source characteristics of the 28 september 2018 m w 7 5 palu sulawesi indonesia se asia earthquake based on inversion of teleseismic bodywaves we study source characteristics of the september 28 2017 mw 7 5 palu sulawesi indonesia earthquake that occurred in central sulawesi and triggered devastating tsunami waves along the coastal plains of the island we apply point source teleseismic p and sh body waveform inversion and kinematic slip inversion techniques to obtain double couple source mechanism and comprehensive finite fault slip model of the source the overall results show a strike slip faulting mechanism strike 353 5 dip 65 5 and rake angles 4 5 with a small amount of dip slip component at a shallow focal depth of 16 2 km associated with the nw se trending left lateral palu koro strike slip fault in the central sulawesi region the p wave first motion polarity readings recorded at near field and regional seismic stations are found to be reasonably consistent with the source mechanism solution of the earthquake and estimated error limits we have extensively studied and considered the rupture velocity to be about 4 1 km s during the slip inversion as previously proposed by seismological and geodetic studies for this event the obtained finite fault slip distribution model displays a rupture starting from the hypocentre located at 16 km and then it propagated south accompanied by high amount of displacement and reached the surface the model has two slip patches of 2 0 4 0 m at north of the fault plane and 5 0 6 3 m at south near palu city which is very well matched with the observed damage and destruction related to the earthquake the fault length and width average slip and stress drop values are estimated to be 150 km 45 km 1 5 m and 13 bars respectively we have also obtained total source duration to be about 40 s with the most of seismic energy released at 10 s and 25 s furthermore a small dip slip component is evidently observed from both source models and we suggest that this oblique shear which reflects the bending of slip vector along the strike direction could be comparatively responsible for tsunami generation along the left lateral palu koro fault the validation of this hypothesis could be done by evaluating the results of the mathematical tsunami simulations based on the comprehensive non uniform slip models along with a high resolution bathymetry data which provides the details of the continental shelf in palu bay

early and persistent supershear rupture of the 2018 magnitude 7 5 palu earthquake the speed at which an earthquake rupture propagates affects its energy balance and ground shaking impact dynamic models of supershear earthquakes which are faster than the speed of shear waves often start at subshear speed and later run faster than eshelby s speed here we present robust evidence of an early and persistent supershear rupture at the sub eshelby speed of the 2018 magnitude 7 5 palu indonesia earthquake slowness enhanced back projection of teleseismic data provides a sharp image of the rupture process along a path consistent with the surface rupture trace inferred by subpixel correlation of synthetic aperture radar and satellite optical images the rupture propagated at a sustained velocity of 4 1 km s 1 from its initiation to its end despite large fault bends the persistent supershear speed is further validated by seismological evidence of far field rayleigh mach waves the unusual features of this earthquake probe the connections between the rupture dynamics and fault structure an early supershear transition could be promoted by fault roughness near the hypocentre steady rupture propagation at a speed unexpected in homogeneous media could result from the presence of a low velocity damaged fault zone

inversion of complex body waves we have developed a method that inverts seismic body waves to determine the mechanism and rupture pattern of earthquakes the rupture pattern is represented as a sequence of subevents distributed on the fault plane this method is an extension of our earlier method in which the subevent mechanisms were fixed in the new method the subevent mechanisms are determined from the data and are allowed to vary during the sequence when subevent mechanisms are allowed to vary however the inversion often becomes unstable because of the complex trade offs between the mechanism the timing and the location of the subevents many different subevent sequences can explain the same data equally well and it is important to determine the range of allowable solutions some constraints must be imposed on the solution to stabilize the inversion we have developed a procedure to explore the range of allowable solutions and appropriate constraints in this procedure a network of grid points is constructed on the i plane where and i are respectively the onset time and the distance from the epicenter of a subevent the best fit subevent is determined at all grid points then the correlation is computed between the synthetic waveform for each subevent and the observed waveform the correlation as a function of and i and the best fit mechanisms computed at each i grid point depict the character of allowable solutions and facilitate a decision on the appropriate constraints to be imposed on the solution the method is illustrated using the data for the 1976 guatemala earthquake

