a seiche hazard study for lake union seattle washington abstract large seismic waves can be a result of earthquakes on local regional or distant fault zones occasionally setting bodies of water into oscillation seismic seiching is a recurrent phenomenon in the state of washington and elsewhere e g berninghausen 1969 barberopoulou et al 2004 cassidy et al 2005 barberopoulou et al 2006 to investigate and characterize wave motion in lakes during strong ground shaking various scenarios of seiche generation are considered for lake union in seattle washington as subjected to a variety of ground motions both relatively simple harmonic and more complex earthquake excitation synthetic and real data are used in the modeling to isolate any effects resulting from a predominantly east west or north south motion or the contribution from parts of the shoreline ground motions are first separated into their horizontal components motions along latitude or longitude before they are combined this approach shows that long linear shorelines are the largest contributors to water wave heights depending on the shape of the lake enhanced wave heights can also be a result of focusing the wave motion in the lake is found to be predominantly east west even when the ground motions are in the north south direction the results of this study suggest that coastal structures can be vulnerable due to resonant excitation initiated from earthquakes on water bodies far from tsunamigenic sources

late quaternary deformation of the toppenish ridge uplift in south central washington mapping of quaternary sedimentary rocks and miocene basalts on toppenish ridge a fold in south central washington reveals a 32 km long zone of nearly 100 surface ruptures the ruptures indicate renewed movement on miocene structures in latest quaternary time the ruptures probably formed in response to regional compressive stress between 500 and 13 000 yr ago these ruptures are interpreted to represent the most recent surface deformation in central washington

definitive evidence of hesperian basalt in acidalia and chryse planitiae 1 the surface materials of acidalia and chryse planitiae mars have been variably interpreted morphologically as basalt and compositionally as andesite or altered basalt a thorough survey using the compact reconnaissance imaging spectrometer for mars crism near infrared spectrometer reveals olivine and high calcium pyroxene signatures in the shallow subsurface exposed by impact craters these signatures indicate that the near surface of these regions are primarily basaltic in nature and are similar to other regions of hesperian volcanism across mars e g syrtis major previous spectroscopic studies using coarser resolution data sets have failed to identify these mafic signatures due to obscuration of the underlying material in addition to the relatively small scale exposures in impact craters the nature of the surficial obscuration material is likely multifaceted and includes the deposition of latitude dependent mantling material and the presence of alteration rinds this observation shows that the northern plains of mars are basaltic and must be factored into the thermal and surficial evolution of mars

a global view of martian surface compositions from mgs tes thermal emission spectrometer tes data from the mars global surveyor mgs are used to determine compositions and distributions of martian low albedo regions two surface spectral signatures are identified from low albedo regions comparisons with spectra of terrestrial rock samples and deconvolution results indicate that the two compositions are a basaltic composition dominated by plagioclase feldspar and clinopyroxene and an andesitic composition dominated by plagioclase feldspar and volcanic glass the distribution of the two compositions is split roughly along the planetary dichotomy the basaltic composition is confined to older surfaces and the more silicic composition is concentrated in the younger northern plains

the 1983 borah peak idaho earthquake and its aftershocks abstract the 28 october 1983 borah peak idaho earthquake m s 7 3 occurred in an area of low historic seismicity within east central idaho along a segment of the lost river fault active during the holocene a dense network of portable short period seismographs up to 45 stations station spacings of 2 to 10 km was installed beginning several hours after the main shock and operated for 22 days in addition to records from the portable instrumentation data from permanent seismograph stations operating in idaho utah montana oregon washington and wyoming provide a good regional data base no foreshock activity above m c coda magnitude 2 0 was detected for the 2 month period preceding the main shock the epicenter of the main shock is 14 km south southwest of the end of the surface faulting this relationship suggests unilateral rupture propagating to the northwest the distribution of 421 aftershocks of m c 2 defines an epicentral pattern 75 km 10 km trending north northwest parallel to the surface rupture but displaced laterally southwest by 5 to 10 km aftershocks extend to depths of approximately 16 km and in the central and southeastern portion of the aftershock pattern define a zone dipping approximately 45 southwest that intersects the surface near the fault scarp the entire aftershock zone as observed during the first 3 weeks was active shortly after the main shock occurred fault plane solutions for 47 aftershocks show predominantly normal faulting with varying amounts of strike slip motion tension axis orientations indicate a dominant extension direction of nne ssw during the aftershock sequence there is considerable diversity among the aftershock focal mechanisms even along the central and southeast portions of the fault where the hypocenters appear to outline the main fault break we therefore interpret most of the aftershocks to represent complex fracturing on subsidiary structures adjacent to the main fault

initial results from the mini tes experiment in gusev crater from the spirit rover the miniature thermal emission spectrometer mini tes on spirit has studied the mineralogy and thermophysical properties at gusev crater undisturbed soil spectra show evidence for minor carbonates and bound water rocks are olivinerich basalts with varying degrees of dust and other coatings dark toned soils observed on disturbed surfaces may be derived from rocks and have derived mineralogy 5 to 10 of 45 pyroxene 20 ca rich pyroxene and 25 pigeonite 40 sodic to intermediate plagioclase and 15 olivine forsterite 45 5 to 10 two spectrally distinct coatings are observed on rocks a possible indicator of the interaction of water rock and airfall dust diurnal temperature data indicate particle sizes from 40 to 80 microm in hollows to approximately 0 5 to 3 mm in soils

olivine rich exposures at bellicia and arruntia craters on 4 vesta from dawn fc we present an analysis of olivine rich exposures at bellicia and arruntia craters using dawn framing camera fc color data our results confirm the existence of olivine rich materials at these localities as described by ammannito et al 2013a using visual infrared spectrometer vir data analyzing laboratory spectra of various howardite eucrite diogenite meteorites high ca pyroxenes olivines and olivine orthopyroxene mixtures we derive three fc spectral band parameters that are indicators of olivine rich materials combining the three band parameters allows us for the first time to reliably identify sites showing modal olivine contents 40 the olivine rich exposures at bellicia and arruntia are mapped using higher spatial resolution fc data the exposures are located on the slopes of outer inner crater walls on the floor of arruntia in the ejecta as well as in nearby fresh small impact craters the spatial extent of the exposures ranges from a few hundred meters to few kilometers the olivine rich exposures are in accordance with both the magma ocean and the serial magmatism model e g righter and drake 1997 yamaguchi et al 1997 however it remains unsolved why the olivine rich materials are mainly concentrated in the northern hemisphere approximately 36 42 n 46 74 e and are almost absent in the rheasilvia basin

seismic activity of the san francisco bay region moment magnitude m with objective confidence level uncertainties are estimated for felt san francisco bay region earthquakes using bakun and went worth s 1997 analysis strategy for seismic intensity observations the frequency magnitude distribution is well described for m 5 5 events since 1850 by a gutenberg richter relation with a b value of 0 90 the seismic moment rate m yr since 1836 is 2 68 1018 n m yr 95 confidence range 1 29 1018 n m yr to 4 07 1018 n m yr the seismic moment rate since 1850 is nearly the same m yr in the 56 years before 1906 is about 10 times that in the 70 years after 1906 in contrast m yr since 1977 is about equal that in the 56 years before 1906 80 1 14 of the plate motion moment accumulation rate is available for release in earthquakes the historical m yr and the portion of the plate motion moment accumulation rate available for release in earthquakes are used in a seismic cycle model to estimate the rate of seismic activity in the twenty first century high and low rates of future seismic activity are both permissible given the range of possible seismic cycle recurrence times t and the uncertainties in the historical m and in the percentage of plate motion available for release in earthquakes if the historical seismic moment rate is not greater than the estimated 2 68 1018 n m yr and the percentage of the plate motion moment accumulation available for release in earthquakes is not less than the estimated 80 then for all t the rate of seismic moment release from now until the next 1906 sized shock will be comparable to the rate from 1836 to 1905 when m 6 1 2 shocks occurred every 15 to 20 years

seismicity of california s north coast at least three moment magnitude m 7 earthquakes occurred along california9s north coast in the second half of the nineteenth century the m 7 3 earthquake on 23 november 1873 occurred near the california oregon coast and likely was located on the cascadia subduction zone or within the north american plate the m 7 0 earthquake on 9 may 1878 was located about 75 km offshore near the mendocino fault the surface wave magnitude m s 7 0 earthquake on 16 april 1899 was located about 150 km offshore within the gorda plate there were at least three m 7 north coast earthquakes in the 35 years before 1906 two m 7 earthquakes in the 20 years after 1906 no m 7 earthquakes from 1923 until 1980 and four m 7 earthquakes since 1980 the relative seismic quiescence after 1906 for m 7 earthquakes along california9s north coast mimics the post 1906 seismic quiescence in the san francisco bay area for m 6 earthquakes the post 1906 relative quiescence did not extend to lower magnitudes in either area the 18 april 1906 earthquake apparently influenced the rate of occurrence of m 7 north coast earthquakes as it apparently influenced the rate of m 6 earthquakes in the san francisco bay area the relative seismic quiescence along the california north coast region after 1906 should be taken into account when evaluating seismic hazards in northwest california

spectral evidence for weathered basalt as an alternative to andesite in the northern lowlands of mars mineral abundances derived from the analysis of remotely sensed thermal emission data from mars have been interpreted to indicate that the surface is composed of basalt surface type 1 and andesite surface type 2 1 the global distribution of these rock types is divided roughly along the planetary dichotomy which separates ancient heavily cratered crust in the southern hemisphere basalt from younger lowland plains in the north andesite 1 but the existence of such a large volume of andesite is difficult to reconcile with our present understanding of the geological evolution of mars here we reinterpret martian surface rock lithologies using mineral abundances from previous work1 and new mineralogies derived from a spectral end member set representing minerals common in unaltered and low temperature aqueously altered basalts our results continue to indicate the dominance of unaltered basalt in the southern highlands but reveal that the northern lowlands can be interpreted as weathered basalt as an alternative to andesite the coincidence between locations of such altered basalt and a suggested northern ocean basin implies that lowland plains material may be composed of basalts weathered under submarine conditions or weathered basaltic sediments transported into this depocentre

