structure and evolution of the northern potwar deformed zone pakistan the northern potwar deformed zone npdz is part of the active foreland fold and thrust belt of the salt range and potwar plateau in northern pakistan about 500 km of seismic reflection profiles are integrated with surface geologic and drilling data to examine the deformation style and structure of the npdz with particular emphasis on history of deformation of the dhurnal oil field the seismic lines suggest that the overall structure of the eastern npdz is a duplex structure developed beneath a passive roof thrust the roof thrust is generated from a tipline in the miocene murree formation and the sole thrust is initiated from the same eocambrian evaporite zone that extends 80 km southward beneath the soan syncline and salt range the dhurnal oil field structure is a pop up at the southern margin of the npdz and developed beneath the passive roof thrust the passive roof thrust crops out just north of dhurnal on the steep northern limb of the soan syncline an overstep passive roof thrust sakhwal fault is interpreted west of dhurnal this fault developed due to

mesoscale vortices in the weddell sea region antarctica abstract preliminary results of investigations of antarctic mesocyclones in the weddell sea region are presented for the antarctic summer periods 1983 88 based on noaa and meteor satellite images a total of 195 mesoscale vortices scale less than 1000 km were observed and classified using a simple classification scheme depending on lifetime and cortex diameter the highest frequency of vortices was found over the ice free part of the eastern weddell sea mean synoptic conditions for vortices with scales less than 400 km near halley station indicate an offshore flow being most favorable for their development a case study with satellite images surface measurements synoptic analyses derived from tovs data shows the evolution of several mesoscale vortices in a pool of cold air in the eastern weddell sea

development of the himalayan frontal thrust zone salt range pakistan the salt range is the active frontal thrust zone of the himalaya in pakistan seismic reflection data show that a 1 km offset of the basement acted as a buttress that caused the central salt range potwar plateau thrust sheet to ramp to the surface exposing mesozoic and paleozoic strata the frontal part of the thrust sheet was folded passively as it overrode the subthrust surface on a ductile layer of eocambrian salt lack of internal deformation of the rear part of the thrust sheet is due to decoupling of sediments from the basement along this salt layer early to middle pliocene 4 5 ma conglomerate deposition in the southern potwar plateau previously interpreted in terms of compressional deformation may instead document uplift related to basement normal faulting stratigraphic evidence paleomagnetic dating of unconformities and sediment accumulation rates suggest that the thrust sheet began to override the basement offset from 2 1 to 1 6 ma cross section balancing demonstrates at least 20 to 23 km of shortening across the ramp the rate of himalayan convergence that can be attributed to underthrusting of indian basement beneath sediments in the pakistan foreland is therefore at least 9 14 mm yr about 20 35 of the total plate convergence rate

the numerical simulation of non supercell tornadogenesis part i initiation and evolution of pretornadic misocyclone circulations along a dry outflow boundary abstract high resolution three dimensional simulations are used to study misocyclone initiation and development along the leading edge of an outflow boundary model conditions were designed such that this development could be simulated independent of moist processes the outflow boundary is allowed to propagate into a region of southerly low level flow which results in a vertical vortex sheet along the outflow s leading edge lobe and cleft instabilities follow and provide perturbations for the subsequent development of horizontal shearing instabilities these growing instabilities are the inaugural circulations of leading edge misocyclones with wavelengths ranging from 1 6 to 3 2 km the structure of these modeled misocyclones compares favorably to observed pretornadic misocyclones along outflow boundaries in northeast colorado vortex sheet dynamics are observed to exert substantial control over the structure of the evolving outflow leading edge the vertical vortex sheet passes through discrete evoluti

site amplifications for generic rock sites seismic shear wave velocity as a function of depth for generic rock sites has been estimated from borehole data and studies of crustal velocities and these velocities have been used to compute frequency dependent amplifications for zero attenuation for use in simulations of strong ground motion we define a genetic rock site as one whose velocity at shallow depths equals the average of those from the rock sites sampled by the borehole data most of the boreholes are in populated areas for that reason the rock sites sampled are of particular engineering significance we consider two genetic rock sites rock corresponding to the bulk of the borehole data and very hard rock such as is found in glaciated regions in large areas of eastern north america or in portions of western north america the amplifications on rock sites can be in excess of 3 5 at high frequencies in contrast to the amplifications of less than 1 2 on very hard rock sites the consideration of unattenuated amplification alone is computationally convenient but what matters for ground motion estimation is the combined effect of amplification and attenuation for reasonable values of the attenuation parameter k 0 the combined effect of attenuation and amplification for rock sites peaks between about 2 and 5 hz with a maximum level of less than 1 8 the combined effect is about a factor of 1 5 at 1 hz and is less than unity for frequencies in the range of 10 to 20 hz depending on t using these amplifications we find provisional values of about ao 70 bars and k 0 0 035 sec for rock sites in western north america by fitting our empirically determined response spectra for an m 6 5 event to simulated values the borehole data yield shear velocities 033o of 618 and 306 rrdsec for rock and soil sites respectively when averaged over the upper 30 m from this we recommend that v30 equals 620 and 310 m sec for applications requiring the average velocity for rock and soil sites in western north america by combining the amplifications for rock sites and the site factors obtained from our analysis of strong motion data we derive amplifications for sites with 17 3o 520 m sec nehrp class c corresponding to a mix of rock and soil sites and v3o 310 and 255 m sec average soil and nehrp class d sites respectively for the average soil site the combined effect of amplification and attenuation exceeds a factor of 2 0 for frequencies between 0 4 and about 4 hz with a peak site effect of 2 4 the peak of the nehrp class d site effect is 2 7

