reassessing the rupture process of the 2009 l aquila earthquake mw 6 3 on the paganica fault and investigating the possibility of coseismic motion on secondary faults the kinematic rupture of the l aquila earthquake on the paganica fault is reassessed with a highly comprehensive set of data this very complete dataset is also used to explore the possibility that secondary faults may be involved in the coseismic process the main characteristics of the slip distribution of the paganica normal fault found by previous studies are confirmed an initial propagation around and up dip of the hypocenter associated with a high velocity rupture 3 5 km s a main asperity centered about 6 7 km southeast of the hypocenter rupturing in the subsequent stage with a maximum slip of nearly 1 5 m a total rupture measuring about 15 km along strike and 12 km along dip and an overall low average velocity rupture 2 km s the statement that the main features of the slip distribution are confirmed by different studies based on distinct inversion schemes is by itself an achievement knowing that many past studies provided strongly discrepant slip maps for common events moreover we focus specifically on the existence of slip at shallow depth and its relations with the other known active faults in the vicinity of the paganica fault we find that 1 as found in previous studies shallow slip near the ground surface up dip of the hypocenter is incompatible with the available synthetic aperture radar interferograms and 2 the only secondary fault that is likely to have been activated during the mainshock is the san gregorio synthetic fault located 2 3 km southwest of the paganica fault online material figures of waveform fitting using different velocity models time versus distance distribution of slip from the single fault model variations in the geometry of the paganica fault geometry of complex faults models and geodetic data modeling uncertainty on the slip value and the rupture time effect of noise on resolution tests quantification of the improvement on the gps data fitting with the preferred two faults model with respect to the single fault model and a posteriori modeling of leveling data

application of stochastic simulation to co2 flux from soil mapping and quantification of gas release 1 conditional sequential gaussian simulations sgs have been applied for the first time to the study of soil diffuse degassing from different volcanic and nonvolcanic systems the application regards five data sets of soil co2 fluxes measured with the accumulation chamber methodology at the volcanic areas of solfatara of pozzuoli italy vesuvio cone italy nisyros greece and horseshoe lake california and at the nonvolcanic degassing area of poggio dell olivo italy the sgs algorithm was used to generate 100 realizations of co2 flux for each area probabilistic summaries of these simulations together with the information given by probability plots were used 1 to draw maps of the probability that co2 fluxes exceed thresholds specific for a background flux i e to define the probable extension of the degassing structures 2 to calculate the total co2 output and 3 to quantify the uncertainty of the estimation the results show that the sgs is a suitable tool to model soil diffuse degassing producing realistic images of the distribution of the co2 fluxes that honor the histogram and variogram of the original data moreover the relation between the sample design and the uncertainty of estimation was investigated leading to an empirical relation between uncertainty and the sampling density that can be useful for the planning of future co2 flux surveys

evolution of the canadas edifice and its implications for the origin of the canadas caldera tenerife canary islands the volcano stratigraphic and geochronologic data presented in this work show that the tenerife central zone has been occupied during the last 3 ma by shield or central composite volcanoes which reached more than 3000 m in height the last volcanic system the presently active teide pico viejo complex began to form approximately 150 ka ago the first canadas edifice ce volcanic activity took place between about 3 5 ma and 2 7 ma the ce i is formed mainly by basalts trachybasalts and trachytes the remains of this phase outcrop in the canadas wall cw sectors of la angostura 3 5 3 0 ma and 3 0 2 7 ma boca de tauce 3 0 ma and in the bottom of some external radial ravines 3 5 ma the position of its main emission center was located in the central part of the cc the volcano could have reached 3000 m in height this edifice underwent a partial destruction by failure and flank collapse forming debris avalanches during the 2 6 2 3 ma period the debris avalanche deposits can be seen in the most distal zones in the n flank of the ce i tigaiga breccia a new volcanic phase whose deposits overlie the remains of ce i and the former debris avalanche deposits constituted a new volcanic edifice the ce ii the dyke directions analysis and the morphological reconstruction suggest that the ce ii center was situated somewhat westward of the ce i reaching some 3200 m in height the ce ii formations are well exposed on the cw especially at the el cedro 2 3 2 00 ma sector they are also frequent in the s flank of the edifice 2 25 1 89 ma in tejina 2 5 1 87 ma as well as in the tigaiga massif to the n 2 23 ma during the last periods of activity of ce ii important explosive eruptions took place forming ignimbrites pyroclastic flows and fall deposits of trachytic composition their ages vary between 1 5 and 1 6 ma adeje ignimbrites to the w in the cw the upper ucanca phonolitic unit 1 4 ma could be the last main episode of the ce ii afterwards the can adas iii phase began it is well represented in the cw sectors of tigaiga 1 1 ma 0 27 ma las pilas 1 03 ma 0 78 ma diego hernandez 0 54 ma 0 17 ma and guajara 1 1 ma 0 7 ma the materials of this edifice are also found in the se flank these materials are trachybasaltic lava flows and abundant phonolitic lava and pyroclastic flows 0 6 ma 0 5 ma associated with abundant plinian falls the ce iii was essentially built between 0 9 and 0 2 ma a period when the volcanic activity was also intense in the dorsal edifice situated in the easterly wing of tenerife the so called valleys of la orotava and gu imar transversals to the ridge axis also formed during this period in the central part of tenerife the ce iii completed its evolution with an explosive deposit resting on the top of the ce for which ages from 0 173 to 0 13 ma have been obtained the cc age must be younger due to the fact that the present caldera scarp cuts these deposits on the controversial origin of the cc central vertical collapse vs repeated flank failure and lateral collapse of mature volcanic edifices the data discussed in this paper favor the second hypothesis clearly several debris avalanche type events exist in the history of the volcano but most of the deposits are now under the sea the caldera wall should represent the proximal scarps of the large slides whose intermediate scarps are covered by the more recent teide pico viejo volcanoes

source complexity of the 6 april 2009 l aquila central italy earthquake and its strongest aftershock revealed by elementary seismological analysis 1 seismic recordings are immediately available when an earthquake occurs their analysis allows the reconstruction of the rupture dynamics by means of sophisticated techniques which usually need some tests to provide robust results however immediate information on the source kinematics is required in order to imagine the fault location and extent and quickly reconstruct the areas of stress release and subsequent accumulation very simple analysis may provide useful information giving insight in source complexity right after the 6 april 2009 l aquila earthquake mw 6 3 we analyzed the seismograms recorded at broadband and strong motion stations and provided firm constraints on rupture kinematics slip distribution and static surface deformation also discriminating the actual fault plane the fracture occurred in two stages with initial updip propagation successively proceeding toward se possibly on a different plane we also analyzed the strongest aftershock mw 5 6 showing that useful indications could be retrieved for lower magnitude events

finite fault inversion of dinsar coseismic displacement of the 2009 l aquila earthquake central italy 1 we define the geometric and kinematic characteristics of the fault activated during the mw 6 3 6 april 2009 l aquila earthquake from the modeling of envisat and cosmo skymed the first ever x band interferogram inverted for a coseismic dislocation study dinsar interferograms our best fit solution for the main shock is represented by a normal fault 16 km long and 12 km wide with a small right lateral component dipping 47 sw with a maximum slip of 90 cm although the seismic dislocation probably ended at 1 km depth the updip projection of the fault plane corresponds to the northern segment of the mapped paganica s demetrio fault where alignment of surface breaks was observed in the field the absence of this fault in existing seismic source catalogues suggests that an improved approach involving detailed surface and subsurface geological and geophysical investigations is needed for a better assessment of the seismic hazard at the local scale

helium 3 emission in and around teide volcano tenerife canary islands spain air corrected he 4he ratios of fluid samples collected in and around teide volcano tenerife canary islands ranged from 5 97 to 8 06 ra helium 3 emission spatial distribution has a quite different pattern from other stratovolcanoes which show commonly a decreased trend for the he 4he ratio with respect to distance from the summit crater this finding might be related to the volcano tectonic setting differences between subduction type and oceanic island type statrovolcanoes radiogenic helium production is a significant process for the dilution of uprising derived mantle fluids in and around subduction type stratovolcanoes while it can be almost negligible for polygenetic volcanoes at oceanic islands

waveguide effects in very high rate gps record of the 6 april 2009 mw 6 1 l aquila central italy earthquake this work has partially benefited from the activities performed in the nera project network of european research infrastructures for earthquake risk assessment and mitigation 262330 funded by the european commission fp7 program and in the firb abruzzo project funded by the italian ministery of education university and research

