instabilities on moraine slopes induced by loss of suction a case history in comparison with saturated conditions negative pore water pressures arising from partial saturation increase the available shear strength on a potential slip surface this additional contribution is lost progressively during infiltration of rainfall leading to instabilities sometimes before full saturation is reached in such cases reliable prediction of the safety factor may be achieved by taking the suction history of the soil into account a combination of field and laboratory tests was carried out recently to investigate the triggering effect of rainfall on shallow slips in alpine moraine slopes the problem is complicated by the strong heterogeneity of these soils with particle sizes varying from silts to boulders the data highlight the influence of suction on the peak shear strength and allow for the calibration of simple models which take into account the dependence of shear strength on the saturation degree an infinite slope stability analysis is performed the results are compared wit

scaling law of static liquefaction mechanism in geocentrifuge and corresponding hydromechanical characterization of an unsaturated silty sand having a viscous pore fluid fast landslides induced by rainfall impose considerable damage on infrastructure and cause major casualties worldwide static liquefaction is one of the triggering mechanisms mentioned frequently in the literature as a cause of this type of landslide the scaling laws required to model this mechanism in the geotechnical centrifuge are developed and it is shown that either a reduction in the soil pore size or use of a viscous pore fluid is needed to unify the time scaling factors of contractive volume change of the saturated voids and dissipation of the excess pore pressure generated the latter option was used in this research therefore the influences of the viscous pore fluid on the hydromechanical characteristics of a silty sand were investigated subsequently geocentrifuge tests were conducted to compare the behaviour of a slope having a viscous solution as the pore fluid with that of a model with water as the pore fluid both slopes were subjected to rainfall and the evolution of the pore pressur

middle to late jurassic tectonic evolution of the klamath mountains california oregon the geochronology stratigraphy and spatial relationships of middle and late jurassic terranes of the klamath mountains strongly suggest that they were formed in a single west facing magmatic arc built upon older accreted terranes a middle jurassic arc complex is represented by the volcanic rocks of the western hayfork terrane and consanguineous dioritic to peridotitic plutons new u pb zircon dates indicate that the middle jurassic plutonic belt was active from 159 to 174 ma and is much more extensive than previously thought this plutonic belt became inactive just as the 157 ma josephine ophiolite which lies west and structurally below the middle jurassic arc was generated late jurassic volcanic and plutonic arc rocks rogue formation and chetco intrusive complex lie outboard and structurally beneath the josephine ophiolite u pb and k ar age data indicate that this arc complex is coeval with the josephine ophiolite both the late jurassic arc complex and the josephine ophiolite are overlain by the galice formation a late jurassic flysch sequence and are intruded by 150 ma dikes and sills the following tectonic model is presented that accounts for the age and distribution of these terranes a middle jurassic arc built on older accreted terranes undergoes rifting at 160 ma resulting in formation of a remnant arc back arc basin island arc triad this system collapsed during the late jurassic nevadan orogeny 150 ma and was strongly deformed and stacked into a series of east dipping thrust sheets arc magmatism was active both before and after the nevadan orogeny but virtually ceased at 140 ma

formation and emplacement of the josephine ophiolite and the nevadan orogeny in the klamath mountains california oregon u pb zircon and 40ar 39ar geochronology cordilleran ophiolites typically occur as basement for accreted terranes in the klamath mountains ophiolitic terranes were progressively accreted by underthrusting beneath north america the josephine ophiolite is the youngest of the klamath ophiolites and forms the basement for a thick late jurassic flysch sequence galice formation this ophiolite flysch terrane forms an east dipping thrust sheet sandwiched between older rocks of the klamath mountains above and a coeval plutonic volcanic arc complex below the outcrop pattern of the roof orleans thrust indicates a minimum displacement of 40 km and geophysical studies suggest 110 km of displacement the basal madstone cabin thrust is associated with an amphibolitic sole and has a minimum displacement of 12 km a rapid sequence of events from ophiolite generation to thrust emplacement has been determined using 40 ar 39 ar and pb u geochronology ophiolite generation occurred at 162 164 ma a thin hemipelagic sequence was deposited from 162 to 157 ma and flysch deposition took place between 157 and 150 ma tight age constraints on thrusting and low grade metamorphism associated with ophiolite emplacement nevadan orogeny are provided by abundant calc alkaline dikes and plutons ranging in age from 151 to 139 ma deformation and metamorphism related to the nevadan orogeny appears to have extended from 155 to 135 ma most of the crustal shortening took place by thrusting constrained to have occurred from 155 to 150 ma on both the roof and basal thrusts minimum rates of displacement are 2 4 and 3 6 mm year for the basal and roof thrusts respectively but correlations with coeval thrusts yield rates of 8 4 and 22 mm year within the range of plate velocities the high displacement rates and synchronous movement along the basal and roof thrusts suggest that the ophiolite may have behaved as a microplate situated between western north america and an active arc from 155 to 150 ma a steep thermal gradient was present in the josephine galice thrust sheet from 155 to 150 ma with amphibolite facies conditions developed along the basal thrust after accretion of the ophiolite by underthrusting the ophiolite and overlying flysch underwent low grade dynamothermal regional metamorphism from 150 to 135 ma the upper age limit is tightly constrained by a 135 ma k feldspar cooling age syntectonic plutons as young as 139 ma and a lower cretaceous angular unconformity very rapid exhumation is indicated by the late valanginian to hauterivian age 130 ma of the unconformably overlying strata suggesting unroofing by extensional tectonics

stability assessment of slide zones in lesser himalayan part of yamunotri pilgrimage route uttarakhand india the present study deals with the slope stability analysis and geotechnical assessment of a part of pilgrimage route to one of the holy shrines of india i e yamunotri the route also embraces a proposed site for 204 m high concrete gravity dam across river yamuna near lakhwar village with the aim of generation of 300 mw power several slide zones were identified and based on the discontinuity orientation structural features and debris materials they are recognised as planar wedge or circular failure types the morphological dimensions structural data orientations and geotechnical parameters of circular failure slides within weathered quartzites phyllites and shales were evaluated by extensive field work and by laboratory tests for their stability analysis internal mechanisms cohesion and angle of internal friction that resist shear stress in slope materials obtained from direct shear test are showing minor variation due to relatively consistent grain size distribution and mineralogical composition general slope is about 40 43 with sparse vegetation materials in and around slide zones are sands with appreciable amount of fines falling in sp sm category as per unified soil classification system uscs except niste b slide which has clean sands lying in sp group factor of safety computed by requisite parameters of strength soil and slope properties in circular failure charts varies from 1 02 to 1 23 in dry conditions while it reduces below unity with increasing saturation representing stable conditions in dry conditions but with seepage and saturation along the cracks and discontinuities during rainfall make them unstable presence of steep slopes proximity to stream channels and significant weathered and jointed area are causative factors in the route with rainfall and road widening as major triggers initiating the failure

the 2002 denali fault earthquake alaska a large magnitude slip partitioned event the mw moment magnitude 7 9 denali fault earthquake on 3 november 2002 was associated with 340 kilometers of surface rupture and was the largest strike slip earthquake in north america in almost 150 years it illuminates earthquake mechanics and hazards of large strike slip faults it began with thrusting on the previously unrecognized susitna glacier fault continued with right slip on the denali fault then took a right step and continued with right slip on the totschunda fault there is good correlation between geologically observed and geophysically inferred moment release the earthquake produced unusually strong distal effects in the rupture propagation direction including triggered seismicity

