oil origin and accumulation in the paleozoic chepaizi xinguang field junggar basin china abstract the chepaizi xinguang area is a petroliferous region in the western junggar basin that contains several permian tight reservoirs and has a complex petroleum system and accumulation mechanism the oil sources and accumulation mechanisms are investigated by an integrated analysis of biomarker assemblages in reservoir oil samples microscopic analysis of rock samples study of fluid inclusions and simulation of the thermal evolution the results show that the permian oil in the xinguang bulge is mainly generated from the permian fengcheng formation with tricyclic terpane ratios c19 tt c23 tt lower than 0 15 c23 tt c21 tt higher than 1 0 and gammacerane c30 hopane higher than 0 6 the permian oil in the chepaizi area is mostly derived from permian wuerhe formation with c19 tt c23 tt higher than 0 15 c23 tt c21 tt lower than 1 0 and gammacerane c30 hopane lower than 0 4 the permian oils from the xinguang bulge show higher maturity compared to the permian oils from the chepaizi area possibly as a result of later oil filling the fluid inclusions and fluorescence record the main oil charging movements during the late triassic to early jurassic and the late jurassic to early cretaceous in this area and most of the generated oils in late permian are lost the unconformities between permian strata show higher porosity and more oil and gas enrichment comparatively and are the main pathways for lateral oil migration laumontite has had a considerable effect on reservoir properties laumontite dissolution creates pores that provide good oil reservoir space and favorable exploration targets

earthquake generated tsunamis in the mediterranean sea scenarios of potential threats to southern italy italian civil defense project development of new technologies for the protection of the italian territory from natural hazards funded by the italian ministry of university and research

slip distribution of the 2003 boumerdes zemmouri earthquake algeria from teleseismic gps and coastal uplift data 1 using a joint inversion of seismological waveforms and ground displacement observations we estimate several parameters of the fault geometry and rupture process of the mw 6 9 may 21 2003 boumerdes zemmouri earthquake the relocated epicenter is considered as a known parameter total rupture length rupture duration and maximum slip are 55 km from 3 4 e to 4 0 e 12 s and 3 m the modeled south dipping reverse fault oriented ene wsw outcrops a few km offshore which is consistent with the absence of observed surface rupture inland two shallow and relatively localized slip zones are found on both sides of the hypocenter to the sw between boumerdes and zemmouri slip is concentrated between 11 and 2 km depth to the ne between zemmouri and dellys slip is concentrated between 6 km depth and the sea floor various resolution tests indicate that our model is well constrained by the available data and help understanding which data constrains each parameter of the model

t waves from the 1998 papua new guinea earthquake and its aftershocks timing the tsunamigenic slump t waves recorded at hydrophone and seismic stations following the papua new guinea earthquake of 17 july 1998 and its aftershocks show that a small event at 09 02 gmt featured source properties incompatible with an elastic dislocation of appropriate body wave magnitude m b 4 4 these include an exceptional duration 47 s at the wake island hydrophone station wk31 a spectrum rich in high frequencies 7 to 12 hz and a generally low spectral amplitude these characteristics can be explained by the model of an underwater slump accelerating from a standstill and eventually slowing down the relocation of the 09 02 event is compatible with its location within an amphitheater inside which shipboard cruises in 1998 and 1999 documented the presence of a 4 c km3 geologically fresh slump we propose that the slump took place at 09 02 on 17 july 1998 i e 13 minutes after the mainshock and that it generated the locally catastrophic tsunami whose properties amplitude and distribution of runup timing could not be explained by a dislocation model

turbidite chronostratigraphy off algiers central algerian margin a key for reconstructing holocene paleo earthquake cycles northern algeria is threatened by moderate to large magnitude earthquakes resulting from the slow convergence between the african and european plates main active faults are located offshore along the algerian coast as exemplified by the 2003 mw 6 8 boumerdes earthquake this event triggered numerous and widespread turbidity currents over 150 km along strike in the algerian basin reaching 2800 m of water depth and demonstrates the multi source and multi path characteristics of earthquake triggered turbidity flows along this margin segment we rely on the sedimentological analysis of five cores located at the toe of the algiers margin close to the 2003 cable break sites to explore the potential for holocene turbidite paleoseismology radiocarbon measurements provide age models for hemipelagic sediments based on sedimentary facies identification analysis of depositional sequences stacking pattern and a stratigraphic framework established by age models a first correlation of turbidites between the 5 cores is attempted the number of turbidites is constant at the base of the continental slope and decreases seawards over 80 km away from the coast from turbidite correlations 36 synchronous events are identified along the algiers margin segment over the last 9 kyr and are tentatively interpreted as seismically triggered providing a 250 yr mean recurrence interval the main historical earthquakes in the algiers area 2003 1716 and 1365 ce reasonably correlate with three out of the four last turbidites strengthening the hypothesis that turbidites are suitable markers for holocene paleoseismology recurrence intervals of turbidites range between 50 and 900 yr defining quiescence periods exceeding 450 yr three quiescence periods lasting about 800 1400 and 500 yr 7 6 2 ka bp 5 4 4 ka bp and 1 5 1 ka bp respectively support irregular earthquake cycling earthquake triggered turbidites are more frequent in the study area than in the western adjacent margin segment offshore el asnam this higher frequency could arise from the close location of the seismogenic faults beneath the continental slope whereas they are located several tenths of kilometers onland in the el asnam area implying less instabilities of the submarine slope

