stochastic finite fault ground motion simulation in a wave field diffusive regime case study of the mt vesuvius volcanic area abstract the main aim of the present work consists in the validation of stochastic method for simulating weak ground motion in a diffusive regime due to low to moderate magnitude earthquakes and in particular in its application to a volcanic area we simulated the peak ground acceleration and the response acceleration spectra caused by two earthquakes scenarios m d 4 3 and m d 5 4 at mt vesuvius volcanic area by using the stochastic finite fault simulation method we validated the stochastic methodology by combining source path and site parameters of the investigated area considering the time duration parameter t rms calculated on the study seismograms the values of time durations are confirmed by calculating the same parameter t rms on the seismogram energy envelope described by multiple scattering models in terms of scattering and the intrinsic dissipation coefficient initially the simulations were evaluated for 10 local earthquakes 1 7 m d 3 6 that occurred at mt vesuvius in 1999 and are then compared with the observed data the comparison between simulated and observed seismograms has been used to calibrate the stochastic procedure and has been considered as the starting point for simulating ground motion for the scenario earthquake m d 3 6 that could occur in the study area the scenario earthquake and the relative fault features were chosen on the base of statistical tectonic structural and historical studies of the study area we simulated ground motions for a maximum magnitude value m max of 4 3 determined from examination of the gutenberg richter law for the study area and also for an m max 5 4 a magnitude that is associated with the earthquakes that struck the ancient town of pompei 17 yr before the eruption of mt vesuvius that occurred in a d 79 the largest values of a max for the m d 4 3 seismic event are in the range of 0 140 g 0 029 g in the case of m d 5 4 we obtain peak ground acceleration values in the range between 0 17 g and 0 55 g

geophysical evidence for the locations shapes and sizes and internal structures of magma chambers beneath regions of quaternary volcanism this paper is a review of seismic gravity magnetic and electromagnetic techniques to detect and delineate magma chambers of a few cubic kilometres to several thousand cubic kilometres volume a dramatic decrease in density and seismic velocity and an increase in seismic attenuation and electrical conductivity occurs at the onset of partial melting in rocks the geophysical techniques are based on detecting these differences in physical properties between solid and partially molten rock although seismic refraction techniques with sophisticated instrumentation and analytical procedures are routinely used for detailed studies of crustal structure in volcanic regions their application for magma detection has been quite limited in one study in yellowstone national park u s a fan shooting and time term techniques have been used to detect an upper crustal magma chamber attenuation and velocity changes in seismic waves from explosions and earthquakes diffracted around magma chambers are observed near some volcanoes in kamchatka strong attenuation of shear waves from regional earthquakes interpreted as a diffraction effect has been used to model magma chambers in alaska kamchatka iceland and new zealand one of the most powerful techniques in modern seismology the seismic reflection technique with vibrators was used to confirm the existence of a strong reflector in the crust near socorro new mexico in the rio grande rift this reflector discovered earlier from data from local earthquakes is interpreted as a sill like magma body in the kilauea volcano hawaii mapping seismicity patterns in the upper crust has enabled the modelling of the complex magma conduits in the crust and upper mantle on the other hand in the usu volcano japan the magma conduits are delineated by zones of seismic quiescence three dimensional modelling of laterally varying structures using teleseismic residuals is proving to be a very promising technique for detecting and delineating magma chambers with minimum horizontal and vertical dimensions of about 6 km this technique has been used successfully to detect low velocity anomalies interpreted as magma bodies in the volume range 10 3 10 6 km 3 in several volcanic centres in the u s a and in mt etna sicily velocity models developed using teleseismic residuals of the cascades volcanoes of oregon and california and kilauea volcano hawaii do not show appreciable storage of magma in the crust however regional models imply that large volumes of parental magma may be present in the upper mantle of these regions in some volcanic centres teleseismic delays are accompanied by p wave attenuation and linear inversion of spectral data have enabled computation of three dimensional q models for these areas the use of gravity data for magma chamber studies is illustrated by a study in the geysers clear lake volcanic field in california where a strong gravity low has been modelled as a low density body in the upper crust this body is approximately in the same location as the low velocity body delineated with teleseismic delays and is interpreted as a magma body in yellowstone national park magnetic field data have been used to map the depth to the curie isotherm and the results show that high temperatures may be present at shallow depths beneath the yellowstone caldera the main application of electrical techniques in magma related studies has been to understand the deep structure of continental rifts electromagnetic studies in several rift zones of the world provide constraints on the thermal structure and magma storage beneath these regions