toward mapping surface deformation in three dimensions using insar 1 one of the limitations of deformation measurements made with interferometric synthetic aperture radar insar is that an interferogram only measures one component of the surface deformation in the satellite s line of sight we investigate strategies for mapping surface deformation in three dimensions by using multiple interferograms with different imaging geometries geometries for both current and future missions are evaluated and their abilities to resolve the displacement vector are compared the north component is always the most difficult to determine using data from near polar orbiting satellites however a satellite with an inclination of about 60 120 would enable all three components to be well resolved we attempt to resolve the 3d displacements for the 23 october 2002 nenana mountain alaska earthquake the north component s error is much larger than the signal but proxies for eastward and vertical motion can be determined if the north component is assumed negligible inversions of hypothetical coseismic interferograms demonstrate that earthquake model parameters can be well recovered from two interferograms acquired on ascending and descending tracks

stratigraphy and sedimentology of upper cretaceous rocks in coastal southwest oregon evidence for wrench fault tectonics in a postulated accretionary terrane southwest oregon is a region of complex juxtaposition of tectonostratigraphic terranes in southwest oregon three upper cretaceous campanian maastrichtian formations occur in fault and depositional contact with the upper jurassic otter point complex an oceanic assemblage these four units occur only west of high angle north northwest trending faults and they make up a terrane gold beach terrane unlike any terrane east of these faults the patterns of sedimentation and the stratigraphic relationships of the three upper cretaceous formations indicate that they were deposited in a tectonically active setting influenced by vertical tectonics source areas for clasts in the cretaceous conglomerates cannot be found in the adjacent klamath mountains or other nearby terranes we postulate that they were deposited in a borderland type basin with a sediment source at least as far south as southern california they were translated north during latest cretaceous to early paleogene time and were then accreted to the oregon margin

in situ rainfall infiltration studies at a hillside in hubei province china field infiltration tests were conducted at a hillside near the ship lock of the three gorges dam in hubei province china the test site consists of residual soil and decomposed granite the infiltration rate is estimated from the in situ tests to be 1 465 2 778 10 6 ms 1 depending on the initial water content the rate at which the infiltration front moves down through the soil matrix within 2 m of the ground surface is estimated to be ca 0 26 m day 1 on average at the end of the in situ tests the matric suction profiles show that the soil below a depth of 80 cm remained unsaturated while the zone above was almost fully saturated this finding was unexpected the site was excavated after the test to examine the abnormal behaviour of the matric suction profiles in the depth a relic joint was identified at a depth of 78 cm at an attitude almost parallel to the slope surface it is surmised that the joint transmitted water laterally and limited further penetration of the wetting front the water in the zone above the joint appeared to be perched this experiment indicates that to describe thoroughly the infiltration process within a weathered jointed granite profile for slope engineering design purposes a model based on the assumption of a uniform porous media is inadequate the model should include the discontinuities this is challenging since it requires field studies to identify the pattern and distribution of the joints the implications of the experimental results on slope stability are discussed the in situ tests provide important information for further studying groundwater seepage under rainfall conditions and a dewatering system design for the slope above the ship lock of the three gorges dam in china 2000 elsevier science b v all rights reserved

application of geotechnical and geophysical field measurements in an active alpine environment abstract a gravelly scree slope in the meretschibach catchment a location in the swiss alps in the vicinity of agarn canton valais has been observed to deform downslope at up to 0 5 m p a the potential instabilities at this site include surficial landslides some of them originally thought to be triggered by an increase in pore water pressure with a subsequent loss of shear strength as a consequence of rainfall infiltration and rockfalls a programme consisting of monitoring laboratory testing and investigation was developed to perform a thorough soil characterisation needed in order to produce a realistic ground model the long term geotechnical monitoring included in situ soil temperature suction as well as volumetric water content measurements using dielectric permittivity and time domain reflectometry tdr sensors this data was complemented by electrical resistivity tomography ert to provide extensive knowledge on the depth to bedrock and to validate the volumetric water contents in specific locations the datasets are completed by recordings from two nearby weather stations seasonal changes of precipitation and temperature were reflected in corresponding trends in all measurements a comparison of volumetric water content records was obtained using capacitance and time domain reflectometry tdr sensors with ert yielding reasonable agreement the resulting ground model which integrates all currently available parameters delivers the essential information and boundary conditions for predicting and validating slope instabilities in the future using numerical and physical modelling

constraining the slip distribution and fault geometry of the mw 7 9 3 november 2002 denali fault earthquake with interferometric synthetic aperture radar and global positioning system data the m w 7 9 denali fault earthquake dfe is the largest continental strike slip earthquake to occur since the development of interferometric synthetic aperture radar insar we use five interferograms constructed using radar images from the canadian radarsat 1 satellite to map the surface deformation at the western end of the fault rupture additional geodetic data are provided by displacements observed at 40 campaign and continuous global positioning system gps sites we use the data to determine the geometry of the susitna glacier fault thrusting on which initiated the dfe and to determine a slip model for the entire event that is consistent with both the insar and gps data we find there was an average of 7 3 0 4 m slip on the susitna glacier fault between 1 and 9 5 km depth on a 29 km long fault that dips north at 41 0 7 and has a surface projection close to the mapped rupture on the denali fault a simple model with large slip patches finds a maximum of 8 7 0 7 m of slip between the surface and 14 3 0 2 km depth a more complex distributed slip model finds a peak of 12 5 0 8 m in the upper 4 km significantly higher than the observed surface slip we estimate a geodetic moment of 670 10 10 18 n m m w 7 9 consistent with seismic estimates lack of preseismic data resulted in an absence of insar coverage for the eastern half of the dfe rupture a dedicated geodetic insar mission could obviate coverage problems in the future

evidence of nonlinear elasticity of the crust from the mw7 6 manyi tibet earthquake satellite synthetic aperture radar sar interferometry shows that the magnitude 7 6 manyi earthquake of 8 november 1997 produced a 170 kilometer long surface break with up to 7 meters of left lateral slip reactivating a n76 e quaternary fault in western tibet the radar interferometric map reveals asymmetric along strike displacement profiles between the two sides of the surface rupture a pattern that cannot be explained with linear elastic theory this observation suggests that the elastic moduli of the crust in tension and in compression are different because of the presence of cracks in the crust at shallow depth a model indicates that a ratio of 2 between compressive and tensile elastic moduli can account for the observed asymmetry a ratio that is consistent with laboratory and borehole measurements

response of a residual soil slope to rainfall rainfall induced landslides are a common problem in residual soil slopes of the tropics it is widely known that rainfall induced slope failures are mainly caused by infiltration of rainwater howe

assessment of ground based monitoring techniques applied to landslide investigations a landslide complex in the whitby mudstone formation at hollin hill north yorkshire uk is periodically re activated in response to rainfall induced pore water pressure fluctuations this paper compares long term measurements i e 2009 2014 obtained from a combination of monitoring techniques that have been employed together for the first time on an active landslide the results highlight the relative performance of the different techniques and can provide guidance for researchers and practitioners for selecting and installing appropriate monitoring techniques to assess unstable slopes particular attention is given to the spatial and temporal resolutions offered by the different approaches that include real time kinematic gps rtk gps monitoring of a ground surface marker array conventional inclinometers shape acceleration arrays saa tilt meters active waveguides with acoustic emission ae monitoring and piezometers high spatial resolution information has allowed locating areas of stability and instability across a large slope this has enabled identification of areas where further monitoring efforts should be focused high temporal resolution information allowed the capture of s shaped slope displacement time behaviour i e phases of slope acceleration deceleration and stability in response to elevations in pore water pressures this study shows that a well balanced suite of monitoring techniques that provides high temporal and spatial resolutions on both measurement and slope scale is necessary to fully understand failure and movement mechanisms of slopes in the case of the hollin hill landslide it enabled detailed interpretation of the geomorphological processes governing landslide activity it highlights the benefit of regularly surveying a network of gps markers to determine areas for installation of movement monitoring techniques that offer higher resolution both temporally and spatially the small sensitivity of tilt meter measurements to translational movements limited the ability to record characteristic s shaped landslide movements at hollin hill which were identified using saa and ae measurements this high sensitivity to landslide movements indicates the applicability of saa and ae monitoring to be used in early warning systems through detecting and quantifying accelerations of slope movement