a high frequency magnitude scale a high frequency magnitude scale m is proposed m 2 log a h f 3 where ahf is the high frequency level of the fourier amplitude spectrum of acceleration in cm sec average or random horizontal component at a hypocentral or closest fault distance of 10 km m can be determined from either instrumental data or the felt area of an earthquake the definition of m has been arranged such that m m moment magnitude for events of average stress drop in both eastern north america ena and california m provides a measure of the stress drop if m is also known the observed relationship between m and m indicates that the average stress drop is about 150 bars for ena earthquakes and about 70 bars for california earthquakes the variability of stress drop is much larger in ena than in california the chief justification for the m scale is its utility in the interpretation of the large preinstrumental earthquakes that are so important to seismic hazard estimation in eastern north america for such events m can be determined more reliably than can m or mn nuttli magnitude and forms a much better basis for estimating high frequency ground motions when used as a pair m and m provide a good index of ground motion over the entire engineering frequency band if both of these magnitudes can be defined for an earthquake then a ground motion model such as the stochastic model can be used to obtain reliable estimates of response spectra and peak ground motions

olivine and pyroxene diversity in the crust of mars datafromthe observatoire pour la mineralogie l9eau les glaces et l9activite omega on the mars express spacecraft identify the distinct mafic rock forming minerals olivine low calcium pyroxene lcp and high calcium pyroxene hcp on the surface of mars olivine and hcp rich regions are found in deposits that span the age range of geologic units however lcp rich regions are found only in the ancient noachian aged units which suggests that melts for these deposits were derived from a mantle depleted in aluminum and calcium extended dark regions in the northern plains exhibit no evidence of strong mafic absorptions or absorptions due to hydrated materials

geology and mineralogy of the auki crater tyrrhena terra mars a possible post impact induced hydrothermal system abstract a variety of hydrothermal environments have been documented in terrestrial impact structures due to both past water interactions and meteoritic bombardment on the surface of mars several authors have predicted various scenarios that include the formation of hydrothermal systems geological and mineralogical evidence of past hydrothermal activity have only recently been found on mars here we present a geological and mineralogical study of the auki crater using the spectral and visible imagery data acquired by the crism compact reconnaissance imaging spectrometer for mars ctx context camera and hirise high resolution imaging science experiment instruments on board the nasa mro mission the auki crater is a complex crater that is 38 km in diameter located in tyrrhena terra 96 8 e and 15 7 s and shows a correlation between its mineralogy and morphology the presence of minerals such as smectite silica zeolite serpentine carbonate and chlorite associated with morphological structures such as mounds polygonal terrains fractures and veins suggests that the auki crater may have hosted a post impact induced hydrothermal system although the distribution of hydrated minerals in and around the central uplift and the stratigraphic relationships of some morphological units could also be explained by the excavation and exhumation of carbonate rich bedrock units as a consequence of crater formation we favor the hypothesis of impact induced hydrothermal circulation within fractures and subsequent mineral deposition the hydrothermal system could have been active for a relatively long period of time after the impact thus producing a potential transient habitable environment

teleseismic estimates of the energy radiated by shallow earthquakes the energy flux contained in the p wave groups p pp sp or the s wave groups s ps ss radiated by a shallow earthquake is modeled assuming that the energy flux in the direct and depth phases adds incoherently by defining generalized radiation patterns which incorporate this neutral interference the wave groups are analyzed as though they were comprised of a single phase measurements of the energy flux in the wave groups are corrected in the frequency domain for both the body wave attenuation and the frequency band of the recording the corrected measurements are then used to estimate the seismic energy radiated by the earthquake this analysis is applied to digital recordings of the teleseismic wave groups radiated by the may 2 1983 coalinga california earthquake and the october 28 1983 borah peak idaho earthquake for the coalinga earthquake an estimate of es 1 6 0 4 1021 dyn cm was determined from six p wave groups while the sh wave group recorded at station col returned an estimate of es 1 2 1021 dyn cm for the borah peak earthquake an estimate ofes 3 2 0 5 1021 dyn cm was determined from seven p wave groups the distribution of the isoseismals for the borah peak earthquake indicate that the energy radiated by this event was focussed to the northwest in the direction of rupture propagation correcting the teleseismic estimate for this focussing gives es 3 6 0 5 1021 dyn cm combining these estimates of the radiated energy with broad band estimates of the seismic moment yields estimates of the apparent stress of 17 and 7 bars for the coalinga and the borah peak earthquakes respectively

coda q for the state of washington abstract frequency dependent coda q values for subregions of the state of washington have been determined using a time domain coda decay method a total of 95 earthquakes digitally recorded on a regional seismograph network of over 100 short period stations were selected to obtain 206 on scale high signal to noise ratio traces for analysis grouping the data by structural regions of the state showed only small variations in coda q by region other than in a very localized area at mount st helens at mount st helens coda q was significantly lower than for all other areas an average of all of the data except that from the local mount st helens area results in a q relationship of q c 63 f 0 97 for the frequency band 2 to 16 hz there is little variation of this coda q relationship when using sources down to 50 km depth and thereby uniformly sampling the top 50 to 100 km of the crust and upper mantle

mineralogy of the nili fossae region with omega mars express data 2 aqueous alteration of the crust 1 nili fossae is a region with fresh exposures of old material omega spectral data have revealed a strong diversity of minerals in the nili fossae region including mafic minerals and phyllosilicates phyllosilicates are found to be primarily fe rich smectites a type of clay minerals these phyllosilicates are observed only on the noachian crust in four types of locations three are without any signatures other than phyllosilicates on 1 smooth layered deposits 2 massive exhumed material and 3 crater ejecta and one type of location is associated with olivine 4 over an altered mafic unit this diversity suggests a widespread liquid water activity and a variety of alteration processes the formation of phyllosilicates underwent considerable reduction if not cessation by the time of formation of syrtis major lava flows in the hesperian period phyllosilicates are spatially and chronologically disconnected from the fluvial and depositional landforms observed in the nili fossae region observations suggest that these landforms formed after the extensive formation of phyllosilicates during short periods of time and or temperatures close to freezing

prediction of some weathering trends of plutonic and volcanic rocks based on thermodynamic and kinetic considerations abstract the exposed crust consists mainly of plagioclase 35 quartz 20 k feldspar 11 volcanic glass 12 biotite 8 and muscovite 5 quartz is a resistate thus feldspars and glass represent approximately 75 percent of the labile minerals the weathering characteristics of these constituents are summarized in the context of thermodynamic mass balance and kinetic considerations experimentally determined release rate constants were used to predict the proportions of ca na and k released by feldspars of plutonic rocks granites to gabbros to weathering solutions the chemical weathering trends of the weathered residues calculated from the kinetic data conform closely to the initial trends observed in some recent weathering profiles demonstrating the accuracy of the predictions since the weathering of feldspars is controlled by processes that should not change through geological time the relative release rates of ca na and k from the feldspars of granitic rocks can be calculated for future and past episodes of continental weathering experimentally determined release rate constants are not available for a wide range of volcanic glass compositions but the limited data indicate that compositional trends are predictable in weathering profiles developed on volcanic rocks the kinetic data available for rhyolitic glasses accurately predict the initial weathering trends observed in a recent rhyolite weathering profile

late quaternary deformation saddle mountains anticline south central washington grabens and beheaded streams above a subjacent thrust fault illuminate late quaternary deformation on the north limb of the saddle mountains anticline yakima fold belt washington geologic mapping and trenches excavated across a scarp on the north flank of a 13 km long graben and a 5 m high scarp north of the graben confirm that deformation is related to coseismic slip on the underlying saddle mountains fault graben development began ca 100 ka and continued into the holocene at least 6 5 m of vertical displacement in a ca 20 40 ka paleosol yields minimum normal fault slip rates of 0 16 0 33 mm yr assuming that normal slip in the hanging wall above the daylighting fault tip is related to primary reverse slip on the fault resolution of throw on the 30 dipping saddle mountains fault yields minimum slip of 13 m and minimum slip rates of 0 33 0 65 mm yr 2 3 9 4 times greater than slip rates used in a recent seismic hazard analysis for the hanford reservation

impact melts and glasses on mars 1 dark mobile materials on mars are widely considered to be volcanically derived windblown particulates such a conclusion is consistent with the large volcanic edifices on mars and the assumption that a volatile rich crust would not favor significant impact melt generation several post viking discoveries however provide new perspectives for reconsidering alternative origins not only for some of the mobile dark veneers but also certain materials at the pathfinder and viking landing sites first certain dark materials on mars do not exhibit the expected mafic absorption features in their reflectance spectra second the pathfinder mission revealed unexpected feldspathic compositions of vesicular blocks that lead to a preliminary conclusion that they represent andesites or basaltic andesites rather than basalts third recent discoveries of holocene to miocene impacts in argentine loessoid deposits provide new insights for the nature of melts generated from eolian sediments fourth global dispersal of impact melt products are now recognized in the terrestrial record throughout the cenozoic consequently the generation and preservation of impact glass on mars should be reconsidered possible occurrences include possible tektite like strewnfields downrange from recent oblique impacts dark avalanches emerging from backwasting cliffs of easily eroded unconformable deposits global dispersal of glassy ejecta from hesperian and amazonian craters of chicxulub scale and dark mobile veneers emerging from noachian craters we propose that the mobile dark materials comprising many of the named features of mars as well as some blocks at the pathfinder viking landing sites may represent impact melt products

probability distribution of intensity attenuations for colombia and western venezuela abstract this paper presents a database of isoseismal maps and referenced processed isoseismal contour areas and equivalent radii data for colombia and neighboring regions based on earthquakes occurring between 1766 and 2004 the database is used to develop a model for the conditional exceedence probability of a level of seismic intensity given distance to a site and the epicentral intensity the model comprises mixed discrete continuous joint probability distributions the conditional distribution of distance for a given intensity or intensity difference is continuous and is represented by a lognormal distribution the distribution of intensities is discrete and is represented by bimodal poisson functions the bimodal representation may be due to wave reflections at the boundary between the lithosphere and the asthenosphere in the region bayes theorem is used to integrate the continuous and discrete distributions to provide the conditional exceedence probabilities of intensity given distance and epicentral intensities two separate models are proposed one for shallow crustal events with depths less than 40 km and the second for subduction events the models are applied to colombia and western venezuela