loss of floating glacier tongues from the yelverton bay region ellesmere island canada a total of eight floating glacier tongues have shrunk in area by 85 from the yelverton bay region of northern ellesmere island since 1959 with unusually large losses since 2005 to better understand the causes of these losses this study undertakes the first examination of ice tongue changes in this region including an assessment of changes in surrounding marine ice i e sea ice sikussak and melange and atmospheric and oceanographic forcings from 1959 to 2017 the total ice tongue area decreased by 49 07 km 2 with the majority of this loss occurring from 2005 to 2009 34 68 km 2 the loss of ice tongues since 2005 occurred when open water replaced multi year landfast sea ice mlsi and first year sea ice in the regions adjacent to the ice tongues these changes were accompanied by an increase in mean annual mid depth i e 100 and 200 m ocean temperatures from 0 29 c from 1999 to 2005 to 0 67 c from 2006 to 2012 despite the recent return of ocean temperatures to below pre 2006 levels atmospheric summer temperatures have continued to rise 0 15 c decade 1 between 1948 and 2016 with open water continuing to occur without the sustained presence of mlsi in this region the ice tongues are unable to stabilize making it unlikely that they will re form in the current climate

stable isotope 18o 16o tracing of fresh brackish and sea ice in multi year land fast sea ice ellesmere island canada la salinite de la glace et les rapports 18 o 16 o ont ete mesures sur 12 carottes de glace prelevees sur la glace marine au large de la cote nord de ellesmere island canada les 3 types de glace douce saum tre et marine ont ete identifies dans les carottes en utilisant les rapports isotopiques 18 o 16 o l utilisation des mesures 18 o pour identifier la glace marine et saum tre est discutee la proportion de chaque type de glace presente est etablie et les implications pour les proprietes et la structure de l eau sous glaciaire sont presentees

the magma system of mount st helens non linear high resolution p wave tomography abstract high resolution three dimensional images of p wave velocity anomalies below mt st helens washington were derived using tomographic inversion the model is a 27 5 21 20 km target volume parameterized by blocks 0 5 km per side the area included 39 stations and 5454 local events leading to 35 475 rays used in the inversion to diminish the effects of noisy data the laplacian was constrained to be small within horizontal layers providing smoothing of the model non linear effects were compensated for by iterating three dimensional ray tracing using pseudo bending between inversions and relocating earthquakes relative to the updated three dimensional model the structural differences between the linear and non linear inversions appear to be insignificant although the amplitudes of the anomalies are larger in the non linear models results indicate a low velocity anomaly 7 approximately 1 km in lateral extent from 1 5 to 3 km depths between 3 and 6 km depth the anomaly appears to spread out below 6 km depth the low velocity feature changes to a higher velocity perturbation with lower velocity perturbations flanking around the perimeter of the volcano the higher velocity material which correlates with the higher seismicity at that depth is interpreted as being a plug capping the low velocity magma chamber which begins below 9 km depth

calculation of strong ground motion due to an extended earthquake source in a laterally varying structure abstract lateral heterogeneity of the crust combined with the complexity of an extended earthquake source may account for observations of strong ground motion not easily explained by simplified source models in a laterally homogeneous medium both the effects of an extended source and lateral heterogeneity can be examined using a forward modeling technique that combines distributed nonuniform slip on a fault plane with dynamic ray tracing in a three dimensional medium using this technique velocity seismograms are calculated at ranges less than 10 km for a finite source which occurs in a wedge shaped zone of low velocity this structure is chosen to approximate the structure of fault zones found in reflection and refraction surveys across active faults in california iterative paraxial ray tracing is used to solve the two point ray tracing problem the low velocity zone surrounding the fault causes arrivals in the laterally varying structure to be delayed and rays to leave the fault more closely to the fault normal at most locations examined the effect of the three dimensional structure on isochrone velocity is small compared to the effects on geometric spreading and radiation pattern because rays are bent substantially in the near source region the seismograms calculated for the laterally varying structure vary substantially in amplitude and polarity from seismograms calculated for the laterally homogeneous structure

