseismic area vertical fluid flow is blocked by a syncline that cups the base of the reservoir in the seismic area a plunging anticline that crops out beneath the reservoir allows water to flow to depth in the high permeability direction along bedding because effective stress changes at depth are dependent on permeability characteristics knowledge of subsurface permeability or permeability anisotropy can serve as a means by which to predict the distribution of induced seismic activity thus while regional geologic studies may indicate the presence of lithologies that are conducive to the transmission of pore water pressure access ofmore water to these units depends on the structural arrangement beneath the reservoir on a very local scale less

crustal structure from deep seismic soundings along the koyna ii kelsi loni profile in the deccan trap area india abstract the crustal depth section obtained from deep seismic soundings along the koyna ii kelsi loni profile which lies near latitude 18 n roughly in the east west direction in that part of the deccan trap maharashtra state india shows a number of reflection segments below the deccan traps down to the moho discontinuity a deep fault below the deccan traps 13 km east of mahad divides the entire cross section including the moho boundary into two crustal blocks the reflection segments show updip towards the west coast in the western block the moho discontinuity which is at a depth of 39 km near the deep fault starts rising towards the coast reaching a depth of 31 5 km at the west coast the eastern block is thrown up by 1 5 km with respect to the western block along the deep fault a structural contour map of the moho discontinuity for the koyna reservoir area has been prepared from the present results and the crustal information obtained along the koyna i profile kaila et al 1979a shows that the deep fault in the koyna area is aligned in the nnw sse direction refraction seismic data analysis by the wave front method reveals that the thickness of the deccan trap increases towards the west coast the deccan trap is 600 700 m thick in the eastern region between nira sp 130 and loni sp 200 and attains a thickness of 1500 m at 10 km east of the west coast the longitudinal wave velocity in the deccan traps along the profile varies from 4 8 to 5 0 km sec and in the crystalline basement from 6 0 to 6 15 km sec a tentative isopach contour map of the deccan traps and a tentative structural contour map of the pre deccan trap contact have been prepared for the koyna reservoir area from the results along the koyna ii and koyna i profiles a flexure aligned in a nnw sse direction in the pre deccan trap contact which is an expression of the deep fault into the basement has been clearly brought out the flexure coincides in general with the orientation of the deccan volcanic scarp in this area

modelling earthquake rupture rates in fault systems for seismic hazard assessment the eastern betics shear zone abstract earthquake surface fault ruptures can show very complex geometries and involve different faults simultaneously consequently modern fault based probabilistic seismic hazard assessments psha need to account for such complexities in order to achieve more realistic modellings that treat fault systems as a whole and consider the occurrence of earthquake ruptures as aleatory uncertainties we use sherifs a recent approach of modelling annual rates of complex multi fault ruptures to obtain system level magnitude frequency distributions mfds for the eastern betics shear zone ebsz spain considering four fault rupture hypotheses we then analyze the consistency of each scenario based on data from the earthquake catalogue and paleoseismic studies the definition of the different rupture hypotheses was discussed within the frame of fault2sha esc working group and critical fault input data is extracted from previous published studies the four rupture hypotheses are defined as incremental scenarios based on fault geometry and kinematics with lengths varying from minimal fault sections to a rupture of nearly the whole system the results suggest that multi fault ruptures involving lengths up to single to several whole faults are consistent with the annual rates from both the instrumental catalogue and paleoseismic record the method does not allow to completely discard any hypothesis but it allows to weight the different models in a logic tree for seismic hazard assessment the approach is revealed as a practical tool for obtaining fault system mfds and as a useful tool for highlighting limitations and uncertainties in geological and paleoseismic data to be assessed this study aims to constitute a step forward in the consideration of complex multi fault ruptures for future seismic hazard assessments in the region