a long term field study for the investigation of rainfall induced landslides a two year monitoring experiment has been conducted on a slope in shallow weathered soils overlying sandstone bedrock in toessegg switzerland water balance and suctions were measured together with the meteorological inputs in preparation for predicting environmental effects on slope stability electrical resistivity tomography proved particularly helpful in establishing the spatial distribution of soil layering with clayey sand overlying silty sand and bedrock this paper describes monitoring of the field measurements and shows that the double layer causes a bi seasonal response with the smallest factor of safety after the wetter winter months

source and tectonic implications of tonalite trondhjemite magmatism in the klamath mountains in the klamath mountains voluminous tonalite trondhjemite magmatism was characteristic of a short period of time from about 144 to 136 ma early cretaceous it occurred about 5 to 10 m y after the 165 to 159 ma josephine ophiolite was thrust beneath older parts of the province during the nevadan orogeny thrusting from 155 to 148 ma the magmatism also corresponds to a period of slow or no subduction most of the plutons crop out in the south central klamath mountains in california but one occurs in oregon at the northern end of the province compositionally extended members of the suite consist of precursor gabbroic to dioritic rocks followed by later more voluminous tonalitic and trondhjemitic intrusions most plutons consist almost entirely of tonalite and trondhjemite poorly defined concentric zoning is common tonalitic rocks are typically of the low al type but trondhjemites are generally of the high al type even those that occur in the same pluton as low al tonalite the suite is characterized by low abundances of k2o rb zr and heavy rare earth elements sr contents are generally moderate 450 ppm by comparison with sr rich arc lavas interpreted to be slab melts up to 2000 ppm initial 87sr 86sr 18o and nd are typical of mantle derived magmas or of crustally derived magmas with a metabasic source compositional variation within plutons can be modeled by variable degrees of partial melting of a heterogeneous metabasaltic source transitional mid ocean ridge to island arc basalt but not by fractional crystallyzation of a basaltic parent melting models require a residual assemblage of clinopyroxene garnet plagioclase amphibole residual plagioclase suggests a deep crustal origin rather than melting of a subducted slab such models are consistent with the metabasic part of the josephine ophiolite as the source because the josephine ophiolite was at low t during nevadan thrusting an external heat source was probably necessary to achieve significant degrees of melting heat was probably extracted from mantle derived basaltic melts which were parental to the mafic precursors of the tonalite trondhjemite suite thus under appropriate tectonic and thermal conditions heterogeneous mafic crustal rocks can melt to form both low and high al tonalitic and trondhjemitic magmas slab melting is not necessary

surface displacements and source parameters of the 2003 bam iran earthquake from envisat advanced synthetic aperture radar imagery 1 the mw 6 6 26 december 2003 bam iran earthquake was one of the first earthquakes for which envisat advanced synthetic aperture radar asar data were available using interferograms and azimuth offsets from ascending and descending tracks we construct a three dimensional displacement field of the deformation due to the earthquake elastic dislocation modeling shows that the observed deformation pattern cannot be explained by slip on a single planar fault which significantly underestimates eastward and upward motions se of bam we find that the deformation pattern observed can be best explained by slip on two subparallel faults eighty five percent of moment release occurred on a previously unknown strike slip fault running into the center of bam with peak slip of over 2 m occurring at a depth of 5 km the remainder occurred as a combination of strike slip and thrusting motion on a southward extension of the previously mapped bam fault 5 km to the east

probing the mechanical properties of seismically active crust with space geodesy study of the coseismic deformation due to the 1992 mw7 3 landers southern california earthquake 1 the coseismic deformation due to the 1992 m w 7 3 landers earthquake southern california is investigated using synthetic aperture radar sar and global positioning system gps measurements the ers 1 satellite data from the ascending and descending orbits are used to generate contiguous maps of three orthogonal components east north up of the coseismic surface displacement field the coseismic displacement field exhibits symmetries with respect to the rupture plane that are suggestive of a linear relationship between stress and strain in the crust interferometric synthetic aperture radar insar data show small scale deformation on nearby faults of the eastern california shear zone some of these faults in particular the calico rodman and pinto mountain faults were also subsequently strained by the 1999 m w 7 1 hector mine earthquake i test the hypothesis that the anomalous fault strain represents essentially an elastic response of kilometer scale compliant fault zones to stressing by nearby earthquakes fialko et al 2002 the coseismic stress perturbations due to the landers earthquake are computed using a slip model derived from inversions of the insar and gps data calculations are performed for both homogeneous and transversely isotropic half space models the compliant zone model that best explains the deformation on the calico and pinto mountain faults due to the hector mine earthquake successfully predicts the coseismic displacements on these faults induced by the landers earthquake deformation on the calico and pinto mountain faults implies about a factor of 2 reduction in the effective shear modulus within the similar to 2 km wide fault zones the depth extent of the low rigidity zones is poorly constrained but is likely in excess of a few kilometers the same type of structure is able to explain high gradients in the radar line of sight displacements observed on other faults adjacent to the landers rupture in particular the lenwood fault north of the soggy lake has likely experienced a few centimeters of left lateral motion across 1 km wide compliant fault zone having the rigidity reduction of more than a factor of 2 the inferred compliant fault zones are interpreted to be a result of extensive damage due to past earthquakes

structural study of intra oceanic thrusting in the klamath mountains northern california implications on accretion geometry the kinematics of the basal intra oceanic thrust of the trinity preston peak seiad and josephine ultramafic bodies of the klamath mountains are deduced from microstructural and mineral preferred orientation studies when corrected of possible postthrusting rotations these kinematics are thought to reflect the paleoconvergence geometry of the pacific plate relative to the north american continent at the time of intra oceanic thrusting we first detail the kinematics of thrusting for each studied massif these results are then integrated in a plate tectonics reconstruction and a model of continuous ne sw convergence for mesozoic times is proposed

coseismic fault related folding during the south golbaf earthquake of november 20 1989 in southeast iran the south golbaf earthquake of november 20 1989 m s 5 7 m b 5 6 i vii in southeast iran was associated with coseismic surface faulting and folding surface faults 11 km west dipping and 8 km east dipping long with oblique reverse mechanisms developed on both sides of a small holocene playa apparently repeated coseismic fault related folding was responsible for the holocene 20 tilting of the playa deposits above the active fault tip at the ground surface this study provided the first evidence of earthquake folding of holocene playa deposits in iran

measuring ground displacements from sar amplitude images application to the landers earthquake ers sar amplitude images are utilized to map ground displacements from a sub pixel correlation method it yields a ground two dimensional displacement field with independent measurements about every 128m in azimuth and 250m in range the accuracy depends on the characteristics of the images for the landers test case the 1 uncertainty is 0 8m in range and 0 4m in azimuth we show that this measurement provides a map of major surface fault ruptures accurate to better than 1km and information on coseismic deformation comparable to the 92 gps measurements available although less accurate this technique is more robust than sar interferometry and provides complementary information since interferograms are only sensitive to the displacement in range