a terrain based site conditions map of california with implications for the contiguous united states abstract we present an approach based on geomorphometry to predict material properties and characterize site conditions using the v s 30 parameter time averaged shear wave velocity to a depth of 30 m our framework consists of an automated terrain classification scheme based on taxonomic criteria slope gradient local convexity and surface texture that systematically identifies 16 terrain types from 1 km spatial resolution 30 arcsec shuttle radar topography mission digital elevation models srtmdems using 853 v s 30 values from california we apply a simulation based statistical method to determine the mean v s 30 for each terrain type in california we then compare the v s 30 values with models based on individual proxies such as mapped surface geology and topographic slope and show that our systematic terrain based approach consistently performs better than semiempirical estimates based on individual proxies to further evaluate our model we apply our california based estimates to terrains of the contiguous united states comparisons of our estimates with 325 v s 30 measurements outside of california as well as estimates based on the topographic slope model indicate our method to be statistically robust and more accurate our approach thus provides an objective and robust method for extending estimates of v s 30 for regions where in situ measurements are sparse or not readily available

topographic slope as a proxy for seismic site conditions and amplification we describe a technique to derive first order site condition maps directly from topographic data for calibration we use global 30 arc sec topographic data and v s 30 measurements here v s 30 refers to the average shear velocity down to 30 m aggregated from several studies in the u s as well as in taiwan italy and australia v s 30 values are correlated against topographic slope to develop two sets of parameters for deriving v s 30 one for active tectonic regions where topographic relief is high and one for stable shields where topography is more subdued by taking the gradient of the topography and choosing ranges of slope that maximize the correlation with shallow shear velocity observations we can recover to first order many of the spatially varying features of sitecondition maps developed for california our site condition map for the low relief mississippi embayment also predicts the bulk of the v s 30 observations in that region despite rather low slope ranges we find that maps derived from the slope of the topography is often well correlated with other independently derived regional scale site condition maps but the latter maps vary in quality and continuity and subsequently also in their ability to match observed v s 30 measurements contained therein alternatively the slope based method provides a simple approach to uniform site condition mapping

observation of coexisting mesoscale lake effect vortices over the western great lakes mesoscale vortices are one of several types of wintertime lake effect structures that are observed over the great lakes region as cold arctic air is rapidly modified from below by warm lake waters these vortices are thought to occur less frequently than other lake effect structures such as wind parallel snowbands e g kristovich 1993 which are responsible for greater than half of the yearly snowfall downwind of the western great lakes kelly 1986 and more intense shore parallel snowbands which can produce localized heavy snowfalls e g braham 1983 through the examination of visible satellite imagery forbes and merritt 1984 found 14 cases of mesoscale vortex formation over the great lakes in the years 1978 82 this suggests that on average a mesoscale vortex will occur within the great lakes region less than four times a winter during an early winter lakeeffect event on 13 november 1995 intense land breeze circulations and four mesoscale vortices 50 km diameter developed over lakes superior huron and michigan simultaneously fig 1 this unique observation of coexisting lake effect vortices over the western great lakes has not previously been reported in the literature and suggests that atmospheric conditions favorable for vortex development were widespread throughout the region previous cases have typically observed a single vortex suggesting that favorable meteorological conditions were localized the author is aware of only two other reported observations of simultaneous mesoscale vortices within the great lakes region schoenberger 1986 pitts et al 1977 however the lake effect vortices that schoenberger 1986 and

changes in seismic moment rates along the rupture zone of the 1964 great alaska earthquake we examined seismic moment rates associated with the prince william sound and kodiak island asperities of the 1964 great alaska earthquake rupture zone to determine how seismicity has varied through time and space our results indicate that there has been a factor of 5 10 decrease in seismic moment rates within the prince william sound asperity region since 1964 whereas seismic moment rates have actually increased within the kodiak asperity region since 1964 primarily because of a sequence of m w 7 0 earthquakes that have occurred since 1998

site characterization using integrated imaging analysis methods on satellite data of the islamabad pakistan region we develop an integrated digital imaging analysis approach to produce a first approximation site characterization map for islamabad pakistan based on remote sensing data we apply both pixel based and object oriented digital imaging analysis methods to characterize detailed 1 50 000 geomorphology and geology from advanced spaceborne thermal emission and reflection radiometer aster satellite imagery we use stereo correlated relative digital elevation models rdems derived from aster data as well as spectra in the visible near infrared vnir to thermal infrared tir domains the resulting geomorphic units in the study area are classified as mountain including the margala hills and the khairi murat ridge piedmont and basin terrain units the local geologic units are classified as limestone in the margala hills and the khairi murat ridge and sandstone rock types for the piedmonts and basins shear wave velocities for these units are assigned in ranges based on established correlations in california these ranges include vs30 values to be greater than 500 m sec for mountain units 200 600 m sec for piedmont units and less than 300 m sec for basin units while the resulting map provides the basis for incorporating site response in an assessment of seismic hazard for islamabad it also demonstrates the potential use of remote sensing data for site characterization in regions where only limited conventional mapping has been done

the 1964 prince william sound earthquake joint inversion of tsunami and geodetic data the 1964 prince william sound alaska earthquake mw 9 2 ruptured a large area beneath the continental margin of alaska from prince william sound to kodiak island a joint inversion of tsunami waveforms and geodetic data consisting of vertical displacements and horizontal vectors gives a detailed slip distribution two areas of high slip correspond to seismologically determined areas of high moment release the prince william sound asperity with average slip of 18 m and the kodiak asperity with average slip of 10 m the average slip on the fault is 8 6 m and the seismic moment is estimated as 6 3 1022 n m or over 75 of the seismic moment determined from long period surface waves