a method for producing digital probabilistic seismic landslide hazard maps abstract the 1994 northridge california earthquake is the first earthquake for which we have all of the data sets needed to conduct a rigorous regional analysis of seismic slope instability these data sets include 1 a comprehensive inventory of triggered landslides 2 about 200 strong motion records of the mainshock 3 1 24 000 scale geologic mapping of the region 4 extensive data on engineering properties of geologic units and 5 high resolution digital elevation models of the topography all of these data sets have been digitized and rasterized at 10 m grid spacing using arc info gis software on a unix computer combining these data sets in a dynamic model based on newmark s permanent deformation sliding block analysis yields estimates of coseismic landslide displacement in each grid cell from the northridge earthquake the modeled displacements are then compared with the digital inventory of landslides triggered by the northridge earthquake to construct a probability curve relating predicted displacement to probability of failure this probability function can be applied to predict and map the spatial variability in failure probability in any ground shaking conditions of interest we anticipate that this mapping procedure will be used to construct seismic landslide hazard maps that will assist in emergency preparedness planning and in making rational decisions regarding development and construction in areas susceptible to seismic slope failure

instrumental evidence of normal mode rock slope vibration summary a unique field experiment was performed to constrain the seismic response of a large potentially unstable rock slope in the southern swiss alps small aperture seismic arrays were deployed to record ambient vibrations both inside and outside of the mapped instability boundary the recordings were analysed by means of the high resolution f k method site to reference spectral ratios and time frequency dependent polarization analysis all three methods indicated that the wavefield within the potentially unstable rock mass is dominated by normal mode motion standing waves rather than horizontal propagation of seismic waves both fundamental frequency and relative amplification could be recovered from ambient noise data the observed amplification is strongly directional and the maximum amplification is oriented perpendicular to open tension cracks mapped at the ground surface our results highlight site response characteristics relevant for analysis of earthquake triggered rock slope failures

closure of the africa eurasia north america plate motion circuit and tectonics of the gloria fault we examine the closure of the current plate motion circuit between the african north american and eurasian plates to test whether these plates are rigid and whether the gloria fault is an active transform fault we also investigate the possible existence of microplates that have been previously proposed to lie along these plate boundaries and compare the predicted direction of motion along the african eurasian plate boundary in the mediterranean with the direction of slip observed in earthquakes from marine geophysical data we obtain 13 transform fault azimuths and 40 3 m y average spreading rates 34 of which are determined from comparison of synthetic magnetic anomaly profiles to 140 observed profiles slip vectors from 32 earthquake focal mechanisms further describe plate motion detailed magnetic surveys north of iceland provide 11 rates in a region where prior plate motion models had few data magnetic profiles north of the azores triple junction record a rate of 24 mm yr 4 mm yr slower than used by prior models gloria and sea beam surveys accurately measure the azimuths of seven transform faults our plate motion model fits six of the seven within 2 two transform faults surveyed by gloria side scan sonar lie near famous area transform faults a and b and give azimuths 13 clockwise of them because recent studies show that short offset transforms such as transforms a and b are in many places oblique to the direction of plate motion we exclude azimuths from transforms with less than 35 km offset the best fitting and closure enforced vectors fit the data well except for a small systematic misfit to the slip vectors on right lateral slipping transforms slip vectors tend to be a few degrees clockwise of plate motion and mapped fault azimuths whereas on left lateral slipping transforms slip vectors tend to be a few degrees counterclockwise of plate motion and mapped fault azimuths we search the long eurasia north america boundary for evidence of an additional plate but find no systematic misfits to the data in particular if a spitsbergen plate exists and moves relative to eurasia its motion is less than 3 mm yr an africa eurasia euler vector determined by adding the eurasia north america and africa north america euler vectors is consistent with the gloria fault trend and with slip vectors from eastern azores gibraltar ridge focal mechanisms a small circle centered at the africa eurasia closure enforced pole fits the trace of the gloria fault the model in which closure was enforced predicts 4 mm yr slip across the azores gibraltar ridge and west northwest convergence near gibraltar 45 more oblique than suggested by a recent model based on compressive axes of focal mechanisms moreover our model predicts directions of plate motion that agree well with northwest trending slip vectors from thrust earthquakes between gibraltar and sicily because closure enforced vectors fit the data nearly as well as the best fitting vectors we conclude that the data are consistent with a rigid plate model and with the gloria fault being a transform fault