seismic moment tensors of the april 2009 l aquila central italy earthquake sequence summary on 2009 april 6 the central apennines were hit by an mw 6 3 earthquake the region had been shaken since 2008 october by seismic activity that culminated in two foreshocks with mw 4 1 week and a few hours before the main shock we computed seismic moment tensors for 26 events with mw between 3 9 and 6 3 using the regional centroid moment tensor rcmt scheme most of these source parameters have been computed within 1 hr after the earthquake and rapidly revised successively the focal mechanisms are all extensional with a variable and sometimes significant strike slip component this geometry agrees with the ne sw extensional deformation of the apennines known from previous seismic and geodetic observations events group into three clusters those located in the southern area have larger centroid depths and a wider distribution of t axis directions these differences suggest that towards south a different fault system was activated with respect to the sw dipping normal faults beneath l aquila and more to the north

diffuse emission of carbon dioxide methane and helium 3 from teide volcano tenerife canary islands diffuse emission of co2 ch4 and he was investigated in the summit crater of teide volcano tenerife canary islands the results indicate that teide volcano releases abundant co2 not only from its active crater but also from its flanks as diffuse soil emanations the spatial distribution of these emanations correlates quite closely with that of geothermal anomalies and manifestations our flux measurements indicate a total output of 380 ton day 1 of co2 and 1 6 on day 1 of ch4 by diffuse degassing from the he co2 ratios and the co2 flux we estimate a diffuse he flux of 0 052 mol year 1 isotopic analysis of carbon in soil gas samples from sites of high soil co2 flux indicates a magmatic origin for the co2 also reported by high he 4he ratios of 5 50 and 5 87 ra the origin of methane is more uncertain with low 13c values suggesting a biogenic contribution

temporal variation of seismic velocity and anisotropy before the 2009 mw 6 3 l aquila earthquake italy we describe a set of seismological observations of the foreshock sequence preceding the 6 april 2009 m w 6 3 l9aquila earthquake the dense configuration of the seismic network in the epicenter area and the occurrence of a long foreshock sequence provide the opportunity for a detailed reconstruction of the preparatory phase of the main shock approaching the earthquake we observed clear variations in the seismic wave propagation properties the elastic properties of rocks in the fault region underwent a sharp change about a week before the earthquake from our observations we infer that a complex sequence of dilatancy diffusion processes takes place and that fluids play a key role in the fault failure process

correlated increase in co2 fumarolic content and diffuse emission from la fossa crater vulcano italy evidence of volcanic unrest or increasing gas release from a stationary deep magma body 1 the peculiarity of the quiescent la fossa volcano is the occurrence of crises characterized by strong increases of fumarole t and output and by chemical changes indicative of an increasing input of magmatic fluids several surveys carried out during a new crisis began in november 2004 indicate that the total diffuse co2 emission for the crater area increases by one order of magnitude during crises up to 1600 ton d 1 in december 2005 concern exists on the possibility that these crises be related to an unrest process leading to eruption the repetition along decades of the same gas compositional variations during crises their temporal coincidence with increases of the local shallow seismicity and the lack of any significant ground motion rather suggest that they correspond to moments of increasing volatile release from a stationary magma system

anomalous far field geodetic signature related to the 2009 l aquila central italy earthquake the broad availability of geodetic measurements for the mw 6 3 april 6th 2009 l aquila earthquake allowed an unprecedented description of the co and post seismic ground deformations leading to the definition of the paganica fault geometry and kinematics through dinsar we found in a wide area of 20 kilometres on the paganica hangingwall a further displacement up to 7 cm which might have occurred in the earthquake proximity in this study we explore the possibility of the co post and pre seismic alternative scenarios although our data are not sufficient to undoubtedly prove that this signal occurred before the main event this seems to be the most likely hypothesis based on tectonics constraints and image acquisition times the nature of this deformation remains unclear but we speculate that deep fluids played a role these results can drive ad hoc requirements for future space based missions and design of the gps network

impulsive source of the 2017 m w 7 3 ezgeleh iran earthquake on 12 november 2017 a m w 7 3 earthquake struck near the iranian town of ezgeleh at the iran iraq border this event was located within the zagros fold and thrust belt which delimits the continental collision between the arabian and eurasian plates despite a high seismic risk the seismogenic behavior of the complex network of active faults is not well documented in this area due to the long recurrence interval of large earthquakes in this study we jointly invert interferometric synthetic aperture radar and near field strong motions to infer a kinematic slip model of the rupture the incorporation of these near field observations enables a fine resolution of the kinematic rupture process it reveals an impulsive seismic source with a strong southward rupture directivity consistent with significant damage south of the epicenter we also show that the slip direction does not match plate convergence implying that some of the accumulated strain must be partitioned onto other faults

investigating the architecture of the paganica fault 2009 mw 6 1 earthquake central italy by integrating high resolution multiscale refraction tomography and detailed geological mapping this article has been accepted for publication in geophysical journal internationa 2017 published by oxford university press on behalf of the royal astronomical society all rights reserved

coseismic deformation of the destructive april 6 2009 l aquila earthquake central italy from gps data 1 on april 6 2009 01 32 39 gmt the city of l aquila was struck by a mw 6 3 earthquake that killed 307 people causing severe destruction and ground cracks in a wide area around the epicenter four days before the main shock we augmented the existing permanent gps network with five gps stations of the central apennine geodetic network cageonet bordering the l aquila basin the maximum horizontal and vertical coseismic surface displacements detected at these stations was 10 39 0 45 cm and 15 64 1 55 cm respectively fixing the strike direction according to focal mechanism estimates we estimated the source geometry with a non linear inversion of the geodetic data our best fitting fault model is a 13 15 7 km2 rectangular fault sw dipping at 55 3 1 8 consistent with the position of observed surface ruptures the estimated slip 495 29 mm corresponds to a 6 3 moment magnitude in excellent agreement with seismological data

shear wave splitting of the 2009 l aquila seismic sequence fluid saturated microcracks and crustal fractures in the abruzzi region central apennines italy

evidence for surface faulting events along the paganica fault prior to the 6 april 2009 l aquila earthquake central italy 1 we performed paleoseismological investigations at four sites across the normal paganica fault pf source of the 2009 mw 6 3 l aquila earthquake with the goal of reconstructing the rupture history and of contributing to the evaluation of the maximum event expected along the pf we recognized five distinct surface faulting earthquakes including the 2009 in the trenches the age of the penultimate event is consistent with the 1461 earthquake the third event back occurred around 1000 ad the two oldest events have larger uncertainties and occurred in the interval 760 bc 670 ad and 2900 760 bc respectively the along strike vertical displacement for each paleoevent has a limited variability consistently with the fairly homogeneous slip observed in 2009 along the northern part of the rupture conversely the throws change between distinct events and range between 0 15 m in 2009 maximum estimate and close to 0 4 lower bound estimate in earlier events these paleorecords and the high fault escarpments imply that earthquakes larger than 2009 occurred on the pf with implications for the level of hazard recurrence intervals also reflect a change with time the average interval before 1000 ad is longer compared to that after this date two events occurred in the 2000 4000 years preceding 1000 ad while three events occurred since 1000 ad the age uncertainties affecting the interpreted events prevent the evaluation of a unique value for interevent interval the older events appear closely spaced in time or far apart depending on the upper or lower boundary of the age interval we tentatively assign an average interevent time of 500 years for the three youngest events whereas the time elapsed between the previous ones could be larger in the order of 1000 2000 years we calculate a late pleistocene dip slip rate for the pf of 0 2 0 4 mm yr consistent with 0 25 0 5 mm yr for the early pleistocene using age and throw of individual events we calculate a similar late holocene average dip slip rate of 0 3 0 4 mm yr this suggests that the portion of the pf where the 2009 continuous surface faulting occurred has fairly a constant average slip release since late pleistocene finally we discuss different rupture scenarios and alternative models of occurrence compatible with our data and their variability

volcanic activity influenced by tectonic earthquakes static and dynamic stress triggering at mt merapi 1 mt merapi is one of the most dangerous volcanoes in indonesia located within the tectonically active region of south central java this study investigates how mt merapi affected and was affected by nearby tectonic earthquakes in 2001 a mw6 3 earthquake occurred in conjunction with an increase in fumarole temperature at mt merapi in 2006 another mw6 3 earthquake took place concomitant with an increase of magma extrusion and pyroclastic flows here we develop theoretical models to study the amount of stress transfer between the earthquakes and the volcano showing that dynamic rather than static stress changes are likely responsible for the temporal and spatial proximity of these events our examination of the 2001 and 2006 events implies that volcanic activity at mt merapi is influenced by stress changes related to remote tectonic earthquakes a finding that is important for volcano hazard assessment in this densely inhabited area