lake effect mode and precipitation enhancement over the tug hill plateau during owles iop2b abstractimproved understanding of the influence of orography on lake effect storms is crucial for weather forecasting in many lake effect regions the tug hill plateau of northern new york hereafter tug hill rising 500 m above eastern lake ontario experiences some of the most intense snowstorms in the world herein the authors investigate the enhancement of lake effect snowfall over tug hill during iop2b of the ontario winter lake effect systems owles field campaign during the 24 h study period total liquid precipitation equivalent along the axis of maximum precipitation increased from 33 5 mm at a lowland 145 m msl site to 62 5 mm at an upland 385 m msl site the latter yielding 101 5 cm of snow however the ratio of upland to lowland precipitation or orographic ratio varied with the mode of lake effect precipitation strongly organized long lake axis parallel bands some of which formed in association with the approach or passage of upper level short wave troughs produced the highest pre

synthetic dual doppler analysis of a winter mesoscale vortex abstract this article presents a detailed examination of the kinematic structure and evolution of the 5 december 1997 winter mesoscale vortex in the vicinity of lake michigan using the synthetic dual doppler sdd technique when such a mesoscale event propagates a distance large enough that the viewing angle from a single doppler radar changes by about 30 and the circulation is sufficiently steady during this time period then the sdd method can reveal reliable details about the circulation one such detail of the observed vortex was a pattern of convergence and divergence associated with radial bands where heavier snowfall was located another was the steadiness and vertical coherence of the derived vorticity and convergence patterns within the cyclonic circulation on 5 december 1997 the observed reflectivity field remained remarkably steady for nearly 2 5 h as the vortex moved southeastward allowing for the application of the sdd technique the reflectivity field exhibited a pronounced asymmetric c

detecting lithology with advanced spaceborne thermal emission and reflection radiometer aster multispectral thermal infrared radiance at sensor data abstract the advanced spaceborne thermal emission and reflection radiometer aster aboard nasa s terra satellite measures multispectral thermal infrared tir emission from the earth s surface to space based on analysis of tir spectral properties of typical rocks on the earth several mineralogic indices including the quartz index qi carbonate index ci and mafic index mi for detecting mineralogic or chemical composition of quartzose carbonate and silicate rocks with aster tir data are proposed these indices are applied to the aster tir data scenes for selected study areas in china and australia the results show that aster tir can discriminate quartz and carbonate rocks as well as mafic ultramafic rocks even with atmospherically uncorrected radiance at sensor data lithologic interpretations agree well with published geologic data and field observations the mineralogic indices applied to aster tir provide one unified approach for lithologic mapping in arid and semi arid regions of the earth

deformation of the kenai peninsula alaska crustal deformation on the kenai peninsula in southern alaska has been studied using data obtained from global positioning system gps measurements in 1993 and 1995 and leveling observations in 1964 immediately after the prince william sound earthquake this analysis shows that the kenai peninsula has experienced as much as 900 mm uplift during the past 3 decades and that the uplift forms an 125 km wide elongate dome with its major axis trending southwest to northeast following the trend of the major tectonic features of the region the averaged uplift rate between 1964 and 1995 is as high as 30 mm yr 1 although the current uplift rate may be substantially lower the gps measurements cast further doubt on previously suspect tide gauge data for nikiski alaska which indicated rapid postseismic uplift at this site located in northwest kenai peninsula adjacent to cook inlet examination of the three dimensional gps data indicates that the eastern kenai peninsula is currently undergoing significant sse to nnw contraction in response to north american pacific plate convergence the horizontal velocities are consistent with the predictions of an elastic half space model for the interseismic deformation this result taken in combination with the small changes in uplift between 1993 and 1995 suggests that most of the present deformation is due to steady plate convergence rather than transient postseismic rebound

spatial variations in present day deformation kenai peninsula alaska and their implications from four years of global positioning system gps measurements we find significant spatial variations in present day deformation between the eastern and western kenai peninsula alaska sites in the eastern kenai peninsula and prince william sound move to the nnw relative to north america in the direction of pacific north america relative plate motion velocities decrease in magnitude from nearly the full plate rate in southern prince william sound to about 30 mm yr at seward and to about 5 mm yr near anchorage in contrast sites in the western kenai peninsula move to the sw in a nearly trenchward direction with a velocity of about 20 mm yr the data are consistent with the shallow plate interface offshore and beneath the eastern kenai and prince william sound being completely locked or nearly so with elastic strain accumulation resulting in rapid motion in the direction of relative plate motion of sites in the overriding plate the velocities of sites in the western kenai along strike to the southwest are opposite in sign with those predicted from elastic strain accumulation these data are incompatible with a significant locked region in this segment of the plate boundary trenchward velocities are found also for some sites in the anchorage area we interpret the trenchward velocities as being caused by a continuing postseismic transient from the 1964 great alaska earthquake there may be significant along strike differences in the long term behavior of the plate interface between the western and eastern kenai based on roughly coincident boundaries in the coseismic slip distribution cumulative postseismic uplift present day plate coupling and stress field the present postseismic response appears to generate purely trenchward motion suggesting a creep process that is purely dip slip our observations suggest that postseismic processes after the largest earthquakes can influence patterns of deformation for decades after the event

climatology of lake effect snowstorms of the great salt lake abstract characteristics of lake effect snowstorms associated with the great salt lake are described using wsr 88d radar imagery 16 well defined and 18 marginal lake effect events were identified from september 1994 through may 1998 excluding june august with the former used for more detailed analysis precipitation during the well defined events was frequently characterized by the irregular development of radar echoes over and downstream of the great salt lake the most commonly observed precipitation structures were solitary wind parallel bands that developed along or near the major axis of the gsl and broad area precipitation shields with embedded convective elements that formed near the southern shoreline regional scale composite analyses and rawinsonde derived statistics showed that the lake effect events occurred in post frontal westerly to northerly 700 hpa flow following the passage of an upper level trough and associated low level cold front the lake effect environment was characterized by