stress field variation related to fault interaction in a reverse oblique slip fault the alhama de murcia fault betic cordillera spain abstract the interpretation of kinematic data from microstructural observations has led many authors to propose a complex dynamic development for the eastern betic cordillera from the late miocene to the present in which different and sometimes contradictory stress fields explain the generation of the same structures the main aim of this work is to determine whether the dynamic variability of the study area observed during the neotectonic period is coherent with a single regional stress field the structure of the area was analysed through the detailed mapping of the alhama de murcia fault amf and the associated structures further microtectonic data from shear veins in an interaction zone between the main and secondary faults were studied by the stress inversion method of reches tectonics 6 1987 849 a hierarchy is proposed for stress fields and their interpretation with respect to the interaction between structures of different scales relative movements of fault bounded blocks with different sizes produce this hierarchy these movements depend on boundary conditions of blocks and their position relative to the alhama fault zone the study shows that adequate cartography and understanding the context of micro and mesotectonic data is necessary for determining the dynamic significance of microtectonic data the use of stress inversion methods without taking the local tectonic context into consideration can give rise to incorrect interpretations incorrect processing of previous data and extrapolations inappropriate at other scales

landslide inventories the essential part of seismic landslide hazard analyses abstract a detailed and accurate landslide inventory is an essential part of seismic landslide hazard analysis an ideal inventory would cover the entire area affected by an earthquake and include all of the landslides that are possible to detect down to sizes of 1 5 m in length the landslides must also be located accurately and mapped as polygons depicting their true shapes such mapped landslide distributions can then be used to perform seismic landslide hazard analysis and other quantitative analyses detailed inventory maps of landslide triggered by earthquakes began in the early 1960s with the use of aerial photography in recent years advances in technology have resulted in the accessibility of satellite imagery with sufficiently high resolution to identify and map all but the smallest of landslides triggered by a seismic event with this ability to view any area of the globe we can acquire imagery for any earthquake that triggers significant numbers of landslides however a common problem of incomplete coverage of the full distributions of landslides has emerged along with the advent of high resolution satellite imagery

azimuth dependent amplification of weak and strong ground motions within a fault zone nocera umbra central italy 1 during three moderate magnitude earthquakes occurred in september october 1997 in the central apennines italy accelerations larger than 0 5 g were recorded in the town of nocera umbra 10 to 15 km n nw of the epicenters the accelerograph is sited in a fault zone close to a n30 e tectonic contact six temporary seismological stations installed across the fault recorded 82 aftershocks occurred in two seismogenic zones the colfiorito sellano area s se of the array and the gualdo tadino area to the north the array data reveal large variations in terms of both peak ground motions and spectral amplitudes within the fault zone amplifications show a strong dependence on the source azimuth at the accelerograph site the effects are particularly large for events from s se peak ground motions are a factor of 14 larger than those of a reference site and conventional spectral ratios attain amplitudes as large as 50 at 7 hz along the n30 e direction of motion parallel to the strike of the fault nineteen strong motion accelerograms were then used to compare ground motion properties between weak and strong events up to m 0 1 2 x 10 25 dyn cm a particle motion analysis shows that the directional effect is also present in the strongest motions even though the amplification of peak ground motion decreases when m 0 increases results from stochastic simulations indicate that such a behavior is not due to nonlinearity applying the empirical weak motion transfer functions in a purely linear model the observed peak ground motions of the largest events are fit satisfactorily