timescales of orogeny jurassic construction of the klamath mountains an electronic supplement of this material may be obtained on a diskette or anonymous ftp from kosmos agu org login to agu s ftp account using anonymous as the username and guest as the password go to the right directory by typing cd apend type ls to see what files are available type get and the name of the file to get it finally type exit to leave the system paper 94ycj2454 timescales of orogeny jurassic construction of the klamath mountains b r hacker m m donato c g barnes m o mcwilliams and w g ernst diskette may be ordered from american geophysical union 2000 florida avenue n w washington dc 20009 15 00 payment must accompany order classical interpretations of orogeny were based on relatively imprecise biostratigraphic and isotopic age determinations that necessitated grouping apparently related features that may in reality have been greatly diachronous isotopic age techniques now have the precision required to resolve the timing of orogenic events on a scale much smaller than that of entire mountain belts forty five new 40ar 39ar ages from the klamath mountains illuminate the deformation metamorphism magmatism and sedimentation involved in the jurassic construction of that orogen leading to a new level of understanding regarding how preserved orogenic features relate to ancient plate tectonic processes the new geochronologic relationships show that many jurassic units of the klamath mountains had 200 ma or older volcanoplutonic basement subsequent formation of a large 170 ma arc was followed by contractional collapse of the arc collision with a spreading ridge may have led to large scale nw se extension in the central and northern klamaths from 167 to 155 ma coincident with the crystallization of voluminous plutonic and volcanic suites marked cooling of a large region of the central klamath mountains to below 350 c at 150 ma may have occurred as the igneous belt was extinguished by subduction of colder material at deeper structural levels these data demonstrate that the klamath mountains and perhaps other similar orogens were constructed during areally and temporally variant episodes of contraction extension and magmatism that do not fit classical definitions of orogeny

origin of the amphibolite sole of the josephine ophiolite emplacement of a cold ophiolite over a hot arc the amphibolite sole that occurs along the basal thrust of the josephine ophiolite madstone cabin thrust is distinct from those described for ophiolites such as the bay of islands and oman antigorite bearing serpentinite mylonites occur directly above the amphibolite and the presence of antigorite brucite indicates formation between 300 and 400 c the antigorite mylonites also contain relict lizardite chrysotile suggesting formation of antigorite by prograde metamorphism along the base of the ophiolite further evidence for prethrusting low temperature serpentinization comes from a lizardite chrysotile shear zone within fresh peridotite directly above the thrust that is cut by undeformed diabase dikes having geochemical affinities to the upper pillow lavas of the josephine ophiolite the prograde metamorphism of the serpentinite at the base of the ophiolite was apparently synchronous with greenschist facies retrogressive metamorphism of the underlying amphibolite the amphibolite is chemically diverse and has been divided into two groups group 1 amphibolite appears to be derived from mafic plutonic rocks and has immobile trace element abundances indicating affinities to volcanic arc magmas group 2 amphibolite is metavolcanic contains some quartzite and has magmatic affinities to mid ocean ridge basalt and within plate basalt an association that is distinctive of older basement rocks elsewhere in the western klamath terrane we suggest the amphibolite was derived from the footwall of the madstone cabin thrust including country rocks for the chetco complex group 2 and possibly older intrusive phases of the chetco complex itself group 1 previous workers have shown that the base of the amphibolite is intruded by gneissic gabbro of the chetco complex that intrusion of the chetco complex overlapped in time with deformation of the amphibolite and that during and after emplacement the josephine ophiolite and overlying flysch were intruded by abundant arc related dikes and plutons emplacement of the josephine ophiolite appears to have occurred by underthrusting of a cold ophiolite by an active magmatic arc

source model for the mw 6 7 23 october 2002 nenana mountain earthquake alaska from insar 1 the 23 october 2002 nenana mountain earthquake mw 6 7 occurred on the denali fault alaska to the west of the mw 7 9 denali earthquake that ruptured the same fault 11 days later we used 6 interferograms constructed using radar images from the canadian radarsat 1 and european ers 2 satellites to determine the coseismic surface deformation and a source model data were acquired on ascending and descending satellite passes with incidence angles between 23 and 45 degrees and time intervals of 72 days or less modeling the event as dislocations in an elastic half space suggests that there was nearly 0 9 m of right lateral strike slip motion at depth on a near vertical fault and that the maximum slip in the top 4 km of crust was less than 0 2 m the nenana mountain earthquake increased the coulomb stress at the future hypocenter of the 3 november 2002 denali earthquake by 30 60 kpa

rainfall triggered landslides in an unsaturated soil a laboratory flume study extreme and or prolonged rainfall events frequently cause landslides in many parts of the world in this study infiltration of rainfall into an unsaturated soil slope and triggering of landslides is studied through laboratory model flume tests with the goal of obtaining the triggering rainfall intensity duration i d threshold flume tests with fine sand at two different relative densities 34 and 48 and at slope angle of 56 5 are prepared and rainfall intensity in the range of 18 to 64 mm h is applied via a mist sprinkler system to trigger landslides soil water characteristic curve and hydraulic conductivity function of the fine sand are also presented in flume tests suction in the soil is measured with tensiometers the progress of wetting front with time and deformations in the soil are also measured some of the findings of this study are for the fine sand used in this study a the failure mechanism is infinite slope type mostly translational and the failure surface is generally coincident with the wetting front or is in its vicinity b the deformations leading to a landslide occurred abruptly c both relatively high intensity short duration rainfalls and relatively low intensity long duration rainfalls triggered landslides d the shape of the i d threshold is demonstrated to be a bilinear relation in log intensity log duration plot e below a certain rainfall intensity landslides are not triggered f the effect of relative density of the soil on the i d threshold is demonstrated by physical laboratory tests as the relative density of the soil increases the triggering rainfall intensity duration threshold moves to larger rainfall events the results of this study could be useful for accurate numerical modeling of rainfall triggered landslides

cryptic tectonic domains of the klamath mountains california and oregon abstract numerous fragments of oceanic crust and island arcs make up the klamath mountains province these fragments were joined together amalgamated in an oceanic setting during paleozoic and mesozoic collisional events and were accreted to north america as a composite unit during latest jurassic or earliest cretaceous time the roughly arcuate and concentric distribution of the terranes of the klamath mountains does not now seem to be a result of simple oroclinal bending as earlier believed although commonly described as a west facing arcuate structure the province is cut diagonally by a vaguely defined nw trending zone of discontinuity or hinge line that divides the province into ne and sw tectonic domains the zone of discontinuity is marked by a number of lithic and structural anomalies and particularly by the distribution of a remarkable series of belts of plutonic rocks the terranes regional structures and plutonic belts of the ne domain trend ne and are generally wider and more coherent than the narrow nw trending terranes and plutonic belts of the sw domain most plutonic belts of the ne domain do not have equivalents in the sw domain paleomagnetic evidence suggests that all the plutonic belts except possibly the youngest the earliest cretaceous shasta bally belt were emplaced before the klamath mountains terranes finally accreted to north america

radar interferometry and its application to changes in the earth s surface geophysical applications of radar interferometry to measure changes in the earth s surface have exploded in the early 1990s this new geodetic technique calculates the interference pattern caused by the difference in phase between two images acquired by a spaceborne synthetic aperture radar at two distinct times the resulting interferogram is a contour map of the change in distance between the ground and the radar instrument these maps provide an unsurpassed spatial sampling density 100 pixels km 2 a competitive precision 1 cm and a useful observation cadence 1 pass month 1 they record movements in the crust perturbations in the atmosphere dielectric modifications in the soil and relief in the topography they are also sensitive to technical effects such as relative variations in the radar s trajectory or variations in its frequency standard we describe how all these phenomena contribute to an interferogram then a practical summary explains the techniques for calculating and manipulating interferograms from various radar instruments including the four satellites currently in orbit ers 1 ers 2 jers 1 and radarsat the next chapter suggests some guidelines for interpreting an interferogram as a geophysical measurement respecting the limits of the technique assessing its uncertainty recognizing artifacts and discriminating different types of signal we then review the geophysical applications published to date most of which study deformation related to earthquakes volcanoes and glaciers using ers 1 data we also show examples of monitoring natural hazards and environmental alterations related to landslides subsidence and agriculture in addition we consider subtler geophysical signals such as postseismic relaxation tidal loading of coastal areas and interseismic strain accumulation we conclude with our perspectives on the future of radar interferometry the objective of the review is for the reader to develop the physical understanding necessary to calculate an interferogram and the geophysical intuition necessary to interpret it