the role of boundary layer convergence zones and horizontal rolls in the initiation of thunderstorms a case study abstract the initiation of thunderstorms is examined through a combined observational and modeling case study the study is based on doppler radar aircraft mesonet balloon sounding and profiler and photographic data from the convection initiation and downburst experiment cinde conducted near denver colorado the study examines the initiation of a line of thunderstorms that developed along a preexisting quasi stationary boundary layer convergence line on 17 july 1987 the storms were triggered at the intersection of the convergence line with horizontal rolls where enhanced updrafts were present the primary effect of the convergence line was to deepen the moist layer locally and provide a region potentially favorable to deep convection the critical factor governing the time of storm development was apparently related to the attainment of a balance between horizontal vorticity in the opposing flows on either side of the convergence line the effect was to cause the updrafts in the convergence line

a site conditions map for california based on geology and shear wave velocity one simple way of accounting for site conditions in calculating seismic hazards is to use the shear wave velocity in the shallow subsurface to classify materials the average shear wave velocity to 30 m v 30s has been used to develop site categories that can be used for modifying a calculated ground motion to account for site conditions we have prepared a site category map of california by first classifying the geologic units shown on 1 250 000 scale geologic maps our classification of geologic units is based on v 30s measured in 556 profiles and geological similarities between units for which we have v s data and the vast majority of units for which we have no data we then digitized the geologic boundaries from those maps that separated units with different site classifications v s data for california shows that several widespread geologic units have ranges of v 30s values that cross the boundaries between nehrp ubc site categories the franciscan complex has v 30s values across ubc categories b and c with a mean value near the boundary between those two categories older alluvium and late tertiary bedrock have v 30s values that range from about 300 to about 450 m sec across the boundary between categories c and d to accommodate these units we have created intermediate categories which we informally call bc and cd geologic units that have or are interpreted to have v 30s values near the boundary of the ubc categories are placed in these intermediate units in testing our map against the available v 30s measurements we have found that 74 of the measured v 30s values fall within the range assigned to the v s category where they fall on the map this ratio is quite good considering the inherent problems in plotting site specific data on a regional map and the variability of physical properties in geologic units we have also calculated the mean and distribution of v 30s for each of our map units and prepared composite profiles showing the variation of v s in the upper 100 m from the available v s data these data show that the map categories that we have defined based on geologic units have different v s properties that can be taken into account in calculating seismic hazards

developing a map of geologically defined site condition categories for california consideration of site conditions is a vital step in analyzing and predicting earthquake ground motion the importance of amplification by soil conditions has long been recognized but though many seismic instrument sites have been characterized by their geologic conditions there has been no consistent simple classification applied to all sites as classification of sites by shear wave velocity has become more common the need to go back and provide a simple uniform classification for all stations has become apparent within the pacific earthquake engineering research center s next generation attenuation equation project developers of attenuation equations recognized the need to consider site conditions and asked that the california geological survey provide site conditions information for all stations that have recorded earthquake ground motion in california to provide these estimates we sorted the available shear wave velocity data by geologic unit generalized the geologic units and prepared a map so that we could use the extent of the map units to transfer the velocity characteristics from the sites where they were measured to sites on the same or similar materials this new map is different from the california geological survey preliminary site conditions map of california in that 19 geologically defined categories are used rather than national earthquake hazards reduction program categories although this map does not yet cover all of california when completed it may provide a basis for more precise consideration of site conditions in ground motion calculations

changes in crustal seismic deformation rates associated with the 1964 great alaska earthquake we calculated seismic moment rates from crustal earthquake information for the upper cook inlet region including anchorage alaska for the 30 yr prior to and 36 yr following the 1964 great alaska earthquake our results suggest over a factor of 1000 decrease in seismic moment rate in units of dyne centimeters per year following the 1964 mainshock we used geologic information on structures within the cook inlet basin to estimate a regional geologic moment rate assuming the structures extend to 30 km depth and have near vertical dips the geologic moment rates could underestimate the true rates by up to 70 since it is difficult determine the amount of horizontal offset that has occurred along many structures within the basin nevertheless the geologic moment rate is only 3 7 times lower than the pre 1964 seismic moment rate suggesting the 1964 mainshock has significantly slowed regional crustal deformation if we compare the geologic moment rate to the post 1964 seismic moment rate the moment rate deficit over the past 36 yr is equivalent to a moment magnitude 6 6 7 0 earthquake these observed differences in moment rates highlight the difficulty in using seismicity in the decades following a large megathrust earthquake to adequately characterize long term crustal deformation

numerical study of the influence of environmental conditions on lake effect snowstorms over lake michigan abstract numerical simulations are used to examine the influence of environmental parameters on the morphology of lake effect snowstorms over lake michigan a series of model sensitivity studies are performed using the colorado state university mesoscale model to examine the effects of lake land temperature difference surface roughness atmospheric boundary layer stability humidity and wind speed and direction on the morphology of simulated storms four morphological types of lake effect snowstorms have been identified i broad area coverage which may become organized into wind parallel bands or cellular convection ii shoreline bands with a line of convection roughly parallel to the lee shore and a well developed land breeze on the lee shore iii midlake band with low level convergence centered over the lake and iv mesoscale vortices with a well developed cyclonic flow pattern in the boundary layer the model is able to reproduce all four morphological types simulations varying environmenta

evaluation of remote sensing based seismic site characterization using earthquake damage data terra nova 24 123 129 2012 abstract preparing seismic site characterization maps requires extensive geological and geotechnical data collection and interpretation this study evaluates a remote sensing based method to generate seismic site characterization map at 30 m spatial resolution geographical object based image analysis was applied to topographic attributes computed from an advance spaceborne thermal emission and reflection radiometer digital elevation model to demarcate terrane units of mountains piedmonts and basins classified terrane units were verified through a field based landform map resulting in an accuracy of 70 to evaluate the importance of classified terrane units for seismic site characterization and their role in earthquake induced building damage the classified terrane units were compared with 2005 kashmir earthquake damage data derived from field visits and spot 5 imagery this shows that 81 of the less moderate and severe damage intensity zones correspond with mountains piedmonts and basins respectively classified terrane units were assigned vs30 to generate a seismic site characterization map