weathering and global denudation a negative correlation between sediment yield and weathering history as measured by the chemical alteration cia of the suspended sediment is observed for many of the world s major rivers and other regions of denudation the weathering history is a first order control on the sediment yield of such areas termed equilibrium denudation regions for other areas data scatter with either apparent increases or decreases of sediment yield for given cia values these areas are termed nonequilibrium denudation regions low sediment yields can be attributed to moderated erosion either natural or human induced and or the incorporation of unweathered glacial debris accelerated erosion resulting in high sediment yield is primarily human induced and results from cultivation and other land use each of these effects has a profound influence on global sediment discharge from the continents pre human suspended sediment discharge from the continents is estimated to be 12 6 times 10 15 g yr or about 0 6 the

centroid moment tensor solutions for 35 earthquakes in western north america 1977 1983 abstract seismic records from the gdsn sro asro dwwssn rstn and ida networks were used to obtain long period t 45 sec focal mechanisms for 35 earthquakes in western north america longitude 140 to 110 latitude 30 to 60 employing the centroid moment tensor method of dziewonski et al 1981 and dziewonski and woodhouse 1983 the same algorithm was applied to all events the smallest m 0 6 4 10 23 dyne cm being an aftershock to the 1979 imperial valley california earthquake and the largest m 0 8 5 10 26 dyne cm the 1980 eureka california earthquake all events were analyzed with and without the constraint m r m r 0 on the moment tensor an ad hoc criterion on the relative variance reduction was employed to determine a favored solution our solutions show general agreement with other published results as well as with tectonic structures agreement with results obtained using the abundant local and regional data confirms the adequacy of the method in determining long period source parameters and verifies its applicability in regions where local and regional data are scarce or nonexistent in some cases disagreement between our solution and results from first motion studies appears to be related to source complexities our moment tensor represents the total stress release of the composite event a consistent westward movement of the centroid locations reflects lateral heterogeneities in the crust and mantle

surface faulting accompanying the borah peak earthquake and segmentation of the lost river fault central idaho on the morning of 28 october 1983 the ms 7 3 borah peak earthquake struck central idaho and formed a y shaped zone of surface faults that is divided into a southern a western and a northern section the total length of the surface faults is 36 4 3 1 km and the maximum net throw is 2 5 to 2 7 m the near surface net slip direction determined from the rakes of striations in colluvium averaged 0 17 m of sinistral slip for 1 00 m of dip slip the 20 8 km long southern section is the main zone of surface faulting and coincides with the thousand springs segment of the lost river fault it has the largest amount of net throw most complex rupture patterns and best evidence of sinistral slip the surface faults include zones of ground breakage as much as 140 m wide en echelon scarps with synthetic and antithetic displacements and individual scarps that are nearly 5 m high the 14 2 km long western section diverges away from the lost river fault near the northern end of the southern section the net throw on this section is generally less than 0 5 m but locally is as much as 1 6 m the new ruptures are poorly developed across the crest and north flank of the willow creek hills they are mostly downhill facing arcuate scars perhaps incipient landslides that may overlie a deeper zone of tectonic movement the northern section at least 7 9 km long is on the warm spring segment of the lost river fault and has a maximum net throw of about 1 m the pattern of surface faulting on this section is simple compared to the other sections a 4 7 km long gap in 1983 surface faults separates the northern and southern sections but contains an older scarp of late pleistocene age geologic seismologic and geodetic data from the earthquake suggest that barriers confined the primary coseismic rupture to the thousand springs segment of the fault the rupture propagated unilaterally to the northwest from a hypocenter near the southeastern end of the segment the southeastern boundary of the segment is marked by an abrupt bend in the range front a 4 km long gap in late quaternary scarps and transverse faults of eocene age that intersect the lost river fault the northwestern boundary of the thousand springs segment is at the junction of the willow creek hills and the lost river fault here the southern and western sections of surface faults diverge and there is a gap in the 1983 scarps during the first few weeks after the main shock the large magnitude and large stress drop aftershocks clustered near this barrier later aftershocks were mainly northwest of the barrier on the warm spring and challis segments and showed that strain adjustments eventually affected the entire northern part of the lost river fault fault scarp morphology and the bedrock geology suggest that the boundary between the thousand springs and warm spring segments has probably ruptured less frequently and had less net slip during much of the late cenozoic than the interior of the adjacent segments the 1983 faulting shows that although segment boundaries can stop or deflect primary ruptures secondary surface faulting can occur on adjacent segments of the main fault a late pleistocene scarp in the 1983 gap suggests that infrequent earthquakes perhaps larger than the 1983 event might break through a segment boundary and thus release strain on two adjacent segments

a tsunami about 1000 years ago in puget sound washington water surged from puget sound sometime between 1000 and 1100 years ago overrunning tidal marshes and mantling them with centimeters of sand one overrun site is 10 kilometers northwest of downtown seattle another is on whidbey island some 30 kilometers farther north neither site has been widely mantled with sand at any other time in the past 2000 years deposition of the sand coincided to the year or less with abrupt probably tectonic subsidence at the seattle site and with landsliding into nearby lake washington these findings show that a tsunami was generated in puget sound and they tend to confirm that a large shallow earthquake occurred in the seattle area about 1000 years ago

a revised magnitude recurrence relation for shallow crustal earthquakes in southwestern british columbia considering the relationships between moment magnitude and regional magnitudes an important component of seismic hazard analysis is the magnitude recurrence relation which provides the cumulative rate of occurrence of earthquakes within a seismic source zone as a function of magnitude in the national seismic hazard maps developed for the 2005 national building code of canada the magnitude recurrence relation for the cascade mountains zone of southwestern british columbia casr the seismic zone in which vancouver and victoria are located is based mainly on earthquakes measured on the local scale m l richter scale but other scales including body wave magnitude m b coda duration magnitude m c and moment magnitude m have been used for some of the events the mixture of magnitude types is a potential source of bias in the relations by using data from recently calculated regional moment tensor solutions a local magnitude moment magnitude relationship is developed for magnitudes of 2 9 m l 6 0 in the casr zone this relation along with relations from other sources for m b and m c and specific moment magnitude values where available are used to develop a homogeneous moment magnitude catalog for use in the formulation of a new casr zone magnitude recurrence relation the use of a homogeneous moment magnitude scale produces a significant change in the shape of the magnitude recurrence curve in the casr zone perhaps more importantly the use of a homogeneous catalog reduces the uncertainty in the recurrence rates of moderate to large earthquakes in casr by nearly an order of magnitude we conclude that the use of a homogeneous magnitude scale is critical to producing unbiased magnitude recurrence relations

a systematic mapping procedure based on the modified gaussian model to characterize magmatic units from olivine pyroxenes mixtures application to the syrtis major volcanic shield on mars clenet et al 2011 have developed an adapted version of the modified gaussian model mgm the improvements allow the characterization of spectra of olivine pyroxene s mixtures addressing both modal composition and individual minerals chemical composition this version of mgm is fully automated and operational with large amounts of hyperspectral imaging data two natural cases are considered the first one is the sumail massif in the oman ophiolite earth based on our approach applied to hymap data two contrasted lithologic units are mapped the mantle which is harzburgite dominated and the crust made of gabbros and clinopyroxene rich cumulates with spectral variations interpreted in terms of pyroxenes chemical compositions once this new mgm mapping approach has been validated on a controlled natural situation we map the distribution of mafic assemblages across the syrtis major volcano on mars using a visible and near infrared vnir short wave infrared swir observatoire pour la mineralogie l eau les glaces et l activite omega mars express mex mosaic our results are in agreement with previous work but olivine appears to be more abundant than previously estimated in the central part of the volcanic edifice especially in ternary mafic assemblages augite olivine enstatite based on these results we propose a possible scenario for the igneous and thus thermal evolution of the syrtis major region surrounding terrains have formed first and local heterogeneity can be observed between northern and southern areas of the noachian crust we also observe variations in the mineral assemblages within syrtis major lavas which can be interpreted in terms of differentiation from a common parent melt and or of a progressive evolution of the mantle source composition and temperature key points mgm systematic mapping on syrtis major to characterize mafic minerals mixtures olivine and pyroxenes mixture is detected in the central lavas of the volcano pyroxenes have chemical compositions spanning the enstatite augite range

two years at meridiani planum results from the opportunity rover the mars exploration rover opportunity has spent more than 2 years exploring meridiani planum traveling 8 kilometers and detecting features that reveal ancient environmental conditions these include well developed festoon trough cross lamination formed in flowing liquid water strata with smaller and more abundant hematite rich concretions than those seen previously possible relict hopper crystals that might reflect the formation of halite thick weathering rinds on rock surfaces resistant fracture fills and networks of polygonal fractures likely caused by dehydration of sulfate salts chemical variations with depth show that the siliciclastic fraction of outcrop rock has undergone substantial chemical alteration from a precursor basaltic composition observations from microscopic to orbital scales indicate that ancient meridiani once had abundant acidic groundwater arid and oxidizing surface conditions and occasional liquid flow on the surface

source parameters of the 1949 magnitude 7 1 south puget sound washington earthquake as determined from long period body waves and strong ground motions teleseismic p sh and sv first motions and sh to sv amplitude ratios recorded at eight teleseismic receivers from the 1949 magnitude 7 1 olympia washington earthquake in combination with data from three stations at regional distances were utilized in a grid testing routine to constrain focal mechanism identification of the pp phase places the event at 54 km depth distinct pulses assumed to be source effects are observed in the far field waveforms analysis of these pulses for directivity made possible discrimination between the fault and auxiliary planes the plane taken to represent the fault surface strikes east west 15 dips 45 15 to the north and has nearly pure left lateral slip the preferred source model has an eastward propagation of 40 km surface reflections of successive source pulses suggest an upward component of propagation of 5 km bounds on the earthquake location and rupture of the 13 april event were determined using depth and source mechanism constraints from the teleseismic study and characteristics of local strong ground motion recordings the 9 sec s instrument trigger time seen in the seattle acceleration recordings places the event at least 60 km from seattle strong motion velocity at the olympia highway test laboratory is characterized by an impulsive and rectilinear s wave the low amplitude of the vertical component of initial s motion suggests that either the epicenter is within 5 km of the olympia highway test laboratory for a pure incident sv wave or located along an azimuth of n159 if the wave is sh the combined constraint of minimum distance from seattle and the s polarization angle implied by the teleseismic data focal mechanism places the initiation of rupture 5 to 10 km north to north northwest of the olympia highway test laboratory at 47 13 n 122 95 w this is approximately 20 km west of previously determined epicenters the t axis gently dipping to the southeast supports other evidence that the juan de fuca plate dips to the southeast in a zone between segments of the plate north and south of the event s location the fault plane s slip is taken to indicate that subduction is still active beneath washington and that motion of the two segments is probably independent