on the mechanism of conversion of seismic waves to and from t waves in the vicinity of island shores high frequency seismic records from the polynesian seismic network are used to investigate in detail the processes of conversion of acoustic t wave energy from and to seismic waves at island shores on the source side we study the seismic to acoustic conversion based on t phases from hawaiian events recorded at polynesian stations located on the coral platter on the receiver side we study the acoustic to seismic conversion based on t phases from marine sources recorded across the polynesian islands in both instances our results underline the importance of steep slopes typically 50 in allowing an efficient conversion between p waves in the island structure and t waves in the water column these slopes can be coral reefs or the heads of young presumably unconsolidated basalt flows under this geometry modeling based on raytracing indicates that the seismic record of the t phase consists of a p wave at distances from the conversion point greater than 9 km at shorter distances s waves and surface waves are generated in the absence of a steep slope only surface waves are present these models can be used to compute precise and predictable travel time station corrections allowing the use of seismometers located inland to exploit the superb detection and location capabilities of t waves

far field simulation of tsunami propagation in the pacific ocean impact on the marquesas islands french polynesia the islands in the marquesas archipelago are most exposed to far field tsunamis in french polynesia four recent earthquakes located at the pacific rim kurile 1994 chile 1995 mexico 1995 and peru 1996 earthquakes generated trans pacific tsunamis and caused contrasting inundations in several inhabited marquesian bays the aim of this study is to better understand the amplification phenomena observed in the marquesas islands and to improve the risk assessment we present here numerical simulations of these four tsunamis by means of a finite difference model solving the equations of tsunami propagation at different scales the water heights computed in the bays are in excellent agreement with the available observations and thus validate our numerical method these numerical results allow us to determine 1 which propagation azimuths are dangerous for the whole marquesas archipelago and 2 the behavior of each studied bay amplitude frequency in response to tsunami waves we observe that the seismogenic subduction zone along south america is likely to define one of the most dangerous tsunami generation areas for the marquesas archipelago owing to the source geometries and to the trapping of the tsunami energy by bathymetric features in the southern pacific ocean fracture zones seamount chains

the 21 may 2003 zemmouri algeria earthquake mw 6 8 relocation and aftershock sequence analysis 1 a strong earthquake mw 6 8 struck the coastal region east of algiers and the tell atlas of algeria on 21 may 2003 and was responsible of severe damage and about 2400 casualties the coastal mainshock was followed by a large number of aftershocks the largest reaching mw 5 8 on 27 may 2003 we study the mainshock first major aftershocks and about 900 events recorded by temporary seismic stations using master event approach and double difference dd methods although the seismic station array has a large gap coverage the dd algorithm provides with an accurate aftershocks location the mainshock hypocenter relocation is determined using three major aftershocks 5 0 mw 5 8 chosen as master events the new mainshock location shifted on the coastline 36 83n 3 65e at 8 10 km depth seismic events extend to about 16 km depth and form a n 55 60 e trending and 45 55 se dipping fault geometry up to now it is the unique among the recently studied seismic events of the tell atlas of algeria mainshock and aftershocks relocation the thrust focal mechanism harvard cmt n 57 44 se dip 71 rake and the seismic moment 2 86 1019 nm infer a 50 km long fault rupture that may appear at the sea bottom at 6 to 12 km offshore north of the coastline the zemmouri earthquake occurred along the complex thrust and fold system of the tell atlas and provides with new constraints on the earthquake hazard evaluation in northern algeria

erosion of a sandy coast continuous follow up of the coastal groynes of protection in boumerdes algeria the waterfront of boumerdes saw a development in 2005 which consisted of the construction from west to east of two groynes perpendicular to the coast and a shaped spike of t further east these groynes of 50 m in length are constructed of concrete in the middle of the building and are protected by rockfill blocks of metamorphic rocks type our aim is to control the work and make a complete sedimentological study to determine the different sources of sediment supply to follow their distribution at the beach and finally to know the particle trapping zones along the coastal geomorphological entity between boumerdes stream and corso stream before and after the construction of these groynes we have determined fattening areas or depletion sand erosion along the beach which is followed since 1986 we also used heavy minerals as natural tracers to determine the transit directions of sediment supply reaching the study area and their deposition this study will draw up a report on the functioning of the groynes and make a correction in some areas with high risk of erosion after the construction of the groynes

