estimation of seismic hazard parameters for the himalayas and its vicinity from complete data files the maximum likelihood estimation of earthquake hazard parameters has been made in the himalayas and its surrounding areas on the basis of a procedure which utilizes data containing complete files of the most recent earthquakes the entire earthquake catalogue used covers the period from 1900 1990 the maximum regional magnitude m max the activity rate of the seismic event the mean return period r of earthquakes with a certain lower magnitude m max m along with their probability of occurrence as well as the parameter b of of gutenberg richter magnitude frequency relationship have been determined for six different seismic zones of the himalayas and its vicinity it is shown that in general the hazard is higher in the zone nei and ban than the other four zones the high difference of the b parameter and the hazard level from zone to zone reflect the high seismotectonic complexity and crustal heterogeneity

seismicity of the koyna region and regional tectonomagmatism of the western margin india recent findings on the meso cenozoic tectonomagmatism and deep seated anomalous geophysical structures suggest a close linkage between the seismicity of the koyna region the westernghat uplift wg u and associated thermomechanical and fluid activities the wg u seems to be the result of late cretaceous thermal mobilization erosion of the deccan trap cover and superposition of compressional stress the association of seismicity with uplift seems to result from movement of deep seated heat and fluids volatiles along the edges or boundary faults of the uplift because the force required for crustal deformation depends on the relief observed gradients in relief may be attributed to the differential erosion rates and heat inputs due to the time gap of 50 ma in the break ups and plume activities on the eastern and western sides and consequence magmatism further the geology and tectonics strongly indicate that the western margin wm is a relic of a mobile arm ma that included madagascar and which formed a part of the proterozoic mobile belt of greater india fort 85 ma the mobile nature of the wm facilitates mantle upwellings and transient elevation of isotherms at depth raising the possibility of intermittent metamorphism and greater deformation superposition of the ongoing compression and uplift induced forces make local permeability and pore fluid pressure vital in triggering the seismic slip over the peninsular shield certain representative model calculations have been carried out to estimate change in the e m induction characteristics caused by an intermittent hydraulic connectivity the results show a drop in the resistivity which could be a useful monitoring index the close connection of uplift and fluid activity as discussed here seems applicable for other active parts of the south indian shield sis also

source parameters and fmax in kameng region of arunachal lesser himalaya abstract a data set of 79 local events 0 7 mw 3 7 occurred during february 2003 to may 2003 collected by a temporary network deployed in kameng region of arunachal lesser himalaya have been analyzed to study the source parameters and fmax in this study brune model that yield a fall off of two beyond corner frequency along with high frequency diminution factor for frequencies greater than fmax represented by a butterworth high cut filter boore 1983 has been considered the software eqk src para kumar et al 2012 has been used to estimate the spectral parameters namely low frequency displacement spectral levels 0 corner frequency fc above which spectrum decays with a rate of two the high cut frequency fmax above which the spectrum again decays and the rate of decay n above fmax these spectral parameters are used to estimate source parameters viz seismic moments source dimensions and stress drops and to develop scaling laws for the region seismic moments vary from 1 42 1017 dyne cm to 4 23 1021 dyne cm the source radii vary from 88 7 m to 931 5 m for 28 events stress drops are less than 1 bar and 51 events have stress drops between 1 bar and 40 bars a scaling relation m0 dyne cm 2 1022 f c 3 34 has been derived for earthquakes having seismic moments greater than 1 5 1019 dyne cm the estimated values of fmax values by and large conform to the worldwide observations dependence of fmax on source sizes focal depths epicentral distances and recording sites has been studied on the basis of comparative dependency of fc and fmax the fmax and fc show almost similar dependency to seismic moments which shows fmax is also due to source process and is independent of epicentral distances and focal depths at different recording sites the observed values of fmax show consistent increase with seismic moment this reflects that the source is the main controlling factor rather than recording site conditions for the observed variation of fmax in the kameng region

the dibdibba aquifer system at safwan zubair area southern iraq hydrogeology and environmental situation the objective of this research is to study the environment and hydrogeology of the dibdibba aquifer system in the safwan zubair area southern iraq in relation to the study area s geology and anthropogenic activities ten groundwater samples were collected from safwan zubair geochemical data aquachem and gis arcmap 10 1 were used as tools to identify natural and anthropogenic factors that affect geochemical data we analyzed water samples for major cations and anions polycyclic aromatic hydrocarbons pahs total uranium tu and heavy metals pb ni cr cd v zn as se cu fe mn as well as the metalloid b groundwater composition in the area of study is classified into six types ca mg cl ca mg na cl ca mg cl so4 ca mg na cl so4 ca na mg so4 cl and mg ca cl so4 the groundwater is influenced by natural factors particularly the concentrations of tu and major ions the concentrations of tu and major ions in some water samples exceed limits for drinking water however the average of all examined heavy metals except for fe and b was within the limits for drinking water as well as the concentrations of pahs the potential use of this groundwater for drinking and irrigation is discussed

regional variation of the ω upper bound magnitude of giii distribution in hindukush pamir himalaya and the adjacent regions a perspective on earthquake hazard the upper bound magnitude or maximum magnitude in 28 seismogenic source zones in the hindukush pamir himalaya and the adjacent regions have been computed with the help of a complete and homogeneous earthquake catalogue during the period 1900 2010 to estimate the earthquake hazards in the region the gumbel s third asymptotic distribution giii of extreme value method is used to estimate this parameter in this study a comparison of maximum magnitude obtained by giii distribution is carried out with kijko sellevoll method it is observed that the maximum earthquake magnitudes estimated by kijko sellevoll and giii methods are comparable to each other and the average of differences of their values is only 0 13 the results also estimate the most probable earthquake magnitude that can be expected in next 100 years m100 in all 28 seismogenic source zones an effort is made to make regression relations between and maximum magnitude estimated by kijko sellevoll method mmax ks and and maximum observed magnitude mmaxobs the estimated values exceeded the value of 7 00 in 15 and 8 00 in 5 of the 28 seismogenic source zones the geographical distribution of and m100 in 28 seismogenic source zones of the study region is visualized to analyze the localized seismicity parameters it is observed that earthquake hazard level varies spatially from one zone to another which suggests that examined region have high crustal heterogeneity and seismotectonic complexity

earthquake hazard assessment for dehradun uttarakhand india including a characteristic earthquake recurrence model for the himalaya frontal fault hff the seismic hazard has been computed for the city of dehradun uttarakhand india the city lies in the himalayan foothills between two faults the main boundary thrust mbt and the himalayan frontal fault hff the contributions from these two faults have been modelled differently in a probabilistic model while the mbt has been modelled with a poissonian earthquake distribution the hff has been modelled both with a characteristic earthquake recurrence model and a poissonian model the hazard scenarios reveal different patterns depending on the classical approaches and the characteristic models applied and the obtained results indicate that dehradun may experience pga shaking around 2 2 m s2 for 225 years return period and around 4 6 m s2 for a 2 500 years return period

probabilistic seismic hazard assessment of mangalore and its adjoining regions a part of indian peninsular an intraplate region the southwestern part of india investigated in the present study mainly comprises of states such as goa north kerala and a major portion of karnataka a comprehensive regional seismic catalog has been compiled spanning over 190 years apart from a few prehistoric events from the early 16th century the classical cornel mcguire approach has been incorporated in the estimation of seismic hazard the seismic sources are modeled as area sources and the entire study region is divided into four seismogenic source zones the uncertainties involved in the formulation of the seismic source model and ground motion prediction model has been discussed in detail further the procedure for selecting appropriate gmpes involves the evaluation of multidimensional m r t ground motion trends and performance against observed macroseismic data the epistemic uncertainty in the estimation of seismicity parameters and ground motion prediction equations gmpes has been addressed using logic tree computation the results of the hazard analysis demonstrate that the existing seismic code underestimates the seismic potential of seismic zone ii bis 1893 areas the de aggregation of the predicted seismic hazard revealed earthquakes of magnitude range mw 4 6 occurring within a distance of 35kms to be most influential for any given site of interest sensitivity analysis has been performed for crucial input parameters in the formulation of seismic source and ground motion models site amplification study has been carried out using topographic slope as a proxy to shear velocity in the top 30 m vs30 a maximum of 60 to 80 amplification has been observed in the study area the seismic hazard maps in terms of pga have been plotted for the seismic hazard estimated at the bedrock level as well as the surface level for 2 and 10 probability of exceedance in 50 years the hazard estimation specifically for the southern part of the west coast is the first of its kind the investigation suspects mining induced seismicity in bellary and raichur districts though there is no mention of this in the prior literature

earthquake induced soft sediment deformation in the lower shyok river valley northern ladakh india abstract soft sediment deformation structures occur in the 150 m thick pliocene quaternary fluvio lacustrine sediments exposed around the khalsar and tirit areas in the lower shyok river valley northern ladakh and eastern karakoram india these structures vary in morphology and pattern and occur at different stratigraphic horizons they satisfy the criteria for attributing them to seismic events and it is proposed that these structures were formed as a result of earthquake induced liquefaction the deformation structures are thus interpreted to represent pre historic seismic events which occurred up to 5 ma ago and were associated with tectonic activity along the karakoram fault

a probabilistic assessment of earthquake hazard parameters in nw himalaya and the adjoining regions the maximum likelihood estimation method is applied to study the geographical distribution of earthquake hazard parameters and seismicity in 28 seismogenic source zones of nw himalaya and the adjoining regions for this purpose we have prepared a reliable homogeneous and complete earthquake catalogue during the period 1500 2010 the technique used here allows the data to contain either historical or instrumental era or even a combination of the both in this study the earthquake hazard parameters which include maximum regional magnitude mmax mean seismic activity rate the parameter b or b log e of gutenberg richter g r frequency magnitude relationship the return periods of earthquakes with a certain threshold magnitude along with their probabilities of occurrences have been calculated using only instrumental earthquake data during the period 1900 2010 the uncertainties in magnitude have been also taken into consideration during the calculation of hazard parameters the earthquake hazard in the whole nw himalaya region has been calculated in 28 seismogenic source zones delineated on the basis of seismicity level tectonics and focal mechanism the annual probability of exceedance of earthquake activity rate of certain magnitude is also calculated for all seismogenic source zones the obtained earthquake hazard parameters were geographically distributed in all 28 seismogenic source zones to analyze the spatial variation of localized seismicity parameters it is observed that seismic hazard level is high in quetta kirthar sulaiman region in pakistan hindukush pamir himalaya region and uttarkashi chamoli region in himalayan frontal thrust belt the source zones that are expected to have maximum regional magnitude mmax of more than 8 0 are quetta southern pamir caucasus and kashmir himanchal pradesh which have experienced such magnitude of earthquakes in the past it is observed that seismic hazard level varies spatially from one zone to another which suggests that the examined regions have high crustal heterogeneity and seismotectonic complexity

assessment of earthquake hazard in the tokyo area japan abstract the probability of occurrence of an inland earthquake originating beneath the tokyo area is evaluated for a 10 year period from 1991 on the basis of an earthquake catalogue containing some 40 earthquakes which caused some damage to edo now tokyo over a period of 400 years the parameters of the weibull and lognormal probability distributions applied to recurrence interval statistics are estimated with these parameters it is concluded that an earthquake directly beneath the capital the magnitude of which is equal to or greater than 6 0 occurs with a probability of 0 40 for the period in question when the magnitude threshold is assumed as 6 4 and 7 0 the probabilities become 0 17 and 0 049 respectively these probability evaluations are extended to those for the seismic intensity at typical sites in the area although no accurate evaluation is possible because the exact focal depths of historical earthquakes are not known on the assumption that these earthquakes occur near the upper surface of the down going philippine sea plate however a typical depth of 30 km or so is suggested should an earthquake having a mean magnitude of 6 4 say and at a mean location of past earthquakes occur the probability of seismic intensity at typical sites in the capital area exceeding 5 on the japan meteorological agency jma scale would amount to 0 17 the possibility of having a highly damaging earthquake of intensity 6 on the jma scale also cannot be ruled out judging from earthquake disasters in the past although the probability does become lower to summarize it may be said that the probability of japan s capital area being hit by a damaging earthquake in the foreseeable future is not particularly low