the 1971 may 12 burdur earthquake sequence sw turkey a synthesis of seismological and geological observations summary it is now widely accepted that the rapid extension observed in western turkey is mainly accommodated by large active normal faults which control the geomorphology the ne sw trending burdur acigol and baklan basins bounded by large faults form a system of half graben whose orientation is evident in both the topography and the tilting of neogene sediments adjacent to them we used long period p and sh waveforms to determine the source parameters of the two largest earthquakes of the 1971 may 12 sequence that occurred in the burdur region the main shock was followed by many aftershocks which were distributed in a broad zone elongated ne sw parallel to the long axes of the basins in the region documented surface breaks of the 1971 event suggest that the northwest dipping faults along the southern margin of the burdur basin are those which moved well exposed fault planes are found dominantly to the south of burdur lake the surface dips of these faults are greater than that of the nw dipping nodal plane obtained for the main shock combined seismological and geological observations suggest that these faults have listric geometries

fault plane solutions of earthquakes and active tectonics of the tibetan plateau and its margins summary fault plane solutions of earthquakes within and on the margins of the tibetan plateau show diverse styles of faulting and deformation with thrust faulting and crustal shortening normal to the margins of the plateau and with normal and strike slip faulting resulting in roughly east west crustal extension within the plateau the direction of overthrusting of the himalaya onto the indian shield is radially outward varying from southwest in the western himalaya to south southeast in the east assuming that the indian shield behaves rigidly this requires a west northwest divergence of western tibet from southeastern tibet at a rate of 18 9 mm yr 1 comparable with the rate of convergence at the himalaya fault plane solutions of earthquakes in the southern portion of the tibet plateau consistently show large components of normal faulting on roughly north striking planes and corroborate such extension within the high plateau where elevations exceed 5000 m normal and strike slip faulting occur so that an overall east southeast west northwest extension of the region at about 10 mm yr 1 is partitioned into roughly equal parts of crustal thinning and north northeast south southwest crustal shortening about 5 mm yr 1 in general strike slip faulting characterizes solutions for earthquakes within eastern tibet where mean elevations drop below 4500 5000 m but the orientations of the strike slip faults vary across the region in central tibet left lateral slip occurs on planes trending roughly northeast but for earthquakes farther east the orientations of that plane become progressively east west and then southeast this variation in orientation implies a rotation of material along curved left lateral shear zones thus the eastward extrusion of tibet appears to be facilitated not only by rapid left lateral shear but also by large clockwise rotations of the material in eastern tibet the rate of eastward extrusion of material in eastern tibet relative to the tarim basin to its north is roughly 30 40 mm yr 1 fault plane solutions of earthquakes in the northern and eastern margins of tibet show large components of thrust faulting with the p axes oriented radially outward from the plateau and approximately perpendicular to the regional topographic contours of the plateau the orientation of this crustal shortening is northeast southwest on the northeastern margin east west on the eastern margin and northwest southeast in the longmenshan on the southeastern margin thus at least some of the extrusion of eastern tibet out of india s northward path into asia is absorbed by crustal shortening on the margins of the plateau the variation from normal faulting in the high tibetan plateau where elevations exceed 5000 m to dominantly strike slip faulting farther east where elevations are lower and then to thrust faulting on the margins of the plateau where elevations drop below 3000 m surely results at least in part from a decrease in the value of the vertical stress the magnitude of the east west compressive stress need not vary across the plateau

active tectonics of the north and central aegean sea summary in this paper we examine the connection between the westward motion of turkey relative to europe and the extension in and around the aegean sea the principal new data available since the last attempt to synthesize the tectonics of this region by mckenzie 1978 are much improved focal mechanisms of earthquakes constrained by p and sh body wave modelling as well as by first motions these mechanisms show that the faulting in the western part of the aegean region is mostly extensional in nature on normal faults with a nw to wnw strike and with slip vectors directed nnw to nne there is evidence from palaeomagnetism that this western region rotates clockwise relative to stable europe in the central and eastern aegean and in nw turkey distributed right lateral strike slip is more prevalent on faults trending ne to ene and with slip vectors directed ne palaeomagnetic data in this eastern region is more ambiguous but consistent with very small or no rotations in the northern part and possibly anticlockwise rotations relative to europe in the south the strike slip faulting that enters the central aegean from the east appears to end abruptly in the sw against the nw trending normal faults of greece the kinematics of the deformation is controlled by three factors the westward motion of turkey relative to europe the continental collision between nw greece albania and the apulia adriatic platform in the west and the presence of the hellenic subduction zone to the south as the right lateral slip on the north anatolian fault enters the aegean region it splays out becoming distributed on several parallel faults the continental shortening in nw greece and albania does not allow the rotation of the western margin of the region to be rapid enough to accommodate this distributed e w right lateral shear and thus leads to e w shortening in the northern aegean which is compensated by n s extension as the southern aegean margin can move easily over the hellenic subduction zone the dynamics of the system once initiated is self sustaining being driven by the high topography in eastern turkey and by the roll back of the subducted slab beneath the southern aegean the geometry of the deformation resembles the behaviour of a system of broken slats attached to margins that rotate in spite of its extreme simplicity a simple model of such broken slats is able to reproduce quantitatively most of the features of the instantaneous velocity field in the aegean region including the slip vectors and nature of the faulting in the eastern and western parts the senses and approximate rates of rotation the overall extensional velocity across the aegean and the distribution of strain rates as seen in the seismicity and topography or bathymetry and using geodetic measurements as part of this study we re examined the relation between the surface faulting and the focal parameters determined seismologically for the three large 1981 gulf of corinth earthquakes and reassessed the evidence for associating particular earthquakes in the sequence with observed surface faulting an important result is that in one of the events there is a resolvable discrepancy between the slip vector measured at the surface and that determined from the seismic body waves