the el asnam 1980 october 10 inland earthquake a new hypothesis of tsunami generation summary the western mediterranean sea is not considered as a high seismic region only several earthquakes with magnitude above five occur each year and only a handful have consequences on human beings and infrastructure the el asnam algeria earthquake of 1980 october 10 with an estimated magnitude ms 7 3 is one of the most destructive earthquakes recorded in northern africa and more largely in the western mediterranean basin although it is located inland it is known to have been followed by a small tsunami recorded on several tide gauges along the southeastern spanish coast in 1954 a similar earthquake having occurred at the same location induced a turbidity current associated to a submarine landslide which is widely known to have cut submarine phone cables far from the coast this event was followed by a small tsunami attributed to the landslide thus the origin of the tsunami of 1980 was promptly attributed to the same kind of submarine slide as no evidence of such mass movement was highlighted and because the tsunami wave periods does not match with a landslide origin in both cases 1954 and 1980 this study considers two rupture scenarios that the coseismic deformation itself of about 10 cm off the algerian coast near tenes is sufficient to produce a low amplitude several centimetres tsunami able to reach the spanish southeastern coast from alicante to algeciras gibraltar strait to the west after a discussion concerning the proposed rupture scenarios and their respective parameters numerical tsunami modelling is performed on a set of bathymetric grids then the results of wave propagation and amplification maximum wave height maps are discussed with a special attention to alicante spain harbour where the location of two historical tide gauges allows the comparison between synthetic mareograms and historical records showing sufficient signal amplitude this study is part of the active tsunami hazard assessment in mediterranean sea especially concerning its occidental part that is the algerian spanish and french coasts

large boulder accumulation on the algerian coast evidence tsunami events in the western mediterranean abstract evidence of catastrophic mega block deposition is presented for the algerian coast from tipaza to dellys the region is prone to large earthquakes several of which are inferred to be tsunamigenic in origin as attests the 2003 zemmouri earthquake mw 6 8 it is argued here that several former tsunamis have resulted in the detachment of large boulders from the nearshore zone and their deposition inland the estimated size weight volumetric mass and distance from the shoreline of more than 100 boulders has enabled estimates to be made of the nature of the hydrodynamic waves responsible for their transport the boulders weigh up to 200 tons and are scattered along 150 km of rocky headlands and pocket beaches in isolated or grouped elements from the subtidal to supratidal zones boulders covered by biogenic incrustations show morphological features which suggest detached reversed and reworked pieces statistical and hydrodynamic analyses indicate that large boulder transport requires either 30 m high waves or 5 to 10 m high waves for catastrophic storm or tsunami events respectively bio indicators allow us to date two inferred tsunamis as having struck the algerian coastline between ad 400 600 and ad 1700

numerical modeling of the great 2004 indian ocean tsunami focus on the mascarene islands on 26 december 2004 the m w 9 2 sumatra earthquake triggered the greatest tsunami ever observed in recent times the unprecedented quality and variety of observations on modern instruments provide opportunities to refine modeling techniques as well as our perception of tsunami hazard in oceanic regions where historical events are not as frequent as in the pacific ocean we present a numerical modeling of the 2004 tsunami on the mascarene islands with refined computations on la reunion island where postevent survey observations and one tide gauge record are available we use two different source models models a and b to account for the observations and we also test an additional source model model c to study the effect of a tsunami originating in the 1833 epicentral area southern sumatra a wave trapped on the edge of la reunion may explain the greatest water heights reached in the western coastline of the island the observed tide gauge data are reasonably well fit models a and b the run up data can also be explained with our models late disturbances observed in la pointe des galets may be explained by a late tsunami reflection from madagascar or by harbor resonances finally we also show that model c 1833 like strikes la reunion more heavily than models a and b

fault location and source process of the boumerdes algeria earthquake inferred from geodetic and strong motion data the boumerdes earthquake occurred on a fault whose precise location offshore the algerian coast was unknown geodetic data are used to determine the absolute position of the fault the fault might emerge at about 15 km offshore accelerograms are used to infer the space time history of the rupture using a two step inversion in the spectral domain the observed strong motion records agree with the synthetics for the fault location inferred from geodetic data the fault plane ruptured for about 18 seconds the slip distribution on the fault indicates one asperity northwest of the hypocenter with maximum slip amplitude about 3 m this asperity is probably responsible for most of the damage another asperity with slightly smaller slip amplitude is located southeast of the hypocenter the rupture stops its westward propagation close to the thenia fault a structure almost perpendicular to the main fault