complexity of the rupture process during the 2009 l aquila italy earthquake summary in this study we investigate the rupture history of the 2009 april 6 mw 6 1 l aquila normal faulting earthquake by using a non linear inversion of strong motion gps and dinsar data both the separate and joint inversion solutions reveal a complex rupture process and a heterogeneous slip distribution slip is concentrated in two main asperities a smaller shallow patch of slip located updip from the hypocentre and a second deeper and larger asperity located southeastwards along strike direction the key feature of the source process emerging from our inverted models concerns the rupture history which is characterized by two distinct stages the first stage begins with rupture nucleation and with updip propagation at relatively high 4 0 km s 1 but still subshear rupture velocity the second stage starts nearly 2 0 2 5 s after nucleation and it is characterized by the along strike rupture propagation the largest and deeper asperity fails during this stage of the rupture process the rupture velocity is larger in the updip than in the along strike direction the updip and along strike rupture propagation are separated in time and associated with a mode ii and a mode iii crack respectively the comparison between the source models inferred in this study with the poisson ratio anomalies in the crustal volume containing the fault plane allows the interpretation of the delay in along strike rupture propagation in terms of a structural control of the rupture history our results show that the l aquila earthquake featured a very complex rupture with strong spatial and temporal heterogeneities suggesting a strong frictional and or structural control of the rupture process

limits on earthquake nucleation and other pre seismic phenomena from continuous strain in the near field of the 2009 l aquila earthquake 1 two laser strainmeters that operate at 1400 m depth about 20 km ne of the epicenter of the 2009 04 06 magnitude 6 3 l aquila italy earthquake have produced records of strain since 1995 during the two years before the event no anomalous signal larger than a few tens of nanostrains is visible limiting the volume of the possible earthquake preparation zone to less than 100 km3 moreover earth tidal response is stable within 0 5 in amplitude and 0 5 in phase thus reality of large scale precursory phenomena seems unlikely during the last few days there is some evidence of dilatancy of satured rock over the earthquake causative fault maybe related to the foreshocks seconds before the event strain is stable at the 10 12 level and prerupture nucleation slip in the hypocentral region is constrained to have a moment less than 2 1012 nm i e 0 00005 of the main shock seismic moment

control of the 2009 l aquila earthquake central italy by a high velocity structure a receiver function study 1 receiver functions rfs analyzed at two permanent broadband seismic stations operating in the epicentral area of the mw 6 3 2009 l aquila earthquake central italy yield insight on crustal structure along the fault rupture the harmonic decomposition of rfs highlights a subsurface structure in which both isotropic and anisotropic features are present we model the waveforms using recently developed monte carlo methods the retrieved models display a common depth structure between 10 and 40 km depth consistent with the under thrusting of the adria lithosphere underneath the apennines belt along the fault in the uppermost crust the s wave velocity structure is laterally heterogeneous right above the hypocenter we find a 4 6 km thick very high s wave velocity body vs as high as 4 2 km s that is absent in the se portion of the fault where the earthquake propagated the high vs body is coincident with the area of fewer aftershocks and is anticorrelated with the maximum slip patches of the earthquake as modeled by differential interferometric synthetic aperture radar dinsar and strong motion data we interpret this high vs body as a high strength barrier responsible for the high peak ground motion in the near field observed in the l aquila city and surroundings and for the complexity in the rupture evolution the retrieved seismic s wave velocity of this body far exceeds common vs values in the upper crust and it is more compatible with values observed in mafic basement rocks

direct observation of rupture propagation during the 1979 imperial valley earthquake using a short baseline accelerometer array abstract the 1979 imperial valley california earthquake m s 6 9 was recorded on the el centro differential array a 213 m long linear array of 5 three component digital accelerometers 5 6 km from the nearest tectonic surface rupture although absolute time was not recorded on the array elements a relative time base was established using the main shock hypocentral p wave and the p and s waves from a later aftershock a cross correlation technique was used to measure the difference in arrival times of individual seismic waves in a moving 0 6 to 1 2 sec window at each array element which would then be converted into the wave9s slowness 1 velocity along the array when applied to the main shock vertical and horizontal accelerograms results from both components of motion indicated that the early arriving energy came from a source to the south of the array and the source of the energy moved rapidly to the north of the array during the strong shaking the ground motions at the array elements were well correlated for about the first 11 sec of motion these observations suggest that we have observed the initiation of rupture south of the array and its subsequent propagation along the fault to a position north of the array in about 10 sec and that the energy was radiated from a fairly compact region around the rupture front if the observed vertical and horizontal ground motions are assumed to be caused by p and s waves respectively then the observed slownesses show irregularities which can be interpreted as implying that the observed high frequency ground motions originated at irregularly distributed regions on the fault surface or that the rupture velocity was variable or both one possible interpretation of the data suggests that the rupture proceeded at near p wave velocity over a 7 km long section of fault average rupture velocities of about 2 7 to 3 2 km sec at 8 km depth are consistent with the data and 2 8 km sec is weakly preferred under the assumption that rupture propagates at a fixed fraction of the shear velocity the large vertical pulse which had a peak acceleration of 1 7 g at e06 was emitted from the portion of the fault extending 25 to 30 km northwest of the hypocenter near meloland overpass and not from the point on the fault closest to the differential array nothing can be said about fault behavior southeast of the hypocenter

continuous monitoring of distal gas emanations at vulcano southern italy the increasing activity of vulcano island italy since 1985 led to the initiation of continuous geochemical monitoring of the lateral soil gas emissions on the basis both of their relative geochemical characteristics and of local considerations three gaseous components were selected for monitoring namely co2 he and 222rn monitoring has been performed by means of specific analysers gases extracted from a water well located at the foot of the active cone were selected for monitoring on the basis of their geochemical and isotopic characters that indicate their genetic link with central high temperature fumarolic gases emitted at the crater very strong variations of gas composition can be observed within one day from 1 to about 94 for co2 some variations display a daily character and can be correlated with that of atmospheric pressure the three monitored gases are highly correlated suggesting very high kinetics of gas transfer in the system because of these considerable variations of chemical composition bulk concentrations obviously are not suitable for monitoring at vulcano however the evolution with time of ratios such as 222rn co2 and he co2 the latter being corrected for atmospheric contamination supplies numerical parameters that the expected to characterize the intensity of the degassing process a new input of magmatic gases that would lead to an increase in the 222rn co2 and he co2 ratios should therefore be detected by such a monitoring station

deep electrical resistivity tomography along the tectonically active middle aterno valley 2009 l aquila earthquake area central italy three 2 d deep electrical resistivity tomography ert transects up to 6 36 km long were obtained across the paganica san demetrio basin bounded by the 2009 l aquila mw 6 1 normal faulting earthquake causative fault central italy the investigations allowed defining for the first time the shallow subsurface basin structure the resistivity images and their geological interpretation show a dissected mesozoic tertiary substratum buried under continental infill of mainly quaternary age due to the long term activity of the paganica san demetrio normal faults system psdfs ruling the most recent deformational phase our results indicate that the basin bottom deepens up to 600 m moving to the south with the continental infill largely exceeding the known thickness of the quaternary sequence the causes of this increasing thickness can be 1 the onset of the continental deposition in the southern sector took place before the quaternary 2 there was an early stage of the basin development driven by different fault systems that produced a depocentre in the southern sector not related to the present day basin shape or 3 the fault system slip rate in the southern sector was faster than in the northern sector we were able to gain sights into the long term psdfs behaviour and evolution by comparing throw rates at different timescales and discriminating the splays that lead deformation some fault splays exhibit large cumulative throws 300 m in coincidence with large displacement of the continental deposits sequence 100 m thus testifying a general persistence in time of their activity as leading splays of the fault system we evaluate the long term 3 2 5 myr cumulative and quaternary throw rates of most of the leading splays to be 0 08 0 17 mm yr 1 indicating a substantial stability of the faults activity among them an individual leading fault splay extends from paganica to san demetrio ne vestini as a result of a post early pleistocene linkage of two smaller splays this 15 km long fault splay can explain the holocene surface ruptures observed to be larger than those occurred during the 2009 l aquila earthquake such as revealed by palaeoseismological investigations finally the architecture of the basin at depth suggests that the psdfs can also rupture a longer structure at the surface allowing earthquakes larger than m 6 5 besides rupturing only small sections as it occurred in 2009

changes in the diffuse co2 emission and relation to seismic activity in and around el hierro canary islands significant changes in the diffuse emission of carbon dioxide were recorded in a geochemical station located at el hierro canary islands before the occurrence of several seismic events during 2004 two precursory co2 efflux increases started thirteen and nine days before two seismic events of magnitude 2 3 and 1 7 which took place near el hierro island canary islands on march 23 and april 15 reaching a maximun value of 51 1 and 46 2 g m 2 d 1 respectively five and eight days before the two seismic events other similar increases started thirteen and five days before the occurrence of two seismic events of magnitude 1 3 and 1 5 which took place on october 15 and 21 respectively reaching the maximum values four and one day before the earthquakes these changes were not related to variations in atmospheric or soil parameters the material failure forecast method ffm which analyzes the rate of precursory phenomena was successfully applied to forecast the first seismic event that took place in el hierro island in 2004