first results of a bathymetric survey of palu bay central sulawesi indonesia following the tsunamigenic earthquake of 28 september 2018 on 28 september 2018 a 7 7 mw strike slip earthquake struck central sulawesi at 0 18 s 119 85 e 10 km northwest of palu the capital of central sulawesi province affecting more than 230 000 people the rapid arrival of the wave suggests a tsunami source within palu bay a bathymetric campaign was conducted in palu bay and the region south of cape manimbaya from 9 to 18 october 2018 one of the goals was to identify a potential source for the tsunami the bathymetry data show a prominent submarine channel within palu bay with sinuosity controlled by the palu koro fault the submarine channel continues into deeper water south and west of cape manimbaya with a sinuosity index of up to 1 770 several submarine slumps were identified within the bay due to the arcuate head scarp the abrupt change in slope and debris on the seafloor or the undulating shape of the slope one possible source location near the mouth of palu bay is identified from the estimated volume of displaced sediment the bathymetry data also show traces of the palu koro fault and suggestions of uplift of cape manimbaya related to activity of the palu koro fault

earthquake source parameters along the hellenic subduction zone and numerical simulations of historical tsunamis in the eastern mediterranean abstract we studied source mechanism parameters and slip distributions of earthquakes with m w 5 0 occurred during 2000 2008 along the hellenic subduction zone by using teleseismic p and sh waveform inversion methods in addition the major and well known earthquake induced eastern mediterranean tsunamis e g 365 1222 1303 1481 1494 1822 and 1948 were numerically simulated and several hypothetical tsunami scenarios were proposed to demonstrate the characteristics of tsunami waves propagations and effects of coastal topography the analogy of current plate boundaries earthquake source mechanisms various earthquake moment tensor catalogues and several empirical self similarity equations valid for global or local scales were used to assume conceivable source parameters which constitute the initial and boundary conditions in simulations teleseismic inversion results showed that earthquakes along the hellenic subduction zone can be classified into three major categories 1 focal mechanisms of the earthquakes exhibiting e w extension within the overriding aegean plate 2 earthquakes related to the african aegean convergence and 3 focal mechanisms of earthquakes lying within the subducting african plate normal faulting mechanisms with left lateral strike slip components were observed at the eastern part of the hellenic subduction zone and we suggest that they were probably concerned with the overriding aegean plate however earthquakes involved in the convergence between the aegean and the eastern mediterranean lithospheres indicated thrust faulting mechanisms with strike slip components and they had shallow focal depths h

field survey of the east java earthquake and tsunami of june 3 1994 a field survey of the june 3 1994 east java earthquake tsunami was conducted within three weeks and the distributions of the seismic intensities tsunami heights and human and house damages were surveyed the seismic intensities on the south coasts of java and bali islands were small for an earthquake with magnitude m 7 6 the earthquake caused no land damage about 40 minutes after the main shock a huge tsunami attacked the coasts several villages in east java province were damaged severely and 223 persons perished at pancer village about 70 percent of the houses were swept away and 121 persons were killed by the tsunami the relationship between tsunami heights and distances from the source shows that the hatori s tsunami magnitude was m 3 which seems to be larger for the earthquake magnitude but we should not consider this an extraordinary event because it was pointed out by hatori 1994 that the magnitudes of tsunamis in the indonesia philippine region generally exceed 1 2 grade larger than those of other regions