seismicity patterns in the himalayan plate boundary and identification of the areas of high seismic potential abstract space time distribution of earthquakes along the himalayan plate boundary has been investigated with a view to discerning fluctuations in seismicity rates associated with great earthquakes the possibilities of epicentre migration and gaps in seismic activity data from 1800 to 1976 were considered this study shows that all great earthquakes m 8 0 were preceded by seismically quiescent periods of at least 19 years furthermore earthquake quiescence has also been recognised to follow the great earthquakes three possible trends of migration of epicentres of great earthquakes have been recognised 1 1 the first trend starts from the 1905 kangra earthquake the epicentres of subsequent earthquakes migrating eastwards along the plate boundary 2 2 the second trend of migration starts from the great nepal earthquake of 1833 associated with eastward migration 3 3 the third trend commences from the great assam earthquake of 1897 and shows a westward migration of earthquake epicentres the middle section of the himalayan convergent plate boundary 80 e to 90 e in general displays a relatively low level of seismicity as compared to the adjacent sections a remarkable decrease in seismicity following the year 1970 has been observed along a section of the himalaya which lies to the east of the rupture zone of the great 1905 kangra earthquake since 1970 the seismicity rate has also dropped in the region lying in between the rupture zones of the great assam earthquakes of 1897 and 1950 as has earlier been reported by khattri and wyss 1978 such decreases in the level of seismicity along active plate boundaries have been demonstrated to be indicative of building up of stresses leading to future great earthquakes mogi 1969 mccann et al 1979

earthquakes recurrence and interoccurrence times the purpose of this paper is to discuss the statistical distributions of recurrence times of earthquakes recurrence times are the time intervals between successive earthquakes at a specified location on a specified fault although a number of statistical distributions have been proposed for recurrence times we argue in favor of the weibull distribution the weibull distribution is the only distribution that has a scale invariant hazard function we consider three sets of characteristic earthquakes on the san andreas fault 1 the parkfield earthquakes 2 the sequence of earthquakes identified by paleoseismic studies at the wrightwood site and 3 an example of a sequence of micro repeating earthquakes at a site near san juan bautista in each case we make a comparison with the applicable weibull distribution the number of earthquakes in each of these sequences is too small to make definitive conclusions to overcome this difficulty we consider a sequence of earthquakes obtained from a one million year virtual california simulation of san andreas earthquakes very good agreement with a weibull distribution is found we also obtain recurrence statistics for two other model studies the first is a modified forest fire model and the second is a slider block model in both cases good agreements with weibull distributions are obtained our conclusion is that the weibull distribution is the preferred distribution for estimating the risk of future earthquakes on the san andreas fault and elsewhere

probabilistic assessment of earthquake hazards in the north east indian peninsula and hindukush regions the himalayan region is one of the most seismic prone areas of the world the north east ne indian peninsula and the hindukush regions mark the zone of collision of the indian and eurasian plates the probability of the occurrence of great earthquakes with magnitude greater than 7 0 during a specified interval of time has been estimated on the basis of four probabilistic models namely weibull gamma lognormal and exponential for the ne indian peninsula and hindukush regions the model parameters have been estimated by the method of maximum likelihood estimates mle and the method of moments mom the cumulative probability is estimated for a period of 40 years from 1964 and is ranging between 0 881 to 0 995 by the year 1995 using all four models for the ne indian peninsula the conditional probability is also estimated and it is concluded that the ne indian peninsula would expect a great earthquake at any time in the remaining years of the present century for the hindukush region the cumulative probability has already crossed its highest value but no earthquake of magnitude greater than 7 0 has occurred after 1974 in this area it may attribute to the occurrence of frequent shocks of moderate size as seventeen earthquakes of magnitude greater than 6 0 including four greater than 6 4 have been reported until 1994 from this region

modeling of sh and p sv wave fields and seismic microzonation based on response spectra for talchir basin india abstract the p sv and sh wave field in the talchir basin is simulated along eight profiles four profiles strike across the basin and the other four along the basin the hybrid method which combines two computational techniques modal summation and finite differences is used to produce multiphase synthetic seismograms an m 6 earthquake is considered with hypocenter along the north orissa boundary fault nobf at a depth of 5 km and with the focal mechanism parameters dip 90 strike 160 and rake 180 the peak acceleration a max along each profile is determined considering the maximum acceleration obtained at the horizontal components the response spectra ratio rsr as a function of frequency is computed for the eight profiles and the higher amplification is seen to increase in correspondence with the thicker sedimentary cover especially for the radial component higher site amplification for all the profiles is observed in the frequency range from 0 5 to 1 4 hz to validate the obtained site effects the sources for the profiles across the basin are placed near to the southern end of the profile and the site amplifications are recomputed even if the spatial distribution of a max is mainly controlled by the epicentral distance i e the geometrical spreading prevails on local soil effects the rsr shows a pattern that can be easily correlated with the local site conditions the rsr at the intersection of the profiles is dependent not only upon the local lithology and sediment thickness but also upon the epicentral distance the talchir basin is classified into three zones based on the rsr values low rsr zone 1 6 1 9 intermediate rsr zone 2 0 2 8 and high rsr zone 2 9 5 2 the pga estimated for the bedrock model by bhatia et al 1999 for the study region is around 0 05 to 0 10 g while the indian seismic zonation map estimated it to be in the range from 0 1 to 0 2 g in the present study that considers the effects of lateral variations in the structure the pga is estimated to be as high as 0 55 g along the ba profile

probabilistic assessment of tsunami recurrence in the indian ocean the indian ocean is one of the most tsunamigenic regions of the world and recently experienced a mega tsunami in the sumatra region on 26 december 2004 m w 9 2 earthquake with tsunami intensity i soloviev imamura intensity scale equal to 4 5 causing heavy destruction of lives and property in the indian ocean rim countries in this study probabilities of occurrences of large tsunamis with tsunami intensities i 2 0 and i 3 0 average wave heights h 2 83 m and h 5 66 m respectively during a specified time interval were calculated using three stochastic models namely weibull gamma and lognormal tsunami recurrence was calculated for the whole indian ocean and the special case of the andaman sumatra java asj region excluding the 1945 makran event from the main data set for this purpose a reliable homogeneous and complete tsunami catalogue with i 2 0 during the period 1797 2006 was used the tsunami hazard parameters were estimated using the method of maximum likelihood the logarithm of likelihood function ln l was estimated and used to test the suitability of models in the examined region the weibull model was observed to be the most suitable model to estimate tsunami recurrence in the region the sample mean intervals of occurrences of tsunamis with intensity i 2 0 and i 3 0 were calculated for the observed data as well as for the weibull gamma and lognormal models the estimated cumulative and conditional probabilities in the whole indian ocean region show recurrence periods of about 27 30 years 2033 2036 and 35 36 years 2039 2040 for tsunami intensities i 2 0 and i 3 0 respectively while it is about 31 35 years 2037 2041 and 41 42 years 2045 2046 for a tsunami of intensity i 2 0 and i 3 0 respectively in the asj region a high probability 0 9 of occurrence of large tsunamis with i 2 0 in the next 30 40 years in the indian ocean region was revealed

relative sea level fall since the last interglacial stage are coasts uplifting worldwide the growing interest in quantification of vertical ground motion stems from the need to understand in detail how the earth s crust behaves for both scientific and social reasons however only recently has the refinement of dating techniques made possible the use of paleoshorelines as reliable tools for tectonic studies although there are many local studies of quaternary vertical motions of coastlines we know of no comprehensive worldwide synthesis here we provide a compilation of 890 records of paleoshoreline sequences with particular emphasis on the last interglacial stage marine isotopic stage mis 5e 122 ka the quality of dating mis 5e makes it a reliable marker to evaluate vertical ground motion rates during the late quaternary on a global scale the results show that most coastal segments have risen relative to sea level with a mean uplift rate higher than 0 2 mm yr i e more than four times faster than the estimated eustatic drop in sea level the results also reveal that the uplift rate is faster on average for active margins than for passive margins neither dynamic topography nor glacio hydro isostasy may explain sustained uplift of all continental margins as revealed by the wide distribution of uplifted sequences of paleoshorelines instead we suggest that only plate tectonic processes reconcile all observations of quaternary coastal uplift we propose that long term continental accretion has led to compression of continental plates and uplift of their margins therefore this study concludes that plate tectonics processes impact all margins and emphasizes the fact that the notion of a stable platform is unrealistic these results therefore seriously challenge the evaluation of past sea levels from the fossil shoreline record

a review of seismic hazard assessment of gujarat a highly active intra plate region abstract large intraplate earthquakes that occur in the interior of continental plates are rare and often very destructive the gujarat region of western india that witnessed the deadly mw 7 6 earthquake on january 26 2001 and the mw7 8 quake on june 16 1819 is one of the most active intraplate regions of the world the tragedy caused by the 2001 earthquake marked a turning point in the disaster awareness and preparedness in the region in the aftermath of this earthquake several workers investigated the important issue of mitigating seismic hazard through new knowledge based techniques of probabilistic and deterministic ground motion prediction micro and macro zoning of vulnerable areas this paper reviews the results of seismic hazard estimation in the gujarat region from different methodologies we note that the probabilistic seismic hazard estimates by different workers are not consistent even within the same region because of uncertainties in constraining the hazard parameters akin to the global observations using a logical approach we evaluate all the ground motion predictions from different methodologies and constrain the level of expected peak ground acceleration pga by adjusting all the values onto a common platform our assessment reveals that the pga values in gujarat vary from 0 04 to 0 35 g and 0 07 to 0 77 g for 10 and 2 probability of exceedance in 50 years at the engineering bedrock vs 760 m s level the hazard values thus estimated in this study can be directly used to estimate the pgas at the surface by incorporating local site effects which in turn can be utilized in planning and mitigating earthquake hazards further the estimates of pga from deterministic approaches range from 0 05 to 0 90 g we see that within gujarat the ground motion values obtained by deterministic and probabilistic methodologies do not show much variation we affirm that we need to undertake such a logical approach to arrive at realistic probabilistic hazard values that are in conformity with the estimates from deterministic assessment we also advocate the need to upgrade the classical methods of probabilistic and deterministic hazard assessment and incorporate the source and site complexities while estimating the hazard further a comparison of the hazard values of gujarat with those from other intraplate regions of the world reveals that the hazard level in gujarat is higher than in australia brazil and western europe and comparable to north china eastern canada and the new madrid seismic zone

late holocene history of tokotan lake kuril archipelago russian far east the use of lacustrine records for paleoclimatic reconstructions from geologically dynamic settings abstract a high resolution multiproxy analysis of a core from tokotan lake urup island illustrates the complex paleoenvironmental signals that can be preserved in sedimentary deposits from geologically active areas such as the kuril archipelago diatom and geochemical analyses of the tokotan core suggest a shallowing and lessening of the lake area over the last 3450 cal bp without other proxies the record could be interpreted as showing a general decrease in precipitation over the late holocene however palynological data indicate no change in vegetation thereby implying no significant climatic variation neither of these paleoclimatic interpretations agrees with late holocene reconstructions from the kuril archipelago or the russian mainland paleomagnetic data imply variable sediment sources during the lake s history indicating alterations within the tokotan catchment e g shifts in gradients or sediment loads in the inflowing streams such changes would be particularly important in the shabalina river which today has formed a partial dam across the lake s outlet the results of the tokotan study indicate that other factors e g volcanism seismic activity sea level changes rather than climate were more probable determinants of the late holocene lake record given the geologic dynamism of the region it is perhaps not surprising that paleo records from the kuril islands display an inconsistency in the numbers and or duration of proposed holocene climatic oscillations underscoring the importance of multiproxy investigations in areas that are or have been geologically dynamic

holocene environments of central iturup island southern kuril archipelago russian far east two lake records document holocene changes in sea level vegetation and climate on the okhotsk and pacific sides of central iturup island southern kuril islands the sediment cores originated within tidal flats that subsequently developed into a marine strait which crosscut the island as sea levels rose during the early holocene brackish lagoons and eventually freshwater lakes formed by 7100 cal yr bp associated with warmer than present conditions past vegetation changes indicate a clear holocene thermal maximum recorded on the pacific coast but a less distinct optimum on the western shores 7200 6100 cal yr bp a gradual cooling toward modern levels occurred 6100 3500 cal yr bp four prominent layers of coarse sediment found in mid to late holocene lake deposits may correspond to intervals of climate cooling dune formation previously documented in coastal sections although chronological limitations question the synchronicity of these events across the south russian far east it seems probable that they have a regional signature however the mechanisms responsible for holocene climatic changes are likely the result of complex interactions of hemispheric scale atmospheric patterns marine characteristics and regional feedbacks rather than simply fluctuations in sea levels as suggested in the current interpretative model