historical and pre historical tsunamis in the mediterranean and its connected seas geological signatures generation mechanisms and coastal impacts abstract the origin of tsunamis in the mediterranean region and its connected seas including the marmara sea the black sea and the sw iberian margin in the ne atlantic ocean is reviewed within the geological and seismotectonic settings of the region a variety of historical documentary sources combined with evidence from onshore and offshore geological signatures geomorphological imprints observations from selected coastal archeological sites as well as instrumental records eyewitnesses accounts and pictorial material clearly indicate that tsunami sources both seismic and non seismic e g volcanism landslides can be found in all the seas of the region with a variable tsunamigenic potential local regional and basin wide tsunamis have been documented an improved map of 22 main tsunamigenic zones and their relative potential for tsunami generation is presented from west to east the most important tsunamigenic zones are situated offshore sw iberia in the north algerian margin in the tyrrhenian calabria and messina straits in the western and eastern segments of the hellenic arc in the corinth gulf of central greece in the levantine sea offshore the dead sea transform fault and in the eastern side of the marmara sea important historical examples including destructive tsunamis associated with large earthquakes are presented the mean recurrence of strong tsunamis in the several basins varies greatly but the highest event frequency 1 96 years is observed in the east mediterranean basin for most of the historical events it is still unclear which was the causative seismic source and if the tsunami was caused by co seismic slip by earthquake triggered submarine landslides or by a combination of both mechanisms in pre historical times submarine volcanic eruptions i e caldera collapse massive pyroclastic flows volcanogenic landslides and large submarine landslides caused important tsunamis although little is known about their source mechanisms we conclude that further investigation of the tsunami generation mechanisms is of primary importance in the mediterranean region inputs from tsunami numerical modeling as well as from empirical discrimination criteria for characterizing tsunami sources have been proved particularly effective for recent well documented aseismic landslide tsunamis e g 1963 corinth gulf 1979 cote d azur 1999 izmit bay 2002 stromboli volcano since the tsunami generation mechanisms are controlled by a variety of factors and given that the knowledge of past tsunami activity is the cornerstone for undertaking tsunami risk mitigation action future interdisciplinary research efforts on past tsunamis are needed

identification of t waves in the alboran sea analyses of seismograms from 1 100 north moroccan earthquakes recorded at stations of the red sismica de andalucia southern spain reveal the systematic presence of late phases embedded in the earthquake codas these phases have distinctive frequency contents similar to the p and s spectra and quite different to the frequency contents of the earthquake codas they are best detected at near shore stations their amplitudes decay significantly with distance to the shoreline the delays with respect to the p wave onsets of the preceding earthquakes are consistently around 85 s late phases are only detected for earthquakes located in a small region of about 100 60 km centered at 35 4 n 4 0 w near the northern coast of morocco several hypotheses could in principle explain the presence of these late phases in the seismograms for example the occurrence of low energy aftershocks efficient wave reflections or rayleigh waves generated along the source station paths however we conclude that the most likely origin of these phases corresponds to the incidence of t waves generated by conversion from elastic to acoustic energy in the north moroccan coast in the southern coast of the iberian peninsula t waves are thought to be generated by energy trapping in low velocity channels along long oceanic paths in this case we demonstrate that they can be produced in much shorter paths as well although t waves have been already documented in other areas of the mediterranean sea this is the first time that they have been identified in the alboran sea

goringe alboran tell tectonic zone a transpression system along the africa eurasia plate boundary neotectonic structures distributed from the goringe bank to the tell atlas mountains show that the africa eurasia plate boundary in the western mediterranean corresponds to an east west trending deforming zone goringe alboran tell main pliocene and quaternary tectonic structures of the northern atlas mountains are northeast southwest striking fault related folds similar to that of el asnam and are related to north south to northwest southeast compressional movements active tectonics in agreement with the main seismicity distribution and focal mechanisms also support an oblique plate convergence and the existence of a 50 100 km wide transpression zone from goringe across alboran to the tell atlas mountains a kinematic model shows the interaction between dextral transcurrent faults and left lateral faults with block rotations and no lateral extension pinned model shortening and lateral movement rates during the quaternary are estimated to be 1 0 2 3 mm yr and block rotation rate is estimated as 2 5 3 9 m y the plate boundary may correspond to a transpression zone active thrust faults being controlled by deep seated dextral transcurrent faults

tsunami resonance in palma bay and harbor majorca island as induced by the 2003 western mediterranean earthquake abstractthe tsunami induced by the may 21 2003 algerian boumerdes zemmouri earthquake moment magnitude mw 6 9 propagated across the western mediterranean basin thereby causing material damages in some harbors and coastal areas this was the case in the balearic islands and particularly the palma harbor attempts to simulate the 2003 tsunami event found discrepancies between tsunami arrival times and wave amplitude when comparing tide gauge records with results from numerical models to date all published model results of the amplitude of the tsunami are underestimations attributed to numerical limitations due to the lack of high resolution bathymetry and poor definition of harbor geometry other views suggest the inappropriateness of the available seismic source parameterizations and the possible occurrence of submarine landsliding triggered by the earthquake that has not been included in the numerical simulations in this article we present the results of a numerical study aimed at better unders