simulation of the submarine landslide tsunami on 28 september 2018 in palu bay sulawesi island indonesia using a two layer model the strike slip earthquake on 28 september 2018 mw 7 5 along the palu koro fault on sulawesi island has raised concerns about the potential impact of tsunamis generated by submarine landslides in palu bay indonesia the horizontal displacement of the palu koro fault generated landslide tsunamis that covered palu bay creating wave related hazards along the coastal area based on the unusual amount of information on this tsunami this study investigated possible sources using the available preliminary data the generation of comparatively small tsunamis by coseismic seafloor deformation is omitted and only tsunamis generated by submarine subaerial landslides are analyzed in this study two layer modeling soil and water based on the shallow water equation was used to simulate the tsunami propagation in the bay with severe moderate and minor impacts the accuracy of the model was validated based on the waveform at the pantoloan tidal gauge and trace data the tsunami heights from a combination of small to large submarine landslides could reach up to 3 0 7 0 m along the palu shores this model focused on studying the effects of the tidal level on coastal inundation in palu bay using the 2018 palu tsunami event as a benchmark scenario to demonstrate the capabilities of the model one result shows that regardless of the tidal level the 2018 palu tsunami which occurred during high tide will always result in flooding with a maximum tsunami height of up to 7 0 m above mean sea level the main results suggest two causes for this tsunami event the tsunami source and the topography first the model requires one large source at the bay entrance to reproduce the arrival time approximately 5 min and the large wave observed at the pantoloan gauge to reproduce the later waves small sources in the bay s1 s6 and minor large sources l2 and l3 are needed second the datum correction for the terrain is changed to improve the accuracy of the water level additionally the removal of buildings from the topography is important to achieve highly accurate flow depths and to obtain an inundation area close to the real situation the impacts along the coastline of palu bay from peak waves can be used to identify tsunami hazards in the area in the future

tsunami simulations of the sulawesi m w 7 5 event comparison of seismic sources issued from a tsunami warning context versus post event finite source the 28 september 2018 sulawesi earthquake generated a much larger tsunami than expected from its mw 7 5 magnitude and from its dominant strike slip mechanism within a few minutes after the earthquake the tsunami devastated the seafront of palu bay destroying houses and infrastructures over a few hundred meters coastal subsidence and slumping at various locations around the bay were also observed there is debate in the scientific community as to whether submarine landslides and shore collapses contributed to the generation of strong and destructive waves locally the objective of this study is threefold first to determine whether standard seismic inversions could predict the source in the context of tsunami early warning second to define a new seismic source built from optical image correlation and based on the geological and tectonic context third to assess whether the earthquake alone is able to generate up to 9 m wave heights at the coast numerical simulations of the tsunami propagation are performed for different seismic dislocation sources nonlinear shallow water equations are solved by a finite difference method in grids with 200 m and 10 m resolutions the early cmt focal solutions calculated by seismological institutes show dominant strike slip mechanisms with a homogenous slip distribution these sources produce maximum tsunami heights of 40 cm on the coast of palu city two heterogeneous sources are tested and compared the usgs finite fault model calculated from seismic inversion and a new hybrid source inferred from different techniques the latter is based on a segmented fault in agreement with the geological context and built from both from seismic parameters of a cmt solution and the observed horizontal ground displacements this source produces water wave heights of 4 to 5 m in the palu bay the observed inundation heights and distances are reproduced satisfactorily by the model at pantoloan and at the southwestern tip of palu bay however the hybrid source is unable to reproduce the largest 8 to 12 m water heights as reported from field surveys thus even though this hybrid source produces most of the reported tsunami energy we cannot exclude that the numerous coastal collapses observed in palu bay contributed to increase the local tsunami run up