mapping the b value anomaly at 100 km depth in the alaska and new zealand subduction zones a positive anomaly in the frequency magnitude distribution b value is detected at approximately 90 100 km depth in two subduction zones the b value in this anomalous zone is 40 higher than in adjacent volumes we use regional catalogs with a magnitude of completeness of 2 6 central alaska and cook inlet 2 0 shumagin islands and 3 5 new zealand to resolve the b value as a function of space in more detail we project all earthquakes onto planes perpendicular to the strike of the slab these cross section views of the b value distribution locate the high b value anomalies at a depth of 90 100 km on the upper surface of the wadati benioff zone at these depths slab dehydration may increase pore pressure thus lowering the effective stress and increasing the b value increased pore pressure would also lower the liquidus in the overlying asthenosphere giving rise to the volcanism that occurs directly above this zone

variations in the frequency magnitude distribution with depth in two volcanic areas mount st helens washington and mt spurr alaska the frequency magnitude distribution of earthquakes characterized using the b value is examined as a function of space beneath mount st helens 1988 1996 and mt spurr 1991 1995 at mount st helens two volumes of anomalously high b b 1 3 can be observed at depths of 2 6 3 6 km below the crater floor and below 6 4 km these anomalies coincide with 1 the depth of vesiculation of ascending magma and 2 the suggested location of a magma chamber at mount st helens study of mt spurr reveals an area of high b value b 1 3 at a depth of about 2 3 4 5 km below the crater floor of the active vent crater peak we propose that the higher material heterogeneity in the vicinity of a magma chamber or conduit due to vesiculation of the ascending magma is the main cause of the increased b value at shallow depths alternatively interaction of magma with groundwater may have increased pore pressure and lowered the effective stress the deeper anomaly at mount st helens is likely caused by high thermal stress gradients in the vicinity of the magma chamber our results indicate that detailed mapping of the frequency magnitude distribution can be used as a tool to trace vesiculation and locate active magma chambers

spheroidal cannonballs calcite cemented concretions from the faiyum and bahariya depressions egypt evidence of differential erosion by sand storms

simulation of earthquake ground motion and effects on engineering structures during the preeruptive phase of an active volcano several of the world s active volcanoes are located near densely pop ulated areas and therefore the seismic hazard associated with preeruptive earthquake activity and its relation to the potential damage of engineering structures should be considered as a part of risk evaluation and management this is true for mt vesuvius volcano southern italy where several hundred thousand people are exposed to volcanic and related seismic risks this study investigates the effect of preeruptive seismic activity through the massive simulation of earthquake waveforms in the magnitude location and focal mechanism ranges expected for mt vesuvius seis micity synthetics are processed to evaluate the characteristic strong motion param eters which are useful for estimating the seismic damage to a built up environment that would arise from both the maximum expected single event and the cumulative effect of a large number of small events synthetic and observed strong motion pa rameters for a selected set of recorded earthquakes are compared to validate the modeling approach the scaling of the simulated peak ground acceleration pga with distance appears to be influenced by earthquake depth owing to the presence of a sharp velocity discontinuity at shallow depths underneath the vesuvius area on the other hand the hysteretic energy spectrum related to the plastic behavior of the structures depends strongly on the b parameter of the gutenberg richter law g r by varying the g r law parameters across a reasonable expected range we observe that the cumulative hysteretic energy is comparable to the values observed at near source distances during the 1997 umbria marche italy event m 5 8 which produced serious damage to buildings and infrastructure although a significant pga value was not recorded