a general analytical solution for the evolution of cliffs accounting for strength degradation seismic action formation of tension cracks and seepage abstract the evolution of natural slopes over time is ruled by several concurrent physical phenomena namely the strength of its component geomaterials and their weakening over time due to weathering processes the occurrence of seismic events seepage and the formation of tension cracks the paper presents analytical solutions obtained considering a succession of discrete failure events landslides progressively altering the slope morphology over time the model derived in the framework of limit analysis assuming plane strain conditions provides a tool for the assessment of whether manufacts and or infrastructures located on a slope subject to various natural degradation phenomena will be affected by the occurrence of failures unlike current empirical and semi empirical models of slope evolution the analytical solution that is here presented is derived by applying principles of soil and rock mechanics therefore it is of general validity so that no ad hoc calibration against past observations of the evolving slope is needed this analytical technique only requires knowledge of the geotechnical parameters characterising the geomaterials comprising the slope of interest namely angle of shearing resistance cohesion c tensile strength unit weight together with knowledge of the relevant seepage scenarios strength degradation processes and seismic events likely to occur results show that that earthquake loading and seepage can substantially decrease slope stability increase the volume of material sliding away during each landslide event and alter the evolution of the slope over time while tensile strength exhibits a less strong influence especially as strength degradation progresses dimensionless ready to use charts are provided for the benefit of practitioners

geodetic investigation of the 13 may 1995 kozani grevena greece earthquake the ms 6 6 13 may 1995 kozani grevena earthquake struck a region of low historical seismic activity which includes a 10 year old triangulation network in northern greece after the earthquake monuments from this network were occupied with gps to measure co seismic displacements inversion of the co seismic displacement field to yield a source mechanism is achieved by use of a hybrid simplex monte carlo method which requires no a priori constraints the model focal mechanism agrees well with the global cmt solution and locally observed aftershocks but implies a significantly higher scalar moment than do seismological or sar interferometry studies and has a longer fault length than the model based on sar interferometry

comment on structural study of intra oceanic thrusting in the klamath mountains northern california implications on accretion geometry by mathilde cannat and francoise boudier

geophysical monitoring of moisture induced landslides a review author s whiteley js chambers je uhlemann s wilkinson pb kendall jm abstract 2018 the authors geophysical monitoring of landslides can provide insights into spatial and temporal variations of subsurface properties associated with slope failure recent improvements in equipment data analysis and field operations have led to a significant increase in the use of such techniques in monitoring geophysical methods complement intrusive approaches which sample only a very small proportion of the subsurface and walk over or remotely sensed data which principally provide information only at the ground surface in particular recent studies show that advances in geophysical instrumentation data processing modeling and interpretation in the context of landslide monitoring are significantly improving the characterization of hillslope hydrology and soil and rock hydrology and strength and their dynamics over time this review appraises the state of the art of geophysical monitoring as applied to moisture induced landslides here we focus on technical and practical uses of time lapse methods in geophysics applied to monitoring moisture induced landslide the case studies identified in this review show that several geophysical techniques are currently used in the monitoring of subsurface landslide processes these geophysical contributions to monitoring and predicting the evolution of landslide processes are currently underrealized hence the further integration of multiple parametric and geotechnically coupled geophysical monitoring systems has considerable potential the complementary nature of certain methods to map the distribution of subsurface moisture and elastic moduli will greatly increase the predictive and monitoring capacity of early warning systems in moisture induced landslide settings

performance of an unsaturated expansive soil slope subjected to artificial rainfall infiltration a major infrastructure project the south to north water transfer project has been proposed to carry potable water from the yangtze river region in the south to many arid and semi arid areas in the northern regions of china including beijing the proposed 1200 km middle route of the project is likely to be an open channel with a trapezoidal cross section at least 180 km of the proposed excavated canal will pass through areas of unsaturated expansive soils an 11 m high cut slope in a typical expansive clay with medium plasticity in zaoyang close to the middle route in hubei was selected for a comprehensive and well instrumented field study of the effects of rainfall infiltration two artificial rainfall events were created during a month of field investigation and monitoring prior to the rainfall events high soil suction was measured within the top 1 m of soil this high initial soil suction created an upward flux of water and moisture the abundant cracks and fissures near the ground surface p

synthetic aperture radar interferometry to measure earth s surface topography and its deformation synthetic aperture radar interferometry insar from earth orbiting spacecraft provides a new tool to map global topography and deformation of the earth s surface radar images taken from slightly different viewing directions allow the construction of digital elevation models of meter scale accuracy these data sets aid in the analysis and interpretation of tectonic and volcanic landscapes if the earth s surface deformed between two radar image acquisitions a map of the surface dis placement with tens of meters resolution and subcentimeter accuracy can be con structed this review gives a basic overview of insar for earth scientists and presents a selection of geologic applications that demonstrate the unique capabilities of insar for mapping the topography and deformation of the earth

metamorphism of a late jurassic volcano plutonic arc northern california usa the metamorphic history of the middle to upper jurassic volcanic and hypabyssal rocks exposed in the klamath mountains and sierra nevada of california is related in part to the rifting of a volcano plutonic arc the callovian to kimmeridgian rocks exposed in the region consist of from north west to south east a back arc ophiolite a rifted volcanic arc and a volcanic arc complex all of these units have been metamorphosed and contain various combinations of the phases chlorite amphibole epidote prehnite and pumpellyite projection of coexisting phases onto the composition plane mgo mgo feo and al2o3 fe2o3 0 75 cao na2o through quartz water albite and epidote results in consistent mineralogical compatibilities within each region but crossing tie lines between regions this suggests that the volcanic and hypabyssal rocks from each region have equilibrated under different intensive conditions the back arc ophiolite in the north has suffered subseafloor high t p hydrothermal metamorphism with geothermal gradients on the order of 100 c km 1 the rifted volcanic arc has undergone synchronous burial hydrothermal and contact metamorphism metamorphic field gradients in the region pass through the prehnite pumpellyite and greenschist facies suggesting geothermal gradients on the order of 30 c km 1 the southernmost volcanic arc complexes contain metavolcanics of the pumpellyiteactinolite and greenschist facies suggesting moderate to high p t metamorphism and geothermal gradients on the order of 20 c km 1 the apparent increase in rifting and calculated geothermal gradients from south east to north west suggest that the observed very low and low grade metamorphism may be a response to enhanced thermal gradients during extension of the volcanic arc this correlation between the extent of rifting and metamorphism is consistent with a model of diastathermal metamorphism of a propagating rift along the western margin of north america during the late jurassic the plate tectonic setting may be analogous to the present day andaman sea region

assimilation of peridotite in zoned calc alkaline plutonic complexes evidence from the big jim complex washington cascades the big jim complex is a concentrically zoned ultramafic to felsic plutonic complex which intruded the pelitic chiwaukum schist most of the major plutonic rock types from websterite through hornblendite gabbronorite hornblende gabbro and diorite to granodiorite enclose harzburgite and metaperidotite xenoliths similar to foliated metaperidotite lenses included in the chiwaukum schist the larger xenoliths preserve tectonite fabrics all have mg s mole fraction mgo mgo feo from 0 90 to 0 89 the same as those of chiwaukum metaperidotites and distinctly different from undeformed big jim dunite mg s 0 84 to 0 82 and websterite 0 82 to 0 78 contact relations indicate widespread stepwise replacement of harzburgite by pyroxenite hornblendite gabbro and diorite thermodynamic modelling using an expanded regular solution model for silicate liquids ghiorso 1985 ghiorso and carmichael 1985 predicts that reaction between olivine fo90 and a liquid with the composition of big jim diorite 1 5 wt h2o at 1 100 c and 3 kb would produce websterite mg s 0 75 to 0 81 and dunite 0 79 to 0 82 this process is exothermic and results in a negative change in volume since it increases total solid mass under conditions of decreasing temperature modelled crystal fractionation with assimilation of olivine reproduces important features of the chemical variation observed in the big jim complex where crystal fractionation alone fails the big jim complex has affinities with other ultramafic to felsic plutonic complexes such as the bear mountain complex snoke et al 1981 1982 and the emigrant gap complex james 1971 the latter have wehrlite and clinopyroxenite rather than websterite but both have concentric zoning with olivine bearing rock types surrounded by successively more felsic pyroxenite gabbro and diorite in general concentrically zoned complexes of this type may form where magma reacts with mantle derived wall rock or ultramafic cumulates assimilation of peridotite in fractionating magma may be important in subduction related magmatic arcs