fault model for the 2015 leucas aegean arc earthquake analysis based on seismological and geodetic observations the 17 november 2015 m w 6 6 earthquake in leucas leukas lefkas or lefkada island in the ionian sea western aegean arc was modeled using teleseismic long period p and sh waveforms and global positioning system gps slip vectors detailed fault modeling in this region characterized by intense seismicity and deformation rates usually assigned to the cephalonia transform fault is a challenge because of the unfavorable observation system to overcome this problem we independently analyzed seismological and geodetic data and then jointly evaluated the results the adopted model indicates that the 2015 earthquake can be assigned to a shallow strike slip fault with a minor component of thrusting along the southwest coasts of leucas and with relatively high slip for the area additionally mostly low angle fault solutions satisfying geodetic observations were identified but were not further investigated the preferred fault model permits recognition that recent m w 6 0 earthquakes in the area some marked by extreme peak ground accelerations are associated with a string of strike slip or oblique slip occasionally overlapping fault segments with variable characteristics along or close to the west coasts of leucas and cephalonia keffalinia kefalonia islands whereas the catastrophic 1953 m w 7 2 cephalonia and other previous major earthquakes were associated with thrust faulting electronic supplement 1 table of the global positioning system gps derived displacements and figures of p wave first motion polarities comparison of earthquake source parameters gps time series 2d projections of geodetic solutions the variance covariance matrix of the geodetic solution and the geodetic variable slip model 1 http www bssaonline org lookup suppl doi 10 1785 0120160080 dc1

source rupture process of the kocaeli turkey earthquake of august 17 1999 obtained by joint inversion of near field data and teleseismic data the rupture process of the 1999 turkey earthquake is examined using both near field strong motion data and teleseismic body wave data the derived source parameters are as follows strike dip slip 268 86 180 nearly pure strike slip the seismic moment mo 1 7 1020 nm mw 7 4 the source duration 20 sec the fault length 70 km the fault width 15 km the rupture process is characterized by an asymmetric bilateral rupture propagation and smooth slip it consists of two major fault segments a rupture propagating to the west and a second rupture propagating to the east the maximum dislocation and the maximum dislocation velocity are 6 3 m and 2 7 m s respectively both found at the former segment the average dislocation is about 4 m the extent of the coseismic rupture suggests that a considerable part of the anticipated seismic gap remains unruptured

insights on the source of the 28 september 2018 sulawesi tsunami indonesia based on spectral analyses and numerical simulations the 28 september 2018 sulawesi tsunami has been a puzzle because extreme deadly tsunami waves were generated following an mw 7 5 strike slip earthquake while such earthquakes are not usually considered to produce large tsunamis here we obtained processed and analyzed two sea level records of the tsunami in the near field pantoloan located inside the palu bay and far field mamuju located outside the palu bay and conducted numerical simulations to shed light on the tsunami source the two tide gauges recorded maximum tsunami trough to crest heights of 380 and 24 cm respectively with respective dominating wave periods of 3 6 4 4 and 10 min and respective high energy wave duration of 5 5 and 14 h the two observed waveforms were significantly different with wave amplitude and period ratios of 16 and 3 respectively we infer tsunamigenic source dimensions of 3 4 4 1 km and 32 5 km for inside and outside of the palu bay respectively our numerical simulations fairly well reproduced both tsunami observations in pantoloan and mamuju except for the arrival time in mamuju however it was incapable of reproducing the maximum reported coastal amplitudes of 6 11 m it is possible that these two sources are different parts of the same tectonic source a bay oscillation mode of 85 min was revealed for the palu bay through numerical modeling actual sea surface disturbances and landslide generated waves were captured by two video recordings from inside the palu bay shortly after the earthquake it is possible that a large submarine landslide contributed to and intensified the sulawesi tsunami we identify the southern part of the palu bay around the latitude of 0 82os as the most likely location of a potential landslide based on our backward tsunami ray tracing analysis however marine geological data from the palu bay are required to confirm such hypothesis

source models of the 2012 haida gwaii canada and 2015 illapel chile earthquakes and numerical simulations of related tsunamis seismological observations provide essential input parameters for numerical tsunami simulations here we present source mechanism parameters finite fault source rupture models and numerical tsunami simulation results for the destructive october 28 2012 haida gwaii canada mw 7 7 and september 16 2015 illapel chile mw 8 3 earthquakes and resulting tsunamis these two earthquakes were controlled by active tectonic features along the subduction zones that had developed in response to the convergent movements of lithospheric plates the faulting geometry strike dip and rake angles focal depth fault dimensions average and maximum slip values on the fault planes and seismic moments of the earthquakes are estimated by analyzing teleseismic long period p and sh waves and broadband p waveforms and using waveform inversion and hybrid back projection methods the obtained slip models of the earthquakes reveal heterogeneous slip distributions on fault planes with long source durations 80 s and 150 s and low stress drop values 10 15 bars numerical simulations of tsunami wave propagation are further performed using the uniform and non uniform slip models and nonlinear long wave equations in spherical coordinates the shape and arrival times of leading tsunami waves are adequately constrained particularly with the heterogeneous slip distribution models the general characteristics of synthetic tsunami waveforms e g amplitude shape arrival time calculated using the non uniform slip model are more consistent with the observed tsunami records than those of a uniform slip model it is further seen that simulation results using preliminary and fast slip models for both earthquakes give only approximate early tsunami estimates tsunami wave heights and arrival times to the coasts are mostly not well simulated the results indicate that tsunami simulations based on finite fault source slip models likely contribute to the determination of tsunamigenic coastal regions by revealing locations arrival times amplitudes and directions of tsunami waves within a close approximation to observed records off shore and far from the source region they provide sufficient information to facilitate tsunami warning and mitigation challenges after the destructive earthquakes we further suggest that joint inversions of gps tsunami teleseismic and strong ground motion records and higher resolution bathymetry data are needed in order to obtain better correlations between observed and synthetic tsunami data especially for the later arriving waves