estimating locations and magnitudes of earthquakes in eastern north america from modified mercalli intensities we use 28 calibration events 3 7 m 7 3 from texas to the grand banks newfoundland to develop a modified mercalli intensity mmi model and associated site corrections for estimating source parameters of historical earthquakes in eastern north america the model batchmode documentclass fleqn 10pt legalpaper article usepackage amssymb usepackage amsfonts usepackage amsmath pagestyle empty begin document mathrm mmi 1 41 1 68 times mathbf m 0 00345 times delta 2 08 mathrm log delta end document where is the distance in kilometers from the epicenter and m is moment magnitude provides unbiased estimates of m and its uncertainty and if site corrections are used of source location the model can be used for the analysis of historical earthquakes with only a few mmi assignments we use this model mmi site corrections and bakun and wentworth s 1997 technique to estimate m and the epicenter for three important historical earthquakes the intensity magnitude m i is 6 1 for the 18 november 1755 earthquake near cape ann massachusetts 6 0 for the 5 january 1843 earthquake near marked tree arkansas and 6 0 for the 31 october 1895 earthquake the 1895 event probably occurred in southern illinois about 100 km north of the site of significant ground failure effects near charleston missouri manuscript received 14 march 2002

quantitative compositional analysis of martian mafic regions using the mex omega reflectance data 1 methodology uncertainties and examples of application abstract the mars express observatoire pour la mineralogie l eau les glaces et l activite omega collected an unprecedented visible and near infrared hyperspectral dataset covering the low albedo regions of mars we investigate the ability to infer modal abundance of surfaces of these regions from a radiative transfer model developed by shkuratov et al shkuratov y starukhina l hoffmann h arnold g 1999 icarus 137 235 246 and adapted to basaltic surfaces by poulet and erard poulet f erard s 2004 j geophys res 109 e2 doi 10 1029 2003je002179 from omega measurements of mafic surfaces we develop several sensitivity tests to assess the extent to which the model can be applied to predict pyroxene composition high calcium phase and low calcium phase abundance of almost neutral components plagioclase in the near infrared wavelength as well as grain sizes by using a library of selected end members results of the sensitivity tests indicate that the scattering model can estimate both abundances and grain sizes of major basaltic materials of low albedo regions within uncertainties 5 to 15 vol the model is then applied to data from dissected cratered terrains located in terra meridiani the derived grain size including uncertainties is in the 50 500 m range this is consistent with the thermal inertia and albedo of this region which indicates a fine sand sized surface with little dust the abundances of plagioclase 43 57 and pyroxenes 35 45 10 including 11 5 of low calcium phase are in good agreement with previous basalt like compositions of low albedo regions from thermal infrared spectral measurements the method presented in this paper will provide a valuable tool for evaluating the modal mineralogy of other mafic regions of mars observed in the near infrared wavelength range

seismotectonics of the portland oregon region abstract portland oregon lies in the southern half of an approximately rectangular basin measuring 30 by 50 km since 1969 there have been no earthquakes with m 4 0 in or on the margins of the portland basin but this level of seismicity may not be characteristic of the region using microseismicity data collected by the university of washington regional short period seismograph network for the period mid 1982 through 1989 we have determined p wave focal mechanisms for four individual earthquakes and three groups of earthquakes we have also relocated the 6 november 1962 m w 5 2 portland earthquake and analyzed regional surface wave recordings of this event using the seismic moment tensor inversion technique the results of these seismic analyses along with geologic and other geophysical data are integrated into a seismotectonic model of the portland basin the p wave mechanisms are compatible with dextral strike slip motion along approximately nw striking fault zones bounding the eastern and western margins of the basin we speculate that there is a dextral strike slip fault zone which we call the frontal fault zone along the eastern margin of the portland basin the western margin has been previously recognized as a zone of dextral strike slip faulting known as the portland hills fault zone the epicenter of the 1962 earthquake is located between the two fault zones and lies approximately 15 km ne of downtown portland our preferred mechanism is normal faulting on ne or nne trending fault planes these results support the hypothesis posed by previous investigators that the portland basin is a pull apart basin and are evidence for contemporary crustal extension between the frontal and portland hills fault zones

strong ground motion in the 1983 borah peak idaho earthquake and its aftershocks abstract thirteen strong motion accelerographs sited in a permanent array at the idaho national engineering laboratory inel were the closest instruments to the m s 7 3 1983 borah peak idaho earthquake they recorded the event at epicentral distances of 90 to 110 km the peak horizontal accelerations or peak ground accelerations pgas at the basement and free field sites of the array ranged from 0 022 to 0 078 g for 2 weeks after the main shock the u s geological survey maintained an array of digital seismographs in the epicentral area these instruments recorded six large aftershocks at epicentral distances of 4 to 45 km the largest of these aftershocks also triggered four accelerographs in the inel array pgas for the main shock are estimated by two separate analyses first the attenuation of the pgas from the largest aftershock is used to extrapolate the far field pga into the near field obtaining estimates of 0 54 0 58 0 21 and 0 24 g at epicentral distances of 11 12 16 and 18 km respectively second paired recordings for a set of small aftershocks obtained from a near field station u s geological survey portable instrument and a far field station inel telemetered station were used together with an inel main shock acceleration time history to generate four synthetic accelerograms for a hypothetical recording site 18 km southeast of the main shock the pgas measured from these synthetic accelerograms are 0 08 0 14 0 15 and 0 23 g

widespread weathered glass on the surface of mars low albedo sediments cover 10 7 km 2 in the northern lowlands of mars but the composition and origin of these widespread deposits have remained ambiguous despite many previous investigations here we use near infrared spectra acquired by the mars express omega observatoire pour la mineralogie l9eau les glaces et l9activite imaging spectrometer to show that these sediments exhibit spectral characteristics that are consistent with both high abundances of iron bearing glass and silica enriched leached rinds on glass this interpretation is supported by observations of low albedo soil grains with possible rinds at the phoenix mars lander landing site in the northern lowlands by comparison with the extensive glass rich dune fields and sand sheets of iceland we propose an explosive volcanic origin for these glass rich sediments we also propose that the glassy remnant rinds on the sediments are the result of postdepositional alteration as these rinds are commonly formed in arid terrestrial volcanic environments during water limited moderately acidic leaching these weathered glass rich deposits in the northern lowlands are also colocated with the strongest concentrations of a major global compositional surface type previously identified in mid infrared spectra suggesting that they may be representative of global processes our results provide potential confirmation of models suggesting that explosive volcanism has been widespread on mars and also raise the possibilities that glass rich volcaniclastics are a major source of eolian sand on mars and that widespread surficial aqueous alteration has occurred under amazonian climatic conditions

the wallula fault and tectonic framework of south central washington as interpreted from magnetic and gravity anomalies abstract the yakima fold and thrust belt yftb in central washington has accommodated regional mostly north directed deformation of the cascadia backarc since prior to emplacement of miocene flood basalt of the columbia river basalt group crbg the yftb consists of two structural domains northern folds of the yftb strike eastward and terminate at the western margin of a 20 mgal negative gravity anomaly the pasco gravity low straddling the north american continental margin southern folds of the yftb strike southeastward form part of the olympic wallowa lineament owl and pass south of the pasco gravity low as the wallula fault zone an upper crustal model based on gravity and magnetic anomalies suggests that the pasco gravity low is caused in part by an 8 km deep tertiary basin the pasco sub basin abutting the continental margin and concealed beneath crbg the pasco sub basin is crossed by north northwest striking magnetic anomalies caused by dikes of the 8 5 ma ice harbor member of the crbg at their northern end dikes connect with the eastern terminus of the saddle mountains thrust of the yftb at their southern end dikes are disrupted by the wallula fault zone the episode of ne sw extension that promoted ice harbor dike injection apparently involved strike slip displacement on the saddle mountains and wallula faults the amount of lateral shear on the owl impacts the level of seismic hazard in the cascadia region ice harbor dikes as mapped with aeromagnetic data are dextrally offset by the wallula fault zone a total of 6 9 km assuming that dike offsets are tectonic in origin the wallula fault zone has experienced an average dextral shear of 0 8 mm y since dike emplacement 8 5 ma consistent with right lateral stream offsets observed at other locations along the owl southeastward the wallula fault transfers strain to the north striking hite fault the possible location of the m 5 7 milton freewater earthquake in 1936

crustal structure and relocated earthquakes in the puget lowland washington from high resolution seismic tomography 1 the availability of regional earthquake data from the pacific northwest seismograph network pnsn together with active source data from the seismic hazards investigation in puget sound ships seismic experiments has allowed us to construct a new high resolution 3 d p wave velocity model of the crust to a depth of about 30 km in the central puget lowland in our method earthquake hypocenters and velocity model are jointly coupled in a fully nonlinear tomographic inversion active source data constrain the upper 10 15 km of the model and earthquakes constrain the deepest portion of the model a number of sedimentary basins are imaged including the previously unrecognized muckleshoot basin and the previously incompletely defined possession and sequim basins various features of the shallow crust are imaged in detail and their structural transitions to the mid and lower crust are revealed these include the tacoma basin and fault zone the seattle basin and fault zone the seattle and port ludlow velocity highs the port townsend basin the kingston arch and the crescent basement which is arched beneath the lowland from its surface exposure in the eastern olympics strong lateral velocity gradients consistent with the existence of previously inferred faults are observed bounding the southern port townsend basin the western edge of the seattle basin beneath dabob bay and portions of the port ludlow velocity high and the tacoma basin significant velocity gradients are not observed across the southern whidbey island fault the lofall fault or along most of the inferred location of the hood canal fault using improved earthquake locations resulting from our inversion we determined focal mechanisms for a number of the best recorded earthquakes in the data set revealing a complex pattern of deformation dominated by general arc parallel regional tectonic compression most earthquakes occur in the basement rocks inferred to be the lower tertiary crescent formation the sedimentary basins and the eastern part of the olympic subduction complex are largely devoid of earthquakes clear association of hypocenters and focal mechanisms with previously mapped or proposed faults is difficult however seismicity structure and focal mechanisms associated with the seattle fault zone suggest a possible high angle mode of deformation with the north side up we suggest that this deformation may be driven by isostatic readjustment of the seattle basin

