crustal structure and moho geometry of the northeastern tibetan plateau as revealed by sinoprobe 02 deep seismic reflection profiling abstract underthrusting of india below eurasia has resulted in the formation of the himalayan and the qinghai tibet plateau distributed deformation coupled with block translation and rotation has generated the qilian shan thrust belt and a series of east and northwest striking strike slip faults across northeastern tibet because these structures lie in a transition zone between the high plateau region to the south and the lowlands of the north china craton in the north determining their deep crustal and upper mantle structures has important implications for unraveling the mechanism of tibetan plateau formation in this paper we present new results from the sinoprobe 02 deep seismic reflection project across the eastern part of the qilian shan and the southern margin of the alxa block interpretation of the reflection profile obtained from this study is based on constraints from surface geology and detailed geometric analysis of structural relationships among key reflectors in the crust and the upper mantle our results indicate that the upper crust of the eastern qilian shan is characterized by fault bend folds and duplex systems involving phanerozoic strata that may have resulted from early paleozoic collisional tectonics and cenozoic intra continental deformation locally half graben structures hosting cretaceous strata are also present the active structures in the region are dominated by left slip haiyuan and tianjian fault systems marking the northern margin of the tibetan plateau the strike slip structures have variable dips and dip directions and sole into a common decollement with a depth of 40 45 km because the two faults do not cut and offset the moho below the active crustal and mantle deformation in the northeastern tibet must be decoupled

the distribution of the mid to lower crustal low velocity zone beneath the northeastern tibetan plateau revealed from ambient noise tomography we collected continuous seismic data recorded between 2007 and 2010 by 208 broadband stations from the chinese provincial digital seismic networks a seismic collaborative experiment of northern tibet and the northeastern tibet seismic experiment cross correlations of vertical component records are computed to extract the rayleigh wave empirical green s functions group and phase velocities are then constructed from the empirical green s functions in 8 to 50 s period at periods 25 s more than 10 lower velocities are imaged beneath the qaidam basin and high velocities are observed beneath the nonbasin regions at periods 30 s up to 10 lower velocities are imaged in the qiangtang and songpan ganze terranes from these group and phase velocity maps a three dimensional 3 d vsv model of the crust is derived the model shows that the qiangtang and songpan ganze terranes have a very thick crust with a prominent low velocity zone lvz in the middle crust the lvz thins out in the vicinity of the eastern kunlun mountains providing a new constraint on the mode of deformation across the tibetan plateau the northwestern qilian orogen where receiver functions reveal a moho deeper than the surrounding areas also features a relatively weak midcrustal lvz which we interpret as an intracrustal response associated with the shortening between the north china craton and the tibetan plateau

volcano geodesy and magma dynamics in iceland abstract here we review the achievements of volcano geodesy in iceland during the last 15 years extensive measurements of crustal deformation have been conducted using a variety of geodetic techniques including leveling electronic distance measurements campaign and continuous global positioning system gps geodesy and interferometric analysis of synthetic aperture radar images insar results from these measurements provide a comprehensive view of the behavior of icelandic volcanoes between inflation intrusion and eruption episodes volcanoes are likely to deflate or show no sign of seismic activity subsidence rates are often in the range of a few millimeters to a few centimeters a year reducing progressively with time since the last eruption or intrusion at the volcano subsidence can be caused by cooling and contraction of magma outflow of magma it can be related to plate spreading volcano subsidence or lack of deformation is often interrupted by episodic magma flow towards near surface locations such magma recharge has been observed geodetically at hengill hekla eyjafjallajokull katla grimsvotn and krafla volcanoes with inflow inferred to last from a few months up to two decades in the last 15 years five volcanic eruptions three intrusive events and two m6 earthquakes have occurred in recent years the grimsvotn and katla volcanoes have exhibited continuous inflation of a few centimeters per year which at grimsvotn culminated in an eruption on 1 november 2004 hekla and torfajokull volcanoes have inflated at rates an order of magnitude less subsidence is occurring presently at the askja and krafla volcanoes within the period of geodetic measurement signals consistent with no deformation are typical for most of the 35 active volcanoes in iceland