marine terraces of western sakhalin island abstract biostratigraphical and sedimentological studies of deposits of terraces with heights of 2 3 3 4 4 6 8 10 12 15 20 30 35 40 60 80 and 100 120 m on western sakhalin island have shown that they were all marine in origin the upper complex of terraces q i q ii formed during a period of slow tectonic uplift in this area to 120 m above modern sea level the lower complex of terraces q iii q iv may have formed in response to sea level oscillations without any influence of tectonic uplift

the characteristics of the seismic activity in the qinghai xizang tibet plateau of china abstract based on the analysis of the spatial distribution of many shallow and intermediate depth earthquakes in the qinghai xizang plateau and its marginal region their fault plane solutions and the seismo tectonics in the continental plate this paper studies the characteristics of this plateau and the transitional zone of collision and compression between the indian and eurasian plates and the relations between this plateau and continental plate movement

a new ground motion prediction model for northeastern india nei crustal earthquakes in this study a stochastic point source model is used to develop a ground motion prediction model for northeastern india nei crustal earthquakes calibrated using region specific source path and site parameters the nei strong ground motion database is too limited to derive an empirical ground motion prediction model valid for all magnitudes and distances in the present study we simulated 30 000 ground motions to develop the horizontal ground motion prediction model for nei these simulations are for 1000 earthquakes of moment magnitudes m w 4 8 5 and epicentral distances of 1 300 km in simulating ground motions quality factor stress drop and kappa derived from available nei strong motion records have been used the model has been validated by comparing it with the available but sparse database of recorded events the best fit between the model and observed strong ground motion records indicate that the new model is consistent with the available data and can be used in seismic hazard analyses until more data are collected and the model is improved

recent earthquake swarms in garhwal himalaya a precursor to moderate to great earthquakes in the region abstract himalayas one of the most seismically active belts have been formed due to continent continent collision and are probable locations for future moderate to great earthquakes it is of paramount importance to recognize precursory swarm activity considered to be long predictors of main events recently two earthquake swarms occurred across main central thrust mct in garhwal himalayan region in a time interval of nearly one month the first swarm of april 2009 had epicentral locations lying north of mct on hanging wall side which has shown less seismic activity in recent times while the second swarm occurred in may 2009 near gopeshwar having epicenters on active seismic zone located south of mct the approximate distance between the two swarms is about 50 km in present study preparation zone of 100 100 km 2 has been demarcated recognizing these swarms as precursors to moderate to great earthquake in the garhwal himalaya

seismic hazard assessment and mitigation in india an overview the indian subcontinent is characterized by various tectonic units viz himalayan collision zone in north indo burmese arc in north east failed rift zones in its interior in peninsular indian shield and andaman sumatra trench in south east indian territory during the last about 100 years the country has witnessed four great and several major earthquakes soon after the occurrence of the first great earthquake the shillong earthquake m w 8 1 in 1897 efforts were started to assess the seismic hazard in the country the first such attempt was made by geological survey of india in 1898 and since then considerable progress has been made the current seismic zonation map prepared and published by bureau of indian standards broadly places seismic risk in different parts of the country in four major zones however this map is not sufficient for the assessment of area specific seismic risks necessitating detailed seismic zoning that is microzonation for earthquake disaster mitigation and management recently seismic microzonation studies are being introduced in india and the first level seismic microzonation has already been completed for selected urban centres including jabalpur guwahati delhi bangalore ahmadabad dehradun etc the maps prepared for these cities are being further refined on larger scales as per the requirements and a plan has also been firmed up for taking up microzonation of 30 selected cities which lie in seismic zones v and iv and have a population density of half a million the paper highlights the efforts made in india so far towards seismic hazard assessment as well as the future road map for such studies

probabilistic models for forecasting earthquakes in the northeast region of india northeast india and its adjoining areas are characterized by very high seismic activity according to the indian seismic code the region falls under seismic zone v which represents the highest seismic hazard level in the country this region has experienced a number of great earthquakes such as the assam 1950 and shillong 1897 earthquakes that caused huge devastation in the entire northeast and adjacent areas by flooding landslides liquefaction and damage to roads and buildings in this study an attempt has been made to find the probability of occurrence of a major earthquake m w 6 in this region using an updated earthquake catalog collected from different sources thereafter dividing the catalog into six different seismic regions based on different tectonic features and seismogenic factors the probability of occurrences was estimated using three models the lognormal weibull and gamma distributions we calculated the logarithmic probability of the likelihood function ln l for all six regions and the entire northeast for all three stochastic models a higher value of ln l suggests a better model and a lower value shows a worse model the results show different model suits for different seismic zones but the majority follows lognormal which is better for forecasting magnitude size according to the results weibull shows the highest conditional probabilities among the three models for small as well as large elapsed time t and time intervals t whereas the lognormal model shows the lowest and the gamma model shows intermediate probabilities only for elapsed time t 0 the lognormal model shows the highest conditional probabilities among the three models at a smaller time interval t 3 15 yrs the opposite result is observed at larger time intervals t 15 25 yrs which show the highest probabilities for the weibull model however based on this study the indoburma range and eastern himalaya show a high probability of occurrence in the 5 yr period 2012 2017 with 90 probability

seismic characteristics and seismic hazard assessment source region of the 2015 nepal earthquake mw 7 8 in central himalaya seismicity and seismic characteristics like b value fractal dimension energy release and recurrence period are assessed for the region 80 e 89 e and 26 n 31 n which includes the 2015 large nepal earthquake mw 7 8 in central himalaya the international seismological centre isc catalogue of earthquakes with mb 3 8 for the period august 1964 january 2013 are used the b values are estimated using the maximum likelihood and least square methods the fractal dimension is estimated using the correlation integral method the events are also used for estimating radiated energy in the region the probability of occurrence of moderate earthquakes mb 5 0 using isc data and mw 6 0 using usgs data for the period 1964 2015 during a specified interval of time is estimated on the basis of three probabilistic models namely weibull gamma and lognormal the model parameters are estimated by the maximum likelihood estimates it is found that there is a 99 probability for occurrence of at least one earthquake mb 5 0 in this region in a time window of 2 3 years from the year 2013 and in 20 30 years for an earthquake mw 6 0 from the year 2015 the b value maps identified variable stressed zones and the fractal dimension maps fractal characteristics of the active fault zones the energy release map identified the zones of higher and lower energy release the percent probability maps prepared using the poisson distribution identify the zones of higher and lower probability earthquakes and thus indicate the areas of future probable earthquakes

a deterministic seismic hazard map of india and adjacent areas a seismic hazard map of the territory of india and adjacent areas has been prepared using a deterministic approach based on the computation of synthetic seismograms complete with all main phases the input data set consists of structural models seismogenic zones focal mechanisms and earthquake catalogues there are few probabilistic hazard maps available for the indian subcontinent however this is the first study aimed at producing a deterministic seismic hazard map for the indian region using realistic strong ground motion modelling with the knowledge of the physical process of earthquake generation the level of seismicity and wave propagation in anelastic media synthetic seismograms at a frequency of 1 hz have been generated at a regular grid of 0 2 x 0 2 by the modal summation technique the seismic hazard expressed in terms of maximum displacement d m a x maximum velocity v m a x and design ground acceleration dga has been extracted from the synthetic signals and mapped on a regular grid over the studied territory the estimated values of the peak ground acceleration are compared with the observed data available for the himalayan region and are found to be in agreement many parts of the himalayan region have dga values exceeding 0 6 g the epicentral areas of the great assam earthquakes of 1897 and 1950 in northeast india represent the maximum hazard with dga values reaching 1 2 1 3 g the peak velocity and displacement in the same region is estimated as 120 177 cm s 1 and 60 90 cm respectively

hydrochemistry of groundwater in the savelugu nanton district northern ghana calcite caco3 dolomite camg co3 2 silicate dissolution ion exchange and reverse ion exchange reactions are the predominant processes influencing groundwater quality in the savelugu nanton district the main objective of this study is to characterize groundwater and delineate water rock interactions responsible for the chemical evolution of groundwater in the district eighty one 81 boreholes were sampled for quality assessment results showed that the ph of the boreholes are slightly acidic to basic ranging from 6 1 8 3 ph units conductivity values are low to high ranging from 147 23 200 s cm with 23 5 of groundwater within the study area being either brackish 1 500 5 000 s cm or saline 5 000 s cm and therefore unsuitable for potable purposes tds values in groundwater varied widely ranging from 62 11 900 mg l 61 7 of groundwater within the study area are fresh tds na mg2 k and hco3 cl so4 2 no3 respectively multivariate statistical analysis showed expected process based relationship derived mainly from the geochemical and biochemical processes within the aquifer hydrochemical facies using piper plot of major ions showed one major hydrochemical water type the ca mg hco3 water type due to the high cost of drilling of boreholes coupled with the high percentage 1 of people without access to potable water in the northern region it is recommended that the government of ghana and other stakeholders within the water sector take immediate measures to reduce to recommended limits for potable uses the levels of dissolved solids either by installing reverse osmosis equipments on such boreholes or employ other relatively known cheaper methods to reduce the dissolved solids to recommended limits high yielding boreholes with hydrochemical parameters within who guideline limits in the savelugu nanton district could also be mechanized to serve a wider area

simulation based distributions of earthquake recurrence times on the san andreas fault system earthquakes on a specified fault or fault segment with magnitudes greater than a specified value have a statistical distribution of recurrence times the mean recurrence time can be related to the rate of strain accumulation and the strength of the fault very few faults have a recorded history of earthquakes that define a distribution well for hazard assessment in general a statistical distribution of recurrence times is assumed along with parameter values assumed distributions include the weibull stretched exponential distribution the lognormal distribution and the brownian passage time inverse gaussian distribution the distribution of earthquake waiting times is the conditional probability that an earthquake will occur at a time in the future if it has not occurred for a specified time in the past the distribution of waiting times is very sensitive to the distribution of recurrence times an exponential distribution of recurrence times is poissonian so there is no memory of the last event the distribution of recurrence times must be thinner than the exponential if the mean waiting time is to decrease as the time since the last earthquake increases neither the lognormal or the brownian passage time distribution satisfies this requirement we use the virtual california model for earthquake occurrence on the san andreas fault system to produce a synthetic distribution of earthquake recurrence times on various faults in the san andreas system we find that the synthetic data are well represented by weibull distributions we also show that the weibull distribution follows from both damage mechanics and statistical physics

a seismic hazard map of india and adjacent areas abstract we have produced a probabilistic seismic hazard map showing peak ground accelerations in rock for india and neighboring areas having a 10 probability of being exceeded in 50 years seismogenic zones were identified on the basis of historical seismicity seismotectonics and geology of the region procedures for reducing the incompleteness of earthquake catalogs were followed before estimating recurrence parameters an eastern united states acceleration attenuation relationship was employed after it was found that intensity attenuation for the indian region and the eastern united states was similar the largest probabilistic accelerations are obtained in the seismotectonic belts of kirthar hindukush himalaya arakan yoma and the shillong massif where values of over 70 g have been calculated

representative seismic hazard map of coimbatore india the seismic hazard value of any region depends upon three important components such as probable earthquake location maximum earthquake magnitude and the attenuation equation this paper presents a representative way of estimating these three important components considering region specific seismotectonic features rupture based seismic hazard analysis rbsha given by anbazhagan et al 2011 is used to determine the probable future earthquake locations this approach is verified on the earthquake data of bhuj region the probable earthquake location for this region is identified considering earthquake data till the year 2000 these identified locations match well with the reported locations after 2000 the further coimbatore city is selected as the study area to develop a representative seismic hazard map using rbsha approach and to compare with deterministic seismic hazard analysis probable future earthquake zones for coimbatore are located considering the rupture phenomenon as per energy release theory discussed by anbazhagan et at 2011 rupture character of the region has been established by estimating the subsurface rupture length of each source and normalized with respect to the length of the source average rupture length of the source with respect to its total length is found to be similar for most of the sources in the region which is called as the rupture character of the region maximum magnitudes of probable zones are estimated considering seismic sources close by and regional rupture character established representative gmpes for the study area have been selected by carrying out efficacy test through an average log likelihood value llh as ranking estimator and considering the isoseismal map new seismic hazard map of coimbatore has been developed using the above regional representative parameters of probable earthquake locations maximum earthquake magnitude and best suitable gmpes the new hazard map gives acceleration values at bedrock for maximum possible earthquakes these results are compared with deterministic seismic hazard map and recently published probabilistic seismic hazard values c 2014 elsevier b v all rights reserved