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

spatial variations in the frequency magnitude distribution of earthquakes at soufriere hills volcano montserrat west indies the frequency magnitude distribution of earthquakes measured by the b value is determined as a function of space beneath soufriere hills volcano montserrat from data recorded between august 1 1995 and march 31 1996 a volume of anomalously high b values b 3 0 with a 1 5 km radius is imaged at depths of 0 and 1 5 km beneath english s crater and chance s peak this high b value anomaly extends southwest to gage s soufriere at depths greater than 2 5 km volumes of comparatively low b values b 1 are found beneath st george s hill windy hill and below 2 5 km depth and to the south of english s crater we speculate the depth of high b value anomalies under volcanoes may be a function of silica content modified by some additional factors with the most siliceous having these volumes that are highly fractured or contain high pore pressure at the shallowest depths

airborne uhf radar sounding of glaciers and ice shelves northern ellesmere island arctic canada more than 2000 line kilometres of ice were sounded in 1981 using an 840 mhz pulsed radar system the surveyed regions include mt oxford ice cap disraeli glacier milne glacier ward hunt ice shelf and milne ice shelf in northern ellesmere island arctic canada the maximum ice thickness that was reliably recorded was 750 m for milne glacier in addition to ice thickness interpretation the power reflection coefficient prc and propagation loss rate were estimated from the data measured basal prc s differ for ice shelves floating glaciers and grounded glaciers spatial variations of prc have been used to infer a composite structure for the ice shelves ward hunt ice shelf proved difficult to sound probably because of its known saline and brackish chemistry excellent results were obtained for milne ice shelf and its depth was found to average roughly 70 m in places attaining 100 m bottom side crevasses were observed within milne ice shelf the characteristic ridge and trough topography of the ice

correlating seismicity parameters and subsidence in the tokai region central japan 1 we demonstrate that transients in subsidence rate in the tokai area of central japan correlate with changes in the rate and size distribution of earthquakes three largely independent seismic catalogs cover this region national research institute for earth science and disaster prevention nied japanese meteorological agency jma and japan university network catalog junec comparing seismicity patterns between these three data sets offers a unique opportunity to verify seismicity anomalies based on independent sources a study of data quality magnitude reporting consistency and consistency across the three data sources reveals that the nied data for the period 1981 2002 are best suited for seismicity analysis we spatially and temporally map seismicity rates finding that a significant decrease in the earthquake rate of m 2 0 events coincides with an accelerated subsidence period however this anomaly disappears when including smaller magnitudes in the analysis this relative quiescence of larger events can readily be explained when interpreting the transient in seismicity in the framework of a change in the earthquake size distribution or b value the background b value of about 0 8 increased in the period 1987 5 1989 5 to a value of b 1 2 a highly significant change that can be confirmed in all three data sets the correlation between subsidence and b value change is significant stress tensor inversions of focal mechanism data for the anomalous period show an increase in thrusting type earthquakes while a unique interpretation of the relationship between subsidence and b value is not possible we propose that an increase in the locking stress a slow stick event is consistent with all observations

a characteristic earthquake model of the seismicity preceding the eruption of mount st helens on 18 may 1980 abstract the two classes of earthquakes which preceded the explosive eruption of mount st helens washington on 18 may 1980 can be related to two different forms of energy release this is manifest both in the predominant periods of the two classes of seismic energy release at 1 0 and 0 55 s and in the ratio of their source dimensions in the range 2 1 to 6 1 inferred from characteristic magnitudes of the two possible classes of earthquakes apparent in the discrete frequency magnitude distribution the observed increase in the ratio of long to short period amplitudes of surface waves recorded on mso a local wwssn station can be numerically related to the growth of a magma chamber or conduit within which are generated the transient oscillations thought to be responsible for volcanic tremor these calculations predict an increase in the chamber s diameter at a rate of 2 7 m day 1 at depth in the 2 months preceding the eruption and this is consistent with an observed growth rate of 2 m day 1 of the precursory bulge which appeared at the surface on the mountain s north flank at the time the frequency magnitude distribution is analysed in two parts corresponding to a power law at low magnitudes and a gaussian distribution of typical fault lengths at high magnitudes an extension of the characteristic earthquake model first developed for individual fault zones the power law can in general have a non integer exponent which can be equated to a fractal self similarity dimension d temporal changes in d which is proportional to the seismic b value are proposed as an alternative and complementary description of the way seismic energy is released to the more commonly used viewpoints of changes in stress and heterogeneity despite a reassessment of the completeness of the magnitude catalogue no clear seismic precursor to the explosive eruption is observed in the b value although an earlier phase of phreatic eruptions was strongly associated with a b value anomaly