mapping the megathrust beneath the northern gulf of alaska using wide angle seismic data in the northern gulf of alaska and prince william sound we have used wide angle seismic reflection refraction profiles earthquake studies and laboratory measurements of physical properties to determine the geometry of the prince william and yakutat terranes the aleutian megathrust and the subducting pacific plate in this complex region the yakutat terrane is underthrust beneath the prince william terrane and both terranes are interpreted to be underlain by the pacific plate wide angle seismic reflection refraction profiles recorded along five seismic lines are used to unravel this terrane geometry modeled velocities in the upper crust of the prince william terrane to 18 km depth agree closely with laboratory velocity measurements of orca group phyllites and quartzofeldspathic graywackes the chief components of the prince william terrane to hydrostatic pressures as high as 600 mpa 6 kbar a landward dipping reflector at depths of 16 24 km is interpreted as the base of the prince william terrane this reflector corresponds to the top of the wadati benioff zone seismicity and is interpreted as the megathrust immediately beneath the megathrust is a 4 km thick 6 9 km s refractor which we infer to be the source of a prominent magnetic anomaly and which is interpreted by us and previous workers to be gabbro in eocene age oceanic crust of the underthrust yakutat terrane wide angle seismic data magnetic anomaly data and tectonic reconstructions indicate that the yakutat terrane has been underthrust beneath the prince william terrane for at least a few hundred kilometers wide angle seismic data are consistent with a 9 to 10 landward dip of the subducting pacific plate beneath the outer shelf and slope distinctly different from the inferred average 3 to 4 dip of the overlying 6 9 km s refractor and the wadati benioff seismic zone beneath the inner shelf our preferred interpretation of the geophysical data is that one composite plate composed of the pacific plate of a fairly uniform thickness and the yakutat plate of varying thickness is subducting beneath southern alaska

the transition from tethys to the himalaya as recorded in northwest pakistan early cenozoic sedimentary rocks exposed in the kohat plateau of northwestern pakistan record tectonic closure of the tethys sea and development of a restricted marine basin that formed during himalayan collision between india asia and a series of microplates in the paleocene initial subsidence of the basin was caused by the downward deflection of the indian plate in response to loading of the asian plate the western margin of the early eocene basin was dominated by deposition of shale sandstone and conglomerate derived from microplates located to the north and west of the indian continental margin the eastern margin of the basin was a carbonate shelf and sabkha flat salt deposition occurred subaqueously in the central parts of the basin in the late early eocene redbeds derived from the northwest were deposited by a fluvial and or deltaic system this influx of clastic sediments marks the earliest record of terrestrial foreland basin deposition in northwest pakistan during the middle eocene the basin was reflooded and a carbonate shelf developed relative sea level rise may reflect subsidence of the indian plate in response to continued crustal loading in the himalayan suture zone uplift and erosion occurred between the late eocene and miocene possibly related to a peripheral bulge south of the himalayan suture zone the main phase of himalayan foreland basin fluvial deposition began in the miocene renewed uplift related to final collision of india and afghanistan during the pliocene is recorded by a thick sequence of conglomerate in the western kohat plateau correlation with eocene sedimentary rocks from southern pakistan to northern india delineates the depositional systems that developed as the tethys sea closed during himalayan convergence

a large slow slip event and the depth of the seismogenic zone in the south central alaska subduction zone abstract we modeled crustal deformation before during and after a slow slip event sse on the plate interface in southern alaska we divided the gps time series into three time periods before 1998 1998 to 2001 and 2001 2002 the first and last periods represent the steady deformation while the middle period represents the sse we found a stationary zone of 100 slip deficit in the shallow part of the seismogenic zone to depths of 25 30 km which we identify with the main asperity that ruptured in 1964 earthquake the sse occurs downdip of the asperity on a section that accumulated some slip deficit during the steady time periods during the sse 20 000 sq km of the plate interface slipped 10 cm for a cumulative moment magnitude of m w 7 2 the area of the sse did not have a significant slip in the 1964 earthquake compared to the slip of the main asperity we propose that between earthquakes this zone fails repeatedly in sses and remains at relatively low shear stress compared to the main asperity up dip of it

lithologic mapping of the mordor nt australia ultramafic complex by using the advanced spaceborne thermal emission and reflection radiometer aster abstract spectral measurements made in the mordor pound nt australia study area using the advanced spaceborne thermal emission and reflection radiometer aster in the laboratory and in situ show dominantly al oh and ferric iron vnir swir absorption features in felsic rock spectra and ferrous iron and fe mg oh features in the mafic ultramafic rock spectra aster ratio images matched filter and spectral angle mapper processing sam were evaluated for mapping the lithologies matched filter processing in which vnir swir image spectra were used for reference resulted in 4 felsic classes and 4 mafic ultramafic classes based on al oh or fe mg oh absorption features and in some subtle reflectance differences related to differential weathering and vegetation these results were similar to those obtained by match filter analysis of hymap data from a previous study but the units were more clearly demarcated in the hymap image aster tir spectral emittance data and laboratory emissivity measurements document a wide wavelength range of si o spectral features which reflect the lithological diversity of the mordor ultramafic complex and adjacent rocks sam processing of the spectral emittance data distinguished 2 classes representing the mafic ultramafic rocks and 4 classes comprising the quartzose to intermediate composition rocks utilization of the complementary attributes of the spectral reflectance and spectral emittance data resulted in discrimination of 4 mafic ultramafic categories 3 categories of alluvial colluvial deposits and a significantly more completely mapped quartzite unit than could be accomplished by using either data set alone