different communities different perspectives issues affecting residents response to a volcanic eruption in southern iceland this research investigates residents knowledge and perception of the katla volcano and emergency response procedures in all rural and urban communities located in the eastern and southern katla hazard zones using a questionnaire survey conducted in 2008 we demonstrate that there is an apparent difference between rural and urban communities knowledge and perceptions and identify some of the issues influencing residents perspectives and behaviour all rural and most urban residents have an accurate knowledge of katla the proposed warning system and emergency response plan urban residents perceived the emergency response plan to be appropriate in comparison rural residents did not perceive the emergency response plan as appropriate rural residents stated that they would personally assess the situation before deciding on a course of action independent of the proposed plan livelihood connections and inherited knowledge affect rural residents ability and willingness to comply with the recommended procedures factors such as hazard knowledge sense of community and attachment to place indicate that rural residents are more resilient to volcanic hazards based on our findings we recommend that emergency management agencies consider issues such as personal responsibility neighbourliness and community involvement and cooperation to develop and implement more appropriate volcanic risk mitigation strategies in light of the recent eyjafjallajokull eruptions we provide a brief discussion on the 2010 emergency response although our findings are iceland specific our recommendations may be applied internationally to other volcanic and disaster prone regions

residents attitudes and behaviour before and after the 2010 eyjafjallajokull eruptions a case study from southern iceland while the disruption to international air travel caused by the eruption of iceland s eyjafjallajokull volcano in 2010 has been well documented the significant social impacts on local residents from ash fall to the south and east of the crater are less well known these impacts and attitudes of impacted residents and emergency managers are the foci of our present study prior to and during the eruption officials worked to protect the local population from the glacial outburst floods jokulhlaup that were of primary concern the success of these endeavours can in part be attributed to a regional evacuation exercise held in march 2006 an exercise that was carried out with respect to a possible eruption at another volcano katla that is located 25 km to the east of eyjafjallajokull eruptions at either volcano will impact the same communities our study here concentrates on alftaver a small farming community located approximately 60 km east southeast of eyjafjallajokull and 30 km southeast of katla alftaver has been the subject of longitudinal studies carried out in 2004 2006 and 2008 these studies highlighted the difficulties that emergency managers face in developing appropriate response strategies acceptable to vulnerable communities the 2010 eyjafjallajokull eruptions presented an opportunity to re assess residents attitudes and behaviour in relation to volcanic risk management in the wake of their first hand experiences with volcanic hazards to achieve this interviews were conducted with residents and emergency management officials and a questionnaire was distributed to residents this paper presents the results of this survey and examines changes in attitudes towards volcanic risk management it was apparent that the experience of ash fall from eyjafjallajokull provided a better perspective of what could be expected from a katla eruption and that attitudes towards emergency management had evolved accordingly importantly officials perceptions of risk are now more aligned with those of residents and both recognise the need for more detailed and concise information regarding the impacts of ash fall during and following volcanic eruptions

neogene extension and volcanism in the kunlun fault zone northern tibet new constraints on the age of the kunlun fault 1 the geology of the jingyu basin north tibet provides constraints on the relationship between localized e w extension in the qiangtang block and strike slip motion along the kunlun fault eocene to oligocene sw ne compression formed topographic relief in the present western kunlun shan pull apart basins started forming in the western kunlun ranges around 15 ma possibly coincident with the initiation of subduction of the tarim qaidam lithosphere under the kunlun shan extensional tectonism is still active and the jingyu basin is extending as a normal fault connected with the kunlun fault was recently active localized extension allows tertiary and quaternary shoshonitic magmas to reach the surface from crustal depths of 50 to 60 km miocene strike slip faulting indicates that the initiation of the kunlun strike slip fault is early neogene in age and that the total amount of horizontal movement that occurred along the fault has to be reconsidered