an increasing trend of diffuse co2 emission from teide volcano tenerife canary islands geochemical evidence of magma degassing episodes multiple soil co 2 efflux surveys have been undertaken at the summit cone of teide volcano tenerife from 1997 to 2011 to determine the total co 2 emissions from the summit cone and to evaluate the temporal variations of co 2 efflux and their relationships with seismic volcanic activity our results reveal significant fluctuations in degassing rate which do not seem to be masked by atmospheric variations these geochemical observations provide evidence for the unrest of the volcanic system as has been suggested previously by anomalous seismic activity recorded in tenerife during 22 29 april 2004 a new trend of increasing co 2 efflux and co 2 ch 4 ratio in fumarolic gas discharges was observed from 2006 to 2009 suggesting that subsurface magma movement is the cause for the observed changes in the total output of diffuse co 2 emission at the summit cone of teide

late extensional modification of a compressional orogen evidence from eastern ghats granulite belt india and its analogue in other gondwana fragments

co2 ch4 ratio in fumaroles a powerful tool to detect magma degassing episodes at quiescent volcanoes 1 long time series of fumarolic compositions at campi flegrei italy mammoth mountain california panarea italy and nisyros greece show rapid increases up to orders of magnitude of the co2 ch4 ratio systematically with the occurrence of volcanic unrest periods these easily detected anomalies originate with the arrival of ch4 poor magmatic fluids in the shallower levels of the volcanoes the data suggest that volcanoes are characterized by magmatic activity at depth also in periods of apparent quiescence the activity is constituted by the pulsing release of large amount of fluids which either cause unrest periods seismicity and ground deformation or possibly could precede volcanic eruption this type of volcanic activity can be monitored trough the classical geophysical techniques together with the systematic sampling and analysis of fumaroles

regional moment tensors of the 2009 l aquila earthquake sequence broadband waveform inversion of ground velocities in the 0 02 0 10 hz frequency band is successfully applied to 181 earthquakes with m l 3 of the april 2009 l aquila italy earthquake sequence this was made possible by the development of a new regional crustal velocity model constrained by deep crustal profiles surface wave dispersion and teleseismic p wave receiver functions and tested through waveform fit although all earthquakes exhibit normal faulting with the fault plane dipping southwest at about 55 for the majority of events a subset of events had much shallower dips the issue of confidence in the derived parameters was investigated by applying the same inversion procedure by two groups who subjectively selected different traces for inversion the unexpected difficulty in modeling the regional broadband waveforms of the mainshock as a point source was investigated through an extensive finite fault modeling of broadband velocity and accelerometer data which placed the location of major moment release up dip and about 4 7 s after the initial first arrival hypocentral parameters

refined rupture velocity estimation of the 2009 l aquila earthquake mw 6 3 central italy derived from apparent source time functions in this paper we obtain an accurate estimation of the rupture velocity of the 6 april 2009 mw 6 3 l aquila earthquake central apennines by analyzing its apparent source time functions astfs these astfs have been extracted by deconvolv ing an empirical green s function egf at seismic stations located 200 800 km from the earthquake from the study of duration shape and directivity of astfs at numerous and well distributed stations we show that the area between the two main slip patches of the earthquake ruptured at a relatively slow velocity 1 6 km s we next validate simulta neously the astfs and the slip model independently obtained through the joint inversion of strong motion broadband teleseismic global positioning system and interferometric synthetic aperture radar data the good agreement in shape and duration between the observed and theoretical astfs is an indication for the reliability of the inferred source model and for the robustness of the rupture velocity estimations of this study

the 2009 l aquila central italy mw6 3 earthquake main shock and aftershocks 1 a m w 6 3 earthquake struck on april 6 2009 the abruzzi region central italy producing vast damage in the l aquila town and surroundings in this paper we present the location and geometry of the fault system as obtained by the analysis of main shock and aftershocks recorded by permanent and temporary networks the distribution of aftershocks 712 selected events with m l 2 3 and 20 with m l 4 0 defines a complex 40 km long nw trending extensional structure the main shock fault segment extends for 15 18 km and dips at 45 to the sw between 10 and 2 km depth the extent of aftershocks coincides with the surface trace of the paganica fault a poorly known normal fault that after the event has been quoted to accommodate the extension of the area we observe a migration of seismicity to the north on an echelon fault that can rupture in future large earthquakes

deep learning of aftershock patterns following large earthquakes aftershocks are a response to changes in stress generated by large earthquakes and represent the most common observations of the triggering of earthquakes the maximum magnitude of aftershocks and their temporal decay are well described by empirical laws such as bath s law1 and omori s law2 but explaining and forecasting the spatial distribution of aftershocks is more difficult coulomb failure stress change3 is perhaps the most widely used criterion to explain the spatial distributions of aftershocks4 8 but its applicability has been disputed9 11 here we use a deep learning approach to identify a static stress based criterion that forecasts aftershock locations without prior assumptions about fault orientation we show that a neural network trained on more than 131 000 mainshock aftershock pairs can predict the locations of aftershocks in an independent test dataset of more than 30 000 mainshock aftershock pairs more accurately area under curve of 0 849 than can classic coulomb failure stress change area under curve of 0 583 we find that the learned aftershock pattern is physically interpretable the maximum change in shear stress the von mises yield criterion a scaled version of the second invariant of the deviatoric stress change tensor and the sum of the absolute values of the independent components of the stress change tensor each explain more than 98 per cent of the variance in the neural network prediction this machine learning driven insight provides improved forecasts of aftershock locations and identifies physical quantities that may control earthquake triggering during the most active part of the seismic cycle neural networks trained on data from about 130 000 aftershocks from around 100 large earthquakes improve predictions of the spatial distribution of aftershocks and suggest physical quantities that may control earthquake triggering

effects of three dimensional crustal structure and smoothing constraint on earthquake slip inversions case study of the mw6 3 2009 l aquila earthquake earthquake slip inversions aiming to retrieve kinematic rupture characteristics typically assume 1 d velocity models and a flat earth surface however heterogeneous nature of the crust and presence of rough topography lead to seismic scattering and other wave propagation phenomena introducing complex 3 d effects on ground motions here we investigate how the use of imprecise green s functions achieved by including 3 d velocity perturbations and topography affect slip inversion results we create sets of synthetic seismograms including 3 d heterogeneous earth structure and topography and then invert these synthetics using green s functions computed for a horizontally layered 1 d earth model we apply a linear inversion regularized by smoothing and positivity constraint and examine in detail how smoothing effects perturb the solution among others our tests and resolution analyses demonstrate how imprecise green s functions introduce artificial slip rate multiples especially at shallow depths and that the timing of the peak slip rate is hardly affected by the chosen smoothing the investigation is extended to recordings of the 2009 mw6 3 l aquila earthquake considering both strong motion and high rate gps stations we interpret the inversion results taking into account the lessons learned from the synthetic tests the retrieved slip model resembles previously published solutions using geodetic data showing a large slip asperity southeast of the hypocenter in agreement with other studies we find evidence for fast but subshear rupture propagation in updip direction followed by a delayed propagation along strike we conjecture that rupture was partially inhibited by a deep localized velocity strengthening patch that subsequently experienced afterslip

linearized inversion for fault rupture behavior application to the 1984 morgan hill california earthquake we present a technique to infer the rupture history of an earthquake from near source records of ground motion unlike most previous studies each point on the fault is assumed to slip only once when the rupture front passes with a spatially variable slip intensity in this parameterization the data are linearly related to slip intensity but nonlinearly related to rupture time we perform a linearized inversion for slip intensity and rupture time by iteratively perturbing an assumed starting model the inverse problem for the model perturbation is solved using a tomographic back projection technique smoothing and inequality constraints are applied to ensure that the resulting solution is stable and feasible asymptotic ray theory is used to calculate theoretical seismograms and partial derivatives with respect to model parameters in test cases with noisy synthetic data sets we found that it is possible to distinguish between rupture models having variable slip amplitude and models having variable rupture velocity provided the station coverage is adequate we apply the technique to recordings of the april 24 1984 morgan hill earthquake the results indicate that slip amplitude on the fault plane was extremely variable and that the rupture front did not propagate uniformly away from the hypocenter in particular rupture was delayed on a 12 km2 section of the fault approximately 14 km to the southeast of the hypocenter the rupture front surrounded the region which subsequently failed with a component of rupture propagation back toward the hypocenter similar behavior has been observed in dynamic rupture models with stress or strength inhomogeneities this segment of the fault ruptured with a large slip amplitude releasing 12 of the total seismic moment from 4 of the total area of the aftershock zone the surface trace of this section of the fault is characterized by a complex left step that could act to increase the normal stress acting across the fault however the distribution of aftershocks suggests that the fault at depth is simpler and that it may bend to the right in either case our rupture model suggests that this segment of the fault represents an asperity which initially resisted rupture but eventually ruptured massively we estimate the shear fracture energy for this earthquake to be 2 106 j m2