simulated aster data for geologic studies the advanced spaceborne thermal emission and reflectance radiometer aster is a high spatial resolution imaging instrument scheduled to be launched on nasa s earth observing system am 1 satellite platform in 1988 aster acquires data in 14 bands spanning the visible near infrared short wavelength infrared and thermal infrared spectral regions with spatial resolution varying from 15 90 m depending on wavelength in order to evaluate the authors ability to use aster data for geological mapping they created a simulated 14 band aster data set for cuprite nevada the study site has sparse vegetation and exposes a wide range of unaltered and hydrothermally altered volcanic rocks the wide range of wavelengths covered by aster allowed them to distinguish iron oxide minerals clay bearing minerals sulfate minerals ammonia minerals siliceous rocks and carbonates based on interpretation of the aster data and in conjunction with laboratory and field spectral measurements they produced an alteration map showing the distribution of argillized rocks opalized rocks with alunite silicified rocks and areas dominated by kaolinite and buddingtonite the map was as accurate as published maps made by traditional field methods aster should be an improvement over existing satellite systems for geologic mapping

climatological characteristics and orographic enhancement of lake effect precipitation east of lake ontario and over the tug hill plateau abstractlake effect snowstorms east of lake ontario are frequently intense and contribute to substantial seasonal accumulations especially over the tug hill plateau hereafter tug hill which rises at a gentle 1 25 slope to 500 m above lake level using a variety of datasets including radar imagery from the ktyx fort drum new york wsr 88d this paper examines the characteristics of lake effect precipitation east of lake ontario over 13 cool seasons 16 september 2001 15 may 2014 during this period days with at least 2 h of lake effect account for 61 76 of the mean cool season snowfall and 24 37 of the mean cool season liquid precipitation mean monthly lake effect frequency and snowfall peak in december and january the highest lake effect frequency and snowfall occur over the western and upper tug hill with an arm of relatively high lake effect frequency and snowfall extending to the southeast shore of lake ontario to the east lee lake effect frequency and snowfall decrease abruptly ov

mesoscale vortices over the great lakes in wintertime abstract the occasional occurrence of wintertime mesoscale lake vortices is documented the vortices are readily discernible in satellite imagery in which they take one of three forms a miniature comma cloud a swirl of cloud bands resembling a miniature tropical storm or a swirl of cloud streets despite their impressive appearance in satellite imagery these vortices are usually relatively mild in comparison with other lake effect storms and produce only gusty winds and brief snow squalls as they move onshore the vortices are accompanied by a slightly lowered surface pressure and a weak cyclonic low level wind circulation fourteen vortices were detected over the great lakes in the years 1978 82 they occurred under conditions of relatively weak surface pressure gradient with a ridge of high pressure usually found over or west of the region convergence was generally detected in the surface winds prior to vortex development apparently related to land breeze circulations comparisons are made betw

geomorphometric analysis for characterizing landforms in morelos state mexico landforms can be described and quantified into simple relief elements by parametrization of digital elevation model dem in this research we investigate the use of morphometric parameters and a new classification scheme to characterize selected elemental forms associated with landforms we apply and test this methodology on a geomorphologically diverse region located in central mexico these simple elements are known as morphometric classes and include ridge plane channel pit peak and pass these classes correspond to real entities and are of practical significance the morphometric classes were grouped according to their areal parameters ridge plane and channel and pointed parameters pit peak and pass which can be used to form the basis of a system of characterization and classification of landforms landform elements display statistically significant compositional differences with respect to their proportions of morphometric classes this in turn can be plotted onto a diagram of characterization and classification known as a double ternary diagram dtd which comprises both areal and pointed parameters and any combination thereof the dtd is useful for studying geomorphological processes wherein areal and point values and properties have expressions which are topographically quantifiable

relation between the subducting plate and seismicity associated with the great 1964 alaska earthquake tectonic studies of the great 1964 alaska earthquake have underappreciated the nature of the subducted plate in influencing seismicity we compare seismological observations in the prince william and kodiak areas that ruptured during this earthquake with the corresponding morphology and structure of the subducting plate the upper plate geology prince william terrane and velocity structure are the same in both areas in the prince william area where the yakutat terrane subducted the energy released and coupling were stronger than above the kodiak subduction zone where thick trench sediment subducts the conjecture that lower plate character or the amount of subducted sediment affects coupling helps explain variability in seismology geodetic inversions and the horizontal velocity of gps stations

mesoscale spiral vortex embedded within a lake michigan snow squall band high resolution satellite observations and numerical model simulations abstract it is known that great lakes snow squall convection occurs in a variety of different modes on various factors such as air water temperature contrast boundary layer wind shear and geostrophic wind direction an exceptional and often neglected source of data for mesoscale cloud studies is the ultrahigh resolution multispectral data produced by landsat satellites on 19 0ctober 1972 a clearly defined spiral vortex was noted in a landsat 1 image near the southern end of lake michigan during an exceptionally early cold air outbreak over a still very warm lake in a numerical simulation using a 3 d eulerian hydrostatic equation mesoscale model 8 km grid 36 46 11 with an initially uniform wind field a definite analog to the observed vortex was generated this suggests that intense surface heating can be a principal cause in the development of a low level mesoscale vortex