deposition processes from echo character mapping along the western algerian margin oran tenes western mediterranean abstract the westernmost algerian margin south algero provencal basin depicts a few offshore active faults moderate to rare seismicity and generally very steep slopes 16 we classified and mapped 12 echo types according to their sub bottom acoustic facies observed on this margin on 2 5 2 khz chirp echo sounder data maradja 2003 cruise the echo character maps are interpreted in terms of sedimentary processes the b1 echo type parallel to subparallel high to low amplitude sub bottom reflections mainly in the deep basin corresponds to hemipelagic sedimentation r1 prolonged single echo with no sub bottoms and r2 small irregular overlapping hyperbolae echo types generally near or in canyon systems are associated with turbidity currents or more rarely to contour currents or mass transport deposits such as slumps slides and debris flows the transparent echo types t1 t5 and r3 chaotic lens of low amplitude reflections on top of higher amplitude often located at the foot of the slope or canyons walls typically indicate mass transport deposits like slides or turbidites large zones that display a large variety of echo types are evidenced in the study area and are generally associated with turbidity currents but could also be associated with bottom currents it appears that active tectonics plays a significant role in this part of the margin which presents a few active faults offshore but also a strong and relatively frequent seismicity onland the general pattern of the distribution of mass transport deposits is particular i e many but small slides all along the margin and suggests a probable triggering by recurrent earthquake shakings however active tectonics is not the only factor influencing the deposition pattern as some zones seem characterized by predominant strong turbidity currents transporting sediments far away from the foot of the margin whereas others depict retrogressive erosion features on the slope i e small slides scarps in gullies rather than transport by turbidity currents in particular the rivers sediment discharge fluxes and the geomorphologic characteristics of the margin seem to be very important factors too

vulnerability of the dover strait to coseismic tsunami hazards insights from numerical modelling summary on 1580 april 6 a large earthquake shook the eastern english channel and its shores with numerous casualties and significant destruction documented some reports suggest that it was followed by a tsunami meanwhile earthquake magnitudes of mw 7 have been deemed possible on intraplate fault systems in neighbouring benelux this study aims to determine the possibilityofamw 5 5magnitudeearthquakegeneratingatsunamiinthedoverstrait oneof the world s busiest seaways in a series of numerical models focusing on sensitivity analysis earthquake source parameters for the dover strait are constrained by palaeoseismological evidence and historical accounts producing maps of wave heights and analysis of frequencies based on six strategically located virtual tide gauges of potential concern to engineering geologists a maximum credible scenario is also tested for mw 6 9 for earthquakes with mw of 5 5 none of the fault models we tested produced a tsunami on neighbouring shores however forearthquakeswithmw 6 9 bothextensionalandthrustingeventsproducedtsunami waves with open water amplitudes of up to 1 5 m and higher amplitudes might be expected in regions where waves are amplified by regional nearshore bathymetry sensitivity to parameter choice is emphasized but a pattern of densely inhabited coastal hotspots liable to tsunamirelated damage because of bathymetric forcing factors is consistently obtained

the tsunami induced by the 2003 zemmouri earthquake mw 6 9 algeria modelling and results summary a strong tsunami with sea disturbances observed along the algerian coast but with significant damage mainly in the balearic islands spain harbours affected the western mediterranean following the 2003 zemmouri earthquake m w 6 9 algeria an average regional uplift of 0 55 m was measured along the shoreline in the epicentral area field observations main shock and aftershocks characteristics are consistent with thrust along a 55 km long rupture trending ne sw dipping se the seismotectonic parameters indicate a hypocentre 7 8 km deep and a possible fault break between 5 and 15 km offshore several tide gauges located in the western mediterranean coast indicated an average of 0 4 m of sea level change with a maximum of 2 m in the balearic islands we generated high resolution bathymetry grids from the algerian coasts to the balearic islands coasts in order to test different seismic sources with different fault rupture location strike and dip and model the tsunami initiation and propagation for the modelling we employed the crank nicolson numerical schema with a finite difference method and the okada elastic dislocation theory for the fault rupture we also highlight the different factors responsible for waves amplification around the balearic coast the best fit between synthetic and real data tide gauges gps levelling and coastal uplift as compared to run up values are obtained for a thrust rupture comparable with the earthquake fault inferred from seismotectonic studies and located within 15 km offshore an analysis of t waves reinforces the earthquake rupture origin for the tsunami this study presents the results and modelling of a major tsunami recorded in the western mediterranean sea