the anatomy of the 2009 l aquila normal fault system central italy imaged by high resolution foreshock and aftershock locations 1 on 6 april 01 32 utc 2009 a mw 6 1 normal faulting earthquake struck the axial area of the abruzzo region in central italy we study the geometry of fault segments using high resolution foreshock and aftershock locations two main sw dipping segments the l aquila and campotosto faults forming an en echelon system 40 km long nw trending the 16 km long l aquila fault shows a planar geometry with constant dip 48 through the entire upper crust down to 10 km depth the campotosto fault activated by three events with 5 0 mw 5 2 shows a striking listric geometry composed by planar segments with different dips along depth rather than a smoothly curving single fault surface the investigation of the spatiotemporal evolution of foreshock activity within the crustal volume where the subsequent l aquila main shock nucleated allows us to image the progressive activation of the main fault plane from the beginning of 2009 the foreshocks activated the deepest portion of the fault until a week before the main shock when the largest foreshock mw 4 0 triggered a minor antithetic segment seismicity jumped back to the main plane a few hours before the main shock secondary synthetic and antithetic fault segments are present both on the hanging and footwall of the system the stress tensor obtained by inverting focal mechanisms of the largest events reveals a ne trending extension and the majority of the aftershocks are kinematically consistent deviations from the dominant extensional strain pattern are observed for those earthquakes activating minor structures

complexity of the 2009 l aquila earthquake causative fault system abruzzi apennines italy and effects on the middle aterno quaternary basin arrangement abstract an mw 6 1 devastating earthquake on april 6 2009 struck the middle aterno valley abruzzi apennines italy due to the activation of a poorly known normal fault system structural analysis of the fault population and investigation of the relationships with the quaternary continental deposits through integrated field and laboratory techniques were conducted in order to reconstruct the long term tectono sedimentary evolution of the basin and hypothesize the size of the fault segment a polyphasic evolution of the middle aterno valley is characterized by a conjugate e w and n s striking fault system during the early stage of basin development and by a dip slip nw striking fault system in a later phase the old conjugate fault system controlled the generation of the largest sedimentary traps in the area and is responsible for the horst and graben structures within the basin during the early pleistocene the e w and n s system reactivated with dip slip kinematics this gave rise to intra basin bedrock highs and a significant syn tectonic deposition causing variable thickness and hiatuses of the continental infill subsequently since the end of the early pleistocene with the inception of the nw striking fault system several nw strands linked into longer splays and their activity migrated toward a leading segment affecting the paganica san demetrio basin the paganica san demetrio fault alignment the findings from this work constrain and are consistent with the subsurface basin geometry inferred from previous geophysical investigations notably two major elements of the e w and n s striking faults likely act as transfer to the nearby stepping active fault systems or form the boundaries as geometric complexities that limit the paganica san demetrio fault segment overall length to 19 3 km the resulting size of the leading fault segment is coherent with the extent of the 6 april 2009 l aquila earthquake causative fault the positive match between the geologic long term and coseismic images of the 2009 seismogenic fault highlights that the comprehensive reconstruction of the deformation history offers a unique contribution to the understanding faults seismic potential

earthquakes and fault zone structure the characterization of fault zone structure and its evolution is essential for understanding earthquake mechanics and rupture evolution most of our knowledge about fault structure is derived from field studies of ancient faults by using earthquake locations we reconstruct the complex structure of a normal fault at a resolution directly comparable with field geological investigations at the surface conjugate sets of faults are connected with the main fault plane which with depth shows bending and dilational jogs parallel slipping planes occur at the base of the seismogenic volume and minor synthetic and antithetic structures are widespread fault zone thickness ranges from 0 5 to 1 5 km while the damage density decays exponentially away from the fault plane with values comparable to those observed on fault outcrops the strong similarities between seismological and geological images of fault structure indicate that earthquakes have a key role in the evolution of fault architecture

fault zone properties affecting the rupture evolution of the 2009 mw 6 1 l aquila earthquake central italy insights from seismic tomography 1 we have inverted p and s wave travel times from seismograms recorded by a dense local network to infer the velocity structure in the crustal volume where the april 6th 2009 main shock nucleated the goal is to image local variations of p wave velocity and poisson ratio along the main shock fault zone for interpreting the complexity of the rupture history the initial stages of the mainshock rupture are characterized by an emergent phase ep followed by an impulsive phase ip 0 87 s later the ep phase is located in a very high vp and relatively low poisson ratio region the ip phase marks the beginning of the large moment release and is located outside the low volume the comparison between the spatial variations of vp and poisson ratio within the main shock nucleation volume inferred in this study with the rupture history imaged by inverting geophysical data allows us to interpret the delayed along strike propagation in terms of heterogeneity of lithology and material properties

coseismic deformation and triggered landslides of the 2016 mw 6 2 amatrice earthquake in italy the central apennines in italy have had multiple moderate size but damaging shallow earthquakes in this study we optimize the fault geometry and invert for fault slip based on coseismic gps and interferometric synthetic aperture radar insar for the 2016 mw 6 2 amatrice earthquake in italy our results show that nearly all the fault slip occurred between 3 and 6 km depth but extends 20 km along strike there was less than 4 cm static surface displacement at the town amatrice where the most devastating damage occurred landslides triggered by earthquake ground shaking are not uncommon but triggered landslides with submeter movement are challenging to be observed in the field we find evidence of coseismically triggered deep seated landslides northwest and northeast of the epicenter where coseismic peak ground acceleration was estimated 0 5 g by combining ascending and descending insar data we are able to estimate the landslide thickness as at least 100 and 80 m near monte vettore and west of castelluccio respectively the landslide near monte vettore terminates on the preexisting fault monte vettore fault mvef scarp our results imply that the long term fault slip rate of mvef estimated based on paleoseismic studies could potentially have errors due to triggered landslides from nearby earthquake events

estimation of the high frequency radiation of the 2000 tottori japan earthquake based on a dynamic model of fault rupture application to the strong ground motion simulation abstract in the present study we investigate the high frequency hf radiation mechanism of the 2000 tottori earthquake in japan based on a 3d spontaneous fault rupture dynamic model we generalize the model of hf radiation of a suddenly stopping circular crack madariaga 1977 boatwright 1982 to the radiation from a general 3d rupture in a planar fault where hf is radiated during gradual changes of rupture velocity at the rupture front local rupture velocity changes are expressed as the divergence of local rupture velocity vectors that are derived from gradients of rupture times from the dynamic model our numerical model of the tottori earthquake indicates that rupture velocity changes are largely induced by barriers locally stronger fault sections across the fault plane and that hf radiation mainly originates within asperities large stress drop regions in areas where the product of dynamic stress drop and rupture velocity changes is maximum we develop a strong ground motion simulation methodology that incorporates hf radiation inferred from a dynamic fault rupture model using this methodology we investigate the hf radiation of the tottori earthquake by inverting observed near source acceleration envelopes of the earthquake our inversion results corroborate that hf radiation originates within asperities and show that significant hf radiation represents no more than a 20 of the total asperity area our results show that the incorporation of a directivity factor on the basis of a well defined physical rupture model to the radiation pattern leads to a significant improvement in fitting of observed ground motions our simulated near source strong ground motions of the tottori earthquake are also able to reproduce the 2 radiation theoretically predicted in 2d dynamic fault rupture models

a new nonlinear finite fault inversion with three dimensional green s functions application to the 1989 loma prieta california earthquake 1 we present a new procedure to invert for kinematic source parameters on a finite fault on the basis of the reciprocity relation of the green s functions we use a newly developed fourth order viscoelastic finite difference algorithm to calculate three dimensional 3 d green s functions actually the tractions on the fault we invert the data for the unknown source parameters at the nodes or corners of the subfaults the source parameters within a subfault area are allowed to vary this variation is calculated through bilinear interpolation of the four nodal quantities we have developed a global nonlinear inversion algorithm that is based on simulated annealing methods to solve efficiently for the nodal parameters we apply this method to the 1989 loma prieta california m 6 9 earthquake for both a 1 d and 3 d velocity structure we show 1 the bilinear interpolation technique reduces the dependence of inversion results on the subfault size by naturally including the effects of nearby subfaults 2 while the number of synthetic seismograms that must be computed is greatly increased by the bilinear interpolation the structure of the inversion method minimizes the actual numbers of computations 3 as expected complexity in the velocity structure is mapped into the source parameters that describe the rupture process there are significant differences between faulting models derived from 1 d and 3 d structural models