obtaining suitable logic tree weights for probabilistic earthquake induced landslide hazard analyses abstract in this study an inventory of landslides induced by the 2011 lorca earthquake mw 5 1 has been used in order to develop a new procedure to obtain objective logic tree weights for a probabilistic earthquake induced landslide hazard analysis the 2011 lorca earthquake triggered more than 250 landslides mainly of disrupted type the logic tree was designed having regard to variability of relevant geotechnical parameters involved in the problem and uncertainties associated with the use of several empirical relationships in order to compute newmark displacements for the purpose the resulting hazard maps were compared with this landslide inventory and weights estimated for each branch of the logic tree based on these results the best model for seismic landslide hazard mapping for a moderate earthquake correctly identifies around 72 of landslide areas based on the set of parameters that comprises depth of failure surface specific weight cohesion friction angle and newmark displacement model the corresponding weights were objectively established these weights are reliable enough for the obtaining seismic landslide hazard maps and may be implemented in similar environments characterized by moderate low magnitude earthquakes mw

magnitude distance relations for earthquake induced landslides in greece a data set of 47 earthquake induced landslides occurring in greece from ad 1650 to 1995 has been compiled and the landslide distribution has been examined the spatial distribution indicates landslides occurrence almost everywhere in greece with the exception of the north greek mainland which is likely due to the low occurrence frequency of large earthquakes the earthquake magnitude m s ranges between 5 3 and 7 9 while the main bulk of events falls within the range 7 5 m s 5 3 with peaks at m s 6 4 and 6 7 the upper bound of the maximum epicentral distance r e from a reported landslide has been approximated by the line log r e 2 98 0 75m s for m s 5 3 which is compatible with curves proposed world wide and constitutes a realistic solution at least for hazard assessment purposes we discuss the importance of the results for assessing hazards from earthquake induced landslides and for calculating focal parameters of historical earthquakes 2000 elsevier science b v all rights reserved

study of the damaging earthquakes of 1911 1999 and 2002 in the murcia southeastern spain region seismotectonic and seismic risk implications a detailed study of four earthquakes that occurred in the murcia region southeastern spain in 1911 1999 and 2002 has been carried out new intensity maps have been plotted for the march and april 1911 shocks these show maximum values of vii viii ems we have found values of vi and v respectively for the 1999 and 2002 earthquakes surface wave magnitudes range from 5 2 for the bullas 2002 event to 5 7 for the march 1911 event focal mechanisms for the mula 1999 and bullas 2002 events indicate reverse and strike slip motions with scalar seismic moments of 5 9 10 16 n m and 8 6 10 15 n m respectively and focal dimensions of 4 0 and 1 5 km both earthquakes were recorded at epicentral distances greater than 21 km showing low values of peak ground acceleration pga 0 020 g these records involve a ground motion less than the ones expected in the region according to different hazard studies the seismic hazard map that we obtained for the murcia region for a return period of 475 years shows higher values than those given in the spanish building code ncse 02 2002 e g 0 24 g for pga in the city of murcia compared with 0 16 g in the code

earthquake magnitude recent research and current trends abstract the magnitude recommendations adopted by the iaspei assembly at zurich in 1967 have had both a stabilizing and a stimulating effect on magnitude determinations and related research from 1967 onwards one magnitude research paper has appeared on the average almost every week thus making this parameter the most studied one in seismology new facilities and more accurate methods e g concerning instrumental equipment and interpretation techniques have made it possible to improve earlier achievements the application of magnitude scales has been extended in all respects e g with regard to epicentral distances focal depths wave types and wave periods magnitude frequency relations have become the most investigated equations within seismology observationally as well as theoretically they have wide applications e g for estimating the maximum magnitudes of future earthquakes an important item in earthquake prediction the magnitudes provide significant information on other source parameters such as wave energy fault length seismic moment relations between different types of magnitude yield valuable information on source properties for instance relations between magnitudes based on body and surface waves are used for efficient discrimination between earthquakes and underground explosions it is our purpose to review the magnitude development in the post zurich period 1967 1980 partly for geologists tectonophysicists and engineers who need an overview partly for seismologists who need an introduction to an overwhelmingly comprehensive literature