propagation and amplification of tsunamis at coastal boundaries when tsunamis hit a coastal area they often cause substantial damage and loss of life at locations otherwise well protected from normal even severe wind generated waves an example of such a catastrophe took place on 12 december 1992 when an earthquake of magnitude ms 7 5 occurred in the eastern region of flores island indonesia1 2 one of the areas hardest hit by the resulting tsunamis was babi a small coastal island two villages on the island were completely destroyed even though both were located in sheltered areas where wave conditions are normally calm here we describe the results of numerical and laboratory experiments that show how unlike wind generated waves tsunamis are capable of penetrating into sheltered coastal areas without significantly losing their energy for the case of babi island the original tsunami wave was split into two with one wave propagating around each side of the island the two waves met in the sheltered region and the subsequent amplification of wave amplitude resulted in the destructive flow onto the beach

coastal amplification laws for the french tsunami warning center numerical modeling and fast estimate of tsunami wave heights along the french riviera tsunami modeling tools in the french tsunami warning center operational context provide rapidly derived warning levels with a dimensionless variable at basin scale a new forecast method based on coastal amplification laws has been tested to estimate the tsunami onshore height with a focus on the french riviera test site nice area this fast prediction tool provides a coastal tsunami height distribution calculated from the numerical simulation of the deep ocean tsunami amplitude and using a transfer function derived from the green s law due to a lack of tsunami observations in the western mediterranean basin coastal amplification parameters are here defined regarding high resolution nested grids simulations the preliminary results for the nice test site on the basis of nine historical and synthetic sources show a good agreement with the time consuming high resolution modeling the linear approximation is obtained within 1 min in general and provides estimates within a factor of two in amplitude although the resonance effects in harbors and bays are not reproduced in nice harbor especially variation in tsunami amplitude is something that cannot be really assessed because of the magnitude range and maximum energy azimuth of possible events to account for however this method is well suited for a fast first estimate of the coastal tsunami threat forecast

coseismic deformation of the may 21st 2003 mw 6 8 boumerdes earthquake algeria from gps measurements 1 on may 21st 2003 a mw 6 8 earthquake struck the central part of northern algeria causing extensive damage in the boumerdes area 40 km east of algiers it is among the largest events to occur in the western mediterranean over the past 25 years we present gps measurements of horizontal coseismic displacements that provide new constraints on the rupture geometry modeling the data with a uniform dislocation on a rectangular fault in an elastic half space we find that the rupture occurred on a reverse fault dipping 42 s with its upper edge 6 km offshore and lower edge 4 km inland the amplitude distribution of the coseismic displacements indicates that the rupture did not reach the surface at least in its western part and ended to the west around 3 4 e offshore faults like that of the boumerdes earthquake could account for part of the africa eurasia relative plate motion in the western mediterranean and represent a significant seismic threat for algeria

earthquake induced flooding and paleoseismicity of the el asnam algeria fault related fold late quaternary activity of the el asnam thrust fault responsible for the october 10 1980 ms 7 3 earthquake and 36 km coseismic faulting is explored through diverse paleoseismological field methods we trenched through the main and secondary 1980 coseismic scarps made an analysis of earthquake induced flood deposits conducted a geomorphic study of leveling profiles and offset geological units across thrust and normal scarps and considered the geomorphology of the active fold twenty five radiocarbon ages from colluvial and alluvial deposits along with conventional fossils and artefacts dating of geological units show the timing of successive net vertical displacements on the thrust related fold and bending moment faults previous work showed that eight pre 1980 earthquakes occurred in clusters during the late holocene cumulative net vertical slip that amounts to 3 times the 1980 displacement is observed on multiple thrust fault scarps and offsets of geological units on bending moment faults maximum cumulative vertical displacements which are visible in different zones along the fault segments can reach 10 to 25 times the 1980 coseismic displacements the late quaternary uplift rate on the el asnam fault is 0 6 mm yr and taking into account slip variation along the fault this rate may range between 0 25 1 6 mm yr from which we obtain a shortening rate of 0 17 1 2 mm yr because the tell atlas mountains exhibit comparable seismogenic fault related folds with parallel and sequential structures of active faults a total average shortening rate of 2 05 mm yr during the late quaternary represents part of the convergence accommodated along the africa eurasia plate boundary

coastal uplift and thrust faulting associated with the mw 6 8 zemmouri algeria earthquake of 21 may 2003 1 a shoreline uplift marked by a continuous white band visible at rocky headlands occurred during the 21 may 2003 earthquake mw 6 8 in northern algeria we measured the amount of coastal uplift on a white band emerged algae and harbors quays between boumerdes and dellys most of measured points were collected using tape and differential gps on rocky headlands with 0 15 m error bar tidal prism leveling lines running parallel and orthogonal to the coast also provide the precise amount of uplift in the epicentral area the uplift distribution shows an average 0 55 m along the shoreline with a maximum 0 75 m east of boumerdes and a minimum close to 0 near cap djinet the active deformation related to a thrust fault is modeled along the 55 km coastline the dislocation model predicts surface slip on a n 54 e trending reverse fault dipping 50 se in agreement with cmt solution and coastal uplift the faulting characteristics imply a fault geometry with possible sea bottom ruptures between 5 to 10 km offshore