ash storms impacts of wind remobilised volcanic ash on rural communities and agriculture following the 1991 hudson eruption southern patagonia chile tephra fall from the august 1991 eruption of volcan hudson affected some 100 000 km 2 of patagonia and was almost immediately reworked by strong winds creating billowing clouds of remobilised ash or ash storms the immediate impacts on agriculture and rural communities were severe but were then greatly exacerbated by continuing ash storms this paper describes the findings of a 3 week study tour of the diverse environments of southern patagonia affected by ash storms with an emphasis on determining the impacts of repeated ash storms on agriculture and local practices that were developed in an attempt to mitigate these impacts ash storms produce similar effects to initial tephra eruptions prolonged for considerable periods these have included the burial of farmland under dune deposits abrasion of vegetation and contamination of feed supplies with fine ash these impacts can then cause problems for grazing animals such as starvation severe tooth abrasion gastrointestinal problems corneal abrasion and blindness and exhaustion if sheep fleeces become laden with ash in addition ash storms have led to exacerbated soil erosion human health impacts increased cleanup requirements sedimentation in irrigation canals and disruption of aviation and land transport ash deposits were naturally stabilised most rapidly in areas with high rainfall 1 500 mm year through compaction and enhanced vegetation growth stabilisation was slowest in windy semi arid regions destruction of vegetation and

injection of tibetan crust beneath the south qaidam basin evidence from indepth iv wide angle seismic data 1 the international deep profiling of tibet and the himalaya phase iv indepth iv active source seismic profile in northeast tibet extends 270 km roughly north south across the songpan ganzi terrane the predominantly strike slip north kunlun fault along the kunlun suture the east kunlun mountains and the south qaidam basin refraction reflection and gravity modeling provide constraints on the velocity and density structure down to the moho the central qaidam basin resembles average continental crust whereas the songpan ganzi terrane and east kunlun mountains exhibit thickened lower velocity crust also characteristic of southern tibet the crustal thickness changes from 70 km beneath the songpan ganzi terrane and east kunlun mountains to 50 km beneath the qaidam basin this jump in crustal thickness is located 100 km north of the north kunlun fault and 45 km north of the southern kunlun qaidam boundary farther north than previously suggested ruling out a moho step caused by a crustal penetrating north kunlun fault the qaidam moho is underlain by crustal velocity material 6 8 7 1 km s for 45 km near the crustal thickness transition the southernmost 10 km of the qaidam moho are underlain by a 70 km reflector that continues to the south as the tibetan moho the apparently overlapping crustal material may represent songpan ganzi lower crust underthrusting or flowing northward beneath the qaidam basin moho thus the high tibetan plateau may be thickening northward into south qaidam as its weak thickened lower crust is injected beneath stronger qaidam crust

volcanic hazard communication using maps an evaluation of their effectiveness hazard maps are considered essential tools in the communication of volcanic risk between scientists the local authorities and the public this study investigates the efficacy of such maps for the volcanic island of montserrat in the west indies using both quantitative and qualitative research techniques normal plan view maps which have been used on the island over the last 10 years of the crisis are evaluated against specially produced three dimensional 3d maps and perspective photographs thirty two demographically representative respondents of mixed backgrounds sex education and location were interviewed and asked to complete a range of tasks and identification on the maps and photographs the overall results show that ordinary people have problems interpreting their environment as a mapped representation we found respondents ability to locate and orientate themselves as well as convey information relating to volcanic hazards was improved when using aerial photographs rather than traditional plan view contour maps there was a slight improvement in the use of the 3d maps especially in terms of topographic recognition however the most striking increase in effectiveness was found with the perspective photographs which enabled people to identify features and their orientation much more readily for montserrat it appears that well labelled aerial and perspective photographs are the most effective geo spatial method of communicating volcanic risks