earthquake recurrence of a particular type the recurrence relation for turkish earthquakes expressed as the single frequency versus magnitude dependence exhibits significant maxima and minima reflecting true physical conditions various mathematical formulations are developed to fit the observed data for the single or the cumulative frequency and are compared with each other as regards their accuracy and simplicity the results may be applicable to regions with high seismicity

is the northern bay of bengal tsunamigenic the giant tsunami generated by the great 26 december 2004 sumatra andaman earthquake and the resultant destruction have necessitated appropriate assessment of tsunami potential in the northern bay of bengal where high population density in the coastal area 100 million makes this region very vulnerable if a large tsunami were to occur here we examine whether the india burma plate boundary in the arakan and irrawady region can produce a tsunamigenic earthquake we find a the region is characterized by oblique plate motion leading to strike slip dominated earthquakes with low tsunami generating potential b the deformation front associated with the plate boundary between india and sunda plates in the northern bay of bengal is either landward or in shallow water in the arakan region and hence a great earthquake is unlikely to displace large amounts of water to create a significant tsunami c convincing evidence that the 1762 arakan earthquake generated a large tsunami is lacking and d no large tsunami has affected the region in the past 2000 years we conclude that while a great earthquake could occur in the arakan region the physiographic situation may not lead to generation of a large tsunami

probabilistic seismic hazard macrozonation of tamil nadu in southern india abstract the south indian state of tamil nadu in the peninsular shield is a zone of low to moderate seismic activity with a sparse historical record of significant earthquakes the current intensity based zoning adopted by the indian seismic code stipulates an effective peak ground acceleration pga of either 0 10 or 0 16 g for different parts of the state for the maximum considered earthquake mce and the service life of a structure in the current study probabilistic seismic hazard contour maps for tamil nadu and the union territory of pondicherry in terms of the ground motion parameters pga and spectral accelerations at 0 1 0 5 and 1 0 sec for 2 5 and 10 probabilities of exceedance in a 50 yr period have been produced hazard computations have been performed over a grid of sites covering the territory at an interval of 0 2 a comprehensive earthquake catalog has been compiled for the region extending between 2 and 20 7 n latitude and 68 and 88 e longitude and spanning 950 yrs the hazard maps are produced by suitably accounting for epistemic uncertainty in the hazard computations within a logic tree framework incorporating parameters such as different probabilistic hazard analysis methods classical cornell mcguire and zone free approaches catalog completeness estimation methods maximum cutoff magnitude and ground motion predictive equations for shallow crustal intraplate environments the hazard maps are compared to the zoning prescribed by the seismic code the current estimations show that the potential seismic hazard in considerable parts of the state is underestimated by the broad zoning adopted by the indian standards

probabilistic appraisal of earthquake hazard parameters deduced from a bayesian approach in the northwest frontier of the himalayas a straightforward bayesian statistic is applied in five broad seismogenic source zones of the northwest frontier of the himalayas to estimate the earthquake hazard parameters maximum regional magnitude mmax value of g r relationship and seismic activity rate or intensity for this purpose a reliable earthquake catalogue which is homogeneous for mw 5 0 and complete during the period 1900 to 2010 is compiled the hindukush pamir himalaya zone has been further divided into two seismic zones of shallow h 70 km and intermediate depth h 70 km according to the variation of seismicity with depth in the subduction zone the estimated earthquake hazard parameters by bayesian approach are more stable and reliable with low standard deviations than other approaches but the technique is more time consuming in this study quantiles of functions of distributions of true and apparent magnitudes for future time intervals of 5 10 20 50 and 100 years are calculated with confidence limits for probability levels of 50 70 and 90 in all seismogenic source zones the zones of estimated mmax greater than 8 0 are related to the sulaiman kirthar ranges hindukush pamir himalaya and himalayan frontal thrusts belt suggesting more seismically hazardous regions in the examined area the lowest value of mmax 6 44 has been calculated in northern pakistan and hazara syntaxis zone which have estimated lowest activity rate 0 0023 events day as compared to other zones the himalayan frontal thrusts belt exhibits higher earthquake magnitude 8 01 in next 100 years with 90 probability level as compared to other zones which reveals that this zone is more vulnerable to occurrence of a great earthquake the obtained results in this study are directly useful for the probabilistic seismic hazard assessment in the examined region of himalaya

groundwater quality assessment and its suitability in celtikci plain burdur turkey the celtikci burdur plain is located in the southwest of turkey and is a semi closed basin groundwater is densely used as drinking irrigation and domestic water in the plain hydrogeochemical processes controlling groundwater chemistry and geochemical assessment of groundwater were investigated in the celtikci burdur turkey plain in this study groundwater samples for two seasons were analyzed and major ion chemistry of groundwater was researched to understand the groundwater geochemistry two major hydrochemical facies ca hco3 and ca mg hco3 were determined in the area various graphical plots and multivariate statistical analysis were used for identifying the occurrence of different geochemical processes in the study area weathering is one of the key geochemical processes which controlled the solute concentration in groundwater chemical indexes such as sodium adsorption ratio na residual sodium carbonate magnesium hazard and permeability index were calculated and results show that groundwater is suitable for irrigation purpose except for permeability index values concentrations of mn no3 and total hardness exceed the prescribed limits of who and are the major limiting parameters of groundwater use for potable and domestic purposes

recurrence of extreme floods in southern sakhalin island as evidence of paleo typhoon variability in the northwestern pacific since 6 6 ka abstract history of variability of tropical cyclones tc in the north western pacific is critical for understanding impacts of future climatic changes natural archives of paleo typhoon variability can be used to assess how changes in the planetary climatic system during the holocene could influence tc frequency and intensity in this part of pacific extreme typhoon related rains are the main cause of catastrophic floods on sakhalin island and deposits of these floods are evidence of paleo typhoon the paleo typhoons that triggered extreme floods on southern sakhalin during the last 6 6 kyr are recorded in the sequence on the interfluvial surface in the northern susunay lowland naiba river basin the sequence includes peat bog with numerous loam interlayers deposited during extreme floods inundating the bog we reconstructed paleo environmental conditions including humidity and flood activity based on analysis of diatoms we found biological indicators that point to the past floods the mineral content in the peat being one criteria indicative of the high frequency of floods the peat bog developed in place of a lagoon that existed at the maximum phase of the holocene transgression peat accumulation began in the freshened lagoon coast 6010 cal yr b p when sea level dropped the lagoon turned into a coastal lake 5710 5040 cal yr b p a swamp formed in place of the lake under varying moisture conditions we identified and dated 25 extreme floods and assessed the paleoclimatic background of the events a recent catastrophic flood from typhoon phyllis 1981 ce is considered as an analogue of the paleo events the frequency of extreme typhoons increased both during warm wet and dry phases and in cold dry phases of the climate fluctuations we identified three periods of a high typhoon activity 4640 4360 4030 3580 1860 1380 cal yr b p when super typhoons came onto the island once every 30 90 years a comparison between the extreme typhoons in the south of sakhalin and in the sea of japan region show both synchronism and metachronism of the periods of typhoon activity instrumental measurements during 20th 21st centuries revealed considerable changes in super typhoon tracks a similar variability may be safely supposed in typhoon tracks in the past to predict future tropical cyclone activity and the risk of floods under modern climatic instability it is necessary to understand factors influencing variability in the occurrence of strong typhoons and associated extreme floods events on a paleo scale this is especially important for areas with rapidly developing coastal economies and intensive use of gas and oil resources such as sakhalin island

relationship of tsunami intensity to source earthquake magnitude as retrieved from historical data operational prediction of near field tsunamis in all existing tsunami warning systems twss is based on fast determination of the position and size of submarine earthquakes exceedance of earthquake magnitude above some established threshold value which can vary over different tsunamigenic zones results in issuing a warning signal usually a warning message has several from 2 to 5 grades reflecting the degree of tsunami danger and sometimes contains expected wave heights at the coast current operational methodology is based on two main assumptions 1 submarine earthquakes above some threshold magnitude can generate dangerous tsunamis and 2 the height of a resultant tsunami is in general proportional to the earthquake magnitude while both assumptions are physically reasonable and generally correct statistics of issued warnings are far from being satisfactory for the last 55 years up to 75 of warnings for regional tsunamis have turned out to be false while each tws has had at least a few cases of missing dangerous tsunamis this paper presents the results of investigating the actual dependence of tsunami intensity on earthquake magnitude as it can be retrieved from historical observations and discusses the degree of correspondence of the above assumptions to real observations tsunami intensity based on the soloviev imamura scale is used as a measure of tsunami size its correlation with the ms and mw magnitudes is investigated based on historical data available for the instrumental period of observations from 1900 to present

surface motions and continental deformation in the indian plate and the india eurasia collision zone the collision of the indian plate with eurasia has played a major role in controlling the dynamics of central asia leading to the world s largest continental deformation zone in order to study the deformation within the indian plate as well as the india eurasia collision zone we model the lithospheric stress field by calculating the two primary sources of stress one arising due to topography and shallow lithospheric structure estimated by gravitational potential energy differences and the other arising from basal tractions derived from density driven mantle convection we use several tomography models to calculate horizontal tractions using the convection code hc for two radially varying viscosity structures we also take into account lateral viscosity variations in the lithosphere model arising from stiff cratons weak plate boundaries and strength variations due to old and young oceanic lithosphere we do a quantitative comparison of our predicted deviatoric stresses strain rates and plate velocities with surface observables and find that the regional tomography model of singh et al 2014 embedded in the global s wave model s40rts does a remarkable job of fitting the observations of gps velocities and strain rates as well as intraplate stress field from the world stress map

fault displacement rates on a range of timescales abstract displacements on tectonic faults primarily accrue during earthquakes at rates that vary through time to examine the processes that underlie the temporal changes in fault displacement rates we analyse displacements and displacement rates for time periods from the present to 5 10 20 300 500 1000 and 5000 kyr for 261 active reverse or normal faults from a worldwide dataset displacement rates depart from million year average rates by up to three orders of magnitude with the size of these departures inversely related to the duration of the sample period and to fault length short term 20 kyr displacement rates generally span a greater range on small faults than large a feature which suggests more variable growth on smaller faults simple earthquake slip modeling shows that variations in displacement rates require changes in both recurrence interval and slip per event and do not support the characteristic slip earthquake model as long as fault system strain rates are uniform displacement rates generally become constant over time periods between 20 and 300 kyr with the length of time required to reach stability being inversely related to the regional basin wide strain rates stable long term displacement rates and fluctuations in earthquake recurrence intervals and slip arise in part due to fault interactions

great earthquakes seismicity gaps and potential for earthquake disaster along the himalaya plate boundary abstract analysis of the space time patterns of seismicity in the himalaya plate boundary has established the existence of three seismic gaps 1 1 the kashmir gap lying west of the 1905 kangra earthquake 2 2 the central gap situated between the 1905 kangra and the 1934 bihar earthquakes 3 3 the assam gap between the 1897 and 1950 assam earthquakes this study has shown that the above great earthquakes were preceded as well as followed by long periods 19 years of decreased levels of seismic activity in the epicentral regions remarkable decrease in the seismicity following the year 1970 has been observed in the western half of the central gap as well as in the assam gap local seismic investigation in the assam gap confirms this feature and the seismicity suggests the existence there of an asperity the local seismic investigations in garhwal himalaya have shown that the small earthquakes are confined to the upper 6 8 km of the crust and may have strike slip motions these earthquakes occur in a region where teleseismically recorded events were few