near infrared spectral reflectance of mineral mixtures systematic combinations of pyroxenes olivine and iron oxides near infrared spectral reflectance data are presented for systematic variations in weight percent of two component mixtures of ferromagnesian and iron oxide minerals mixtures were chosen for application to the study of the dark materials on mars but the results are equally applicable to mafic and ultramafic assemblages elsewhere in the solar system olivine spectral features are greatly reduced in contrast by admixture of other phases but remain distinctive even for low olivine contents clinopyroxene and orthopyroxene mixtures show resolved pyroxene absorptions near 2 m the addition of limonite greatly modifies pyroxene and olivine reflectance but does not fully eliminate distinctive spectral characteristics using only spectral data in the 1 m region it is difficult to differentiate orthopyroxene and limonite goethite in a mixture additional spectral coverage or other evidence may be required for a unique interpretation all composite mineral absorptions observed in this study are either weaker than or intermediate in strength to the end member absorptions and have bandwidths greater than or equal to those for the end members in general spectral properties in an intimate mixture combine in a complex nonadditive manner with features demonstrating a regular but usually nonlinear variation as a function of end member phase proportions

spectrally distinct ejecta in syrtis major mars evidence for environmental change at the hesperian amazonian boundary analysis of visible and near infrared vnir imaging spectrometer data of the syrtis major volcanic complex on mars shows spectrally distinct ejecta sde around a subset of the region s impact craters we explore the nature of this spectral difference with the intention of constraining the physical cause of the distinction and the significance of their near random spatial distribution crater counting performed by baratoux et al 2007 indicated that the craters with sde are systematically younger than craters without sde extensive crater counts of the craters with sde show that they fit a consistent hartmann 2005 isochron indicting that they represent temporally continuous population this population was dated near 2 ga consistent with the counts of baratoux et al 2007 this modeled age corresponds to just after the hesperian amazonian boundary indicating that it may be related to a global event we explore possible explanations for the lack of sde around older craters including atmospheric changes significant but brief regional emplacement of materials and volcanic activity we conclude that the preferred explanation is that the sde represent the true composition of the syrtis major volcanics and that surfaces older than 2 ga were altered by interactions with water vapor or volcanic gases under different hesperian climatic and atmospheric conditions leading to all craters formed after this alteration event to display sde

abrupt uplift within the past 1700 years at southern puget sound washington shorelines rose as much as 7 meters along southern puget sound and hood canal between 500 and 1700 years ago evidence for this uplift consists of elevated wave cut shore platforms near seattle and emerged peat covered tidal flats as much as 60 kilometers to the southwest the uplift was too rapid for waves to leave intermediate shorelines on even the best preserved platform the tidal flats also emerged abruptly they changed into freshwater swamps and meadows without first becoming tidal marshes where uplift was greatest it adjoined an inferred fault that crosses puget sound at seattle and it probably accompanied reverse slip on that fault 1000 to 1100 years ago the uplift and probable fault slip show that the crust of the north america plate contains potential sources of damaging earthquakes in the puget sound region

the december 1872 washington state earthquake the largest historical earthquake in eastern washington occurred on 15 december 1872 we used modified mercalli intensity mmi assignments for 12 twentieth century earthquakes to determine attenuation relations for different regions in the pacific northwest mmi attenuation for propagation paths east and west of the cascade mountains differs significantly only for epicentral distances greater than about 225 km we used these attenuation relations and the mmi assignments for the 15 december 1872 earthquake to conclude that its epicentral region was east of the cascade mountains near lake chelan washington and most probably near the south end of lake chelan the intensity magnitude m i is 6 8 and moment magnitude m is 6 5 7 0 at the 95 confidence level manuscript received 23 october 2001

relation of the spectroscopic reflectance of olivine to mineral chemistry and some remote sensing implications using high resolution visible and near infrared diffuse spectral reflectance we have systematically investigated apparent wavelength shifts as a function of mineral chemistry in the fe mg olivine series from fo11 to fo91 the study also shows that trace amounts of nickel can be spectrally detected in the olivine structure we show that significant compositional information can only be extracted at relatively high resolution because the overall spectral characteristics of the olivines change only subtly as a function of the fe mg ratio significant spectral variation as a function of grain size is also demonstrated adding a further complication to the interpretation of remotely sensed data from olivine rich surfaces this laboratory study is expected to aid in the interpretation of remotely sensed data from both terrestrial and extraterrestrial bodies terrestrial applications may include the recognition of ultramafic ultrabasic and basaltic terrains which in themselves may have mineral potential among extraterrestrial applications the asteroids are obvious candidates for further examination if instrumentation can provide the necessary wavelength coverage resolution and signal to noise ratio so that spectra can be compared to those laboratory data discussed here some permutations of fe mg ni relations in olivines are discussed as they apply to the interpretation of asteroid surfaces and other extraterrestrial bodies

evidence for distributed clockwise rotation of the crust in the northwestern united states from fault geometries and focal mechanisms paleomagnetic and gps data indicate that washington and oregon have rotated clockwise for the past 16 myr late cenozoic and quaternary fault geometries seismicity lineaments and focal mechanisms provide evidence that this rotation is accommodated by north directed thrusting and right lateral strike slip faulting in washington and sw to w directed normal faulting and right lateral strike slip faulting to the east several curvilinear nw to nnw trending high angle strike slip faults and seismicity lineaments in washington and nw oregon define a geologic pole 117 7 w 47 9 n of rotation relative to north america many faults and focal mechanisms throughout northwestern u s and southwestern british columbia have orientations consistent with this geologic pole as do gps surface velocities corrected for elastic cascadia subduction zone coupling large quaternary normal faults radial to the geologic pole which appear to accommodate crustal rotation via crustal extension are widespread and can be found along the lewis and clark zone in montana within the centennial fault system north of the snake river plain in idaho and montana to the west of the wasatch front in utah and within the northern basin and range in oregon and nevada distributed strike slip faults are most prominent in western washington and oregon and may serve to transfer slip between faults throughout the northwestern u s

mineralogical composition structure morphology and geological history of aram chaos crater fill on mars derived from omega mars express data 1 aram chaos is a crater 280 km in diameter centered at 2 5 n 338 5 e it is filled by chaotic terrains overlain by a dome shaped layered 900 m thick formation displaying spectral signatures of ferric oxides on thermal emission spectrometer tes and observatoire pour la mineralogie l eau les glaces et l activite omega medium spatial resolution data we describe in detail the mineralogical composition structure and morphology of this crater fill using high resolution data omega mars orbiter laser altimeter mars orbiter camera tes thermal emission imaging system and high resolution imaging science experiment we infer the following formation scenario the crater was first filled by a geological formation the composition of which remains unclear because it is covered by dust widespread fracturing of this formation led to the development of chaotic terrains later a second layered formation presently dome shaped was emplaced unconformably on the chaotic terrains this younger unit is composed of a bright poorly consolidated material that contains both monohydrated sulfates and ferric oxides according to omega data the surface of this formation is partially covered by dust and displays landforms indicating that the bright material has been mobilized by wind during or after its deposition after its emplacement this formation has been grooved down to various depths by large eolian erosion corridors in these corridors eolian removal of the bright material with a sulfate rich matrix has left debris fans sand sheets and dunes which display some of the strongest spectral signatures of ferric oxides on mars similar residual deposits enriched in ferric oxides overlying a layered formation containing both ferric oxides and sulfates have been observed by the opportunity rover in meridiani planum suggesting a common formation process

evidence from opportunity s microscopic imager for water on meridiani planum the microscopic imager on the opportunity rover analyzed textures of soils and rocks at meridiani planum at a scale of 31 micrometers per pixel the uppermost millimeter of some soils is weakly cemented whereas other soils show little evidence of cohesion rock outcrops are laminated on a millimeter scale image mosaics of cross stratification suggest that some sediments were deposited by flowing water vugs in some outcrop faces are probably molds formed by dissolution of relatively soluble minerals during diagenesis microscopic images support the hypothesis that hematite rich spherules observed in outcrops and soils also formed diagenetically as concretions

martian surface mineralogy from observatoire pour la mineralogie l eau les glaces et l activite on board the mars express spacecraft omega mex global mineral maps 1 after 2 years of operation the observatoire pour la mineralogie l eau les glaces et l activite omega imaging spectrometer on board mars express has acquired data coverage of the martian surface with spatial resolution varying between 300 m and 4 8 km depending on the pericenter altitude of the spacecraft s elliptical orbit we report the global surface distributions of some minerals using the omega observations in the visible and near infrared vnir wavelength domains 0 35 2 5 m global maps of ferric phases mafic minerals pyroxenes and olivines and hydrated minerals have been derived from spectral parameters the limits of detection in terms of abundance for some minerals of different grain size distributions are given the distribution of pyroxenes is in general agreement with the mineral maps of previous telescopic and space observations the fe3 absorption feature in the visible wavelength region is present everywhere on the surface the spectra of the bright regions compare with anhydrous nanophase ferric oxides terrains with water bearing minerals cover a very small fraction of the martian surface olivine mg rich compositions is detected in more extensive regions of the pyroxene rich zones than previously reported olivine with higher iron content and or larger grain size 100 m is only detected in isolated areas the mineralogy of the northern low albedo regions is discussed in the light of these mineral maps chemical alteration or oxidation during extrusion producing a coating or varnish of anhydrous ferric phases over a dark basaltic surface best accounts for the vnir spectral properties of these regions although a glassy composition resulting from impact is also considered