high slip rate for a low seismicity along the palu koro active fault in central sulawesi indonesia accurate chronological records are critical for understanding the landformsevolution and in particular of alluvial fan sequences emplaced during glocal global climatic changes toward this end we measured in situ produced 10be in quartz boulders exposed on top surfaces of sulawesian late quaternary alluvial fans combined geomorphic study spot image and field analyses indicate that this site is composed of twoalluvial fan units in situ produced 10be concentrations suggest that they were emplaced during two successive major climatic events the calculated minimum exposure ages date the younger unit abandonment at 11 000 2 000 years and seem consistent with a late interglacial abandonment age 120 000years for the older unit this study demonstrates that using both the neutron and muon components implicated in the production of in situ10be surficial erosion rates can be estimated 6 m ma in sulawesi and alluvial fan surfaces dated in particular it shows that10be may be used to date fan surface emplacement during the last 120 ka under humid tropical conditions significantly helping to constrain continental paleo climatology in these regions

field survey of the 2018 sulawesi tsunami inundation and run up heights and damage to coastal communities on september 28 2018 a large earthquake and its accompanying tsunami waves caused severe damage to the coastal area of palu bay in the central western part of sulawesi island indonesia to clarify the distribution of tsunami inundation and run up heights and damage to coastal communities due to the tsunami the authors conducted a field survey 1 month after the event in the inner part of palu bay tsunami inundation and run up heights of more than 4 m were measured at many locations and severe damage by the tsunami to coastal low lying settlements was observed in the areas to the north of the bay and around its entrance the tsunami inundation and run up heights were lower than in the inner part of the bay the tsunami inundation distance depended on the topographical features of coastal areas the southern shore of the bay experienced a longer inundation distance than other shores though generally severe damage to houses was limited to within around 200 m from the shoreline the main lessons that can be learnt from the present event are also discussed

rupture process of the 2014 iquique chile earthquake in relation with the foreshock activity the rupture process of the 2014 iquique chile earthquake is inverted from teleseismic p wave data applying a novel formulation that takes into account the uncertainty of green s function which has been a major error source in waveform inversion the estimated seismic moment is 1 5 1021 nm mw 8 1 associated with a 140 km long and 140 km wide fault rupture along the plate interface the source process is characterized by unilateral rupture propagation during the first 20 s the dynamic rupture front propagated from the hypocenter to the large asperity located about 50 km southward crossing a remarkably active foreshock area at high velocity of about 3 0 km s but small and irregular seismic moment release rate our result may suggest that the 20 s long initial phase was influenced by the stress drop due to the foreshock activity near the main shock hypocenter moreover the 2 week long swarm like foreshock activity migrating roughly at 5 km day toward the main shock hypocenter and possibly associated slow slip contributed to the stress accumulation prior to the mw 8 1 megaquake the main shock initial rupture phase might have triggered the rupture of the large asperity which had large fracture energy