magmatic system geometry at mount st helens modeled from the stress field associated with posteruptive earthquakes earthquakes following the may 18 1980 and june 12 1980 explosive eruptions of mount st helens were concentrated at depths below 6 km the hypocenters of these posteruption earthquakes define two seismic lobes separated by an aseismic volume of 2 km width that is located beneath the position of the crater the timing and location of the posteruption seismicity suggests that the earthquakes occurred in the country rock surrounding a magma body located within the aseismic volume the withdrawal of magma caused a pressure decrease within the reservoir and the earthquakes occurred as a brittle response to the resulting stress change focal mechanism solutions for posteruption earthquakes distributed within the seismic lobes are calculated using polarity and amplitude data results show that a perturbation from the regional stress field occurs between depths of 7 and 11 km this anomalous stress field is successfully modeled by a decrease in pressure within a cylindrical magma body located between the seismic lobes and subject to conditions representing the regional shear stress regime in the best fitting model the magma body is centered at 46 204 n 122 187 w 600 m to the north of the present dome and is under a regional shear stress of 20 bars the radius of the chamber is calculated to be between 0 65 and 0 75 km when using pressure drops within the cylinder of 220 and 150 bars respectively the magma body extends from 7 to 11 km and has a volume of between 5 and 7 km3 posteruption earthquakes located below 11 km fall on a northeast striking fault that is preferentially aligned with the regional tectonic stress regime this fault may be a conduit to transport magma to the shallow reservoir from greater depths within the crust

precursory swarms of long period events at redoubt volcano 1989 1990 alaska their origin and use as a forecasting tool abstract during the eruption of redoubt volcano from december 1989 through april 1990 the alaska volcano observatory issued advance warnings of several tephra eruptions based on changes in seismic activity related to the occurrence of precursory swarms of long period lp seismic events dominant period of about 0 5 s the initial eruption on december 14 occurred after 23 years of quiescence and was heralded by a 23 hour swarm of lp events that ended abruptly with the eruption after a series of vent clearing explosions over the next few days dome growth began on december 21 another swarm with lp events similar to those of the first began on the 26th and ended in a major tephra eruption on january 2 eruptions continued over the next two weeks and then ceased until february 15 when a large eruption initiated a long phase of repetitive dome building and dome destroying episodes that continued into april warnings were issued before the major events on december 14 and january 2 but as the eruptive sequence continued after january 2 the energy of the swarms decreased and forecasting became more difficult a significant but less intense swarm preceded the february 15 eruption which was not forecast this eruption destroyed the only seismograph on the volcanic edifice and stymied forecasting until march 4 when the first of three new stations was installed within 3 km of the active vent from march 4 to the end of the sequence on april 21 there were eight eruptions six of which were preceded by detectable swarms of lp events although weak these swarms provided the basis for warnings issued before the eruptions on march 23 and april 6 the initial swarm on december 13 had the following features 1 short duration 23 hours 2 a rapidly accelerating rate of seismic energy release over the first 18 hours of the swarm followed by a decline of activity during the 5 hours preceding the eruption 3 a magnitude range from 0 4 to 1 6 4 nearly identical lp signatures with a dominant period near 0 5 s 5 dilatational first motions everywhere and 6 a stationary source location at a depth of 1 4 km beneath the crater this occurrence of long period events suggests a model involving the interaction of magma with groundwater in which magmatic gases steam and water drive a fixed conduit at a stationary point throughout the swarm the initiation of that sequence of events is analogous to the failure of a pressure relief valve connecting a lower supercharged magma dominated reservoir to a shallow hydrothermal system a three dimensional model of a vibrating fluid filled crack recently developed by chouet is found to be compatible with the seismic data and yields the following parameters for the lp source crack length 280 380 m crack width 140 190 m crack thickness 0 05 0 20 m crack stiffness 100 200 sound speed of fluid 0 8 1 3 km s compressional wave speed of rock 5 1 km s density ratio of fluid to rock 0 4 and ratio of bulk modulus of fluid to rigidity of rock 0 03 0 07 the fluid filled crack is excited intermittently by an impulsive pressure drop that varies in magnitude within the range of 0 4 to 40 bar such disturbance appears to be consistent with a triggering mechanism associated with choked flow conditions in the crack