very fast characterization of focal mechanism parameters through w phase centroid inversion in the context of tsunami warning most of the tsunami potential seismic sources in the neam region are in a magnitude range of 6 5 le m w le 7 5 e g the tsunami triggered by the boumerdes earthquake of 2003 with m w 6 9 the centre d alerte aux tsunamis cenalt in operation since 2012 as the french national tsunami warning centre ntwc and candidate tsunami service provider ctsp has to issue warning messages within 15 min of earthquake origin time these warnings are based on the seismic source parameters m w magnitude focal depth and type of fault which are computed by focal mechanisms and centroid inversion methods the w phase method developed by kanamori and rivera allows quick computation of seismic source parameters due to the early arrival time between p waves and surface waves and is therefore particularly useful for monitoring we assess the w phase method with 29 events of magnitude m w ge 5 8 for the period 2010 2015 in the neam region results with 10 min of signal length are in good agreement compared to the global centroid moment tensor gcmt catalog

the 21 may 2003 tsunami in the western mediterranean sea statistical and wavelet analyses we report the statistical and wavelet analyses of the 21 may 2003 tsunami produced by an mw 6 8 6 9 thrust earthquake in the western mediterranean sea using 19 tide gauge records the largest trough to crest wave height was 196 cm recorded at the sant antoni station in the lee of the incoming tsunami wave except at one station the first wave was not the largest wave at all the analyzed stations and the largest wave arrived several hours after the first arrival in addition the tsunami waves persisted for more than 1 day at most stations as the spectra of coastal tide gauge stations are strongly influenced by topographic features special care was taken here while interpreting the results of spectral and wavelet analysis our wavelet analysis shows that only a peak at around 23 min is persistent for long duration and other peaks at 14 30 45 and 60 min appeared at short durations the 23 min signal is possibly associated with the width of the source fault whereas the fault length contributed to the 45 min signal based on these dominant periods the tsunami source dimensions are estimated as 95 km 45 km the statistical and wavelet analyses performed here provide some new insights into the characteristics of the tsunami that was generated and propagated in the western mediterranean basin

numerical modeling of the 1995 chilean tsunami impact on french polynesia on the 30th july 1995 an earthquake with magnitude of 8 1 occurred off the coast of chile the associated tsunami propagated across the pacific ocean and reached french polynesia 10 hours after the seismic event with maximum run up heights of about 2 5 meters the most affected islands in french polynesia were the marquesas islands that present few outer reefs more gradual bottom slopes and large bays the tsunami propagation has been modeled from chile to polynesian islands solving the shallow water equations the water surface initialisation has been computed from okada s formulas using seismic parameters of ruegg 1996 the tsunami propagation is simulated by a finite difference numerical model using a system of multiple grids with different grid sizes the computed waves are in fair agreement with the recorded waves along the chilean coasts in tahiti and in nuku hiva the numerical results obtained in the marquesas islands confirm the observations of numerous eyewitnesses

using multi band insar data for detecting local deformation phenomena induced by the 2016 2017 central italy seismic sequence abstract in this work we exploit x and c band insar data for detecting local deformation phenomena induced by the 2016 2017 central italy seismic sequence our goal is to highlight the usefulness of multi band insar analysis for hazard assessing and rapid mapping purposes when in situ investigations are difficult or dangerous to be performed indeed local seismic induced effects such as landslides avalanches subsidence etc could severely impact the environment and the population in the surrounding of areas hit by earthquakes we focused on four areas named monte vettore podalla bolognola and cicconi where insar outcomes revealed how the main seismic events of the sequence activated several landslides and secondary faults interested by deformation of 2 3 cm along the satellite line of sight los the use of multi band insar data allows the observation of multi scale deformation phenomena with both different spatial resolution and coverage highlighting the limits and constraints of different sar sensors moreover it ensures the crosschecking of displacement patterns retrieved through different insar products especially when no ground truth or in situ ancillary data are available for validation purposes as a result the retrieved insar information can support the scientific community and the institutions in the management of crisis emergencies

source spectrum for the algerian tsunami of 21 may 2003 estimated from coastal tide gauge data 1 on 21 may 2003 a submarine earthquake occurred near algiers producing a tsunami that propagated northward and reached the balearic islands and the levantine coast of the iberian peninsula within an hour despite that the generated tsunami was moderate sea level variations inside certain harbors at the balearic islands were significant producing severe damage to moored boats available tsunami records in the affected harbors are examined to estimate amplifications factors of arriving waves and spectral characteristics of the source comparison between background and tsunami oscillations at various sites allowed separation of the tsunami source properties from local topographic effects the fundamental period of the reconstructed source spectrum is 21 min which is in close agreement with that found by alasset et al 2006 based on modeling the tsunami initiation