the 14 february 1981 elk lake washington earthquake sequence a magnitude 5 5 ml earthquake occurred on 14 february 1981 near elk lake in the southern washington cascade range it was the largest earthquake to occur in washington since the 1965 seattle earthquake mb 6 5 the epicenters of 1050 located aftershocks mcoda 0 delineate a fault zone 6 km long north south by 3 km wide that extends from 5 to 12 km in depth immediately after the main shock aftershocks occurred at generally deeper depths to the north and south indicating that the break propagated bilaterally and downward first motion patterns for the main shock and 84 aftershocks mcoda 2 0 indicate predominantly right lateral strike slip faulting along a nearly vertical plane striking essentially north south in agreement with the alignment of epicenters earthquake activity at elk lake for the 7 yr period to 1980 was low nine months before the main shock an earthquake swarm began just southeast of what was to become the present aftershock zone the swarm lasted 2 months and was followed by 7 months of quiescence before two immediate foreshocks occurred on 11 february 1981 the overall pattern of seismicity observed throughout the elk lake sequence corresponds well to that predicted by an asperity model examination of the magnitude frequency relation b indicates that there was no significant temporal variation in b throughout the swarm main shock after shock sequence however b is significantly higher on the east side of the fault zone than on the west side for the entire aftershock sequence b 0 77 0 05 this earthquake sequence is important for three reasons 1 the main shock is the largest earthquake to occur in the pacific northwest since 1965 2 the sequence has been long and aftershocks are numerous and 3 its occurrence indicates that the potential seismic hazard in southwest washington must be reevaluated

global maps of anhydrous minerals at the surface of mars from omega mex 1 we here reassess the global distribution of several key mineral species using the entire omega mars express vis nir imaging spectrometer data set acquired from orbit insertion in january 2004 to august 2010 thirty two pixels per degree global maps of ferric oxides pyroxenes and olivines have been derived a significant filtering process was applied in order to exclude data acquired with unfavorable observation geometries or partial surface coverage with water and co2 frosts because of strong atmospheric variations over the 3 6 martian years of observations primarily due to the interannual variability of the aerosol opacity a new filter based on the atmospheric dust opacity calibrated by the mars exploration rovers measurements has also been implemented the fe3 absorption features are present everywhere on the surface with a variety of intensities indicating distinct formation processes the pyroxene bearing regions are localized in low albedo regions while the bright regions are spectrally comparable to anhydrous nanophase ferric oxides the expanded data set increases by a factor of about 2 the number of olivine detections reported in previous omega based studies olivine is mainly detected in three types of areas over the martian surface discontinuous patches on the terraces of the three main basins smooth inter crater plains and smooth crater floors throughout the southern highlands and crater sand dunes crater ejectas and extended bedrock exposures in the northern plains olivine is also detected in the low albedo pyroxene bearing dunes surrounding the northern polar cap

properties of a martian local dust storm in atlantis chaos from omega mex data abstract in this study we present the analysis of the dust properties of a local storm imaged in the atlantis chaos region on mars by the omega imaging spectrometer on march 2nd 2005 we use the radiative transfer model mitra to study the dust properties at solar wavelengths between 0 5 m and 2 5 m and infer the connection between the local storm dynamics and the topography we retrieve maps of effective grain radius reff optical depth at 9 3 m 9 3 and top altitude ta of the dust layer our results show that large particles reff 1 6 m are gathered in the centre of the storm lat 33 5 s lon 183 5 w where the optical depth is maximum 9 3 7 0 and the top altitude exceeds 18 km outside the storm we obtain 9 3 we speculate that a low thermal inertia region at the western border of atlantis chaos is a possible source of the dust storm moreover we find evidence that topography plays a role in confining the local storm in atlantis chaos the vertical wind component from the gcm does not provide any hint for the triggering of dust lifting on the other hand the combination of the horizontal and vertical wind profiles suggests that the dust once lifted is pushed eastward and then downward and gets confined within the north east ridge of atlantis chaos from our results the thickness of the dust layer collapsed on the surface ranges from about 1 m at the storm boundaries up to more than 100 m at its centre we verify that a layer of dust thicker than 1 m deposited on the surface can prevent the detection of mafic absorption features however such features are still present in omega data of atlantis chaos registered after the storm hence we deduce that once the storm is over the dust deposited on an area larger than the one where it has been observed

global investigation of olivine on mars insights into crust and mantle compositions 1 we present the distribution of olivine on mars derived from spectral parameters based on the 1 m olivine absorption band the olivine can be defined with respect to two spectral end members type 1 corresponds to olivine with low iron content and or small grain size and or small abundance and type 2 which corresponds to olivine with higher iron content and or larger grain size and or larger abundance the spatial and statistical analysis of the global olivine distribution points out five major geological settings where olivine is detected 1 early hesperian olivine bearing smooth crater floors and flat intercrater plains throughout the southern highlands 2 olivine deposits around the three main basins argyre hellas and isidis 3 olivine in intercrater dunes crater ejecta or extended deposits in the northern plains 4 olivine associated with outcrops and sand in the floor of valles marineris and 5 olivine bearing butte outcrops in the vicinity of hellas the geological context the age and the composition of the olivine detections associated with these five major geological settings are detailed their origin and the implication of their occurrence on the composition of the martian mantle and crust as well as on the evolution of mars volcanism are discussed

source parameters of the 28 october 1983 borah peak idaho earthquake from body wave analysis modeling of long period body waves of the m s 7 3 borah peak idaho earthquake suggests that the earthquake was a simple rupture that nucleated at a depth of about 16 km and propagated unilaterally northwestward toward the surface the seismic moment tensor obtained from the inversion of teleseismic body wave amplitude data agrees well with the fault plane solution obtained from short period first motion data strike 138 3 dip 45 3 rake 60 5 and the observed surface faulting the scalar double couple moment of 2 1 10 26 dyne cm obtained from the inversion is comparable to a moment of 1 4 10 26 dyne cm estimated from the observed surface faulting estimates of stress drop based on these values for the moment are 17 to 12 bars respectively

regional intensity attenuation models for france and the estimation of magnitude and location of historical earthquakes summary intensity assignments for 33 calibration earthquakes were used to develop intensity attenuation models for the alps armorican provence pyrenees and rhine regions of france intensity decreases withmost rapidly in the french alps provence and pyrenees regions and least rapidly in the armorican and rhine regions the comparable armorican and rhine region attenuation models are aggregated into a french stable continental region model and the com parable provence and pyrenees region models are aggregated into a southern france model we analyse msk intensity assignments using the technique of bakun wentworth which provides an objective method for estimating epicentral location and intensity magnitude m i m i for the 1356 october 18 earthquake in the french stable continental region is 6 6 for a location near basle switzerland and moment magnitude m is 5 9 7 2 at the 95 per cent 2 confidence level m i for the 1909 june 11 trevaresse lambesc earthquake near marseilles in the southern france region is 5 5 and m is 4 9 6 0 at the 95 per cent confidence level bootstrap resampling techniques are used to calculate objective reproducible 67 per cent and 95 per cent confidence regions for the locations of historical earthquakes these confidence re gions for location provide an attractive alternative to the macroseismic epicentre and qualitative location uncertainties used heretofore

iron mineralogy of the surface of mars from the 1 μm band spectral properties 1 we study the 1 m absorption from omega mex spectra to map martian iron mineralogy at a global scale this band is covered on the left by the vnir visible and near infrared omega channel and on the right by the swir short wavelengths infrared one we first perform a systematic spatial coregistration of the two channels after an improvement of the vnir radiometric calibration the update of the vnir instrumental transfer function itf and the internal stray light estimation is based on the spectra of the phobos red units and of the water ice north polar cap of mars which have been fitted according to an iterative process the level of the signal in the blue wavelength range previously systematically overestimated due to a stray light residual and the general shape of the spectrum for 0 7 m are improved global maps of the 1 m signature have been derived from 9 new spectral indices the largest values of the 1 m band integral are found in noachian terrains and in the dunes around the north polar cap in the south polar region an area centered at 155 w and 83 s is mapped as a distinctive spectral unit dominated by pyroxene the northern lowlands of mars together with other dark terrains located in the northern hemisphere show very low values of some spectral indices due to the negative spectral slope in the nir this behavior is consistent with the presence of weathered basalts with a possible glassy or amorphous component among the hydrated terrains the only ones that can be isolated by studying the 1 m band are those located in terra meridiani aram chaos and capri chasma enriched in sulfate and hematite on the other hand the sulfates of the dark dunes surrounding the northern polar cap and the phyllosilicates of the bright hydrated deposits of mawrth vallis cannot be isolated combining the parameters used in this study this suggests that their distinctive mineralogy does not affect the 1 m band remaining similar to the global martian average shape

magnitude and location of historical earthquakes in japan and implications for the 1855 ansei edo earthquake 1 japan meteorological agency jma intensity assignments ijma are used to derive intensity attenuation models suitable for estimating the location and an intensity magnitude mjma for historical earthquakes in japan the intensity for shallow crustal earthquakes on honshu is equal to 1 89 1 42mjma 0 00887 h 1 66log h where mjma is the jma magnitude h 2 h2 1 2 and and h are epicentral distance and focal depth km respectively four earthquakes located near the japan trench were used to develop a subducting plate intensity attenuation model where intensity is equal to 8 33 2 19mjma 0 00550 h 1 14 log h the ijma assignments for the mjma7 9 great 1923 kanto earthquake on the philippine sea eurasian plate interface are consistent with the subducting plate model using the subducting plate model and 226 ijma iv vi assignments the location of the intensity center is 25 km north of the epicenter mjma is 7 7 and mjma is 7 3 8 0 at the 1 confidence level intensity assignments and reported aftershock activity for the enigmatic 11 november 1855 ansei edo earthquake are consistent with an mjma 7 2 philippine sea eurasian interplate source or philippine sea intraslab source at about 30 km depth if the 1855 earthquake was a philippine sea eurasian interplate event the intensity center was adjacent to and downdip of the rupture area of the great 1923 kanto earthquake suggesting that the 1855 and 1923 events ruptured adjoining sections of the philippine sea eurasian plate interface

the saddle mountains the evolution of an anticline in the yakima fold belt the saddle mountains uplift is an asymmetrical north vergent anticline with a length of about 110 km it varies from an open to tight fold and is divided into six segments based upon differences in geometry flows of the columbia river basalt group intercalated sedimentary deposits of the ellensburg formation and suprabasalt sediments thin over the uplift and thicken into the synclines variations in thickness are used to determine the timing of deformation and age of major and minor structures the close correlation of growth rate of the folds with rate of magma supply of the columbia river basalt group suggests that the yakima fold belt resulted from the same tectonic processes that produced eruption of the columbia river basalt modified journal abstract