model simulations examining the relationship of lake effect morphology to lake shape wind direction and wind speed abstract idealized model simulations with an isolated elliptical lake and prescribed winter lake effect environmental conditions were used to examine the influences of lake shape wind speed and wind direction on the mesoscale morphology this study presents the first systematic examination of variations in lake shape and the interplay between these three parameters the array of 21 model simulations produced cases containing each of the three classic lake effect morphologies i e vortices shoreline bands and widespread coverage and in some instances the mesoscale circulations were composed of coexisting morphologies located over the lake near the downwind shoreline or inland from the downwind shore as with lake effect circulations simulated over circular lakes the ratio of wind speed u to maximum fetch distance l was found to be a valuable parameter for determining the morphology of a lake effect circulation when variations of lake shape wind speed and wind direction were introduced f

comparison of observations with idealized model results for a method to resolve winter lake effect mesoscale morphology abstract forecasters in the great lakes region have for several decades recognized a general relationship of wind speed and overlake fetch to lake effect snowstorm morphology a recent study using idealized mesoscale model simulations of lake effect conditions over circular and elliptical lakes showed the ratio of wind speed to maximum fetch distance u l may be used to effectively predict lake effect snowstorm morphology the current investigation provides an assessment of the u l criteria using observational datasets previously published great lakes lake effect snowstorm observational studies were used to identify events of known mesoscale morphology hindcasts of nearly 640 lake effect events were performed using historical observations with u l as the predictor results show that the quantity u l contains important information on the different mesoscale lake effect morphologies however it provides only a limited benefit when being used to predict mesoscale morphology in real lake effect situations

a geostatistical approach to mapping site response spectral amplifications article if quantitative estimates of the seismic properties do not exist at a location of interest then the site response spectral amplifications must be estimated from data collected at other locations currently the most common approach employs correlations of site class with maps of surficial geology analogously correlations of site class with topographic slope can be employed where the surficial geology is unknown our goal is to identify and validate a method to estimate site response with greater spatial resolution and accuracy for regions where additional effort is warranted this method consists of three components region specific data collection a spatial model for interpolating seismic properties and a theoretical method for computing spectral amplifications from the interpolated seismic properties we consider three spatial interpolation schemes correlations with surficial geology termed the geologic trend gt ordinary kriging ok and kriging with a trend kt we estimate the spectral amplifications from seismic properties using the square root of impedance method thereby linking the frequency dependent spectral amplifications to the depth dependent seismic properties thus the range of periods for which this method is applicable is limited by the depth of exploration a dense survey of near surface s wave slowness ss throughout kobe japan shows that the geostatistical methods give more accurate estimates of ss than the topographic slope and gt methods and the ok and kt methods perform equally well we prefer the kt model because it can be seamlessly integrated with geologic maps that cover larger regions empirical spectral amplifications show that the region specific data achieve more accurate estimates of observed median short period amplifications than the topographic slope method

the tectonic history of kohistan and its implications for himalayan structure the tectonic history of kohistan northern pakistan involves two collisional events cleavage and folding developed at 90 100 ma along the northern suture between the kohistan island arc and the asian plate at the same time there was major folding and shearing of the lower part of the kohistan arc approximately 100 km south of the suture this deformation was followed by ocean subduction south of the kohistan arc generating the kohistan calc alkaline batholith with subsequent ocean closure during the eocene and obduction of the kohistan arc together with the adjacent part of the asian plate over the indian continental crust the construction of balanced cross sections through the imbricated upper part of the indian continental crust in the footwall to this southern suture indicates a minimum displacement of 470 km requiring the western himalayan hinterland to be underlain by a large wedge of indian middle to lower crust there is some shortening of the overriding kohistan and asian plates by thrusts and shear zones but it is insufficient to satisfy the palaeomagnetic data there must be major crustal shortening involving thrusts in the hindu kush and pamirs north of kohistan the post eocene thrust direction which for most of pakistan is towards 160 is almost perpendicular to that immediately to the east in the himalayan belt generating complex refolded thrust patterns in the hazara syntaxis and large scale folding and rapid uplift with associated brittle faulting and seismic activity adjacent to the nanga parbat syntaxis these different thrust trends indicate that major thrust movement as well as the folds and deformation fabrics cannot always be related to plate movement vectors but are modified by or develop from complex rotations during place collision or from the gravitational spreading of a thickened crust a regional approach is required to recognize and correctly attribute the various components in thrust displacements

testing the applicability of correlations between topographic slope and vs30 for europe in the past few years a series of articles have been published concerning the use of topographic slope from digital elevation models dems constructed through remote sensing satellite imaging to give first order estimates of national earthquake hazards reduction program nehrp site classes based on the average shear wave velocity in the top 30 m vs30 wald and allen 2007 we evaluate the potential applicability of these methods taking advantage of a large 706 sites new database of measured and estimated vs30 values and their topographic slopes for locations in europe and the middle east novel statistical tests are performed to evaluate the predictive power of the procedure in this region we evaluate the percentage of sites correctly classified misclassified for each site class for active and stable regimes we also analyze the marginal distributions of the input vs30 and slope values and their impact on the vs30 slope correlations and we evaluate whether the method performs better than does chance we also consider the surface geology of sites and investigate whether differences in geology can help explain why certain sites are poorly classified by the method finally we use the city of thessaloniki greece as a test case for comparison between the results of a recent microzonation and the site classes predicted by vs30 slope correlations our results show that the method does a better job than blind chance for all site classes in active regions but only for class b rock and to a lesser extent class c stiff soil sites located in stable areas although the conclusions for stable areas are based on limited data we recommend that site classifications based on the vs30 slope correlations proposed by wald and allen 2007 be used only for regional or national and not local or site specific first order studies in active parts of europe and only in the absence of other more detailed information excluding sites inside small basins or those with special geological conditions that may affect results e g flat lying volcanic plateaus carbonate rocks continental glaciated terrain or a coastal location if slope is not calculated using bathymetric data