widespread landslides induced by the mw 5 1 earthquake of 11 may 2011 in lorca se spain abstract on 11 may 2011 a moderate magnitude mw 5 1 earthquake struck the city of lorca se spain and nearby areas causing notable damage injuries and fatalities field inspection of the area affected allowed the location and characterization of more than 250 induced landslides mainly of disrupted type rock soil falls disrupted soil slides and rock avalanches this number was very high when compared with the inventories of previous events of similar magnitude mw 4 7 to 5 0 in the zone and with the results of previous models for predicting slope behavior during earthquakes several factors are proposed here to explain the observed differences i the comparatively high magnitude mw 4 5 of a foreshock of the seismic series that may have weakened the slopes ii the high peak ground motion values recorded for these events and iii the occurrence of topographic site effects the results of this study point out the importance of including such effects as improvements in the models for studying the regional behavior of slopes

study of the 6 june 1977 lorca spain earthquake and its aftershock sequence on 2 may 1977 a portable array of five stations was installed for the reconnaisance of the alhama de murcia fault in southern spain during this survey on 6 june 1977 a 4 2 mb lg shock took place within the array and was followed by a long series of aftershocks due to the good quality of the records a comprehensive study of location magnitude seismic moment focal mechanism and related parameters has been carried out in the seismic moment calculation we have used the coda wave analysis which also gives information about q values of approximately 320 and 617 for body and surface waves respectively in evaluating the focal mechanisms of the sequence we have used a joint treatment which permits us to separate the two types of faulting involved in the rupture process finally to interpret these results in terms of the tectonics of the region the focal mechanism of the earthquake of 5 march 1981 which occurred in a neighboring area has also been studied

esi 07 shakemaps for instrumental and historical events in the betic cordillera se spain an approach based on geological data and applied to seismic hazard abstract this work presents high resolution shakemaps for three earthquakes occurred in the betic cordillera se spain the 2011 ce lorca event viii esi 07 the 1863 ce huercal overa event viii esi 07 and the 1829 ce torrevieja event x esi 07 detailed field characterizations and mapping of their coseismic environmental effects eees are catalogued and classified following the esi 07 scale the resulting macroseismic information reaches up to ten times the existing information based on conventional damage based scales e g ems 98 providing a better constrain towards more realistic ground motion scenarios the 2011 lorca earthquake has been used as a calibration event since there is a relevant record of instrumental measures on source and ground motion parameters allowing a direct comparison with the modelled pga values from a methodological standpoint the obtained shakemaps follow the basic guidelines and methodology proposed by the usgs shakemap program the two historical earthquakes analysed in this paper produced a wide variety of secondary eees but no surface faulting was reported these effects need to be properly identified by high resolution dtms 5 m pixel far from the c 900 m pixel terrain models used by usgs program additionally the proposed esi 07 shakemaps incorporate correction factors to solve inconsistencies derived from the large scale terrain models considered in standard usgs program workflows 1 empirical slope derived v s 30 models result in overestimations of the pga values in flat terrains in absence of unconsolidated deposits 2 the topographic amplification factor included here explains the occurrence of rock falls and landslides in steep areas where ground motion is underestimated by the sole use of slope derived v s 30 models basic geological and geomorphological information need to be implemented in the modelling workflow in both cases to prevent pga overestimations in flat terrains a correction factor related to the spatial distribution and thickness of the quaternary unconsolidated deposits has been incorporated i e isopach maps to correct pga underestimations in steep terrains an amplification factor was modelled following standard guidelines of seismic topographic amplification the comparison via iteration of the spatial distribution of both esi effects and ems macroseismic data with the obtained ground motion spatial distribution enables a better definition of the geological parameters for the studied historical earthquakes a more accurate location and or size of the suspect seismic sources are obtained for these historical earthquakes providing scenarios more realistic than those resulting from old intensity maps quaternary geology and geomorphology are behind the implementation of the proposed esi 07 shakemaps being especially useful when exploring historic or ancient moderate earthquakes with scarce damage based macroseismic data but with sufficient paleoseismic or archaeoseismic records in summary the methodological workflow proposed here contemplates the implementation of a computational configuration seismologically relevant and able to test repeated seismic scenarios with different parametric data in a controlled gis environment useful to reproduce historical events