spatial variation of seismic b values beneath makushin volcano unalaska island alaska abstract the frequency magnitude distribution was spatially mapped beneath makushin volcano unalaska island alaska using an earthquake catalog of 491 events that occurred between july 2001 and april 2005 an area of high seismic b values 2 0 is found 4 km east of makushin s main vent at a depth between 4 and 7 km the anomaly is statistically significant based on utsu s p test t utsu on seismicity in report of the joint research institute for statistical mathematics tokyo 1992 139 157 and is not data processing method or parameter dependent interestingly a recent insar interferometric study z lu j a power v s mcconnell c wicks jr d dzurism preeruptive inflation and surface interferometric coherence characteristics by satellite radar interferometry at makushin volcano alaska 1993 2000 j geophys res 107 2002 2266 doi 10 1029 2001jb000970 inferred a surface uplift of about 7 cm during the two year period prior to october 1995 centered approximately in the area with the observed anomalous b values the uplift was caused by the volume increase of an inferred magma chamber at a depth of about 7 km the close correspondence of the seismic and insar observations suggests that the heterogeneous area associated with the observed high b values is most likely the result of increased crack density associated with the magma chamber this study demonstrates the effectiveness of combining insar and seismological observations in locating magma chambers and areas of high heterogeneity in the crust

the history and nature of wind erosion in deserts recently the importance of wind erosion has been reevaluated many low angle surfaces developed on susceptible materials possess closed depressions pans and these often have a distinctive morphology and lunette dunes on their lee sides it has also become apparent that in drylands there are extensive areas of stone pavements some of which have been molded by deflation however it is now recognized that other horizontal sorting processes have played a role especially movement of fines by overland flow vertical sorting associated with wetting and drying salt heave bioturbation frost action and dust accretion have also played a role in hyperarid areas especially with unidirectional winds bedrock outcrops and old lake beds have been molded to give aerodynamic forms called yardangs the study of dust storms by analysis of climatological data and remote sensing has revealed the importance of deflation especially in hyperarid areas with centripetal drainage deflation hot spots such as the bo

assessment of pre crisis and syn crisis seismic hazard at campi flegrei and mt vesuvius volcanoes campania southern italy in this study we address the issue of short term to medium term probabilistic seismic hazard analysis for two volcanic areas campi flegrei caldera and mt vesuvius in the campania region of southern italy two different phases of the volcanic activity are considered the first which we term the pre crisis phase concerns the present quiescent state of the volcanoes that is characterized by low to moderate seismicity the second phase syn crisis concerns the unrest phase that can potentially lead to eruption for the campi flegrei case study we analyzed the pattern of seismicity during the 1982 1984 ground uplift episode bradyseism for mt vesuvius two different time evolutionary models for seismicity were adopted corresponding to different ways in which the volcano might erupt we performed a site specific analysis linked with the hazard map to investigate the effects of input parameters in terms of source geometry mean activity rate periods of data collection and return periods for the syn crisis phase the analysis in the present study of the pre crisis phase allowed a comparison of the results of probabilistic seismic hazard analysis for the two study areas with those provided in the italian national hazard map for the mt vesuvius area in particular the results show that the hazard can be greater than that reported in the national hazard map when information at a local scale is used for the syn crisis phase the main result is that the data recorded during the early months of the unrest phase are substantially representative of the seismic hazard during the whole duration of the crisis