spectral element simulations of seismic waves generated by the 2009 l aquila earthquake abstract we adopt a spectral element method sem to perform numerical simulations of the complex wavefield generated by the 6 april 2009 m w 6 3 l aquila earthquake in central italy the mainshock is represented by a finite fault solution obtained by inverting strong motion and global positioning system data testing both 1d and 3d wavespeed models for central italy surface topography attenuation and the moho discontinuity are also accommodated including these complexities is essential to accurately simulate seismic wave propagation three component synthetic waveforms are compared to corresponding velocimeter and strong motion recordings the results show a favorable match between data and synthetics up to 0 5 hz in a 200 km 200 km 60 km model volume capturing features mainly related to topography or low wavespeed basins we construct synthetic peak ground velocity maps that for the 3d model are in good agreement with observations thus providing valuable information for seismic hazard assessment exploiting the sem in combination with an adjoint method we calculate finite frequency kernels for specific seismic arrivals these kernels capture the volumetric sensitivity associated with the selected waveform and highlight prominent effects of topography on seismic wave propagation in central italy online material movie of wave propagation waveform fits and stable of station parameters

surface displacements associated with the l aquila 2009 mw 6 3 earthquake central italy new evidence from sbas dinsar time series analysis 1 we investigate the surface displacements in the area affected by the april 2009 l aquila earthquake central italy through an advanced dinsar analysis in particular we apply the sbas approach to retrieve deformation maps and displacement time series from envisat data acquired between february 2003 and october 2009 and from cosmo skymed data relevant to the six month interval following the earthquake our analysis shows no evidence of pre seismic surface deformation at the 35 day temporal sampling of the envisat sensor on the other hand by benefiting of the high spatial resolution and temporal sampling of the cosmo skymed satellites we measure post seismic displacements at an unprecedented level of detail for a dinsar analysis this allows us to identify three main areas continuing to deform after the earthquake in addition our modeling shows that post seismic displacements are very likely related to the fault afterslip since their decay times are on the order of 101 102 days

locating distributed faulting contributions from insar imaging to probabilistic fault displacement hazard analysis pfdha abstract prediction of location and amount of slip for distributed faulting associated to strong earthquakes is a recently explored issue with major implications in terms of hazard assessment currently the best practice involves the applications of probabilistic fault displacement hazard analysis pfdha whose results fit sufficiently well real data in the near range of the primary fault but show considerable inaccuracies in the far range we believe that this inaccuracy descends from the biased earthquake databases used for regression analysis whose data relative to old earthquakes were largely collected only by field surveys focused close to the primary fault i e near range remotely sensed data i e interferometric radar imaging insar offer the opportunity to precisely measure the surface deformation induced by strong earthquakes and thus to explore its possible relation with distributed faulting we analyze the l aquila earthquake case study 29th april 2009 mw 6 3 and explore the correlation between location and slip on distributed faulting and insar derived deformation field we find a significant correlation between occurrence of distributed faulting and profile curvature of the dislocation field in spite of the distance from the primary fault moreover distributed faults tend to occur within the area deformed by the earthquake as imaged by insar data and whose extent is directly proportional to the earthquake magnitude mw according to a dataset of 30 recent earthquakes we then propose that these observations have to be incorporated into the present pfdha practice as limit boundaries to possible scenarios of probabilistic analysis and that an integrated use of field based and remotely data collection have to be implemented following strong earthquakes

a new biem for rupture dynamics in half space and its application to the 2008 iwate miyagi nairiku earthquake summary we developed a code for dynamic rupture propagation on arbitrarily shaped faults embedded in half space using boundary integral equation method biem it is based on an existing code for the full space case in which virtual free surface elements were introduced computations in half space are definitely necessary for the modelling of shallow dipping fault ruptures first we describe the implementation and conduct some validation tests that demonstrate the accuracy of the code the validation tests are carried out by comparing the biem results both with the analytical static solution and with the seismic wavefield obtained by a discrete wavenumber method then we apply the code to the study of the 2008 iwate miyagi japan earthquake mw 6 9 rupture dynamics the average stress drop was estimated to be rather large 16 mpa in the asperity area while the average strength excess was 5 mpa the average fracture energy inside the asperity was found to be 36 mjm 2 finally the free surface effect examination showed that the stress drop and the fracture energy were overestimated at shallow depth in the full space computation

a magmatic source for fumaroles and diffuse degassing from the summit crater of teide volcano tenerife canary islands a geochemical evidence for the 2004 2005 seismic volcanic crisis the present work reports the results of 15 studies of diffuse co2 degassing performed at teide volcano crater canary island spain and the chemical and isotopic compositions of fluids discharged from a fumarolic field located at the top of the volcano as measured between 1991 and 2010 a higher contribution of magmatic gases accompanied by enhanced total diffuse co2 emissions were observed in relation with a seismic crisis that occurred in tenerife island between 2001 and 2005 with the main peak of seismic activity between april and june 2004 a significant pulse in total diffuse co2 emission was observed at the crater of teide up to 26 3 t day 1 in 2001 in december 2003 the chemical composition of the teide fumarole changed significantly including the appearance of so2 an increase in the hcl and co concentrations and in the c2h6 c2h4 and c3h8 c3h6 ratios and a decrease in the h2s ch4 and c6h6 concentrations and in the gas steam ratio a few months after a drastic decrease in seismic activity the so2 hcl and co concentrations and the c2h6 c2h4 and c3h8 c3h6 ratios strongly decreased whereas the ch4 and c6h6 concentrations and the gas steam ratios increased according to the trends shown by both the geochemical parameters and the seismic signals late in the observation period the risk of a rejuvenation of volcanic activity at teide is considered to be low the associated temporal changes in seismic activity and magmatic degassing indicate that geophysical and fluid geochemistry signals in this system are related future monitoring programs aimed at mitigating volcanic hazard on tenerife island should involve coupled geophysical and geochemical studies

complex fault geometry and rupture dynamics of the mw 6 5 2016 october 30th central italy earthquake we study the october 30th 2016 norcia earthquake mw 6 5 to retrieve the rupture history by jointly inverting seismograms and coseismic gps displacements obtained by dense local networks the adopted fault geometry consists of a main normal fault striking n155 and dipping 47 belonging to the mt vettore mt bove fault system vbfs and a secondary fault plane striking n210 and dipping 36 to the nw the coseismic rupture initiated on the vbfs and propagated with similar rupture velocity on both fault planes up dip from the nucleation point two main slip patches have been imaged on these fault segments both characterized by similar peak slip values 3 m and rupture times 3 s after the breakage of the two main slip patches coseismic rupture further propagated southeastward along the vbfs rupturing again the same fault portion that slipped during the august 24th earthquake the retrieved coseismic slip distribution is consistent with the observed surface breakages and the deformation pattern inferred from insar measurements our results show that three different fault systems were activated during the october 30th earthquake the composite rupture model inferred in this study provides evidences that also a deep portion of the nne trending section of the olevano antrodoco sibillini oas thrust broke co seismically implying the kinematic inversion of a thrust ramp the obtained rupture history indicates that in this sector of the apennines compressional structures inherited from past tectonics can alternatively segment boundaries of nw trending active normal faults or break co seismically during moderate to large magnitude earthquakes

rupture kinematics and structural rheological control of the 2016 m w 6 1 amatrice central italy earthquake from joint inversion of seismic and geodetic data

frictional heterogeneities on carbonate bearing normal faults insights from the monte maggio fault italy observations of heterogeneous and complex fault slip are often attributed to the complexity of fault structure and or spatial heterogeneity of fault frictional behavior such complex slip patterns have been observed for earthquakes on normal faults throughout central italy where many of the mw 6 to 7 earthquakes in the apennines nucleate at depths where the lithology is dominated by carbonate rocks to explore the relationship between fault structure and heterogeneous frictional properties we studied the exhumed monte maggio fault located in the northern apennines we collected intact specimens of the fault zone including the principal slip surface and hanging wall cataclasite and performed experiments at a normal stress of 10 mpa under saturated conditions experiments designed to reactivate slip between the cemented principal slip surface and cataclasite show a 3 mpa stress drop as the fault surface fails then velocity neutral frictional behavior and significant frictional healing overall our results suggest that 1 earthquakes may readily nucleate in areas of the fault where the slip surface separates massive limestone and are likely to propagate in areas where fault gouge is in contact with the slip surface 2 postseismic slip is more likely to occur in areas of the fault where gouge is present and 3 high rates of frictional healing and low creep relaxation observed between solid fault surfaces could lead to significant aftershocks in areas of low stress drop