empirical constraints on magnitude distance relationships for seismically induced submarine tsunamigenic landslides abstract seismically induced submarine landslide tsunamis here called silts attract growing attention due to their unique setting damage potential and short warning time a question of key importance especially for tsunami early warning is how far can an earthquake trigger a tsunamigenic slump here we investigate the relationships between earthquake magnitude and the maximal distance between the seismogenic fault and the tsunamigenic slumps rf and between the earthquake epicenter and the slump re and propose empirical constraints on these magnitude distance m d relations the 49 identified silts are spread in various seismotectonic and bathymetric settings in different seas around the globe we found that the maximal distance of the tsunamigenic submarine landslide from the parent earthquake grows with the magnitude and is bounded by an envelope constrained by mw as low as 4 9 for several kilometers the 1968 liguria coast italy and as far as 250 km for mw 7 7 the 1819 rann of kachchh india higher earthquake magnitudes also produce silts seemingly distances lower than 250 km however it is suspected that the available data is limited and unable to reflect the true nature of silt s generation generalized empirical relations between the earthquake magnitude mw and the maximal distance from the seismogenic fault to its generated silt rf in km are log rf 1 17 0 49 mw r2 0 78 the empirical distance between the earthquake epicenter and the corresponding tsunamigenic slump re in km is log re 0 87 0 45 mw r2 0 83 although many earthquakes within the m d bounding envelope did not produce tsunamis the successful events still enable the delineation of the m d zone vulnerable to tsunami generation which in turn can be applied to tsunami early warning procedures this is particularly important for near coast inland earthquakes as their tsunamigenic potential might be overlooked

active thrust faulting offshore boumerdes algeria and its relations to the 2003 mw 6 9 earthquake 1 we investigate the active seismogenic fault system in the area of the 2003 mw 6 9 boumerdes earthquake algeria from a high resolution swath bathymetry and seismic survey a series of 5 main fault propagation folds 20 35 km long leave prominent cumulative escarpments on the steep slope and in the deep basin fault activity creates plio quaternary growth strata within uplifted areas such as a rollover basin on the slope and piggyback basins in the deep ocean most thrusts turn to fault propagation folds at the sub surface and depict ramp flat trajectories we find that the two main slip patches of the 2003 mw 6 9 boumerdes earthquake are spatially correlated to two segmented cumulative scarps recognized on the slope and at the foot of the margin the overall geometry indicates the predominance of back thrusts implying underthrusting of the neogene oceanic crust

modeling of the february 1996 peruvian tsunami the february 1996 peruvian earthquake generated a larger tsunami than expected from its surface magnitude this discrepancy as well as the long rupture duration indicate that this event is a tsunami earthquake the associated tsunami was strong locally with runup heights of 1 to 5 meters along a coastline of 400 km it is shown that this tsunami can be modeled for a seismic moment of 2 1020 nm using a rigidity of 2 1010 n m the tsunami propagation is modeled solving long wave equations by a finite difference method the maximum run up heights in the region of chimbote can be simulated using a grid increment of 10 meters the propagation of this small tsunami across the pacific ocean is modeled taking into account frequency dispersion the only notable amplification occurred in the marquesas islands where wave heights of 2 meters were observed and are simulated

tsunami taxonomy and detection from recent mediterranean tide gauge data abstract sea level records collected in digital form with high sampling rate by recently upgraded tide gauges located along the mediterranean coasts are subjected to a posteriori investigation to examine and characterize occurrence of sea level oscillations in the tsunami period range induced by both underwater or coastal earthquakes and by meteorological events after performing a rigorous quality control procedure on the raw sea level time series a wavelet based analysis is applied to 2 h high pass filtered data to identify oscillations generated by earthquakes and a few events are modeled aiming to verify travel time and expected spectral shape seismic tsunami oscillations that are not reported in published catalogues are identified in the sea level records of the period 2010 2014 just after three different earthquake events a method is proposed to detect occurrence of tsunami like oscillations of meteorological origin from the available tidal records based on the distribution of the detided level process over spectral bandwidth parameter and mean period the developed methodology is also the first presented which allows to distinguish sea wave induced harbor seiches from fluctuations of meteorological origin associated with passage of atmospheric disturbances meteotsunamis in sea level time series the results of the analyses show that during the considered period in the mediterranean sea tsunamis of seismic origin are rare and weak meteotsunamis on the contrary are relatively frequent and in critical areas may reach intensities exceeding astronomical tide the availability of the recently acquired high frequency records and the presented approach allow to extend the list of recorded tsunami events of both seismic and meteorological origin the identified event sets may be used for improved hazard analyses and risk assessments along the mediterranean coasts