a probabilistic tsunami hazard assessment for western australia the occurrence of the indian ocean tsunami on 26 december 2004 has raised concern about the difficulty in determining appropriate tsunami mitigation measures in australia due to the lack of information on the tsunami threat a first step in the development of such measures is a tsunami hazard assessment which gives an indication of which areas of coastline are most likely to experience tsunamis and how likely such events are here we present the results of a probabilistic tsunami hazard assessment for western australia wa compared to other parts of australia the wa coastline experiences a relatively high frequency of tsunami occurrence this hazard is due to earthquakes along the sunda arc south of indonesia our work shows that large earthquakes offshore of java and sumba are likely to be a greater threat to wa than those offshore of sumatra or elsewhere in indonesia a magnitude 9 earthquake offshore of the indonesian islands of java or sumba has the potential to significantly impact a large part of the west australian coastline the level of hazard varies along the coast but is highest along the coast from carnarvon to dampier tsunamis generated by other sources e g large intra plate events volcanoes landslides and asteroids were not considered in this study

global risk from extreme geophysical events threat identification and assessment in an increasingly interconnected world any single geophysical hazard is capable of having consequences far beyond the range of immediate physical effects most recently this was demonstrated by the 2004 asian tsunami which took the lives of citizens from 57 different nations and by hurricane katrina in august 2005 which raised fuel prices worldwide and contributed to a record uk trade deficit in the month following the devastation of new orleans on an altogether wider scale global geophysical events gges are natural phenomena capable of having wholesale deleterious consequences for the world s environment economy and society these may arise i due to a global physical effect such as an episode of severe planetary cooling in response to a volcanic super eruption or large comet or asteroid impact or ii as a result of subsidiary ramifications for the global economy and social fabric of a cataclysmic regional event such as an atlantic or pacific wide mega tsunami or a more spatially confined event at a strategically sensitive location for example the awaited major tokyo earthquake while very infrequent the wide ranging and potentially ruinous consequences of a gge for the well being of the international community make it essential that they are seriously considered within any comprehensive assessment of natural threats

probabilistic assessment of earthquake hazards in the indian subcontinent the indian subcontinent is one of the most seismic prone areas of the world the himalayan mountains in the north mid oceanic ridges in the south and earthquake belts surrounding the indian plate all show that the subcontinent has undergone extensive geological and tectonic processes in the past the probability of the occurrence of earthquakes with magnitude 6 m b 7 during a specified interval of time has been estimated on the basis of four probabilistic models namely lognormal weibull gamma and exponential distribution for the indian subcontinent the seismicity map has been prepared using the earthquake catalogue from the period 1963 1994 and six different zones have been identified on the basis of clustering of events the model parameters have been estimated by the method of maximum likelihood estimates mle and method of moments mom a computer program package has been developed for all four models which represents the distributions of time intervals fairly well the logarithmic of likelihood ln l is estimated for testing the models and different models have been found to be plausible the probability of different magnitude thresholds has been evaluated using the gutenberg richter formula log n a bm for magnitude distribution the constants a and b have been computed for each region and found to be varying between 5 46 8 53 and 0 87 1 34 respectively

earthquake hazard and risk assessment based on unified scaling law for earthquakes state of gujarat india the gujarat state of india is one of the most seismically active intercontinental regions of the world historically it has experienced many damaging earthquakes including the devastating 1819 rann of kachchh and 2001 bhuj earthquakes the effect of the later one is grossly underestimated by the global seismic hazard assessment program gshap to assess a more adequate earthquake hazard for the state of gujarat we apply unified scaling law for earthquakes usle which generalizes the gutenberg richter recurrence relation taking into account naturally fractal distribution of earthquake loci usle has evident implications since any estimate of seismic hazard depends on the size of the territory considered and therefore may differ dramatically from the actual one when scaled down to the proportion of the area of interest e g of a city from the enveloping area of investigation we cross compare the seismic hazard maps compiled for the same standard regular grid 0 2 0 2 1 in terms of design ground acceleration based on the neo deterministic approach 2 in terms of probabilistic exceedance of peak ground acceleration by gshap and 3 the one resulted from the usle application finally we present the maps of seismic risks for the state of gujarat integrating the obtained seismic hazard population density based on india s census 2011 data and a few model assumptions of vulnerability

a probabilistic estimate of the most perceptible earthquake magnitudes in the nw himalaya and adjoining regions nw himalaya and its neighboring region 25 40 n and 65 85 e is one of the most seismically hazardous regions in the indian subcontinent a region that has historically experienced large to great damaging earthquakes in the present study the most perceptible earthquake magnitudes mp are estimated for intensity i vii horizontal peak ground acceleration a 300 cm s2 and horizontal peak ground velocity v 10 cm s in 28 seismogenic zones using the two earthquake recurrence models of kijko and sellevoll bulletin of the seismological society of america 82 1 120 134 1992 and gumbel s third asymptotic distribution of extremes giii both methods deal with maximum magnitudes the earthquake perceptibility is calculated by combining earthquake recurrence models with ground motion attenuation relations at a particular level of intensity acceleration and velocity the estimated results reveal that the values of mp for velocity v 10 cm s show higher estimates than corresponding values for intensity i vii and acceleration a 300 cm s2 it is also observed that differences in perceptible magnitudes calculated by the kijko sellevoll method and giii statistics show significantly high values up to 0 7 0 6 and 1 7 for intensity acceleration and velocity respectively revealing the importance of earthquake recurrence model selection the estimated most perceptible earthquake magnitudes mp in the present study vary from mw 5 1 to 7 7 in the entire zone of the study area results of perceptible magnitudes are also represented in the form of spatial maps in 28 seismogenic zones for the aforementioned threshold levels of intensity acceleration and velocity estimated from two recurrence models the spatial maps show that the quetta of pakistan the hindukush pamir himalaya the caucasus mountain belt and the himalayan frontal thrust belt kashmir kangra uttarkashi chamoli regions exhibit higher values of the most perceptible earthquake magnitudes mw 6 0 these spatially distributed values indicate good agreement with high seismic hazard zones in previously published hazard maps based on seismicity maximum expected earthquake magnitudes during specific time intervals and maximum expected acceleration these maps have useful implications in preparing earthquake selection criteria for the anti seismic design of non critical structures in the study region

impact of fault parameter uncertainties on earthquake recurrence probability examined by monte carlo simulation an example in central taiwan abstract the region around taiwan is well known for its unique geological setting which has resulted in a high seismicity the central geological survey taiwan cgst has launched a series of investigation on characterizing the active faults on the island the cgst revealed that there are 33 active faults and their fault parameters are suggested in the latest publication in 2010 however the uncertainties of return period and earthquake magnitude are not provided the main objective of the paper is to study the impact of unspecified parameter uncertainties on recurrence earthquake probabilities in addition a numerical approach involving the use of monte carlo simulation was proposed to estimate the exceedance probabilities in which the parameter uncertainties were taken into account the meishan fault in central taiwan with the best estimate return period of 162 years and earthquake magnitude of 7 1 was used as an example the analyses verified the impact of parameter uncertainties on the exceedance probability in fault induced earthquake recurrence when uncertainty is high the exceedance probability associated with large magnitudes is high it was also observed that the probabilistic analysis in this study can generate a realistic continuous distribution of exceedance probabilities that cannot be obtained by a deterministic approach the best estimate distribution of exceedance probability was established by enveloping the curves estimated by both deterministic and probabilistic approaches accordingly the best estimate exceedance probability for a 7 5 magnitude earthquake recurring in 2011 2060 induced by the meishan fault in central taiwan was estimated as 11

palaeomagnetic results from the tibetan sedimentary series of the manang area north central nepal summary the remanent magnetization of palaeozoic and mesozoic carbonates from the tibetan sedimentary series tss of the manang area north of the annapurna range north central nepal has been investigated the tss forms part of the tectonic unit between the indian eurasian plate boundary in the north and the main central thrust mct in the south apart from a present field direction three remanence components have been separated a normal polarity post folding remanence negative fold test is carried by pyrrhotite the core corrected mean direction for five sites with 47 specimens from silurian devonian rocks is decl 312 9 incl 58 3 95 17 6 k 19 8 the origin of this component is not understood a more precisely determined reversed polarity post folding remanence 99 per cent negative fold test is also carried by pyrrhotite the core corrected mean direction for 12 sites with 229 specimens from carboniferous triassic rocks is decl 196 4 incl 65 9 95 3 2 k 183 one site of lower carinan age shows in addition to the pyrrhotite component a second stable remanence direction carried by magnetite the fold test is 99 per cent positive and there is a high probability that the remanence is of detrital origin the bedding corrected direction for one site with 40 specimens is decl 334 3 incl 54 1 95 4 2 k 30 2 palaeolatitude 34 6 s the direction of the magnetite component coincides with other triassic palaeodirection data from the literature and the inclination suggests a palaeoposition of the tss at the northern margin of india at this time the northern extent of india in the triassic cannot be reconstructed from the data because of the strong anticlockwise rotation 48 of stable india since this time the inclination of the reverse polarity pyrrhotite component is 19 steeper than expected from the maximum northern position of the area this suggests a regional northward tilt along the mct which is supported by steep inclinations found in other areas declination data for the reverse polarity pyrrhotite component and for the magnetite component deviate clockwise from expected values for the area by 23 34 calculated from the indian apwp utilizing klootwijk conaghan powell s 1985 rotational underthrusting model the minimum magnitude of continental underthrusting between the tss and stable india at the longitude of central nepal 84 e has been calculated from the declination of our reverse polarity pyrrhotite component a possible range of 520 1100 km results from consideration of different tectonic models

modeling earthquake recurrence in the himalayan seismic belt using time dependent stochastic models implications for future seismic hazards interest in and pertinent studies related to the seismic hazard in the himalayan region have increased significantly since the instrumental era and each damaging earthquake encourages its reestimation in the work presented herein the non poissonian probabilities of exceedance of magnitudes in a specified time in the future were investigated for different elapsed times based on the recurrence time intervals of past earthquakes in the himalaya using the weibull log normal gamma and inverse gaussian stochastic models the whole himalayan arc is divided into four seismogenic source zones viz the northwestern himalayas zone 1 the central seismic gap region zone 2 the eastern nepal and sikkim zone 3 and the eastern himalayas zone 4 by considering approximately 380 years of seismological data the suitability of each stochastic model for each zone was estimated using the kolmogorov smirnov k s test to describe the different physical processes responsible for earthquake occurrence the results show that the gamma inverse gaussian log normal and inverse gaussian models were most suitable for zones 1 4 respectively for m 6 0 the cumulative probability of recurrence intervals reaches up to 90 in 30 years for zones 1 and 2 49 years for zone 3 and 41 years for zone 4 the estimated conditional probability reaches 90 in 30 years in zone 1 35 years in zone 2 and 50 years in zones 3 and 4 the most suitable models for m 7 0 were found to be the log normal for zones 1 2 and 3 and gamma for zone 4 the cumulative probability for m 7 0 reaches 90 in 85 years in zone 1 86 years in zone 2 93 years in zone 3 and 148 years in zone 4 the estimated conditional probabilities reach 90 in 80 years in zone 1 90 years in both zone 2 and 3 and 150 years in zone 4 it is strongly recommended that model suitability be evaluated in complex regions such as the himalaya before proceeding with seismic hazard assessments the heterogeneous and complex tectonics of the himalayas differentiated plate motions different stress release patterns spatially and temporally and locking unlocking of faults thrusts are some of the reasons responsible for the different probabilistic models describing the earthquake occurrence phenomena in these four zones

fractal dimension of the 1999 chamoli earthquake from aftershock studies in garhwal himalaya the aftershock sequence of chamoli earthquake mw 6 4 of 29 march 1999 is analyzed to study the fractal structure in space time and magnitude distribution the b value is found to be 0 63 less than which is usually observed worldwide and in the himalayas this indicates that the numbers of smaller earthquakes are relatively less than the larger ones the spatial correlation is 1 64 indicating that events are approaching a two dimensional region meaning that the aftershocks are uniformly distributed along the trend of the aftershock zone temporal correlation is 0 86 for aftershocks of m 1 indicating a nearly continuous aftershock activity however it is 0 5 for aftershocks of m 1 75 indicating a non continuous aftershock activity from the assessment of slip on different faults it is inferred that 70 displacement is accommodated on the primary fault and the remainder on secondary faults