shear wave structure in the northeastern tibetan plateau from rayleigh wave tomography 1 the northeastern tibetan plateau has undergone active shortening due to the india asia collision and has been an ideal place for studying the growth of the plateau to reveal deep structure that is responsible for geological observations in ne tibet we have constructed a 3 d shear wave velocity model from rayleigh waves recorded by 36 stations in the northeast tibetan plateau seismic experiment first the two plane wave tomography method was applied to compute the average and 2 d variations of phase velocities in a period range of 20 to 100 s then 1 d and 3 d shear wave velocity models were developed from the obtained rayleigh wave dispersions the entire region is characterized by a weak upper mantle with a relatively thin lithosphere of 80 100 km thick this observation helps to explain the active deformation at the kunlun mountains and the qinling orogen in ne tibet relative low velocity anomalies appear along and to the south of the kunlun fault kf in contrast to high velocity anomalies in the north and northeast one pronounced slow anomaly centered at 120 km depth is imaged right beneath the restraining bend of the kunlun fault which might be a northern extension of the large scale slow anomaly to the south of the fault we interpret it as a local feature due to its large magnitude and coincidence with the restraining bend it is probably related to anomalously high temperature and associated partial melting resulted from localized asthenosphere upwelling after the delamination of a thick lithosphere root the formation of the thick lithosphere root would require coherent shortening in the crust and mantle lithosphere caused by local compression due to the bend of the strike slip fault indicating that the kunlun fault is probably on lithosphere scale and has played an important role in accommodating the eastward extrusion of the tibetan plateau

geochemistry of historical age silicic tephras in iceland the major element chemistry of nine silicic tephras of historical age from iceland is assessed as a key step in the development of the recent tephrochronology of the north atlantic region the tephras include the largest such layers produced by each of the five central volcanoes hekla o raefajokull eyjafjallajokull torfajokull and askja since the ninth century ad h 1104 o1362 e 1821 landnam tephra c 870 a 1875 and four other tephras h 1158 h 1510 h 1947 o1727 the determination of grain discrete major element chemistry of the glass fraction is a fundamental stage in the identification and correlation of tephra and allows links to be made between icelandic source areas with precise dating evidence and distal deposits elsewhere in the north atlantic region although major element data can be used to discriminate between tephra layers produced by the different central volcanoes on its own it cannot be used to identify all the holocene layers produc

potential impacts of tephra fallout from a large scale explosive eruption at sakurajima volcano japan we present an exposure analysis of infrastructure and lifeline to tephra fallout for a future large scale explosive eruption of sakurajima volcano an eruption scenario is identified based on the field characterization of the last subplinian eruption at sakurajima and a review of reports of the eruptions that occurred in the past six centuries a scenario based probabilistic hazard assessment is performed using the tephra2 model considering various eruption durations to reflect complex eruptive sequences of all considered reference eruptions a quantitative exposure analysis of infrastructures and lifelines is presented primarily using open access data the post event impact assessment of magill et al earth planets space 65 677 698 2013 after the 2011 vei 2 eruption of shinmoedake is used to discuss the vulnerability and the resilience of infrastructures during a future large eruption of sakurajima results indicate a main eastward dispersal with longer eruption durations increasing the probability of tephra accumulation in proximal areas and reducing it in distal areas the exposure analysis reveals that 2300 km of road network 18 km2 of urban area and 306 km2 of agricultural land have a 50 probability of being affected by an accumulation of tephra of 1 kg m2 a simple qualitative exposure analysis suggests that the municipalities of kagoshima kanoya and tarumizu are the most likely to suffer impacts finally the 2011 vei 2 eruption of shinmoedake demonstrated that the already implemented mitigation strategies have increased resilience and improved recovery of affected infrastructures nevertheless the extent to which these mitigation actions will perform during the vei 4 eruption presented here is unclear and our hazard assessment points to possible damages on the sakurajima peninsula and the neighboring municipality of tarumizu

convergence of the indian and eurasian plates under eastern tibet revealed by seismic tomography 1 a three dimensional p wave velocity model of the crust and upper mantle down to 400 km depth beneath eastern tibet is obtained using many temporary seismic stations of the ascent project and the namche barwa broadband seismic network we collected 16 508 arrival times of p pn and pg phases from 573 local and regional earthquakes and 7 450 p wave arrivals from seismograms of 435 teleseismic events our high quality data set enables us to reconstruct the 3 d velocity structure under eastern tibet in more detail than the previous studies in the shallow depth our results show that the low velocity zones are not interconnected well no wide spread low velocity zones which may reflect the complex pattern of material flowing in the study region below the moho we find that the indian lithospheric mantle underthrusts sub horizontally under eastern tibet and the extent of the northward advancing indian lithosphere decreases from west to east in the north the asian lithospheric mantle is detected under the vicinity of the qaidam basin between the indian and asian lithospheric mantles there is an obvious low velocity anomaly which may reflect an upwelling mantle diapir