earthquakes near swift reservoir washington 1958 1963 seismicity along the southern st helens seismic zone abstract five earthquakes m 4 0 that occurred near swift reservoir on the southern st helens seismic zone shz in southwestern washington in 1960 and 1961 were located using a master event technique these five earthquakes include the 17 september 1961 siouxon peak earthquake of magnitude 5 1 m l as well as the swift creek earthquake on 11 october 1960 m coda 4 4 the siouxon peak earthquake focal mechanism exhibits right lateral strike slip faulting on a north south fault plane and is very similar to focal mechanisms calculated for recent earthquakes along the shz the sense of motion for the more poorly determined swift creek earthquake focal mechanism is consistent with either left lateral strike slip on a northerly striking fault plane or thrust both of which are anomalous for southwestern washington based on first motion differences in polarity which results in a different focal mechanism and the temporal separation between the swift creek earthquake and a swarm that preceded the siouxon peak earthquake we have divided the earthquakes near swift reservoir into two sequences the swift creek earthquake sequence beginning in early 1959 and culminating in the october 1960 swift creek earthquake and the siouxon peak sequence that began in january 1961 and included the siouxon peak main shock 8 months later the temporal and spatial pattern for the 1961 siouxon peak sequence agrees well both with that predicted by an asperity model and that observed for the 1980 to 1981 elk lake earthquake sequence along the shz about 35 km to the north the temporal similarities of these two sequences coupled with their similar moment release suggest an empirical model which may permit forecasting the next moderate earthquake along the shz the swift creek activity with its unusual for southwestern washington focal mechanism may have been induced by the impounding of the nearby swift reservoir

discovery of olivine in the nili fossae region of mars we have detected a 30 000 square kilometer area rich in olivine in the nili fossae region of mars nili fossae has been interpreted as a complex of grabens and fractures related to the formation of the isidis impact basin we propose that post impact faulting of this area has exposed subsurface layers rich in olivine linear mixture analysis of thermal emission spectrometer spectra shows surface exposures of 30 olivine where the composition of the olivine ranges from fo30 to fo70

earthquake damage history in israel and its close surrounding evaluation of spatial and temporal patterns abstract israel was hit by destructive earthquakes many times in the course of history to properly understand the hazard and support effective preparedness towards future earthquakes we examined the spatial and temporal distribution of the resulted damage we described in detail our systematic approach to searching the available literature collecting the data and screening the authenticity of that information we used gis geographic information system to map and evaluate the distribution of the damage and to search for recurring patterns overall it is found that 186 localities were hit 54 of them at least twice we also found that israel was affected by 4 17 8 and 2 damaging earthquakes that originated respectively from the southern central central northern and northern parts of the dead sea transform dst the temporal appearance of the northern earthquakes is clustered the central earthquakes are more regular in time whereas no damage from the north central and the central quakes with the exception of the year 363 earthquake seems to have occurred south of the dead sea region analyzing the distribution of the damage we realized that the number of the damage reports reflects only half of the incidents that actually happened attesting to incompleteness of the historical catalogue jerusalem is the most reported city with 14 entries followed by akko acre tiberias nablus and tyre with 8 7 7 and 6 reports respectively in general localities in the galilee and north of it suffered more severely than localities in central israel with the exception of nablus and the localities along the coastal plain of israel most probably due to local site effects for the sake of hazard management these observations should be considered for future planning and risk mitigation

sulfates in the north polar region of mars detected by omega mars express the observatoire pour la mineralogie l eau les glaces et l activite omega imaging spectrometer observed the northern circumpolar regions of mars at a resolution of a few kilometers an extended region at 240 e 85 n with an area of 60 kilometers by 200 kilometers exhibits absorptions at wavelengths of 1 45 1 75 1 94 2 22 2 26 and 2 48 micrometers these signatures can be unambiguously attributed to calcium rich sulfates most likely gypsum this region corresponds to the dark longitudinal dunes of olympia planitia these observations reveal that water alteration played a major role in the formation of the constituting minerals of northern circumpolar terrains

estimating earthquake location and magnitude from seismic intensity data analysis of modified mercalli intensity mmi observations for a training set of 22 california earthquakes suggests a strategy for bounding the epicentral region and moment magnitude m from mmi observations only we define an intensity magnitude m i that is calibrated to be equal in the mean to m m i mean m i where m i mmi i 3 29 0 0206 i 1 68 and i is the epicentral distance km of observation mmi i the epicentral region is bounded by contours of rms m i rms m i m i rms m i m i where rms is the root mean square rms m i m i is the minimum rms over a grid of assumed epicenters and empirical site corrections and a distance weighting function are used empirical contour values for bounding the epicenter location and empirical bounds for m estimated from m i appropriate for different levels of confidence and different quantities of intensity observations are tabulated the epicentral region bounds and m i obtained for an independent test set of western california earthquakes are consistent with the instrumental epicenters and moment magnitudes of these earthquakes the analysis strategy is particularly appropriate for the evaluation of pre 1900 earthquakes for which the only available data are a sparse set of intensity observations

cryptic climatic signatures and tectonic controls on cryogenian diamictites in the nw tarim craton china unravelling the origins of cryogenian diamictites is vital in determining their significance in a snowball earth context and their relationship to environmental processes here we present new sedimentological and geochemical data for the cryogenian sedimentary rocks from the tarim craton nw china the diamictite member of the east qiaoenbrak formation contains 1 granitic pebbles with high sphericity 2 well developed stratification and 3 bed scale grain size changes suggesting cyclicity also 4 ice rafted debris is conspicuously absent rather than deposits of direct glacial origin the succession is instead interpreted as a subaqueous fan complex the major and trace element ratios and ree patterns are consistent throughout 22 sampled intervals in the qiaoenbrak group suggesting a uniformly felsic source area probably from an island arc chemical index of alteration cia analysis indicates low cia values 49 5 54 3 average 51 6 throughout the qiaoenbrak group we suggest that both the qiaoenbrak group and yuermeinak formation were deposited during the marinoan glaciation in a long lasting cold and dry interval it is likely that the qiaoenbrak group was deposited in a fault controlled basin adjacent to an active continental margin although the material may ultimately have derived from a glacial source e g outwash

stress origins and earthquake potentials in cascadia focal mechanism solutions for shallow earthquakes throughout the cascadia plate system indicate that the primary regional stress is northerly compression even though the juan de fuca plate generally is thought to be subducting n50 e this compressional stress is pervasive throughout the gorda juan de fuca explorer plate system and much of the adjoining section of north american plate modeling using a discrete element code shows that this stress primarily is due to the pacific plate being driven into the gorda block and juan de fuca plate at the mendocino and blanco fracture zones this plate collision causes compression of the offshore plate system northward through the 45 w trending vancouver island and leads to transfer of northerly compression into the overriding plate the northerly compression in the cascadia plate system has caused large crustal earthquakes in the regions of vancouver and northern california and may be capable of causing large earthquakes also in and offshore of washington and oregon several independent lines of evidence confirm that the cascadia subduction interface is coupled strongly and that subduction primarily must be accompanied by significant earthquakes rather than occurring aseismically for numerous earthquakes within the subducted plate focal mechanisms indicate extensional stresses that trend downdip these earthquakes reflect plate extension that is due to sinking of the more deeply subducted plate and to plate motion being resisted at the shallow subduction interface the slab pull force of the sinking plate also can lead to earthquakes at the shallow subduction interface and the potential exists for m 7 5 8 0 subduction earthquakes to occur at segments of the subduction boundary at washington and vancouver and less frequently so at segments of the subduction boundary at oregon the in plate driving forces of the offshore cascadia plate system do not appear to contribute significantly to regional stresses stresses and earthquakes at the cascadia province primarily result from the action of the pacific plate on the gorda juan de fuca explorer plate system a transfer of this action into the overriding north american plate and the independent sinking and slab pull force of the subducted oceanic lithosphere

spectral variability among rocks in visible and near infrared multispectral pancam data collected at gusev crater examinations using spectral mixture analysis and related techniques 1 visible and near infrared vnir multispectral observations of rocks made by the mars exploration rover spirit s panoramic camera pancam have been analyzed using a spectral mixture analysis sma methodology scenes have been examined from the gusev crater plains into the columbia hills most scenes on the plains and in the columbia hills could be modeled as three end member mixtures of a bright material rock and shade scenes of rocks disturbed by the rover s rock abrasion tool rat required additional end members in the columbia hills there were a number of scenes in which additional rock end members were required the sma methodology identified relatively dust free areas on undisturbed rock surfaces as well as spectrally unique areas on rat abraded rocks spectral parameters from these areas were examined and six spectral classes were identified these classes are named after a type rock or area and are adirondack lower west spur clovis wishstone peace and watchtower these classes are discriminable based primarily on near infrared nir spectral parameters clovis and watchtower class rocks appear more oxidized than wishstone class rocks and adirondack basalts based on their having higher 535 nm band depths comparison of the spectral parameters of these gusev crater rocks to parameters of glass dominated basaltic tuffs indicates correspondence between measurements of clovis and watchtower classes but divergence for the wishstone class rocks which appear to have a higher fraction of crystalline ferrous iron bearing phases despite a high sulfur content the rock peace has nir properties resembling plains basalts