estimates of long term probabilities for future great earthquakes in the aleutians we compute probabilities for future great earthquakes in the aleutian arc probability distributions are fitted to recurrence periods of great aleutian evens m sub w or 7 8 since 1788 given a probability distribution and data of the last grat earthquake in each arc segment time dependent conditional probabilities are determined for future periods of interest we obtain for the next two decades high probabilities 99 to 30 for great earthquakes in the shumagin yakataga unalaska and kommandorski seismic gaps these probabilities are higher than for any other assessed region of the u s believed to be capable of great earthquakes low probabilities 17 to 9 are found for segments that ruptured most recently in 1965 1964 and 1957 recurrence periods for great earthquakes measure on average about 80 years but vary substantially whether recurrence periods for great aleutian earthquakes follow a normal log normal or any other probability distribution is not resolved because in most arc segments the known seismic record embraces at best one or two recurrences the resulting uncertainty affects the magnitude of estimated probabilities especially in seismic gaps that have not ruptured for a long time in some instances a normal distribution yields a three times higher probability than the correspondingmore log normal distribution less

hydrochemical characteristics of groundwater and surface water for domestic and irrigation purposes in vea catchment northern ghana the vea catchment mainly underlain by crystalline basement rocks is located in northern ghana hydrogeochemical studies were carried out in this area with the objective of identifying the geochemical processes influencing water quality and suitability of surface and groundwater for agricultural and domestic uses sixty one groundwater and four surface water samples were collected from boreholes dams and rivers and analysed for ca2 mg2 na k hco3 cl and so4 2 fetot po4 3 mntot nh4 no3 no2 in addition ph total dissolved solids electrical conductivity total hardness turbidity colour salinity and dissolved oxygen were analysed chloro alkaline indices 1 and 2 and characterization of weathering processes suggest that the chemistry of groundwater is dominated by the interaction between water and rocks cation exchange and silicate weathering are the dominant processes controlling the chemical composition of the groundwater in the area studied mineral saturation indices indicate the presence of at least three groups of groundwater in the vea catchment with respect to residence time the meteoric genesis index suggests that 86 of the water samples belong to the shallow meteoric water percolation type the findings further suggest that the groundwater and surface water in the basin studied are mainly ca mg hco3 water type regardless of the geology compared to the water quality guidelines of who the study results on sodium absorption ratio sodium percentage magnesium hazard permeability index and residual sodium carbonate indicate that groundwater and surface water in the vea catchment are generally suitable for drinking and irrigation purposes

probabilistic assessment of earthquake hazard in gujarat and adjoining region of india the gujarat and adjoining region falls under all four seismic zones v iv iii and ii of the seismic zoning map of india and is one of the most seismically prone intracontinental regions of the world it has experienced two large earthquakes of magnitude m w 7 8 and 7 7 in 1819 and 2001 respectively and several moderate earthquakes during the past two centuries in the present study the probability of occurrence of earthquakes of m 5 0 has been estimated during a specified time interval for different elapsed times on the basis of observed time intervals between earthquakes using three stochastic models namely weibull gamma and lognormal a complete earthquake catalogue has been used covering the time interval of 1819 to 2006 the whole region has been divided into three major seismic regions saurashtra mainland gujarat and kachchh on the basis of seismotectonics and geomorphology of the region the earthquake hazard parameters have been estimated using the method of maximum likelihood the logarithmic of likelihood function ln l is estimated and used to test the suitability of models in three different regions it was found that the weibull model fits well with the actual data in saurashtra and kachchh regions whereas lognormal model fits well in mainland gujarat the mean intervals of occurrence of earthquakes are estimated as 40 455 20 249 and 13 338 years in the saurashtra mainland gujarat and kachchh region respectively the estimated cumulative probability probability that the next earthquake will occur at a time later than some specific time from the last earthquake for the earthquakes of m 5 0 reaches 0 9 after about 64 years from the last earthquake 1993 in saurashtra about 49 years from the last earthquake 1969 in mainland gujarat and about 29 years from the last earthquake 2006 in the kachchh region the conditional probability probability that the next earthquake will occur during some specific time interval after a certain elapsed time from last earthquake is also estimated and it reaches about 0 8 to 0 9 during the time interval of about 57 to 66 years from the last earthquake 1993 in saurashtra region 31 to 51 years from the last earthquake 1969 in mainland gujarat and about 21 to 28 years from the last earthquake 2006 in kachchh region

seismic zonation of the delhi region for bedrock ground motion an endeavor is made to compute peak ground horizontal accelerations at bedrock level in the delhi region due to the seismogenic sources present around delhi the entire area is divided into six seismogenic sources for which seismic hazard analysis is carried out using the complete and extreme part of the seismicity data maximum likelihood estimates of hazard parameters viz seismic activity rate b value and maximum probable earthquake mmax are made for each zone the return periods and the probabilities of occurrence of various magnitudes for return periods of 50 100 and 1000 years are also computed for each zone the peak ground acceleration pga values for 20 exceedance in 50 years are then computed for the delhi region from each zone the maximum pga value considering all the zones is 0 34 g which is due to the mathura fault zone the seismogenic zones v and vi i e mathura fault zone and the sohna fault zone are observed to be contributing maximum pga values in the delhi region governing the isoacceleration contours computed for the region the seismic zonation map for the pga values at the bedrock level is obtained for the delhi region this can be used directly as input for the microzonation of ground motion at the surface by incorporating the local site conditions

probabilistic assessment of earthquake recurrence in northeast india and adjoining regions northeast india and adjoining regions 20 32 n and 87 100 e are highly vulnerable to earthquake hazard in the indian sub continent which fall under seismic zones v iv and iii in the seismic zoning map of india with magnitudes m exceeding 8 7 and 6 respectively it has experienced two devastating earthquakes namely the shillong plateau earthquake of june 12 1897 mw 8 1 and the assam earthquake of august 15 1950 mw 8 5 that caused huge loss of lives and property in the indian sub continent in the present study the probabilities of the occurrences of earthquakes with magnitude m 7 0 during a specified interval of time has been estimated on the basis of three probabilistic models namely weibull gamma and lognormal with the help of the earthquake catalogue spanning the period 1846 to 1995 the method of maximum likelihood has been used to estimate the earthquake hazard parameters the logarithmic probability of likelihood function ln l is estimated and used to compare the suitability of models and it was found that the gamma model fits best with the actual data the sample mean interval of occurrence of such earthquakes is estimated as 7 82 years in the northeast india region and the expected mean values for weibull gamma and lognormal distributions are estimated as 7 837 7 820 and 8 269 years respectively the estimated cumulative probability for an earthquake m 7 0 reaches 0 8 after about 15 16 2010 2011 years and 0 9 after about 18 20 2013 2015 years from the occurrence of the last earthquake 1995 in the region the estimated conditional probability also reaches 0 8 to 0 9 after about 13 17 2008 2012 years in the considered region for an earthquake m 7 0 when the elapsed time is zero years however the conditional probability reaches 0 8 to 0 9 after about 9 13 2018 2022 years for earthquake m 7 0 when the elapsed time is 14 years i e 2009

hydrochemical and isotopic characteristics of groundwater in the ndop plain northwest cameroon resilience to seasonal climatic changes shallow groundwater 30 mbgl is an essential source of drinking water to rural communities in the ndop plain northwest cameroon as a contribution to water management the effect of seasonal variation on the groundwater chemistry hydrochemical controls drinking quality and recharge were investigated during the peaks of the dry january and rainy september seasons field measurements of physical parameters were preceded by sampling 58 groundwater samples during both seasons for major ions and stable isotope analyses the groundwater which was barely acidic mean ph of 6 and less mineralised tds ca2 mg2 k and na mg2 ca2 k in the dry and rainy seasons respectively but that of anions text hco 3 text no 3 cl text so 4 2 f was similar in both seasons this suggests a negligible effect of seasonal variations on groundwater chemistry the groundwater which was camghco3 and nahco3 is chemically evolved rainfall camgso4cl in the area silicate mineral dissolution and cation exchange were the main controls on groundwater chemistry while there was little anthropogenic influence the major ions and tds concentrations classified the water as suitable for human consumption as per who guidelines the narrow cluster of 18o and d of same groundwater from both seasons between the 18o and d values of may june precipitation along the ndop meteoric water line indicates meteoric origin rapid recharge after precipitation and timing of recharge between may and june rainfall diffuse groundwater recharge mainly occurs at low altitudes 1 400 m asl within the plain besides major ions and tds the similar 18o and d of groundwater from both seasons indicate a consistent groundwater recharge and flow pattern throughout the year and resilience to present day short term seasonal climatic variations however controlled groundwater abstraction is recommended given the increasing demand

on the interpretation of the distinctive pattern of geomagnetic induction observed in northwest india the geomagnetic variation data from the 1979 indian array experiment have been reanalyzed and reexamined using the hypothetical event analysis technique the contour map of the z h ratio replicates distinctive anomaly in northwest india previously delineated in maps of the fourier coefficients the anomaly reveals the presence of a significant conductor under the ganga basin the contour map has been used to derive a response profile perpendicular to the strike of the anomaly for comparison with 2 d numerical models an excellent fit was found for a conductor at a depth of 32 km with a width of 110 km and a conductivity contrast of 1000 this result places the conductor deep within the lithosphere in the absence of supporting data the origin of the conductor is difficult to resolve however it is thought to be related to pressure released partial melting caused by fracturing of the indian crust during the collision of india with asia

isoseismal map of the 2015 nepal earthquake and its relationships with ground motion parameters distance and magnitude abstract a devastating earthquake of mw 7 8 struck central nepal on 25th april 2015 6 11 25 ut which resulted in more than 9000 deaths and destroyed millions of houses standing buildings roads and electrical installations worth 25 30 billions of dollars are reduced to rubbles the earthquake was widely felt in the northern parts of india and moderate damage have been observed in the northern part of up and bihar region of india maximum intensity ix according to the usgs report was observed in the meizoseismal zone surrounding the kathmandu region in the present study we have compiled available information from the print electronic media and various reports of damages and other effects caused by the event and interpreted them to obtain modified mercalli intensities mmi at over 175 locations spread over nepal and surrounding indian and tibet region we have also obtained a number of strong motion recordings from india and nepal seismic network and developed an empirical relationship between the mmi and peak ground acceleration pga peak ground velocity pgv we have used least square regression technique to derive the empirical relation between the mmi and ground motion parameters and compared them with the empirical relationships available for other regions of the world further seismic intensity information available for historical earthquakes which have occurred in the nepal himalaya along with the present intensity data has been utilized for developing an attenuation relationship for the studied region using two step regression analyses the derived attenuation relationship is useful for assessing damage of a potential future large earthquake earthquake scenario based planning purposes in the region

recurrence time and frequency slip statistics of slip events on the creeping section of the san andreas fault in central california summary an important question in seismic hazard assessments is the frequency size and recurrence interval statistics at a point on a fault does a point on a fault obey the same statistics as earthquakes in a region do this is a difficult question to answer because the number of repetitive earthquakes on a particular fault that have been observed is small in order to overcome this difficulty we consider slip events on the creeping section of the san andreas fault in central california sequences of up to 100 events are obtained from creepmeter records we compare the statistical distribution of recurrence times with the brownian passage time lognormal and weibull distributions and using goodness of fit tests find that the weibull is the preferred distribution we also consider the frequency amplitude distribution of slip events we find that the data clearly do not obey a gutenberg richter distribution instead there is a uniform distribution of event sizes for a large fraction of events

spatial mapping of earthquake hazard parameters in the hindukush pamir himalaya and adjacent regions implication for future seismic hazard abstract the study deals spatial mapping of earthquake hazard parameters like annual and 100 years mode along with their 90 probability of not being exceeded nbe in the hindukush pamir himalaya and adjoining regions for this purpose we applied a straightforward and most robust method known as gumbel s third asymptotic distribution of extreme values giii a homogeneous and complete earthquake catalogue during the period 1900 2010 with magnitude mw 4 0 is utilized to estimate these earthquake hazard parameters an equal grid point mesh of 1 longitude x 1 latitude is chosen to produce detailed earthquake hazard maps this performance allows analysis of the localized seismicity parameters and representation of their regional variations as contour maps the estimated result of annual mode with 90 probability of nbe is expected to exceed the values of mw 6 0 in the sulaiman kirthar ranges of pakistan and northwestern part of the nepal and surroundings in the examined region the 100 years mode with 90 probability of nbe is expected to exceed the value of mw 8 0 in the hindukush pamir himalaya with caucasus mountain belt the sulaiman kirthar ranges of pakistan northwestern part of the nepal and surroundings the kangra himanchal pradesh and kashmir of india the estimated high values of earthquake hazard parameters are mostly correlated with the main tectonic regimes of the examined region the spatial variations of earthquake hazard parameters reveal that the examined region exhibits more complexity and has high crustal heterogeneity the spatial maps provide a brief atlas of the earthquake hazard in the region