complex rupture mechanism and topography control symmetry of mass wasting pattern 2010 haiti earthquake the 12 january 2010 mw 7 0 haiti earthquake occurred in a complex deformation zone at the boundary between the north american and caribbean plates combined geodetic geological and seismological data posited that surface deformation was driven by rupture on the leog ne blind thrust fault while part of the rupture occurred as deep lateral slip on the enriquillo plantain garden fault epgf the earthquake triggered 4490 landslides mainly shallow disrupted rock falls debris soil falls and slides and a few lateral spreads over an area of 2150 km2 the regional distribution of these slope failures defies those of most similar earthquake triggered landslide episodes reported previously most of the coseismic landslides did not proliferate in the hanging wall of the main rupture but clustered instead at the junction of the blind leog ne and epgf ruptures where topographic relief and hillslope steepness are above average also low relief areas subjected to high coseismic uplift were prone to lesser hanging wall slope instability than previous studies would suggest we argue that a combined effect of complex rupture dynamics and topography primarily control this previously rarely documented landslide pattern compared to recent thrust fault earthquakes of similar magnitudes elsewhere we conclude that lower static stress drop mean fault displacement and blind ruptures of the 2010 haiti earthquake resulted in fewer smaller and more symmetrically distributed landslides than previous studies would suggest our findings caution against overly relying on across the board models of slope stability response to seismic ground shaking

a premonitory pattern of earthquakes in northern greece on 20 june 1978 at 20 h 03 min 23 s an earthquake of surface wave magnitude 6 5 occurred in the migdonian basin between the lagada and volvi lakes and 26 km from thessaloniki the main shock was preceded by a seismic sequence which started on 8 may the largest earthquake of that sequence occurred on 23 may and had a surface wave magnitude of 5 8 the long duration of this sequence before the main shock of 20 june had tremendous psychological effects on the whole country greek seismologists were in a difficult position during that time 8 may 20 june especially after the earthquake of 23 may when pressed to state whether these earthquakes were foreshocks or aftershocks long lasting seismic sequences with earthquakes of magnitude 6 are common in the aegean area because these sequences are sometimes followed by large earthquakes it is important to see whether the latter can be predicted the may june 1978 seismic sequence provided the opportunity for testing hypotheses about statistical properties which it has been suggested could distinguish between foreshocks and aftershocks this particular sequence has been investigated extensively1 4 and more accurate data are available than for any other sequence around greece focal mechanism studies5 6 and field observations2 showed that the largest earthquakes of the sequence were produced by horizontal extension in a nearly north south direction and that the main rupture occurred on a normal fault which strikes almost east west and dips to the north the fault length of the main shock of 20 june was estimated7 to be 32 km accurate determination of earthquake foci using portable seismographs showed that the earthquakes of this sequence were shallow h 17 km while the distribution of the epicentres had a very clear east west elongation4 5 a migration of the seismic activity from east to west has also been observed between 8 may and 14 july we investigate here the time variation of the average magnitude and the frequency of all the shocks with m 3 0 of this sequence the time variations of these seismic parameters are examined in connection with the distribution of well determined epicentres of 38 earthquakes with m 4 3 in order to search for any premonitory pattern of the 23 may and 20 june major earthquakes

impact of tensile strength and incident angles on a soil slope under earthquake sv waves abstract the tensile strength and incident angles play important roles in seismically induced slope failures in this paper a new criterion for tension shear coupling is proposed based on several sets of relevant lab data and is verified using the experimental data provided by previous researchers this criterion can perfectly depict the tension region as well as the compression region in the entire stress space moreover the tension shear criterion was converted into an expression that could be directly used in a numerical method and it was verified by a numerical example in addition the sv waves were input using the equivalent nodal force method based on a viscous spring artificial boundary this process was implemented by the abaqus software and two numerical examples were used to verify this method subsequently based on the proposed new criterion and input method the impacts of the strength criterion and incident angles on an analysis of seismically induced slope failures were studied the results indicated that the evaluation of the tension shear region is extremely important in the analysis of the seismically induced slope failures the tensile strength of the seismically induced landslides was overestimated by the calculation of mohr coulomb criterion owing to the ambiguous description of the tensile failure or the tension shear failure the assessment of the slope stability was thus not conservative the incident angles of seismic waves affected the travel path and the directivity of slope seismic responses the sliding displacement of the slope side near the epicenter rose with increasing angles of wave incidence the critical slip surface deepened and the hazard aggravated therefore it is important to introduce both the tensile strength and incident angles when evaluating the stability of slopes subjected to seismic loads