earthquake mechanisms in the hellenic trench near crete summary in the hellenic trench south of crete convergence between the southern aegean sea and africa occurs at a rate of at least 60 mm yr 1 previously published first motion fault plane solutions show a variety of different fault orientations and types but are not well constrained furthermore the lack of reliable focal depths for these earthquakes has obscured any simple pattern of deformation that might exist nonetheless the mechanisms of these earthquakes have strongly influenced views of the tectonics in the hellenic trench we have improved estimates of the fault parameters and focal depths for 14 of these earthquakes using long period p and sh waveforms the earthquake mechanisms fall into four groups a normal faults with a n s strike in the over riding material above the subduction zone b low angle thrusts with an e w strike at a depth of about 40 km c high angle reverse faults with the same strike but shallower focal depths than b d events within the suducting lithosphere with approximately e w p axes the thrusting in groups b and c is probably the mechanism by which the sediments of the mediterranean sea underplate and uplift crete these events have slip vectors in the direction 025 12 which represents the convergence direction between crete and africa along the sw facing boundary of the hellenic trench one of the events in group d occurred beneath the mediterranean ridge and involved high angle reverse faulting with a wnw ese p axis almost perpendicular to the direction of shortening deduced from folds at the surface the mediterranean sea floor in this region appears to be in a state of e w compression for reasons that are not clear

monitoring of the palu koro fault sulawesi by gps years of gps measurements across the palu koro fault sulawesi indonesia state left lateral strike slip 3 4 cm yr with a small normal component 0 4 cm yr the measurements on intermediate points of the transect show that the fault is locked at a depth estimated around 8 16 km by a very simple model the best measured baseline linking the two most separate sites watatu and toboli shows very interestingly a constant rate of 2 6 cm yr from 1992 to 1995 and an increased rate of 6 3 cm yr since then this increase is due to an earthquake on january 1 1996 in the minahasa trench presumably affecting station toboli s position by 2 cm of co seismic and 2 cm of post seismic displacement which is added to its long term velocity we interpret this phenomenon as additional stress loading on the palu fault driven by the slip during the earthquake 100 km to the north east

the last glaciation and sea level history of fosheim peninsula ellesmere island canadian high arctic the last glaciation of fosheim peninsula is reconstructed on the basis of landform and sediment mapping and associated radiocarbon dates ice growth involved the expansion of cirque glaciers and accumulation on upland surfaces that are now ice free limited ice buildup despite lowering of the paleoglaciation level by 700 800 m is attributed to the hyperaridity of the region during glacial conditions marine deposits in formerly submerged basins beyond the ice margins are interpreted to represent i sedimentation caused by local ice buildup and marine transgression by 10 6 ka bp ii increased ablation and glacier runoff 9 5 ka bp and iii marine regression during the holocene holocene marine limit reaches a maximum elevation of approximately 150 m asl along northern eureka sound and greely fiord and descends southeastwards to 139 142 m asl near the sawtooth mountains a synchronous marine limit is implied where the last ice limit was inland of the sea the magnitude and pattern of holocene emergenc

gently dipping normal faults identified with space shuttle radar topography data in central sulawesi indonesia and some implications for fault mechanics abstract space shuttle radar topography data from central sulawesi indonesia reveal two corrugated domal landforms covering hundreds to thousands of square kilometers that are bounded to the north by an abrupt transition to typical hilly to mountainous topography these domal landforms are readily interpreted as metamorphic core complexes an interpretation consistent with a single previous field study and the abrupt northward transition in topographic style is interpreted as marking the trace of two extensional detachment faults that are active or were recently active fault dip as determined by the slope of exhumed fault footwalls ranges from 4 to 18 application of critical taper theory to fault dip and hanging wall surface slope and to similar data from several other active or recently active core complexes suggests a theoretical limit of three degrees for detachment fault dip this result appears to conflict with the dearth of seismological evidence for slip on faults dipping less than 30 the convex upward form of the gently dipping fault footwalls however allows for greater fault dip at depths of earthquake initiation and dominant energy release thus there may be no conflict between seismological and mapping studies for this class of faults