airborne imaging spectrometer data of the ruby mountains montana mineral discrimination using relative absorption band depth images abstract airborne imaging spectrometer data collected in the near infrared 1 2 2 4 m wavelength range were used to study the spectral expression of metamorphic minerals and rocks in the ruby mountains of southwestern montana the data were analyzed by using a new data enhancement procedure the construction of relative absorption band depth rbd images rbd images like bandratio images are designed to detect diagnostic mineral absorption features while minimizing reflectance variations related to topographic slope and albedo differences to produce an rbd image several data channels near an absorption band shoulder are summed and then divided by the sum of several channels located near the band minimum rbd images are both highly specific and sensitive to the presence of particular mineral absorption features further the technique does not distort or subdue spectral features as sometimes occurs when using other data normalization methods by using rbd images a number of rock and soil units were distinguished in the ruby mountains including weathered quartz feldspar pegmatites marbles of several compositions and soils developed over poorly exposed mica schists the rbd technique is especially well suited for detecting weak near infrared spectral features produced by soils which may permit improved mapping of subtle lithologic and structural details in semiarid terrains the observation of soils rich in talc an important industrial commodity in the study area also indicates that rbd images may be useful for mineral exploration

convective evolution across lake michigan during a widespread lake effect snow event abstract lake effect snowstorms generally develop within convective boundary layers which are induced when cold air flows over relatively warm lakes in fall and winter mesoscale circulations within the boundary layers largely control which communities near the downwind shores of the lakes receive the most intense snow the lack of quantitative observations over the lakes during lake effect storms limits the ability to fully understand and predict these mesoscale circulations this study provides the first observations of the concurrent spatial and temporal evolution of the thermodynamic and microphysical boundary layer structure and mesoscale convective patterns across lake michigan during an intense lake effect event observations analyzed in this study were taken during the lake induced convection experiment lake ice aircraft and sounding observations indicate that the lake effect snows of 13 january 1998 developed within a convective boundary layer that grew rapidly across lake michigan boundary

seismicity of the prince william sound region for over thirty years following the 1964 great alaskan earthquake in this paper we present results of body wave form modeling of 19 earthquakes generally m b 5 7 occurring from 1964 to 1983 in the vicinity and down dip of the large asperity within the prince william sound region that ruptured in 1964 these data are supplemented with source parameters from studies of more recent post 1980 events our results suggest that moderate earthquakes which occurred in the region between 1964 and 1984 were predominantly located in the vicinity of the prince william sound asperity and could be assigned to two groups the first group consists of events occurring above the plate interface within prince william sound along reverse faults or low angle thrusts the second group occurs at 35 to 60 km depth in the region north of prince william sound and represents normal to normal oblique faulting within the subducted pacific crust or upper mantle these earthquakes occur below the northern edge of the 1964 asperity in a region where the subducting plate undergoes a rapid change in strike and dip a third group of events occurs in cook inlet well down dip of the 1964 asperity and below the plate interface these events exhibit a variety of mechanisms and many at depths of 50 to 70 km may be associated with complexities in the shape of the downgoing slab most of the cook inlet events occurred after 1984 whereas a few events of similar magnitude have occurred in the vicinity of the prince william sound asperity since 1984

first level seismic microzonation map of al madinah province western saudi arabia using the geographic information system approach the identification of natural hazard prone areas for future planning requires an efficient decision support tool to provide the appropriate weights for the various topographical geological and seismological factors responsible for the expected hazards in the present study an analytical hierarchy process ahp with six earthquake hazard parameters ehps was used as a decision support system for the identification of earthquake triggered hazards in the al madinah region of the kingdom of saudi arabia the pairwise comparison matrix and the final weights for all the ehps during the implementation of ahp were calculated with an acceptable limit of consistency ratio a gis based integrated analysis was carried out on all the selected attributes to generate the final hazard and microzonation map from the analysis it was observed that 15 of the region fall under a very high or high hazard category the very high seismic hazard zone is located in the northwestern region of al madinah province while the eastern and southern regions show low to very low hazard the result of the study may be used as a first level hazard and reliability map in selecting the appropriate earthquake resistant sites in designing the forthcoming new buildings against the potential seismic hazard of the province

predictions of shear wave velocities in southern california using surface geology a new model of the average shear wave velocity in the uppermost 30 m has been generated by extrapolation of discrete velocity profiles using surface geology at several scales statistical methods have been applied to create a map that is no more complicated than is supported by the velocity data several geologic units with similar responses are grouped together the resulting map is simpler than previous ones and yet fits the observed velocity profiles better than earlier more complicated maps analysis within a geographic information system will permit updates and modification of the map as new velocity data are added

three dimensional elastic dislocation modeling of the postseismic response to the 1964 alaska earthquake 1 gps velocity observations from the kenai peninsula and kodiak island alaska display a pattern of spatial variability suggesting the presence of multiple active processes on the underlying pacific north american plate interface velocities of sites on the eastern kenai peninsula and kodiak island are consistent with elastic strain accumulation at the plate interface whereas velocities of sites on the western kenai peninsula and cook inlet are oriented in the opposite direction and suggest an ongoing postseismic response to the 1964 alaska earthquake we can reproduce the observed velocities using a three dimensional elastic dislocation model to estimate the variation in coupling between the pacific and north american plates two different inversion schemes are examined to check the robustness of the results we find that the gps data can be satisfied by the presence of a locked area near southwest prince william sound a locked area near southwest kodiak island and an area of postseismic reverse slip beneath and north of the western kenai peninsula the shallow plate interface trenchward of the western kenai peninsula does not appear to be locked the locked areas correspond to the prince william sound and kodiak island asperities that ruptured in 1964 and the area of postseismic slip lies downdip of the 1964 rupture area the correspondence between the present shallow coupling distribution and the 1964 slip distribution suggests that the locked regions repeat from one earthquake cycle to another