mineralogy composition and alteration of mars pathfinder rocks and soils evidence from multispectral elemental and magnetic data on terrestrial analogue snc meteorite and pathfinder samples major element multispectral and magnetic properties data were obtained at ares vallis during the mars pathfinder mission to understand the compositional mineralogical and process implications of these data we obtained major element mineralogical and magnetic data for well crystalline and nanophase ferric minerals terrestrial analogue samples with known geologic context and snc meteorites analogue samples include unaltered palagonitic and sulfatetic tephra from mauna kea volcano hydrolytic and acid sulfate alteration steam vent material from kilauea volcano hydrolytic alteration and impactites from meteor crater relithification salient results for mars pathfinder include 1 band depths bd530b and bd600 and the reflectivity ratio r800 r750 are consistent with the dominant ferric mineral being nanophase ferric oxide associated with an unknown amount of h2o and occurring in composite particles along with subordinate amounts of other ferric minerals hematite and hematite plus nanophase goethite are most consistent with the data but maghemite akaganeite schwertmannite and nanophase lepidocrocite are also possible interpretations ferric oxides that are consistently not favored by the data as sole alteration products are jarosites and well crystalline goethite and lepidocrocite 2 the strength of the ferric adsorption edge r750 r445 implies the fe3 fe2 values for pathfinder rock and soil are within the ranges 0 7 3 and 3 20 respectively 3 ferrous silicates are indicated for subsets of pathfinder rocks and soils one subset has a band minimum near 930 nm that can attributed to low ca pyroxene alternatively the band could be a second manifestation of certain ferric oxides including nanophase goethite maghemite akaganeite and schwertmannite another subset has a negative spectral slope from 800 to 1005 nm which could result from the high energy wing of a high ca pyroxene and or olivine band a mixture of bright and dark materials and for rocks thin coatings of bright dust on dark rocks 4 chemical data on pathfinder rocks and soils are consistent with two component mixtures between an andesitic rock with low mgo and so3 concentrations soil free rock and a global basaltic soil with high mgo and so3 concentrations rock free soil pathfinder rock free soil can be modeled as a chemical mixture of snc meteorites and the pathfinder soil free rock 5 pathfinder soil cannot be obtained by chemical alteration of pathfinder rocks by any of the hydrolytic and acid sulfate alteration processes we studied presumably global mixing has obscured and possibly erased the elemental signatures of chemical alteration 6 the strongly magnetic phase in palagonitic and sulfatetic tephra is titanomagnetite and possibly its oxidation product titanomaghemite fe ti spinels the saturation magnetization of the tephra samples 0 5 2 0 am2 kg is at or below the low end of the range inferred for martian dust 4 2 am2 kg implying that lithogenic fe ti spinels are a possible candidate for the martian strongly magnetic phase 7 the predominantly palagonitic spectral signature and magnetic nature of martian soil and dust are consistent with glassy precursors with imbedded fe ti spinel particles comparison with lunar glass production rates suggests that production of sufficient quantities of glassy materials on mars by volcanic and impact processes is sufficient to account for these observations

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

mineralogic and compositional properties of martian soil and dust results from mars pathfinder mars pathfinder obtained multispectral elemental magnetic and physical measurements of soil and dust at the sagan memorial station during the course of its 83 sol mission we describe initial results from these measurements concentrating on multispectral and elemental data and use these data along with previous viking snc meteorite and telescopic results to help constrain the origin and evolution of martian soil and dust we find that soils and dust can be divided into at least eight distinct spectral units based on parameterization of imager for mars pathfinder imp 400 to 1000 nm multispectral images the most distinctive spectral parameters for soils and dust are the reflectivity in the red the red blue reflectivity ratio the near ir spectral slope and the strength of the 800 to 1000 nm absorption feature most of the pathfinder spectra are consistent with the presence of poorly crystalline or nanophase ferric oxide s sometimes mixed with small but varying degrees of well crystalline ferric and ferrous phases darker soil units appear to be coarser grained compacted and or mixed with a larger amount of dark ferrous materials relative to bright soils nanophase goethite akaganeite schwertmannite and maghemite are leading candidates for the origin of the absorption centered near 900 nm in imp spectra the ferrous component in the soil cannot be well constrained based on imp data alpha proton x ray spectrometer apxs measurements of six soil units show little variability within the landing site and show remarkable overall similarity to the average viking derived soil elemental composition differences exist between viking and pathfinder soils however including significantly higher s and cl abundances and lower si abundances in viking soils and the lack of a correlation between ti and fe in pathfinder soils no significant linear correlations were observed between imp spectral properties and apxs elemental chemistry attempts at constraining the mineralogy of soils and dust using normative calculations involving mixtures of smectites and silicate and oxide minerals did not yield physically acceptable solutions we attempted to use the pathfinder results to constrain a number of putative soil and dust formation scenarios including palagonitization and acid fog weathering while the pathfinder soils cannot be chemically linked to the pathfinder rocks by palagonitization this study and mcsween et al 1999 suggest that palagonitic alteration of a martian basaltic rock plus mixture with a minor component of locally derived andesitic rock fragments could be consistent with the observed soil apxs and imp properties

detection of new olivine rich locations on vesta abstract the discovery of olivine on vesta s surface by the vir imaging spectrometer onboard the dawn space mission has forced us to reconsider our views of vestan petrogenetic models olivines were expected to be present in the interior of vesta in the mantle of a vertically layered body as invoked by the magma ocean models or at the base or within the mantle crust boundary as proposed by fractionation models olivines have been detected by vir dawn in two wide areas near arruntia and bellicia regions located in the northern hemisphere interestingly these olivine rich terrains are far from the rheasilvia and the more ancient veneneia basins which are expected to have excavated the crust down to reach the mantle in this work we present our attempts to identify other undetected olivine rich areas on vesta by using spectral parameters sensitive to olivine such as the band area ratio bar and other specific parameters created for the detection of olivines on mars forsterite fayalite and a generic olivine index as a preliminary step we calibrated these parameters by means of vis ir spectra of different hed meteorite samples behaviors versus sample grain size and albedo were analyzed and discussed we selected the bar and the forsterite index as the best parameters that can be used on vesta a cross correlation analysis has been applied in order to detect olivine signature on the vir hyperspectral cubes these detections have then been confirmed by an anti correlation analysis between the bar and one of the olivine parameters independent of the first method applied in agreement with the recent discovery arruntia and bellicia were found to be as the most olivine rich areas i e where the parameter values are strongest in addition we detected 6 new regions all but one located in the vesta north hemisphere this result confirms again that the old petrogenetic models cannot be straightforwardly applied to vesta and should be reshaped in the view of these new detections an alternative and very recent option can be represented by the model according to which surface eruption of material from the mantle including olivine can reach the surface of vesta

pulsed iceberg delivery driven by sturtian ice sheet dynamics an example from death valley california the kingston peak formation is a cryogenian sedimentary succession that crops out in the death valley area california usa it is widely accepted to record pre glacial conditions kp1 followed by two glaciations of pan global extent the older sturtian kp2 to kp3 and younger marinoan glaciation kp4 in the type area the kingston range detailed facies analysis of the sturtian succession reveals that a basal diamictite unit and an upper boulder conglomerate were deposited by proglacial subaqueous sediment gravity flows an olistostrome unit punctuating the succession is interpreted to result from tectonically induced downslope mobilization during isostatic rebound triggered by significant ice meltback focussing on strata onlapping the olistostrome this article provides insight into the processes of glacial re advance following an intra sturtian glacial minimum the first 50 m of strata above the olistostrome are thinly bedded turbidites that are devoid of lonestones a trend towards thicker graded beds upsection in concert with the gradual appearance and then abundance of lonestones testifies to the influence of ice rafting and to the resumption of a direct ice sheet influence upon sedimentation stratigraphic organization into thickening and coarsening upward bedsets over a multi metre scale reveals a subaqueous gravity flow dominated succession composed of a spectrum of high to low density turbidites with thick graded boulder conglomerates at intervals the finer grained facies assemblage is heterolithic current ripple cross laminated sandstones intercalated with shales that bear delicate granule to pebble sized dropstones in abundance intervals of dropstone bearing and dropstone free strata are attributable to dynamic oscillation of the ice margin in the hinterland integrating palaeocurrent data with observations from neighbouring outcrop belts allows a detailed palaeogeographic map of the eastern death valley area to be compiled for the first time

in situ evidence for an ancient aqueous environment at meridiani planum mars sedimentary rocks at eagle crater in meridiani planum are composed of fine grained siliciclastic materials derived from weathering of basaltic rocks sulfate minerals including magnesium sulfate and jarosite that constitute several tens of percent of the rock by weight and hematite cross stratification observed in rock outcrops indicates eolian and aqueous transport diagenetic features include hematite rich concretions and crystal mold vugs we interpret the rocks to be a mixture of chemical and siliciclastic sediments with a complex diagenetic history the environmental conditions that they record include episodic inundation by shallow surface water evaporation and desiccation the geologic record at meridiani planum suggests that conditions were suitable for biological activity for a period of time in martian history

magnitude calibration of north indian earthquakes this article is concerned primarily with the evaluation of the size and location of northern indian and southern tibetan earthquakes during the last 200 yr it draws attention to the problems of assessing intensity of early and more recent earthquakes in a built environment which is different from that for which the intensity scale has been constructed and to the way in which isoseismals are drawn through a re evaluation of intensities and a reassessment of isoseismals a formula for the estimation of surface wave magnitude using isoseismal radii is derived this formula is used to estimate the surface wave magnitudes of 16 earthquakes that occurred in the region between 1803 and 1900 this study shows that it is possible to calculate accurate surface wave magnitudes for earthquakes that occurred before the advent of the scale and that there is no need to resort to empirical formulae for the assessment of the size and seismic moment release of pre 20th century earthquakes also derived are formulae for the conversion of ms to m0 in total locations surface wave magnitudes and m0 estimates are presented for 43 important events that occurred in the region between 1803 and 1974 eight of which were in the lower crust or were subcrustal we find that the m0 ms scaling for india yields smaller ms than the global relation and that the methodology used can help to evaluate more realistic slip rates as well as to address other issues related to earthquake hazard in northern india

identification distribution and possible origins of sulfates in capri chasma mars inferred from crism data crism is a hyperspectral imager onboard the mars reconnaissance orbiter mro nasa 2005 which has been acquiring data since november 2006 and has targeted hydrated minerals previously detected by omega mars express esa 2003 the present study focuses on hydrated minerals detected with crism at high spatial resolution in the vicinity of capri chasma a canyon of the valles marineris system crism data were processed and coupled with mro and other spacecraft data in particular hirise high resolution science experiment mro images detections revealed sulfates in abundance in capri especially linked to the interior layered deposits ild that lie in the central part of the chasma both monohydrated and polyhydrated sulfates are found at different elevations and are associated with different layers monohydrated sulfates are widely detected over the massive light toned cliffs of the ild whereas polyhydrated sulfates seem to form a basal and a top layer associated with lower albedo deposits in flatter areas hydrated silicates phyllosilicates or opaline silica have also been detected very locally on two mounds about a few hundred meters in diameter at the bottom of the ild cliffs we suggest some formation models of these minerals that are consistent with our observations