rupture process of the 2007 niigata ken chuetsu oki earthquake by non linear joint inversion of strong motion and gps data 1 we image the rupture history of the 2007 niigata ken chuestu oki japan earthquake by a nonlinear joint inversion of strong motion and gps data retrieving peak slip velocity rupture time rise time and slip direction the inferred rupture model contains two asperities a small patch near the nucleation and a larger one located 10 15 km to the south west the maximum slip ranges between 2 0 and 2 5 m and the total seismic moment is 1 6 1019 nm the inferred rupture history is characterized by rupture acceleration and directivity effects which are stable features of the inverted models these features as well as the source to receiver geometry are discussed to interpret the high peak ground motions observed pga is 1200 gals at the kashiwazaki kariwa nuclear power plant kknpp situated on the hanging wall of the causative fault despite the evident source effects predicted pgv underestimates the observed values at kknpp by nearly a factor of 10

active tectonics of the adriatic region from gps and earthquake slip vectors 1 to investigate the kinematics of the adriatic region we integrate continuous and episodic gps measurements with mw 4 5 earthquake slip vectors selected from the regional centroid moment tensor catalogue coherent motion of gps sites in the po valley in apulia and in the hyblean plateau allows us to estimate geodetically constrained angular velocities for these regions the predictions of the gps inferred angular velocities are compared with the earthquake slip vectors showing that the seismically expressed deformation at the microplate boundaries is consistent with the observed geodetic motion the remarkable consistency between geodetic seismological and geological evidence of active tectonics suggests that active deformation in the central adriatic is controlled by the relative motion between the adria and apulia microplates the microplates angular rotation rates are then compared with the rotation rates calculated with a simple block model supporting the hypotheses 1 that apulia forms a single microplate with the ionian sea and possibly with the hyblean region and 2 that adria and apulia rotate in such a way as to accommodate the eurasia nubia relative motion we suggest that the present day microplate configuration follows a recent fragmentation of the adriatic promontory that during the neogene rigidly transferred the africa motion to the orogenic belts that now surround the adriatic region

rupture history of the 2009 l aquila italy earthquake from non linear joint inversion of strong motion and gps data 1 we image the rupture history of the 2009 l aquila central italy earthquake using a nonlinear joint inversion of strong motion and gps data this earthquake ruptured a normal fault striking along the apennines axis and dipping to the sw the inferred slip distribution is heterogeneous and characterized by a small shallow slip patch located up dip from the hypocenter 9 5 km depth and a large deeper patch located southeastward the rupture velocity is larger in the up dip than in the along strike direction this difference can be partially accounted by the crustal structure which is characterized by a high velocity layer above the hypocenter and a lower velocity below the latter velocity seems to have affected the along strike propagation since the largest slip patch is located at depths between 9 and 14 km the imaged slip distribution correlates well with the on fault aftershock pattern as well as with mapped surface breakages

a global search inversion for earthquake kinematic rupture history application to the 2000 western tottori japan earthquake 1 we present a two stage nonlinear technique to invert strong motions records and geodetic data to retrieve the rupture history of an earthquake on a finite fault to account for the actual rupture complexity the fault parameters are spatially variable peak slip velocity slip direction rupture time and risetime the unknown parameters are given at the nodes of the subfaults whereas the parameters within a subfault are allowed to vary through a bilinear interpolation of the nodal values the forward modeling is performed with a discrete wave number technique whose green s functions include the complete response of the vertically varying earth structure during the first stage an algorithm based on the heat bath simulated annealing generates an ensemble of models that efficiently sample the good data fitting regions of parameter space in the second stage appraisal the algorithm performs a statistical analysis of the model ensemble and computes a weighted mean model and its standard deviation this technique rather than simply looking at the best model extracts the most stable features of the earthquake rupture that are consistent with the data and gives an estimate of the variability of each model parameter we present some synthetic tests to show the effectiveness of the method and its robustness to uncertainty of the adopted crustal model finally we apply this inverse technique to the well recorded 2000 western tottori japan earthquake mw 6 6 we confirm that the rupture process is characterized by large slip 3 4 m at very shallow depths but differently from previous studies we imaged a new slip patch 2 2 5 m located deeper between 14 and 18 km depth

joint inversion of coseismic and early postseismic slip to optimize the information content in geodetic data application to the 2009 m w 6 3 l aquila earthquake central italy when analyzing the rupture of a large earthquake geodetic data are often critical these data are generally characterized by either a good temporal or a good spatial resolution but rarely both as a consequence many studies analyze the coseismic rupture with data that also include one or more days of early postseismic deformation here we invert simultaneously for the coseismic and postseismic slip with the condition that the sum of the two models remains compatible with data covering the two slip episodes we validate the benefits of this approach with a toy model and an application to the 2009 m w 6 3 l aquila earthquake using a bayesian approach and accounting for epistemic uncertainties for the l aquila earthquake we find that if early postseismic deformation is not an explicitly acknowledged coseismic signal coseismic slip models may overestimate the peak amplitude while long term postseismic models may largely underestimate the total postseismic slip amplitude this example illustrates how the proposed approach could improve our comprehension of the seismic cycle fault frictional properties and the spatial and temporal relationship between seismic rupture afterslip and aftershocks

soil gas co 2 ch 4 and h 2 distribution in and around las canadas caldera tenerife canary islands spain abstract diffuse degassing of co 2 ch 4 and h 2 was investigated at the surface environment of canadas caldera canary islands during the gas survey carried out in the summer of 1995 soil co 2 concentration varied significantly from atmospheric levels to 30 while soil ch 4 and h 2 contents ranged from 5 to 851 ppm and from 0 5 to 620 ppm respectively soil co 2 ch 4 and h 2 distribution suggests that high diffuse degassing at canadas caldera is volcanic structurally controlled anomalous soil h 2 concentrations were identified at the summit of teide and outside caldera boundaries where the most recent eruption of tenerife island occurred 13 c co 2 data showed a magmatic mixed magmatic biogenic and biogenic origin while a biogenic origin is suggested for soil ch 4 at canadas caldera and its surroundings by coupling the co 2 3 he ratio with the 3 he 4 he ratio of fumarolic gas samples from the summit of teide we propose three possible sources for carbon morb type organic carbon and carbonate

site effects of onna during the 2009 l aquila central italy seismic sequence constraints on bedrock depth and 1d local velocity structure from aftershock seismograms

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

coseismic and initial post seismic slip of the 2009 mw 6 3 l aquila earthquake italy from gps measurements summary here we report the preliminary results of gps data inversions for coseismic and initial afterslip distributions of the mw 6 3 2009 april 6 l aquila earthquake coseismic displacements of continuous and survey style gps sites show that the earthquake ruptured a planar sw dipping normal fault with 0 6 m average slip and an estimated moment of 3 9 1018 nm geodetic data agree with the seismological and geological information pointing out the paganica fault as the causative structure of the main shock the position of the hypocentre relative to the coseismic slip distribution supports the seismological evidence of southeastward rupture directivity these results also point out that the main coseismic asperity probably ended downdip of the paganica village at a depth of few kilometres in agreement with the small 1 10 cm observed surface breaks time dependent post seismic displacements have been modelled with an exponential function the average value of the estimated characteristic times for near field sites in the hanging wall of the fault is 23 9 5 4 d the comparison between coseismic slip and post seismic displacements for the first 60 d after the main shock shows that afterslip occurred at the edges of the main coseismic asperity with a maximum estimated slip of 25 cm and an equivalent seismic moment of 6 5 1017 nm the activation of the paganica fault spatially intermediate between the previously recognized main active fault systems suggests that strain accumulation in the central apennines may be simultaneously active on distinct parallel fault systems

geochemical precursors of the activity of an open conduit volcano the stromboli 2002 2003 eruptive events 1 marked increases of co2 h2 and he dissolved in thermal waters and changes in the dissolved carbon isotopic composition were observed at stromboli before the 28 december 2002 eruption and before a violent explosive paroxysm occurred on 5 april 2003 high anomalous co2 flux values were recorded at the crater rim since a week before the eruption onset the first anomalies in the thermal waters dissolved co2 amount appeared some months before the eruption when magma column rose at a very high level in the conduit high peaks of dissolved h2 and he were recorded a few days before the paroxysm carbon isotopic composition indicates a magmatic origin of the dissolved co2 whose increase together with those of h2 and he is attributed to an increasing output of deep gases likely produced by depressurization of a rising batch of a deep gas rich magma whose fragments have been emitted during the explosion