imaging the colliding indian and asian lithospheric plates beneath tibet 1 a high resolution image of the base of the lithosphere from s to p converted seismic waves revealed the collision architecture of the indian and asian continental plates beneath the tibetan plateau the base of the indian lithosphere dips northward from a depth of 160 km beneath the himalayas to a depth of 220 km just south of the bangong suture the base of the asian lithosphere is nearly horizontal at the depth of 160 180 km from central to northern tibet there is a vertical gap of about 50 km between indian and asian lithospheres our observation of a well defined thick lithosphere throughout the entire plateau is not consistent with models of wholesale convective instability of a thickened mantle lithosphere which would predict a very thin asian lithosphere the hypothesized sequential southward subduction of tibetan and asian continental lithospheres leading to the growth of the tibetan plateau if correct cannot be occurring below 180 km depth our results along with available geological and geophysical data strongly support that the plateau is predominantly formed by a relatively coherent north dipping subducted indian continental lithosphere in the south which presently can be traced to the middle of the plateau and a south dipping subducted asian lithosphere in the north at a shallower depth

lithospheric and upper mantle structure of the northeastern tibetan plateau 1 we use receiver functions calculated for data collected by the indepth iv seismic array to image the three dimensional geometry of the crustal and upper mantle velocity discontinuities beneath northeastern tibet our results indicate an average crustal thickness of 65 to 70 km in northern tibet in addition we observe a 20 km moho offset beneath the northern margin of the kunlun mountains a 10 km moho offset across the jinsha river suture and gently northward dipping moho beneath the qaidam basin a region in the central qiangtang terrane with higher than normal crustal vp vs ratio of 1 83 can be the result of the eocene magmatic event in the qiangtang terrane we observe a significant lithospheric mantle discontinuity beneath the bangong nujiang suture at 80 km depth which dips 10 to the north reaching 120 km depth we interpret this feature as either a piece of lhasa terrane or remnant oceanic slab underthrust below northern tibet we detect a 20 km depression of the 660 km discontinuity in the mantle transition zone beneath the northern lhasa terrane in central tibet which suggests this phase transition has been influenced by a dense and or cold oceanic slab a modest 10 km depression of the 410 km discontinuity located beneath the northern qiangtang terrane may be the result of localized warm upwelling associated with small scale convection induced by the penetration of the sinking indian continental lithosphere into the transition zone beneath the central tibetan plateau

the geological evolution of the tibetan plateau the geological evolution of the tibetan plateau is best viewed in a context broader than the india eurasia collision zone after collision about 50 million years ago crust was shortened in western and central tibet while large fragments of lithosphere moved from the collision zone toward areas of trench rollback in the western pacific and indonesia cessation of rapid pacific trench migration 15 to 20 million years ago coincided with a slowing of fragment extrusion beyond the plateau and probably contributed to the onset of rapid surface uplift and crustal thickening in eastern tibet the latter appear to result from rapid eastward flow of the deep crust probably within crustal channels imaged seismically beneath eastern tibet these events mark a transition to the modern structural system that currently accommodates deformation within tibet

geothermal activity in the subglacial katla caldera iceland 1999 2005 studied with radar altimetry the katla caldera is located under the myrdalsjokull ice cap and is one of the most hazardous volcanoes in iceland due to major jokulhlaups that accompany eruptions subglacial geothermal activity is manifested in several 10 50 m deep depressions ice cauldrons within and at the caldera rim and the total geothermal heat output is of the order of a few hundred megawatts a short lived but powerful pulse in geothermal heat output took place in 1999 probably including a minor subglacial eruption when new ice cauldrons formed in three places and an unexpected jokulhlaup occurred following these events a comprehensive monitoring program was set up for katla including ice surface elevation profiling from aircraft to monitor variations in geothermal heat and detect signs of subglacial water accumulation a radar altimeter coupled with a kinematic gps is used achieving an absolute elevation accuracy of 3 m and internal consistency of 1 2 m profiles across the caldera are flown twice a year an annual accumulation ablation cycle in surface elevation with amplitude of 5 10 m is observed by removing this cycle from the data changes due to subglacial geothermal activity are obtained after the events in 1999 a decline in geothermal activity was observed in 2001 03 some ice cauldrons expanded and deepened by 10 15 m indicating renewed increase in geothermal activity this trend is also apparent for 2003 05 the increase in geothermal power amounts to a few tens of megawatts it is likely that the increased thermal output is related to increased seismicity and caused by magma inflow