the betic segment of the lithospheric trans alboran shear zone during the late miocene abstract the betic sinistral transcurrent shear zone betic cordilleras crosses the southeastern part of spain the study of the geodynamics of this area is approached from tectonic sedimentary magmatic and geophysical data large strike slip movements tectono sedimentary processes and magmatic events are seen at the boundary between two different lithospheric slabs they are located in a thinned compartment with a high geothermal gradient the large scale movements vertical and horizontal and the intensity of magmatic activity are the expression of the mechanical behaviour of this hot and thin crust all the geological events from the late miocene to recent are integrated in a crustal scale cross section which shows that the betic sinistral transcurrent shear zone widely affects the lithosphere it appears that subduction zones are not the only geodynamic context in which calc alkaline magmatism occurs

large rock avalanches triggered by the m 7 9 denali fault alaska earthquake of 3 november 2002 the moment magnitude m 7 9 denali fault alaska earthquake of 3 november 2002 triggered thousands of landslides primarily rock falls and rock slides that ranged in volume from rock falls of a few cubic meters to rock avalanches having volumes as great as 20 10 6 m 3 the pattern of landsliding was unusual the number and concentration of triggered slides was much less than expected for an earthquake of this magnitude and the landslides were concentrated in a narrow zone about 30 km wide that straddled the fault rupture zone over its entire 300 km length despite the overall sparse landslide concentration the earthquake triggered several large rock avalanches that clustered along the western third of the rupture zone where acceleration levels and ground shaking frequencies are thought to have been the highest inferences about near field strong shaking characteristics drawn from interpretation of the landslide distribution are strikingly consistent with results of recent inversion modeling that indicate that high frequency energy generation was greatest in the western part of the fault rupture zone and decreased markedly to the east d 2005 elsevier b v all rights reserved

magnitude the relation of ml to mblg abstract the m blg magnitude developed by nuttli 1973 for the central united states is adapted to other regions of the world by incorporating a specific term for the spatial coefficient of anelastic attenuation using region specific values m blg values are determined for earthquakes occurring near the wwssn stations bks gsc and dug a comparison of the m blg values with published m l magnitudes shows that these two magnitude scales are essentially equivalent between magnitudes 3 to 5 because of this observation we now have a direct way of comparing eastern and western united states earthquake sizes for the purpose of adapting western strong motion data bases to the east and also for understanding teleseismic magnitude biases

the effect of topography on earthquake ground motion a review and new results a brief review of experimental and theoretical results about the effect of topography on seismic motion shows that they are consistent only on a qualitative basis amplification at mountain tops for wavelengths comparable with mountain widths is predicted and observed but the numerical simulations often underestimate the actual observed effects we propose that this disagreement is because current models are not complex enough we therefore computed the response to incident sh waves of a set of different complex configurations that include two dimensional surface topography with or without periodic ridges and subsurface layering the results show that 1 the topographic effect in itself is difficult to isolate from other effects like surface layering and therefore the amplification on top of geomorphologically complex sites cannot be predicted by a priori estimations based solely on topography and 2 the high crest base amplification ratio observed in the field cannot usually be matched even with complex two dimensional structures with incident plane sh waves which suggests that more complex models are needed to incorporate more complex wave fields e g sv surface and three dimensional geologic configurations

correlation between regional and global seismic activity abstract the regional seismic activity in sweden is significantly correlated to the global seismic activity this result suggests that the regional swedish activity is linked to the global activity by intraplate tectonics rather than being caused exclusively by regional effects such as the land uplift after the last glaciation