radar interferogram filtering for geophysical applications the use of sar interferometry is often impeded by decorrelation from thermal noise temporal change and baseline geometry power spectra of interferograms are typically the sum of a narrow band component combined with broad band noise we describe a new adaptive filtering algorithm that dramatically lowers phase noise improving both measurement accuracy and phase unwrapping while demonstrating graceful degradation in regions of pure noise the performance of the filter is demonstrated with sar data from the ers satellites over the jakobshavns glacier of greenland

soil efflux and total emission rates of magmatic co2 at the horseshoe lake tree kill mammoth mountain california 1995 1999 abstract we report the results of eight soil co 2 efflux surveys by the closed circulation chamber method at the horseshoe lake tree kill hltk the largest tree kill on mammoth mountain the surveys were undertaken from 1995 to 1999 to constrain total hltk co 2 emissions and to evaluate occasional efflux surveys as a surveillance tool for the tree kills hltk effluxes range from 1 to 10 000 g m 2 day 1 grams co 2 per square meter per day they are not normally distributed station efflux rates can vary by 7 35 during the course of the 8 to 16 h surveys disturbance of the upper 2 cm of ground surface causes effluxes to almost double semivariograms of efflux spatial covariance fit exponential or spherical models they lack nugget effects efflux contour maps and total co 2 emission rates based on exponential spherical and linear kriging models of survey data are nearly identical similar results are also obtained with triangulation models suggesting that the kriging models are not seriously distorted by the lack of normal efflux distributions in addition model estimates of total co 2 emission rates are relatively insensitive to the measurement precision of the efflux rates and to the efflux value used to separate magmatic from forest soil sources of co 2 surveys since 1997 indicate that contrary to earlier speculations a termination of elevated co 2 emissions at the hltk is unlikely anytime soon the hltk co 2 efflux anomaly fluctuated greatly in size and intensity throughout the 1995 1999 surveys but maintained a n s elongation presumably reflecting fault control of co 2 transport from depth total co 2 emission rates also fluctuated greatly ranging from 46 to 136 t day 1 metric tons co 2 per day and averaging 93 t day 1 the large inter survey variations are caused primarily by external meteorological processes operating on time scales of hours to days the externally caused variations can mask significant changes occurring at depth a striking example is the masking of a degassing event generated at depth and detected by a soil gas sensor network in september 1997 while an efflux survey was in progress thus occasional efflux surveys are not an altogether effective surveillance tool for the hltk and making them effective by greatly increasing their frequency may not be practical

stratigraphy structure and geochronology of the las canadas caldera tenerife canary islands after a long period of subaerial fissure fed extrusions of basaltic magmas 12 to 3 ma volcanic activity was then concentrated in the central part of tenerife phonolitic magma chambers formed and a central volcanic complex was constructed the las canadas edifice the formation of a large depression the las canadas caldera truncated the top of the edifice the active twin strato cones teide pico viejo are sited in this depression the history of the las canadas caldera and edifice are established from stratigraphy geochronology k ar dates and volcanological studies two different groups are recognized separated by a major unconformity the lower group is dated at 2 to 3 ma and includes the products of several volcanic centres which together represent several cycles the upper group ranges from 1 56 to 0 17 ma and includes three different formations representing three long term 100 to 300 ka volcanic cycles the periods of dormancy between each formation were of 120 to 250 ka duration the las canadas caldera is a multicyclic caldera which formed over the period 1 18 0 17 ma each cycle of activity represented by a formation culminated in caldera collapse which affected different sectors of the las canadas edifice geological observation and geochronology support an origin by collapse into a magma chamber the minimum volume of pyroclastic ejecta is substantially greater than the present caldera depression volume 45 km3 but approaches the inferred volume of the original caldera depression 140 km3 after the formation of the caldera sector collapses could also occur at the northern flank of the volcano causing the disappearance of the northern side of the caldera wall

genesis and evolution of unrest episodes at campi flegrei caldera the role of thermal fluid dynamical processes in the geothermal system we develop a model for describing water flow in a porous medium under the effect of thermal and pressure gradients the model simulates geothermal systems in calderas given the boundary conditions and the fluid dynamical properties of the medium the model allows computation in fluid dynamical stationary states of parameters characterizing the flow such as flow velocity and temperature and pressure distributions at depth the model is applied to investigate the effects of the local geothermal system on the unrest episodes at campi flegrei caldera using experimentally determined fluid dynamical parameters for the caldera rocks we show that changes of water flow in shallow aquifers under the effect of pressure and or temperature variations within the geothermal system can be very important in the genesis and evolution of unrest crises in particular they can strongly amplify the effect of pressure increase in the magma chamber on ground uplift they can also explain the timescales of evolution of ground movements in terms of transit times of the water front and of the connected temperature fronts due to advective transport on such grounds an integrated mechanic thermal fluid dynamical model was built allowing us to give a semiquantitative global explanation to the genesis and evolution of unrest phenomena results obtained here can be generalized to other similar calderas

deep structural heterogeneities and the tectonic evolution of the abruzzi region central apennines italy revealed by microseismicity seismic tomography and teleseismic receiver functions abstract the crustal structure of central apennines italy is still poorly defined leaving uncertainties on the tectonic style thin or thick skinned responsible for the development of the thrust and fold belt the today active extension which replaced compression since early quaternary is presumably influenced by the pre existing structure that yields location and segmentation of the fault system to focus on such issues we computed p and s wave velocity models of the crust by using the independent methodologies of local earthquakes tomography and teleseismic receiver function we document strong lateral and vertical heterogeneities that define shallow imbricate sheets of the mesozoic cover that overlay exceptionally high vp and high vs bodies these bodies can be interpreted as either dolomitic or partially hydrated mafic rocks the two alternative interpretations respectively imply an ultra thick deposition of dolomitic rocks in the hanging wall of triassic normal fault or a deep exhumation of the pre mesozoic basement during the early mesozoic sin rift tectonic in both cases these bodies influenced the evolution of the thrust and fold belt very remarkably active normal faults like those ruptured during the still ongoing 2009 l aquila sequence concentrate at the border of these bodies suggesting that they have an active role in the segmentation of the normal fault system the rheological behavior of such high vp high vs bodies weak or strong is still uncertain but of utmost importance to understand the risk of future normal faulting earthquakes

finite element inversion of dinsar data from the mw 6 3 l aquila earthquake 2009 italy 1 fault slip distribution is usually retrieved from geodetic data assuming that the local crust is an elastic homogeneous and isotropic half space in the last decades spatially dense geodetic data e g dinsar maps have highlighted complex patterns of coseismic deformation that require new modeling tools such as numerical methods able to represent rheological and geometrical complexities of the earth s crust in this work we develop a procedure to perform inversion of geodetic data based on the finite element method accounting for a more realistic description of the local crust the method is applied to the 2009 l aquila earthquake mw 6 3 using dinsar images of the coseismic displacement results highlight the non negligible influence of the medium structure homogeneous and heterogeneous models show discrepancies up to 20 in the fault slip distribution values furthermore in the heterogeneous models a new area of slip appears above the hypocenter we also perform a resolution study showing that the information about fault slip distributions retrieved from geodetic data should be considered as averaged on surrounding patches

radiography of a normal fault system by 64 000 high precision earthquake locations the 2009 l aquila central italy case study 1 we studied the anatomy of the fault system where the 2009 l aquila earthquake mw 6 1 nucleated by means of 64 k high precision earthquake locations spanning 1 year data were analyzed by combining an automatic picking procedure for p and s waves together with cross correlation and double difference location methods reaching a completeness magnitude for the catalogue equal to 0 7 including 425 clusters of similar earthquakes the fault system is composed by two major faults the high angle l aquila fault and the listric campotosto fault both located in the first 10 km of the upper crust we detect an extraordinary degree of detail in the anatomy of the single fault segments resembling the degree of complexity observed by field geologists on fault outcrops we observe multiple antithetic and synthetic fault segments tens of meters long in both the hanging wall and footwall along with bends and cross fault intersections along the main fault and fault splays the width of the l aquila fault zone varies along strike from 0 3 km where the fault exhibits the simplest geometry and experienced peaks in the slip distribution up to 1 5 km at the fault tips with an increase in the geometrical complexity these characteristics similar to damage zone properties of natural faults underline the key role of aftershocks in fault growth and co seismic rupture propagation processes additionally we interpret the persistent nucleation of similar events at the seismicity cutoff depth as the presence of a rheological i e creeping discontinuity explaining how normal faults detach at depth