seismic evidence for the north china plate underthrusting beneath northeastern tibet and its implications for plateau growth abstract lithospheric deformation of the tibetan plateau is caused by subduction of the indian northward and asian southward plates the effects of this interaction on inner reaches of the asian continent between the tibetan plateau and the north china craton ncc for example remain uncertain due to poor geophysical data coverage in northeastern tibet ne tibet we provide here detailed knowledge of the lithospheric structure beneath ne tibet as determined from a dense broadband seismic profile traversing ne tibet to the westernmost ncc receiver function imaging reveals several significant features including a north dipping intracrustal converter nc moho offset overlap beneath major fault zones and a low velocity layer lvl in the middle lower crust the lithosphere asthenosphere boundary lab is clearly defined and appears as a south dipping interface that runs continuously from the alxa interior to the qilian orogen interpretation of these observations combined with other seismic evidence implies that the ncc lithospheric mantle has been persistently underthrust beneath the qilian orogen this process forms the thick skinned crustal accretionary wedges which develop above a middle lower intracrustal decollement our results provide further deep geophysical constraints on the cenozoic post collisional evolution of the convergent boundary between ne tibet and the ncc and help clarify the mechanism of plateau growth in this boundary area

ash resuspension related to the 2011 2012 cordon caulle eruption chile in a rural community of patagonia argentina abstract the 2011 2012 cordon caulle eruption emitted about 1 km3 of rhyodacitic tephra dominant westerly winds in the region caused most of the primary tephra to deposit in neighboring argentina in addition to the impact of widespread dispersal and fallout of primary tephra during the eruption argentina was also significantly affected by remobilization of the primary ash even several years after the climactic phase of the eruption in this mixed methods study we combine aspects of natural and social sciences to characterize the ash resuspension events associated with the 2011 2012 cordon caulle deposits and assess the impacts on the argentinian farming community of ingeniero jacobacci in the patagonian steppe our findings show the primary importance of wind rainfall and ash availability in controlling the occurrence and persistence of ash resuspension events the role played by these variables was also reflected in the seasonal distribution of events observed regarding the impacts our results complement those of earlier studies and demonstrate that ash resuspension events can exacerbate the negative impact of primary tephra fallout events from the time of deposition to many years after the eruption only after five years has the environment and the farming community begun to show signs of recovery our findings also highlight the importance of assessing ash resuspension events in multi hazard scenarios involving volcanic and hydrometeorologic hazards

widespread dispersal of icelandic tephra how does the eyjafjoll eruption of 2010 compare to past icelandic events widespread dispersal of icelandic tephra how does the eyjafjoll eruption of 2010 compare to past icelandic events

crust and upper mantle structure of the north china craton and the ne tibetan plateau and its tectonic implications abstract understanding the mesozoic cenozoic tectonic evolution of the north china craton ncc and the ne tibetan plateau tp requires detailed knowledge of the lithospheric structure using dense regional networks and temporary deployments as well as updated reference models we obtain the crust and upper mantle structure to 120 km depth our tomographic results show several major features which have particular implications for the weihe shanxi rift system wsrs deformation of the ne tp and lithospheric evolution of the ncc beneath the wsrs the crust gradually thickens from south to north the lithospheric mantle gradually becomes slower and the mid lower crustal velocities are lower in the weihe rift where rifting of the wsrs initiated we suggest that along strike variations of the lithospheric structures of the wsrs have played an important role in its multistage evolution a low velocity zone lvz in the mid crust beneath the qilian orogen is characterized by relatively higher velocities compared to lvzs in other parts of the tp thus coherent lithospheric deformation may occur due to the high viscosity of the lvz during early plateau growth causing strong anisotropy to develop the western ncc including the ordos block and part of the alashan block shows a high velocity cratonic root extending to the base of our model in contrast the lithosphere of the eastern ncc appears to have been completely modified during the mesozoic through cenozoic and presents a thin lithosphere of relatively low velocities underlain by hot asthenosphere we observed significant upper mantle heterogeneities in the ncc which may reflect its diachronous lithospheric modification

