coulomb stress changes following the 2012 mw 7 8 haida gwaii canada earthquake implications for seismic hazard this article examines spatial changes to the local stress field resulting from the 28 october 2012 m w 7 8 haida gwaii earthquake off the west coast of moresby island british columbia this event occurred on a northeast dipping potentially blind thrust fault rather than on the subvertical queen charlotte fault qcf that represents the pacific north american plate boundary this was the largest earthquake along the canadian portion of this plate boundary since the 1949 m s 8 1 queen charlotte earthquake the u s geological survey coulomb software is used to quantitatively estimate the effect of the mainshock on the background stress field the known aftershock nodal planes and the nearby qcf we use two different mainshock finite fault models both of which are seismologically derived by lay et al 2013 and hayes 2013 separately and subsequently adapted by k wang to account for the motion detected at four nearby global positioning system stations see nykolaishen et al 2015 for more information we also use the best located set of aftershocks with information provided by a temporary array of ocean bottom seismometers results indicate an apparent clustering of aftershocks slightly seaward of the main thrust which is consistent with the modeled zone of promoted normal failure likely related to extension in the footwall using existing models we found a high number of aftershocks to be consistent with triggering by the mainshock suggesting that static stress is a dominant control in the months following a large earthquake in this area further we find loading greater than the triggering threshold on the qcf in an area interpreted as a seismic gap this work improves understanding of the evolving seismic hazard along the queen charlotte margin and tests the usefulness of coulomb modeling in this complex tectonic environment online material figures of focal mechanisms and maximum coulomb stress change and table of aftershock moment tensor parameters

stress in western canada from regional moment tensor analysis more than 180 regional moment tensor rmt solutions for moderate sized earthquakes m 4 are used to examine the contemporary stress regime of western canada and provide valuable information relating to earthquake hazard analysis the overall regional stress pattern shows mainly ne sw oriented p axes for most of western canada with local variations in the northern cordillera the maximum compressive stress direction 1 varies from east west to north south to ne sw from south to north the stress direction 1 is consistent with the p axis direction for the largest earthquakes except in the central and northern mackenzie mountains where there is a 16 difference the yakutat collision zone shows a steady change in 1 from east west in the east to north south in the west in the canada united states border region rmt solutions suggest a north south compressional regime may extend through southern british columbia and northern washington to the eastern cordillera in the vancouver island puget sou

an intensity survey of households affected by the northridge california earthquake of 17 january 1994 following the northridge california earthquake of 17 january 1994 the humboldt earthquake education center heec conducted a telephone survey of approximately 6000 adults from within the felt region to study the earthquake s effects on individual households we tabulate human responses to the earthquake and observations of the earthquake s effects on inanimate objects from the heec survey as a function of independently assigned u s geological survey modified mercalli usgs mm intensity for the same communities human responses and subjective judgments about the severity of shaking when averaged over a large number of samples are useful discriminants of the levels of strong ground motion up to those associated with usgs mm intensity vii notwithstanding that individual human responses and subjective judgments are notoriously unreliable a threshold of strong ground motion corresponds to usgs mm intensity of about vii above which over 40 of respondents described the earthquake as violent and most people reported difficulty standing furniture displaced and some damage to their homes even at intensities viii and ix however relatively few people about 15 described their reaction as panic and only about 12 reported major damage to their homes the heec phone survey data show that in communities of low to moderate shaking usgs mm intensities estimated from a single postal questionnaire are quite robust at usgs mm intensity of v and below 88 of usgs mm intensities determined from postal questionnaires are within one intensity unit of intensities determined from the more numerous heec telephone survey data for the same community we introduce the concept of a community decimal intensity scale cdi based on telephone survey data and calibrated to agree on average with the usgs mm intensities the cdis are more regularly distributed than the usgs mm intensities and show much less scatter when plotted as a function of epicentral distance cdis show promise as a tool for comparing regional attenuation for delineating variations in shaking strength within areas mapped as a single mm zone and for rapid preliminary intensity estimates utilizing electronic media