soil water balance in an unsaturated pyroclastic slope for evaluation of soil hydraulic behaviour and boundary conditions flowslides in granular soils pose a major threat to life and the environment their initiation in unsaturated soils is regulated by rainfall infiltration which reduces the matric suction and hence shear strength analysis of such phenomena is of strategic importance especially when it aims to mitigate landslide risk by means of early warning systems ewss in this framework physically based models need to reproduce the hydro mechanical behaviour of the slopes through numerical analyses whose main uncertainty concerns the hydraulic conditions at the boundaries of the studied domain and hydraulic conductivity functions of unsaturated soils hence consummate knowledge of both these factors is absolutely necessary for efficient predictions in this paper hydraulic boundary conditions and hydraulic conductivity functions are investigated at the scale of the slope through an application of soil water balance based on in situ monitoring at the test site of monteforte irpino southern italy meteorological data matric suction and soil water content measurements were collected over four years at the test site the soil water balance was analysed on a seasonal time scale with regard to the whole pyroclastic cover resting on the steep limestone substratum infiltration and runoff are estimated interaction between the soil cover and the substratum is investigated and the hydraulic conductivity functions operative at the site scale are defined

differential preservation in the geologic record of intraoceanic arc sedimentary and tectonic processes abstract records of ancient intraoceanic arc activity now preserved in continental suture zones are commonly used to reconstruct paleogeography and plate motion and to understand how continental crust is formed recycled and maintained through time however interpreting tectonic and sedimentary records from ancient terranes after arc continent collision is complicated by preferential preservation of evidence for some arc processes and loss of evidence for others in this synthesis we examine what is lost and what is preserved in the translation from modern processes to the ancient record of intraoceanic arcs composition of accreted arc terranes differs as a function of arc continent collision geometry forward facing collision can accrete an oceanic arc on to either a passive or an active continental margin with the arc facing the continent and colliding trench and forearc side first in a backward facing collision involving two subduction zones with similar polarity the arc collides backarc first with an active continental margin the preservation of evidence for contemporary sedimentary and tectonic arc processes in the geologic record depends greatly on how well the various parts of the arc survive collision and orogeny in each case preservation of arc terranes likely is biased towards those that were in a state of tectonic accretion for tens of millions of years before collision rather than tectonic erosion the prevalence of tectonic erosion in modern intraoceanic arcs implies that valuable records of arc processes are commonly destroyed even before the arc collides with a continent arc systems are most likely to undergo tectonic accretion shortly before forward facing collision with a continent and thus most forearc and accretionary prism material in ancient arc terranes likely is temporally biased toward the final stages of arc activity when sediment flux to the trench was greatest and tectonic accretion prevailed collision geometry and tectonic erosion vs accretion are important controls on the ultimate survival of material from the trench forearc arc massif intra arc basins and backarc basins and thus on how well an ancient arc terrane preserves evidence for tectonic processes such as subduction of aseismic ridges and seamounts oblique plate convergence and arc rifting forward facing collision involves substantial recycling melting and fractionation of continent derived material during and after collision and so produces melts rich in silica and incompatible trace elements as a result forward facing collision can drive the composition of accreted arc crust toward that of average continental crust

moisture content pore water pressure and wetting front in granite residual soil during collapsing erosion with varying slope angle abstract collapsing erosion is very severe in subtropical regions that are covered extensively by granite residual soil however detailed information about hydraulic responses during collapsing erosion especially for different slope angles remains unclear therefore to control collapsing erosion it is important to attain a more comprehensive understanding of the complex hydraulic responses due to rainfall in this study an artificial rainfall simulator and an experimental device were used to evaluate the collapsing erosion process with particular consideration of the influence of slope angle flume experiments using three slope angles 0 10 and 20 were performed under artificial rainfall this study explored the evolutions and hydraulic responses of collapsing erosion of granite residual soil by simultaneously monitoring moisture content pore water pressure and wetting front during heavy rainfall the results showed that collapsing erosion occurred faster with steeper slope angle collapse occurred in an upslope direction when the corresponding moisture content of the soil was between 30 and 40 pore water pressure increased until the development of collapsing erosion but was released when the soil mass collapsed the descending process of the wetting front on a gentle slope and a steep slope can be divided into two stages and three stages respectively this study presents an improved characterization of collapsing erosion and provides valuable evidence for slope angle impacts on infiltration events during collapsing erosion under heavy rainfall

out of plane effects in 2d borehole to surface resistivity tomography and applications in mineral exploration in this paper we discuss the effects of anomalous out of plane bodies in two dimensional 2d borehole to surface electrical resistivity tomography with numerical resistivity modelling and synthetic inversion tests the results of the two groups of synthetic resistivity model tests illustrate that anomalous bodies out of the plane of interest have an effect on two dimensional inversion and that the degree of influence of out of plane body on inverted images varies the different influences are derived from two cases one case is different resistivity models with the same electrode array and the other case is the same resistivity model with different electrode arrays qualitative interpretation based on the inversion tests shows that we cannot find a reasonable electrode array to determine the best inverse solution and reveal the subsurface resistivity distribution for all types of geoelectrical models because of the three dimensional effect arising from neighbouring anomalous bodies the qualitative interpretation of inverted images from the two dimensional inversion of electrical resistivity tomography data without prior information can be misleading two dimensional inversion with drilling data can decrease the three dimensional effect we employed two and three dimensional borehole to surface electrical resistivity tomography methods with a pole pole array and a bipole bipole array for mineral exploration at abag banner and hexigten banner in inner mongolia china different inverse schemes were carried out for different cases the subsurface resistivity distribution obtained from the two dimensional inversion of the field electrical resistivity tomography data with sufficient prior information such as drilling data and other non electrical data can better describe the actual geological situation when there is not enough prior information to carry out constrained two dimensional inversion the three dimensional electrical resistivity tomography survey is the better choice

imaging rainfall infiltration processes with the time lapse electrical resistivity imaging method electrical resistivity imaging eri was carried out continuously for 10 days to map the subsurface resistivity distribution along a potentially hazardous hillslope at the jieshou junior high school in taoyuan taiwan the reliability of the inverted resistivity structures down to about 25 m depth was examined with synthetic modeling using the same electrode arrangements installed on land surface as in field surveys together with a doi depth of investigation index calculated from the eri data the subsurface resistivity distribution is consistent with results from well logging these eri recordings were taken daily and provided highly resolved imagery of the resistivity distribution underground and illustrated the dynamical fluid flow behavior due to heavy rainfall infiltration using archie s law the resistivity distribution was transformed into a map of relative water saturation rws which is strongly correlated with the rainfall infiltration process we then found that the averaged rws is significantly correlated with daily precipitation our observations indicate that time lapse eri is effective in monitoring subterraneous rainfall infiltration moreover the preferential flow paths can be delineated according to the changes in averaged rws derived from the eri data