crustal structure across the kunlun fault from passive source seismic profiling in east tibet abstract the crust beneath the northeastern ne tibetan plateau records the imprints on paleozoic kunlun orogen and far field effects from continental collision and convergence between the indian and eurasian plates a passive source seismic profile was conducted across eastern kunlun mountains also called animaqing suture belt receiver function imaging and h k stacking results with this dataset demonstrate that 1 crust slightly thins from about 64 km under the songpan ganzi terrane to about 56 62 km under the qaidam kunlun block and the qilian block 2 moho topography is relatively smooth with gradual undulation beneath east kunlun orogeny belt in contrast to 2 5 km moho step at the akms kunlun fault from previous deep seismic soundings or even no moho topography variation from recent deep seismic reflection profiling 3 the average crustal vp vs ratios display an increasing trend to the kunlun fault belt from 1 76 to 1 85 in songpan ganzi terrane while decreases from 1 83 to 1 65 away from the fault belt in qaidam kunlun block 4 the high vp vs ratio in songpan ganzi terrane is similar to previous results from the profile across longmenshan fault belt the normal to low vp vs ratio distribution in qaidam kunlun block supports the viewpoint that the deformation occurring in ne tibet is predominated by upper crustal thickening and 5 the thickness of non seismogenic layer varies slightly about 40 km between 90 and 100 e then decreases to less than 20 km around 106 e along the kunlun fault the change of the non seismogenic layer thickness is consistent with the change of the lower crust thickness derived from deep seismic sounding the increased crustal thickness may be due to the differences in the thickness of the crust of the two plates before their collision and or largely achieved by thickening of the lower crust perhaps indicating a crust flow mechanism operating more strongly in the western region

a new reflective optical extensometer rox system for geomechanical deformation measurements we have developed an extensometer for measurement of distance and displacements in geotechnical and civil engineering applications this is an optical extensometer that measures distance using a modulated laser beam in this design reflecting targets are placed at desired measurement locations and distances between each target and an optical head are measure repeatedly using the modulated laser beam moreover all electronic and moving parts are located outside of the hostile or difficult environment as the optical head is connected to the laser switching and signal analysis hardware using optical fibers a reference beam is utilized to provide direct correction of system behavior the system also utilizes movable reflective anchors that can be repositioned if desired we have installed the system in a field experiment currently being conducted for the yucca mountain site characterization project and report preliminary results

participatory methods of incorporating scientific with traditional knowledge for volcanic hazard management on ambae island vanuatu ambae island is the largest of vanuatu s active volcanoes it is also one of the nation s potentially most dangerous with 60 million m 3 of lake water perched at over 1340 m in the summit caldera and over the ac tive vent in 1995 small phreatic explosions earthquake swarms and heightened gas release led to calls for evacuation preparation and community volcanic hazard awareness programs for the 9500 inhabitants differences in perspective or world view between the island dwellers adhering to traditional beliefs kastom and external sci entists and emergency managers led to a climate of distrust following this crisis in an attempt to address these issues rebuild dialogue and respect between communities out side scientists and administrators and move forward in volcanic hazard education and planning for ambae we adapted and applied participatory rural appraisal pra approaches initial gender segregated pra exercises from two representative communities provided a mechanism for cataloguing local traditional viewpoints and hazard per ceptions ultimately by combining elements of these viewpoints and perceptions with science based manage ment structures we derived volcanic hazard management guidelines supported by an alert system and map that were more readily accepted by the test communities than the earlier top down plans imposed by outside govern mental and scientific agencies the strength of pra ap proaches is that they permit scientists to understand important local perspective issues including visualisations of volcanic hazards weaknesses in internal and external communication systems and gender and hierarchy con flicts all of which can hinder community emergency management the approach we describe has much to offer both developing and industrialised communities that wish to improve their awareness programs and mitigative planning this approach should also enhance communi cation and understanding between volcanologists and the communities they serve