recent research on the physical aspects of earthquakes abstract recent developments in the field of physical aspects of earthquakes which encompasses in present day terminology the analysis of focal dynamics and of catastrophic effects of earthquakes are reviewed in particular individual sections of this review deal with the earthquake source effects of earthquakes on the ground the geographic and temporal distribution of earthquakes the characterization of seismic risk earthquake prediction and with the artificial release of earthquakes in this instance the review supplements earlier information by the author 1975 by new data published mainly between 1975 and 1984

site effects in unstable rock slopes dynamic behavior of the randa instability switzerland we evaluate the dynamic response of the large around five million cubic meters unstable rock slope at randa switzerland based on ground motion recordings during small earthquakes seismic measurements revealed strong polarization of the wavefield in the direction of maximum slope displacement with spectral amplification factors 5 within the unstable area results further highlighted resonant frequencies of both the large unstable rock mass and individual blocks within it block vibration was confirmed by phase analysis of in situ displacement measurements from two bounding tension fractures during a small earthquake numerical simulation using a discontinuous elastic model showed that the presence of steeply dipping compliant fractures is crucial for recreating the observed site response such fractures are common in rock slope instabilities and are here shown to contribute to polarization and amplification of seismic shaking site effects that are rarely considered for hard rock slopes and which may influence the potential for earthquake triggered failure

earthquake induced landslides in central america central america is a region of high seismic activity and the impact of destructive earthquakes is often aggravated by the triggering of landslides data are presented for earthquake triggered landslides in the region and their characteristics are compared with global relationships between the area of landsliding and earthquake magnitude we find that the areas affected by landslides are similar to other parts of the world but in certain parts of central america the numbers of slides are disproportionate for the size of the earthquakes we also find that there are important differences between the characteristics of landslides in different parts of the central american isthmus soil falls and slides in steep slopes in volcanic soils predominate in guatemala and el salvador whereas extensive translational slides in lateritic soils on large slopes are the principal hazard in costa rica and panama methods for assessing landslide hazards considering both rainfall and earthquakes as triggering mechanisms developed in costa rica appear not to be suitable for direct application in the northern countries of the isthmus for which modified approaches are required

messinian salinity crisis deposits widespread over the balearic promontory insights from new high resolution seismic data abstract the current interpretation of the messinian salinity crisis msc involves the deposition of peripheral or marginal evaporites in onshore basins as well as the erosion of the margin and the deposition of thick evaporites in deep basins the so called intermediate basins are formed in domains between the onland outcrops and the deep basins the balearic promontory is a bathymetric high located between the deep algerian and liguro provencal basins and the onland spanish basin the simbad project aims to investigate the spatial variability of the msc related deposits and to assess the extent of post msc reactivation over the balearic promontory we present here the first results of the simbad high resolution seismic survey january 2013 which imaged for the first time a thin msc related unit widely distributed in small sub basins over the balearic promontory borehole analyses have shown that this unit could be correlated with primary gypsum formations linked to the peripheral evaporites locally in the central depression between mallorca and ibiza islands a thicker msc unit is observed whose lowermost transparent part could correspond to a salt layer geometrical relationships suggest that the msc in the central depression could postdate the primary gypsum the occurrence of a halite layer in the central depression at depths of 1000 to 1500 m favours the hypothesis that the evaporites precipitated passively in closed or partially closed perched sub basins possibly as a result of evaporative drawdown at different depths and possibly diachronously at least with respect to the deep basin evaporites

source times and scaling relations of large earthquakes source time is a kinematic fault parameter corresponding to the duration of seismic source time functions and is accurately determined from phase spectra of long period surface waves source times are determined for 36 large earthquakes during the last three decades scaling relations among source times seismic moments and fault dimensions are derived seismic moment is proportional to the cube of source time and fault dimension is proportional to source time source times for low angle thrust earthquakes along deep sea trenches are found to be longer than those of other types such as intraplate shocks and deep shocks they are also significantly longer than the rupture times expected from a haskell model suggesting that generally there exists an introductory stage of faulting that precedes the main stage of the rupture propagation