circulation mechanisms related to northeast brazil rainfall anomalies this study explores the role of the upper ocean for circulation anomalies in the overlying atmosphere with focus on the late boreal winter and extreme climatic events in northeast brazil data sources comprise rainfall records in the nordeste surface ship observations of the sea surface temperature sst pressure and wind fields coads period 1948 1990 satellite observations of tropical convection hrc 1971 1988 and upper air analyses of the european centre for medium range weather forecasts ecmwf 1980 1991 all for the tropical atlantic sector interhemispheric sst gradients are most strongly associated with north south contrasts in pressure and the meridional wind component whereas the inverse sst pressure relations in situ are less close enhanced northward temperature increase in the tropical atlantic is accompanied by steeper meridional pressure gradient and accelerated southerly wind component which is representative of a northward displaced intertropical convergence zone itcz with the latter in turn leading to drought in northeast brazil interhemispheric contrasts in the 850 1000 mbar layer mean temperature are similar to those of sst and account for most of the meridional surface pressure gradient during wet as compared to dry years in northeast brazil the tropical north atlantic is cooler and the south atlantic warmer and accordingly the lower tropospheric thickness is reduced to the north but inflated to the south of the equator resulting in increased reduced surface pressure over the north south atlantic as well as reduced southerly surface wind stronger subsidence over the outer tropics of the northern hemisphere and intensified ascending motion and convective activity over the nordeste related to a southward displaced near equatorial convection belt the surface and upper air evidence thus indicates the ways in which the interhemispheric sst gradients exert a hydrostatic control on the lower tropospheric thickness pattern and thus force the south north surface pressure gradients and the surface meridional wind component and hence modulate the latitude position of the itcz and nordeste rainfall

evidence of supershear during the 2018 magnitude 7 5 palu earthquake from space geodesy a magnitude 7 5 earthquake hit the city of palu in sulawesi indonesia on 28 september 2018 at 10 02 43 coordinated universal time it was followed a few minutes later by a 4 7 m high tsunami palu is situated in a narrow pull apart basin surrounded by high mountains of up to 2 000 m altitude this morphology has been created by a releasing bend in the palu koro fault a rapidly moving left lateral strike slip fault here we present observations derived from optical and radar satellite imagery that constrain the ground surface displacements associated with the earthquake in great detail mapping of the main rupture and associated secondary structures shows that the slip initiated on a structurally complex and previously unknown fault to the north extended southwards over 180 km and passed through two major releasing bends the 30 km section of the rupture south of palu city is extremely linear and slightly offset from the mapped geological fault at the surface this part of the rupture accommodates a large and smooth surface slip of 4 7 m with no shallow slip deficit almost no aftershock seismicity was recorded from this section of the fault as these characteristics are similar to those from known supershear segments we conclude that the palu earthquake probably ruptured this segment at supershear velocities the devastating 2018 magnitude 7 5 earthquake in palu indonesia ruptured at supershear speeds according to evidence from space geodesy

field survey of the 2018 sulawesi tsunami deposits on 28 september 2018 a mw 7 5 earthquake struck sulawesi island soon followed by a destructive tsunami this study provides a case history of tsunami deposition where submarine landslides or coastal collapses have contributed to and intensified tsunami generation the sedimentary features resulting from this complex tsunami mechanism are not yet well understood we surveyed tsunami deposits at six locations along the coastline of palu bay in addition to measuring tsunami flow depth run up height and inundation distance at each site in general the tsunami height was less than 8 m with a maximum inundation distance of 310 m the tsunami deposits are thin with simple sedimentary structures such as fining upward sequences these sedimentary characteristics are typical of tsunami deposits elsewhere around the world this work is a preliminary study in that numerical modeling including sediment transport has not been performed further work is needed to distinguish tsunamis with different source mechanisms

microblock rotations and fault coupling in se asia triple junction sulawesi indonesia from gps and earthquake slip vector data the island of sulawesi eastern indonesia is located within the triple junction of the australian philippine and sunda plates and accommodates the convergence of continental fragments with the sunda margin we quantify the kinematics of sulawesi by modeling gps velocities and earthquake slip vectors as a combination of rigid block rotations and elastic deformation around faults we find that the deformation can be reasonably described by a small number of rapidly rotating crustal blocks relative to the sunda plate the southwestern part of sulawesi makassar block rotates anticlockwise at 1 4 myr the northeastern part of sulawesi the bangai sula domain comprises three blocks the central north sula block moves toward the nnw and rotates clockwise at 2 5 myr the northeastern manado block rotates clockwise at 3 myr about a nearby axis and east sulawesi is pinched between the north sula and makassar blocks along the boundary between the makassar block and the sunda plate gps measurements suggest that the trench accommodates 15 mm yr of slip within the makassar strait with current elastic strain accumulation the tectonic boundary between north sula and manado blocks is the gorontalo fault moving right laterally at about 11 mm yr and accumulating elastic strain the 42 mm yr relative motion between north sula and makassar blocks is accommodated on the palu koro left lateral strike slip fault zone the data also indicate a pull apart structure in palu area where the fault shows a transtensive motion and may have a complex geometry involving several active strands sulawesi provides a primary example of how collision can be accommodated by crustal block rotation instead of mountain building