strong ground motion from the uttarkashi himalaya india earthquake comparison of observations with synthetics using the composite source model the uttarkashi earthquake of 19 october 1991 ms 7 0 occurred in the greater himalayan region north of the main central thrust at an estimated depth of 12 km the fault plane solution indicates a low angle thrust mechanism striking northwest consistent with the tectonic pattern of thrusting in the region aftershocks define a belt parallel to and north of the surface trace of the main central thrust roughly 10 km wide and 30 km long the mainshock is located at the northeast edge of this zone the earthquake was recorded on 13 strong motion accelerographs at distances ranging from 25 to 150 km from the epicenter one station at bhatwari peak horizontal acceleration of 272 cm sec 2 is above the aftershock zone the maximum peak horizontal acceleration was about 313 cm sec 2 at uttarkashi at an epicentral distance of 36 km the amplitudes and frequency content of the strong ground motions are more or less consistent with expectations for an earthquake of this magnitude in california synthetics generated using the composite source model and synthetic green s functions zeng et al 1994a b are successful in producing acceleration velocity and displacement with a realistic appearance and the correct statistical properties of the two accelerograms recorded nearest the fault bhatwari and uttarkashi to produce these we introduced trial and error modifications of the layered medium velocity model within uncertainties at more distant stations we first used the velocity structure that worked for the two nearest stations differences emphasize the large potential role of unknown site and wave propagation effects for the station at tehri we explored different velocity models and found one there that was also quite successful we then used these two velocity models to predict strong ground motions at bhatwari and tehri from a potential magnitude 8 5 earthquake filling part of the seismic gap along the himalayan frontal faults the synthetics show peak accelerations that are only somewhat larger than those in the uttarkashi event but much longer durations and increased amplitudes of response spectra at long periods

simulation of strong ground motion for an mw 7 0 earthquake beneath the bhutan himalaya in ne india and its trans boundary seismic hazard implications abstract we simulate the strong ground motion for an expected major earthquake mw 7 0 beneath the bhutan himalayan region with an empirical green s function method using waveforms recorded from the 2009 bhutan mainshock mw 6 1 and its largest aftershock mw 5 1 fault orientation and location of the simulated event extend the length of the fault plane determined from the 2009 bhutan mainshock and aftershock along its strike the simulated pga values are compared with the results derived from a ground motion prediction equation gmpe for the himalayan region and it is found that different levels of accelerations are associated with different rupture initiation points on the fault plane it is observed that the ne indian region is capable of generating peak ground acceleration pga in exceedance to 121 cm s2 for simulated earthquake mw 7 0 the maximum impacts of shaking will be on the sites located near the rupture initiation points that are poised to generate higher values of ground acceleration to validate our simulation we also estimate the extent of rupture directivity of the simulated earthquake with respect to four initiation points indicating that higher value of pga and shaking duration exist either to south or to south west azimuths from the imitated locations which are corroborated with respective geology of the sites this study suggests that areas of maximum ground shaking would occur in the vicinity of the source initiation where possibility of relatively stronger earthquake hazards does exist which in turn requires attention for adoption of earthquake risk mitigation plans in view of impacts of trans boundary earthquakes in the region

tsunami hazard probability in japan abstract an analysis of future tsunami hazard on the coast of the japanese islands is made in terms of probability for a coastal site being hit by a tsunami of which the wave height exceeds a certain level during a period from 2000 to 2010 tsunami wave height at a site on the pacific coast is estimated mostly based on numerical experiment in which a typical fault model of the tsunami generating earthquake is assumed meanwhile probability of the tsunami generating earthquake occurring during 2000 to 2010 is evaluated either from historical data of earthquake occurrence or from near shore crustal strain accumulation combining the wave height estimate with the probability evaluation of tsunami occurrence probabilities of a site being hit by a tsunami of which the wave height exceeds certain levels are evaluated on the pacific coast it seems that the probability for a violent tsunami of which the wave height exceeds 5 m is highest along the pacific coast in central japan reaching a value of 41 per cent on the other hand a probability value as high as 69 per cent is found for a moderately large tsunami having a wave height of 1 m or so along the shikoku and kyushu coasts a crude probability evaluation is also made for tsunamis on the japan sea coast where tsunami activity is substantially lower than that of the pacific coast the probability for a violent tsunami seems to amount to only 1 per cent or so for a 10 yr period similar probabilities for tsunamis excited by a distant source off peru chile kamchatka and aleutian alaska are also evaluated in this case probabilities of tsunami wave height exceeding 1 and 3 m are respectively evaluated as 19 and 15 per cent on the pacific coast such probabilities being not quite negligible

characteristics of earthquake sequence in northern himalayan region of south central tibet precursor search and location of potential area of future earthquake abstract this paper reports that three earthquake sequence occurred in 1996 m b 5 9 1998 m b 5 8 and 2004 2005 m b 6 2 6 3 were observed preceding the anomalous seismic activity the nature of anomalous seismicity associated with these earthquakes have been investigated considering earthquakes with m b 4 1 cut off magnitude for this region in four seismic episodes nagm normal background n anomalous swarm a precursory gap g and mainshock sequence m respectively it is established here that the anomalous seismicity swarm patterns follow episodes of relatively very low seismic activity and it is an important finding to visualize that an area might be preparing for the occurrence of a forthcoming mainshock such anomalous seismic patterns were observed prior to medium size mainshocks that occurred from 1963 to 2006 in south central tibet sct region to the north of central himalaya from these observations it may be inferred here that the patterns of anomalous seismicity earthquake swarms may be considered as an important parameter precursor for the forecasting of long range earthquake hazards in the sct region in consideration of spatial and the temporal clustering of swarm events that are prominent and confined in a vertical column of 10 45 km enabled to locate potential area enclosed by 29 6 30 1 n and 87 8 88 1 e where future earthquake of magnitude 6 0 and above in the depth range 25 15 km may be seated in view of this multi parameter short term precursory signals monitoring is suggested for the delineated preparatory area to make earthquake prediction forecasting programs more meaningful

probabilistic seismic hazard assessment for northeast india region northeast india bounded by latitudes 20 30 n and longitudes 87 98 e is one of the most seismically active areas in the world this region has experienced several moderate to large sized earthquakes including the 12 june 1897 shillong earthquake mw 8 1 and the 15 august 1950 assam earthquake mw 8 7 which caused loss of human lives and significant damages to buildings highlighting the importance of seismic hazard assessment for the region probabilistic seismic hazard assessment of the region has been carried out using a unified moment magnitude catalog prepared by an improved general orthogonal regression methodology geophys j int 190 1091 1096 2012 probabilistic seismic hazard assessment of northeast india region ph d thesis department of earthquake engineering iit roorkee roorkee 2013 with events compiled from various databases isc neic gcmt imd and other available catalogs the study area has been subdivided into nine seismogenic source zones to account for local variation in tectonics and seismicity characteristics the seismicity parameters are estimated for each of these source zones which are input variables into seismic hazard estimation of a region the seismic hazard analysis of the study region has been performed by dividing the area into grids of size 0 1 0 1 peak ground acceleration pga and spectral acceleration sa values for periods of 0 2 and 1 s have been evaluated at bedrock level corresponding to probability of exceedance pe of 50 20 10 2 and 0 5 in 50 years these exceedance values correspond to return periods of 100 225 475 2475 and 10 000 years respectively the seismic hazard maps have been prepared at the bedrock level and it is observed that the seismic hazard estimates show a significant local variation in contrast to the uniform hazard value suggested by the indian standard seismic code indian standard criteria for earthquake resistant design of structures fifth edition part i bureau of indian standards new delhi 2002 not only holistic treatment of earthquake catalog and seismogenic zones has been performed but also higher resolution in spatial distribution could be achieved the cov maps have been provided with the strong ground motion maps under various conditions to show the confidence in the results obtained results obtained in the present study would be helpful for risk assessment and other disaster mitigation related studies

seismic history and seismotectonics of the sunda arc historic records of the last 300 years reveal two great interplate earthquakes 1833 mw 8 1861 mw 8 8 which ruptured major segments of the sumatra fore arc in western indonesia a significant percentage of interplate slip along this portion of the plate boundary appears to occur seismically the ends of these rupture zones are coincident with clusters of large ms 7 and moderate 6 ms 7 shocks and with heterogeneities in the plate interface as inferred from geologic and geophysical data the northern extent of the 1833 rupture zone is coincident with a group of moderate and large earthquakes a structural arch in the fore arc and a fracture zone on the subducted plate the southern portion is coincident with a very prominent cluster and the along strike extension of a sediment filled trough on the subducted plate prior to this study sumatra was characterized as relatively aseismic as inferred from the lack of great earthquakes in the instrumental record of this century java and the lesser sunda islands had major ms 6 earthquakes in the historic record but none are of the same magnitude as the great events near sumatra there is no clear evidence that shocks in the java fore arc were interplate events yet geophysical data indicate recent uplift of the trench slope break and a change in strike of the trench axis where the northernmost flank of the roo rise a prominent bathymetrie high appears to be interacting with the fore arc this feature was formed at a ridge crest and is more buoyant and thus more difficult to subduct than the surrounding seafloor there is no increase in seismicity associated with this tectonism however that may indicate a lack of contact between the crystalline portions of the plates at this time we infer that a majority of slip on the plate interface near java occurs aseismically the variation in occurrence of great interplate earthquakes along the sunda arc may be interpreted in terms of a model that attributes variation in interplate coupling to the age of the subducted lithosphere great interplate earthquakes occur near sumatra where the age of the youngest crust is 46 ma the characteristics of the sunda arc and analogies with pacific arcs imply that the entire length of sumatra has the potential to produce great thrust earthquakes its seismic potential should be considered high as there has been no recurrence of the great events of 1833 and 1861 in contrast no such events have been reported off java and the lesser sunda islands where the oldest crust is 152 ma the plate interface near java and the lesser sunda islands should be considered to have low seismic potential

assessment of the hydrogeochemical characteristics of groundwater in two aquifer systems in cumra plain central anatolia located in a semi arid climate cumra konya plain is one of the most important agricultural regions in turkey groundwater is the major source for agricultural domestic and other water related activities due to the insufficiency of surface water as groundwater is the only major source of water in this area it is important to know the effects of geological formations and anthropogenic activities on groundwater chemistry this study was carried out with the objective of identifying the hydrogeochemical characteristics and processes controlling the groundwater chemistry in cumra plain central anatolia turkey the study area is comprised of two main aquifers which are the semi confined aquifer of the neogene age and the unconfined aquifer of the quaternary age to identify the hydrogeochemical characteristics of groundwater in two aquifer systems and to understand the major factors and mechanisms controlling the groundwater chemistry graphical plots mineral saturations and multivariate statistical analysis of chemical constituents in the groundwater were used study results show that groundwater is generally neutral to slightly alkaline in nature with a ph ranging from 6 67 to 8 10 and the dominance of ions is in the order of ca2 mg2 na k for the neogene aquifer and hco3 so4 2 cl no3 mg2 ca2 na k and so4 2 hco3 cl no3 for the quaternary aquifer while the chemical composition of groundwater in the neogene aquifer is mainly controlled by water rock interaction including dissolution of carbonates and gypsum calcite precipitation and de dolomitization the main geochemical processes in the quaternary aquifer are reverse ion exchange evaporation dissolution of carbonates gypsum and soil salts calcite precipitation and silicate weathering the mechanism controlling groundwater chemistry in the neogene aquifer is actually regulated by the geogenic processes water rock interaction rather than by anthropogenic activities however the mechanism controlling groundwater chemistry in the quaternary aquifer is regulated by both geogenic processes and anthropogenic activities in addition anthropogenic nitrogen pollution in the study area is currently not serious but evaporation and leaching of soil salts due to anthropogenic activities increase the concentrations of ions in the quaternary aquifer