the role of recent tectonics and hydrological processes in the evolution of recurring landslides on the danube s high bank in dunafoldvar hungary abstract there are high loess banks prone to landslide along the river danube in hungary one of these is the high loess bank in dunafoldvar where several landslides occurred in the last decades quantitative relationships between the movements of the high loess bank and the variation of the water level of the river danube the ground water table precipitation and temperature are investigated by two borehole tiltmeters and a vertical borehole extensometer the twelve year long observation from 2002 to 2014 made it possible to distinguish between the high bank movements due to slow recent tectonic and geomorphologic processes and the short period from hours to months movements caused by hydrometeorological effects the results revealed that besides geomorphologic processes recent tectonics can play an important role in the recurrence of landslides in the area in the investigated period the total tilt of the high bank was 162 rad in the sse direction according to the geomorphologic and recent tectonic processes in the surroundings of dunafoldvar investigations of the relationships between the high bank movements and the water level of the river danube ground water table changes and the precipitation revealed that the tilt magnitudes caused by the ground water table variations are two orders of magnitude greater than the tilts caused by the water level regime of the river and the direct effect of the precipitation on the high bank tilts can be disregarded

offset and evolution of the gowk fault s e iran a major intra continental strike slip system abstract we use drainage reconstructions to estimate long term offsets on the gowk fault an oblique right lateral strike slip fault in eastern iran on which there have been a number of recent large earthquakes a 3 km horizontal offset is inferred from well preserved geomorphology we further identify a total cumulative offset of 12 km which produces a simple reconstruction of geomorphology across the fault filling in pull apart basins restoring rivers to linear courses across the fault trace and aligning structural and bed rock features the probable age of the gowk fault and k ar dating of offset basalts north of the study region suggest an overall slip rate of 1 5 2 4 mm year this is small compared with the overall 10 20 mm year of shear expected between central iran and afghanistan and the deficit is likely to have been accommodated on other faults east of the gowk fault drainage displaced by dextral movement leads to the development of a series of basins along the fault and a longitudinal topographic profile that resembles an asymmetric saw tooth the geomorphic evolution of the fault zone at the surface includes both normal and reverse faulting components reflecting a probable ramp and flat structure in cross section this interpretation is consistent with evidence from the analysis of seismological radar and surface rupture data in recent earthquakes

fe ti basalts and propagating rift tectonics in the josephine ophiolite the jurassic josephine ophiolite of northwest california and southwest oregon is one of the largest and most complete ophiolites in north america and clearly formed in a suprasubduction zone setting the geochemistry of lavas and dikes is highly variable because of a range in magma types and different degrees of fractionation basalts rich in fe and ti occur in the uppermost part of the extrusive sequence and as late dikes cutting oceanic serpentinite they have morb mid oceanic ridge basalt affinities and appear to be unrelated to the rest of the ophiolite that has affinities dominantly transitional between iat and morb iat island arc tholeiite this late fe ti morb suite was erupted while the ophiolite was undergoing the last half of 50 of tilting of the entire crustal sequence and after widespread serpentinization of ultramafic cumulates and uppermantle peridotite related to freezing of the axial magma chamber fe ti basalts are characteristic of propagating spreading centers on mid ocean ridges and in at least one backarc basin geochemical structural stratigraphic and regional geologic constraints suggest formation of the josephine ophiolite by propagation of a spreading center into rifted island arc lithosphere that is preserved along the margin of the ophiolite another possible indication of propagating rift tectonics is the presence of off axis metalliferous sedimentary rocks that may have been deposited as hydrothermal plume fall out from a second propagating spreading center the lau basin provides modern analogues including spreading centers propagating into rifted arc lithosphere into older backarc ocean crust and across the arc into the forearc

the 1998 march 14 fandoqa earthquake mw 6 6 in kerman province southeast iran re rupture of the 1981 sirch earthquake fault triggering of slip on adjacent thrusts and the active tectonics of the gowk fault zone summary the 1998 march 14 fandoqa earthquake ms 6 6 was the penultimate in a series of five substantial earthquakes on the gowk fault system of southeast iran since 1981 all of which were associated with co seismic surface ruptures we use observations of surface faulting analysis of p and sh body waves sar interferometry and geomorphology to investigate the ruptures in these earthquakes and how they are related both to each other and to the regional active tectonics the 1998 fandoqa earthquake produced 23 km of surface faulting with up to 3 m right lateral strike slip and 1 m vertical offsets sar interferometry and seismic waveforms show that the main rupture plane dipped west at 50 and had a normal component although the surface ruptures were more complicated being downthrown to both the east and the west on steep faults in near surface sediments in addition sar interferometry shows that a nearby thrust with a similar strike but dipping at 6 w moved about 8 cm in a time interval and in a position that makes it likely that its slip was triggered by the fandoqa earthquake the 1998 surface ruptures in the gowk valley followed part of a much longer 80 km set of co seismic ruptures with smaller offsets that were observed after larger earthquakes in 1981 mw 6 6 and 7 1 the main ruptures in these 1981 earthquakes probably occurred on different deeper parts of the same fault system producing only minor reactivation of the shallower faults at the surface although the 1981 1998 earthquake sequence apparently ruptured parts of the same fault system repeatedly these earthquakes had very different rupture characteristics an important lesson for the interpretation of both palaeoseismological trenching investigations and historical accounts of earthquakes the regional kinematics which involve oblique right lateral and convergent motion are evidently achieved by a complex configuration of faults with normal reverse and strike slip components some of the complexity at the surface may be related to a ramp and flat fault geometry at depth but could also be related to the large topographic contrast of 2000 m across the fault system which separates the high kerman plateau from the low dasht e lut desert details of the fault geometry at depth remain speculative but it must be unstable and evolve with time it may be this requirement that causes the principal features of geological flower structures to develop such as series of subparallel faults which accommodate dip slip components of motion

source parameters of the 1 october 1995 dinar turkey earthquake from sar interferometry and seismic bodywave modelling abstract the 1 october 1995 m s 6 1 dinar earthquake ruptured a 10 km section of the nw se dinar civril fault there are discrepancies between the published source parameters from seismic data with seismic moments in disagreement by over a factor of two we use both sar interferometry and seismic bodywave modelling to determine earthquake source parameters an interferogram generated from ers 1 2 sar imagery spanning the event and separated by 5 months is used to derive source parameters by a downhill simplex inversion with multiple monte carlo restarts we model the displacements in the satellite line of sight initially using uniform slip on a rectangular dislocation in an elastic half space the resultant model fault plane agrees in strike and location with the observed surface break but systematic residuals exist in the line of sight deformation field resulting in a r m s residual of 20 mm in the interferogram the residuals are reduced if the depth distribution of slip is allowed to vary spatially in four segments along a continuous fault plane our best fitting solution with a r m s misfit of 8 mm reveals two distinct areas of slip on the fault plane strike 145 dip 49 rake 270 a main rupture slipping by 1 44 m between depths of 1 and 8 km becoming deeper to the se and matching the observed surface rupture and an along strike continuation to the nw of the same fault plane but between depths of 8 and 13 km and not associated with a surface break the total geodetic moment 4 5 0 1 10 18 nm is more than twice as large as published seismic moments based on the inversion of p waveforms alone but close to the harvard cmt moment 4 7 10 18 nm we use sh waveforms in addition to the p waves used previously to determine an alternative seismic source mechanism sh waves constrain the depth to be shallower than solutions based on p waves alone agreeing with the depths from the interferometric inversion and resulting in a larger moment 3 1 0 4 10 18 nm than the previous bodywave estimates 2 2 1 10 18 nm the cmt moment reduces in magnitude to a similar size 3 3 10 18 nm if the centroid depth and fault dip are constrained to the values determined from bodywave modelling and interferometry thus the geodetic moment is 40 bigger than the moment determined from seismology