a methodology for seismic loss estimation in urban regions based on ground motion simulations seismic vulnerability assessment of residential buildings in regions of high seismicity is an interdisciplinary problem requiring major inputs from fields of seismology and earthquake engineering the basic two components of loss estimation methods are information on regional seismicity and building stock this study presents a realistic loss estimation methodology where the first component input ground motions is obtained from regional ground motion simulations using the stochastic finite fault technique the second component building vulnerability information on the other hand is taken into account using fragility analyses introducing the ground motion intensity parameters obtained from simulations to the fragility curves we obtain seismic loss distribution in a region in this study we demonstrate the loss estimation methodology with an application to three northwestern cities in turkey duzce bolu and kaynasli that experienced two major earthquakes graphic 1 and graphic 2 in less than three months in 1999 we initially verify the methodology with comparisons of observed and estimated damage ratios for the 12 november 1999 graphic 3 duzce earthquake later we present the estimated damage ratios under scenario earthquakes in the region for a magnitude range of graphic 4 graphic 5 is predicted to be the threshold magnitude for the cities of duzce and kaynasli where more than 60 of the building stock experience moderate and heavy damage because bolu is at a farther distance from the fault plane less damage is estimated for graphic 6 than those in the other centers for graphic 7 all three cities are predicted to experience substantial rates of heavy damage and collapse 1 embed inline graphic 1 gif 2 embed inline graphic 2 gif 3 embed inline graphic 3 gif 4 embed inline graphic 4 gif 5 embed inline graphic 5 gif 6 embed inline graphic 6 gif 7 embed inline graphic 7 gif

statistical analysis of earthquake activity at etna volcano march 1981 eruption seismic activity that preceded accompanied and followed the 17 23 march 1981 etnean eruption has been statistically analyzed

scaling of peak ground motions from digital recordings of small earthquakes at campi flegrei southern italy the dependence of peak ground acceleration and velocity on seismic moment is studied for a set of small earthquakes 0 7 ml 3 2 recorded digitally at distances of a few km in the campi flegrei volcanic area near naples italy during the ground uplift episode of 1982 1984 numerical simulations using the square spectral model with constant stress drop and ane kf high frequency decay fit well both the velocity and acceleration data for an averagek 0 015 the observed ground motions in the 1 24 hz frequency band appear to consist of radiation from simple sources modified only slightly by attenuation effects moreover the scaling of peak values agrees closely with those determined in nonvolcanic areas once the difference in stress drop is taken into account

an origin for laminated glacimarine sediments through sea ice build up and suppressed iceberg rafting laminated glacimarine sediments are observed in visual core logs and x radiographs from scoresby sund and nansen fjord east greenland they are mostly underlain and overlain by massive or stratified glacimarine diamicton dmm or dms which is a product of iceberg delivery of heterogeneous debris and in scoresby sund reworking by deep drafted iceberg keels the laminated sediments are ams radiocarbon dated to two cold periods since the last late weichselian deglaciation the younger dryas stadial milne land stadial in east greenland and the little ice age during cold climatic events multiyear shorefast sea ice sikussak formed in these fjords and trapped the icebergs fine grained laminated muds fl were deposited in scoresby sund when the flux of icebergs was suppressed but turbid meltwater continued to provide some sediment flux to the fjord systems varying through time to produce laminations in nansen fjord thinner and often massive mud layers fm resulted from shorter intervals of sea ice cover with no ice rafting stratified diamicton layers dms which alternate with mud deposition to produce a laminated unit probably represent intervening times of more open conditions with iceberg rafting in scoresby sund foraminifera are either absent from the laminated unit or begin to appear towards the end of its deposition the absence of both benthic and planktonic foraminifera also suggests that multiyear sea ice was covering the core sites there is no evidence of macrofaunal activity and bioturbation is absent from the laminated sediments satellite data show that multiyear shorefast sea ice is present in several areas of the high arctic today and this traps icebergs calved from interior ice cap drainage basins thus the process of laminated glacimarine sediment formation is likely to be applicable to a number of areas of the modern and quaternary arctic