preliminary determination of the interdependence among strong motion amplitude earthquake magnitude and hypocentral distance for the himalayan region summary since the installation of three limited aperture strong motion networks in the himalayan region in 1986 six earthquakes with mw 5 2 7 2 have been recorded up to 1991 the data set of horizontal peak accelerations and velocities consists of 182 component data for the hypocentral distance range 10 400 km this data set is limited in volume and coverage and worst of all it is highly inhomogeneous thus we could not determine regional trends for amplitudes by means of the traditional approach of empirical multiple regression instead we perform the reduction of the observations to a fixed distance and magnitude using independently defined distance and magnitude trends to determine an appropriate magnitude dependent distance attenuation law we use the spectral energy propagation random function approach of gusev 1983 and adjust its parameters based on the residual variance in doing so we confirm the known rather gradual mode of decay of amplitudes with distance in the himalayas this seems to be caused by the combination of high qs and crustal waveguide effects for high frequencies the data are then reduced with respect to magnitude the trend of peak acceleration versus magnitude cannot be determined from observations and we assume that it coincides with that of abundant japanese data for the resulting set of reduced log10 peak acceleration data the residual variance is 0 372 much above commonly found values however dividing the data into two geographical groups western with two events and eastern with four events reduces the residual variance to a more usual level of 0 272 a station site component of 0 222 and an event component of 0 162 this kind of data description is considered acceptable a similar analysis is performed with velocity data and again we have to split the data into two subregional groups with our theoretically grounded attenuation laws we attempt a tentative extrapolation of our results to small distances and large magnitudes our minimum estimates of peak acceleration for the epicentral zone of mw 7 5 8 5 events is apeak 0 25 0 4 g for the western himalayas and as large as apeak 1 1 6 g for the eastern himalayas similarly the expected minimum epicentral values of vpeak for mw 8 are 35 cm s 1 for the western and 112 cm s 1 for the eastern himalayas to understand whether our results reflect the properties of the subregions and not of a small data set we check them against macroseismic intensity data for the same subregion the presence of unusually high levels of epicentral amplitudes for the eastern subregion agrees well with the macroseismic evidence such as the epicentral intensity levels of x xii for the great assam earthquake of 1897 therefore our results represent systematic regional effects and they may be considered as a basis for future regionalized seismic hazard assessment in the himalayan region we see the location of earthquake sources faults at a considerable depth within the relatively drier and higher strength shield crust as the main cause of the observed enhanced amplitudes for the eastern himalayas events western himalayas sources are shallower and occupy the tectonically highly fractured upper part of the crust of accretionary origin the low attenuation common to both subregions is due to the presence of cold low scattering and high q shield crust

probabilistic seismic hazard estimation for peninsular india peninsular india 10 0 n 28 0 n 68 0 e 90 0 e is one of the oldest and seismically most stable landmasses of the indian plate recent seismic history however shows that more than five damaging earthquakes with magnitudes greater than mw 6 0 have occurred in this region highlighting the importance of seismic hazard assessment for the region this article estimates the probabilistic seismic hazard associated with peninsular india with a zoneless approach incorporating the observed seismic activity and known geological characteristics of the region the seismicity parameters for hazard assessment have been estimated incorporating com pleteness criteria for various spans of the catalog data the spatial and temporal variations of seismic activity have been modeled using different source models seis mic source zones for the region have been defined on the basis of large scale geo logical features which are used for assigning the maximum possible earthquake potential due to the poorly known attenuation characteristics of the study region three appropriate attenuation models have been used for the estimation of ground motion parameters hazard maps for peninsular india have been developed using a convolution scheme based on weighting and incorporating various uncertainties in volved while modeling different parameters the comparison of the probabilistic seismic hazard map developed herein with the hazard map specified in the indian standards shows that the design parameters in the indian standards may significantly underestimate the seismic hazard in some regions of peninsular india

use of seismotectonic information for the seismic hazard analysis for surat city gujarat india deterministic and probabilistic approach surat the financial capital of gujarat india is a mega city with a population exceeding five millions the city falls under zone iii of the seismic zoning map of india after the devastating 2001 bhuj earthquake of mw 7 7 much attention is paid towards the seismic microzonation activity in the state of gujarat in this work an attempt has been made to evaluate the seismic hazard for surat city 21 170 n 72 830 e based on the probabilistic and deterministic seismic hazard analysis after collecting a catalogue of historical earthquakes in a 350 km radius around the city and after analyzing a database statistically deterministic analysis has been carried out considering known tectonic sources a further recurrence relationship for the control region is found out probabilistic seismic hazard analyses were then carried out for the surat region considering five seismotectonic sources selected from a deterministic approach the final results of the present investigations are presented in the form of peak ground acceleration and response spectra at bed rock level considering the local site conditions rock level peak ground acceleration pga and spectral acceleration values at 0 01 s and 1 0 s corresponding to 10 and 2 probability of exceedance in 50 years have been calculated further uniform hazard response spectrum uhrs at rock level for 5 damping and 10 and 2 probability of exceedance in 50 years were also developed for the city considering all site classes these results can be directly used by engineers as basic inputs in earthquake resistant design of structures in and around the city

differences in attenuation among the stable continental regions 1 there are systematic differences in the attenuation of damaging earthquake ground motions between different stable continental regions scrs seismic intensity and weak motion data show that the attenuation in seismic waves for eastern north america ena is less than for india africa australia and northwest europe if ena ground motion attenuation relations are used in seismic hazard models for other scrs as is commonly done then the estimated ground motions and resulting hazard may be too large if an attenuation model that averages observations from ena and the other scrs is used to estimate the magnitudes of large historical earthquakes in ena as is the case for recent estimates of m for the 1811 1812 new madrid missouri and the 1886 charleston south carolina events then the magnitude estimates for these events will be too large as will be the resulting hazard

a zone of very low seismicity in the vicinity of the chang thang platform tibet abstract we note that the area of no sn transmission and no lid of previous researchers in the central chang thang platform of tibet has low seismicity whereas the kun lun and lhasa blocks lying north and south of the chang thang platform are seismically active an area bounded by the nujiang kun lun fault and kokoxili suture in the north the bangong nujiang suture and kang ting fault in the south and longitudes 87 and 100 e encompassing a large portion of the chang thang platform in central tibet has low seismicity we also note that portions of this area have a signature in topography as well the elevations are higher by several hundred metres here than over the lhasa and kun lun blocks these observations and the reported extensive quaternary volcanism in the chang thang platform suggest upwelling of hot mantle material below this area as the most likely explanation

tsunami hazards along chinese coast from potential earthquakes in south china sea the pair of earthquakes off taiwan on december 26 2006 and the subsequent disruption of the internet traffic have called attention to the potential destructive hazards along the chinese coast from tsunamis historical records show past tsunami earthquakes in this region using gps earthquake focal mechanisms and geological evolution we have delineated the dangerous zones in the philippine sea plate where major earthquakes may occur the manila trench is identified as being most susceptible to future major earthquakes we have obtained the local gutenberg richter relationship for five sections along the philippine sea plate boundary and use this information for determining the probability distribution for tsunami waves of various heights to impinge on various chinese cities we devise a new method called the probabilistic forecast of tsunami hazard pfth which determines this probability distribution by direct numerical simulation of the waves excited by hypothetical earthquakes in these zones we have employed the linear shallow water equations over the south china sea we have also compared them with results from the nonlinear version and found that the linear treatment serves our purpose sufficiently well in the next century the probability of a wave with a height of over 2 0 m to hit near coast ocean of hong kong and macau is about 10 cities in taiwan are less vulnerable than those on the mainland coast 2007 elsevier b v all rights reserved

a spectral analysis of the 21 may 1997 jabalpur india earthquake mw 5 8 and estimation of ground motion from future earthquakes in the indian shield region the jabalpur earthquake 23 08 n 80 06 e h 36 km is the first event in the indian peninsular shield region to be well recorded by a newly installed 10 station broadband seismographic network using these data we estimate q of lg wave in the indian shield region as q 508 0 48 1 20 hz the corrected source spectrum with m 5 4 1024 dyne cm reported in the harvard cmt catalog and an 2 source model requires a stress parameter p of 420 bar to explain high frequency spectral level the computed seismic energy from the records is 7 4 1020 erg which yields an apparent stress and brune stress drop of 62 and 270 bars respectively the analysis of the jabalpur earthquake provides some elements for the estimation of ground motions during future earthquakes in the indian shield region based on the results of the jabalpur earthquake and on studies of tectonically similar region of eastern north america we assume that 1 the sources follow an 2 model 2 s waves dominate at r 100 km and lg waves dominate at r 100 km 3 q f 508 0 48 4 the ground motion is a bandlimited finite duration gaussian white noise and 5 the effective duration of the ground motion equals 1 c 0 05 r where fc is the corner frequency we apply random vibration theory rvt to compute various measures of ground motion such as a max and v max at near source distances the source finiteness is approximately taken into account the attenuation curves for 5 5 mw 7 and for p of 100 400 bar are presented as expected the predicted values with p 420 bar agree reasonably well with the limited jabalpur data an a max of 150 gal is predicted in the epicentral region of this earthquake the predicted curves imply p 100 bar for the latur earthquake of 1993 mw 6 1 h 2 5 km to explain a max 1 g and the reported isoseismal intensities in the epicentral region for koyna earthquake of 1967 mw 6 3 the inferred a max and v max from isoseismal intensities and the recorded strong motions at the koyna dam site are in agreement with the prediction curves for p 100 bar the rvt predictions seem reasonable but need validation from more strong motion data which is presently lacking

deep structure and tectonics of the burmese arc constraints from earthquake and gravity data abstract active subduction of the indian plate is currently occurring beneath the burmese arc along an east dipping benioff zone which extends to a depth of about 180 km the overriding burma plate has an appearance of an inland seismic slab that is deflected downwards in the vicinity of the benioff zone a crustal seismic zone some 60 80 km east of the benioff zone correlates to backarc activity a triangular aseismic wedge in the top part of the crust outlines the central belt molasse basin east of the burmese foldbdt fault plane solutions show that the burmese benioff zone is characterized by shallow angle thrusting at its upper edge whereas down tip tensional events dominate its lower edge most of the backarc seismicity is accounted for by the sagaing transform or by the activity of the shan scarp normal fault zone at the margin of the asian plate a gravity anomaly pair with amplitude of 175 mgal coincides with the 1100 km long burmese arc lying in a north south direction the gravity anomalies along a profile in central burma and in adjacent areas of the bengal basin are interpreted in terms of plate subduction as well as near surface mass anomalies this suggests that sediments below the central belt may have an average thickness of the order of 10 km but may be as thick as 15 km at the subduction zone the oceanic crust underlying deeper parts of the bengal basin experiences phase transition at about 30 km depth in a benioff zone environment east of the burmese foldbelt several thrust planes are present within the folded and deformed cretaceous tertiary sediments of the fold belt these are often associated with ophiolites and basic to ultrabasic rocks a low density zone at least 60 km wide underlies the andesitic volcanic axis in the overriding plate

an overview on the seismic zonation and microzonation studies in india abstract the present study presents a review on the progressive development of the seismic zonation map of india both from official agencies and also from independent individual studies the zonation map have been modified and updated regularly with the occurrence of major destructive earthquakes over the years in the indian subcontinent with the addition of new data this study discusses the criteria chosen for the progressive zonation and the major earthquakes that were responsible for retrospection of the earlier published maps the seismic zonation maps of india have also been prepared by various independent workers by adopting different approaches to achieve the purpose of the zonation despite the endeavors from various sources to provide a solution for the problem of earthquake hazards in india there were many limitations on the zonation map as it gives the picture at a regional scale mostly on the bedrock level without addressing the local site conditions but nevertheless the seismic zonation map gives basic guidelines for any region to know the hazard scenario and if any city or urban population is under threat from seismic point of view further site specific seismic microzonation may be carried out in the international scenario the global seismic hazard assessment program gshap in 1999 prepared a hazard map for world in terms of peak ground acceleration pga with a 10 probability of exceedance in 50 years but it turned out to be an underestimation of the hazard parameter when compared with the observed pga to tackle the problem of seismic hazards there was a need to have a detail study on the local site conditions in terms of its geological geophysical and geotechnical properties with the advent of better instrumentation and knowledge on the mechanics of earthquakes it was possible to identify zones of hazards at a local level and this gives rise to the study of seismic microzonation seismic microzonation work has been carried out in india in some of the strategic important mega cities and industrial build up that has the potential of being damaged from future earthquakes as has been shown in the past though the microzonation map is not the final output map as it can still be updated at later stage with more input data it does provide a more realistic picture on the site specific seismic hazard