hydrological factors affecting rainfall induced shallow landslides from the field monitoring to a simplified slope stability analysis abstract rainfall induced shallow landslides can seriously affect cultivations and infrastructures and cause human losses a continuous monitoring of unsaturated soil hydrological properties is needed to understand the effects of pore water pressure and water content on shallow landslides triggering and slope safety factor in this work the impact of water content pore water pressure and hydrological hysteresis on safety factor reconstruction is analyzed by applying two different models lu and godt s and slip models to a monitored slope located in oltrepo pavese northern italy a shallow landslide event in the studied slope during the monitoring allowed for identifying the triggering mechanism and modeling the safety factor changes the conditions of instability mechanism develop in periods with frequent rainfalls the uprising of a perched water table in the soil profile gets nil or positive pore water pressure which linked with the nil effective soil cohesion of some soil horizons allows for the shallow landslide triggering the safety factor trends correctly predicted unstable conditions safety factor 1 0 in correspondence of the shallow landslide triggering time on the basis of both water content and pore water pressure a better prediction gets when the safety factor is modeled considering the hysteresis effects modeling the safety factor on the basis of water content can make a good assessment of shallow failures triggering conditions only for failures in unsaturated soils and for completely saturated soils instead considering pore water pressure it is possible estimating safety factor changes linked with the development of positive pore water pressures which can be linked in some cases to shallow landslide development

four dimensional imaging of moisture dynamics during landslide reactivation landslides pose significant risks to communities and infrastructure and mitigating these risks relies on understanding landslide causes and triggering processes it has been shown that geophysical surveys can significantly contribute to the characterization of unstable slopes however hydrological processes can be temporally and spatially heterogeneous requiring their related properties to be monitored over time geoelectrical monitoring can provide temporal and volumetric distributions of electrical resistivity which are directly related to moisture content to date studies demonstrating this capability have been restricted to 2d sections which are insufficient to capture the full degree of spatial heterogeneity this study is the first to employ 4d i e 3d time lapse resistivity imaging on an active landslide providing long term data three years highlighting the evolution of moisture content prior to landslide reactivation and showing its decline post reactivation crucially the time lapse inversion methodology employed here incorporates movements of the electrodes on the unstable surface although seasonal characteristics dominate the shallow moisture dynamics during the first two years with surficial drying in summer and wetting in winter in the months preceding reactivation moisture content increased by more than 45 throughout the slope this is in agreement with independent data showing a significant rise in piezometric heads and shallow soil moisture contents as a result of prolonged and intense rainfall based on these results remediation measures could be designed and early warning systems implemented thus resistivity monitoring that can allow for moving electrodes provides a new means for the effective mitigation of landslide risk

revel a model for recent plate velocities from space geodesy 1 we present a new global model for recent plate velocities revel describing the relative velocities of 19 plates and continental blocks the model is derived from publicly available space geodetic primarily gps data for the period 1993 2000 we include an independent and rigorous estimate for gps velocity uncertainties to assess plate rigidity and propagate these uncertainties to the velocity estimates the velocity fields for north america eurasia and antarctica clearly show the effects of glacial isostatic adjustment and australia appears to depart from rigid plate behavior in a manner consistent with the mapped intraplate stress field two thirds of tested plate pairs agree with the nuvel 1a geologic 3 myr average velocities within uncertainties three plate pairs caribbean north america caribbean south america and north america pacific exhibit significant differences between the geodetic and geologic model that may reflect systematic errors in nuvel 1a due to the use of seafloor magnetic rate data that do not reflect the full plate rate because of tectonic complexities most other differences probably reflect real velocity changes over the last few million years several plate pairs arabia eurasia arabia nubia eurasia india move more slowly than the 3 myr nuvel 1a average perhaps reflecting long term deceleration associated with continental collision several other plate pairs including nazca pacific nazca south america and nubia south america are experiencing slowing that began 25 ma the beginning of the current phase of andean crustal shortening

prediction of rainfall induced shallow landslides in the loess plateau yan an china using the trigrs model in this work a transient rainfall infiltration and grid based regional slope stability model trigrs was implemented in a case study of yan an city northwest china in this area widespread shallow landslides were triggered by the 12 july 2013 exceptional rainstorm event a high resolution dem soil parameters from in situ and laboratory measurements water table depths the maximum depth of precipitation infiltration and rain gauge corrected precipitation of the event were used as inputs in the trigrs model shallow landslides triggered on the same day were used to evaluate the modeling results the summarized results are as follows i the characteristics and distribution of thirty five shallow landslides triggered by the 12 july 2013 rainfall event were identified in the study area and all were classified as shallow landslides with the maximum depth area and volume less than 3 m 200 m2 and 1000 m3 respectively ii four intermediate factor of safety fs maps were generated using the trigrs model to represent the scenarios 6 12 18 and 24 hours after the storm event the area with fs 1 increased with the rainfall duration the percentage of the area with fs 1 was 0 2 3 3 3 8 and 5 1 for the four stages respectively twenty four hours after the rainstorm trigrs predicted that 1255 grid cells failed which is consistent with the field data iii trigrs generated more satisfactory results at a given precipitation threshold than sinmap which is ideal for landslide hazard zoning for land use planning at the regional scale comparison results showed that trigrs is more useful for landslide prediction for a certain precipitation threshold also in the regional scale iv analysis of the responses of loess slope prone to slope failure after different precipitation scenarios revealed that loess slopes are particularly sensitive to extended periods of heavy precipitation copyright 2016 john wiley sons ltd

u pb geochronology of detrital zircon from upper jurassic synorogenic turbidites galice formation and related rocks western klamath mountains correlation and klamath mountains provenance synorogenic turbidites of the upper jurassic galice formation overlie a variety of basement terranes within the western klamath mountains along the oregon california border including the early late jurassic ophiolite assemblages ensimatic arc deposits and sedimentary terranes u pb analyses of 68 multiple grain fractions from 11 samples of detrital zircon support the correlation of galice formation on these various basement terranes although some new complexities in provenance are revealed with one exception upper intercept ages range from 1509 3 3 to 1675 8 8 ma least squares regression of all fractions yields an upper intercept age of 1583 1 ma indicating the importance of an ultimately continental recycled and generally well mixed sedimentary source early mesozoic lower intercept ages range between 183 2 2 and 263 4 3 and average 215 1 ma results from galice cover on sedimentary basement show significantly older 2 1 ga precambrian component however that may be locally derived from pre late jurassic basement rocks that are rich in recycled sedimentary debris existing isotopic data from older zircon bearing klamath units further indicate that galice detritus was derived from immediate source terranes within the klamath mountains reworking of fragile limestone clasts from the biogeographically distinctive eastern klamath terrane mccloud limestone into galice formation substrate also supports early paleogeographic ties between terranes thus the tectonic setting of the late jurassic nevadan orogeny in the klamath mountains is tightly constrained by original paleogeographic ties between subterranes of the western belt and by provenance ties to terranes to the east ultimately continent derived clastic debris and other distinctive tracers were recycled within this long lived ensimatic convergent margin system

surface ruptures and building damage of the 2003 bam iran earthquake mapped by satellite synthetic aperture radar interferometric correlation 1 we use the interferometric correlation from envisat synthetic aperture radar sar images to map the details of the surface ruptures related to the 26 december 2003 earthquake that devastated bam iran the main strike slip fault rupture south of the city of bam has a series of four segments with left steps shown by a narrow line of low correlation in the coseismic interferogram this also has a clear expression in the field because of the net extension across the fault just south of the city limits the surface strain becomes distributed over a width of about 500 m probably because of a thicker layer of soft sedimentary material another fault north of bam shows offset and low correlation over a wider zone in the interferograms but it has no discrete surface rupture possibly because of a net shortening across this fault taking the difference between the interferometric correlation for an interval including the earthquake and an interval before the earthquake separates the changes due to the earthquake from other effects in the partially vegetated city of bam we map the damage to buildings by measuring the change from high correlation to low correlation where buildings were destroyed by the earthquake