long term hydroclimatic variability in monsoon shadow zone of western himalaya india tree ring width data of himalayan cedar cedrus deodara roxb g don from 11 homogeneous moisture stressed sites in the monsoon shadow zone of the western himalaya were used to develop a mean chronology extending back to ad 1353 the chronology developed using regional curve standardization method is the first from the himalayan region of india showing centennial scale variations the calibration of ring width chronology with instrumental precipitation data available from stations close to the tree ring sampling sites showed strong direct relationship with march april may june mamj precipitation this strong relationship was used to supplement the instrumental precipitation data back to ad 1410 the precipitation reconstruction showed extended period of drought in fifteenth and sixteenth centuries increasingly pluvial conditions were recorded since eighteenth century with the highest precipitation in the early part of the nineteenth century the decreasing trend in reconstructed precipitation in the last decade of the twentieth century consistent with the instrumental records is associated with the decreasing trend in frequency of western disturbances mamj precipitation over the monsoon shadow zone in the western himalaya is directly associated with the north atlantic oscillation nao and nino3 sst index of el nino southern oscillation enso the leading modes of climate variability influencing climate over large parts of the northern hemisphere however the relationship between enso and mamj precipitation collapsed completely during 1930 1960 the breakdown in this relationship is associated with the warm phase of atlantic multidecadal oscillation amo a spectral analysis of reconstructed mamj precipitation indicates frequencies in the range of the variability associated with modes of nao enso and amo

palaeotsunamis along canada s pacific coast abstract to fully understand tsunami hazards along canada s pacific coast we must consider all potential sources including local and region wide earthquakes volcanic activity slope failure events and bolide impacts furthermore as climate changes future extreme meteorological conditions will exacerbate slope failures on steep and over steepened slopes and potentially augment the magnitude and frequency of earthquake generated tsunamis there have been numerous reviews of the geological records of palaeotsunamis along the cascadia margin but as yet there has been no attempt made to pull together all data related to palaeotsunamis along the pacific coast of canada we summarise all geological data related to palaeotsunamis reported in the region all relevant non geological data and other information concerning potential tsunamigenic sources evidence for between 10 and 22 palaeotsunamis prior to european arrival have been documented with the cascadia subduction zone y event ad1700 being the most widely recognised geological archaeological and anthropological data all indicate a complex multi sourced prehistory of seismic tsunami activity that is poorly understood a clustering of potential activity off the se coast of vancouver island suggests that we should also attempt to better understand locally generated events along canada s pacific coast

flow and solute transport through the soil matrix and macropores of a hillslope segment subsurface flow from various portions of a soil profile on a steep forested hillslope was evaluated by two sets of step change miscible displacement tests at different application rates and antecedent hydrologic conditions solutions of nacl 1000 mg l 1 cl were applied at steady state rates equivalent to 20 and 30 mm h 1 of standing water over the entire plot area using a line irrigation source located 1 5 m upslope lateral distance from an excavated soil pit subsurface flow and tracer breakthrough from five portions the organic rich soil layer including macropores the mineral soil matrix and three groups of macropores in the mineral soil layer of the soil profile were individually measured and analyzed using a convective dispersive model matrix flow dominated discharge from the soil pit during tracer tests 70 93 of total discharge however during wet periods with upslope drainage macropores including organic rich soil contributed proportionally more flow than during periods when upslope drainage was minimal outflow from macropores during the test with wet antecedent conditions had lower cl concentrations than drainage from the soil matrix suggesting dilution in macropores from upslope drainage effective pore volumes calculated for the flow averaged breakthrough data from the entire profile were much less 40 than the estimates measured by tensiometers of total volume of pore water suggesting that preferential flow significantly contributed to subsurface transport of tracer the pore volume for the entire profile increased only slightly with increasing application rate however the relative proportions of pore volumes calculated for individual portions varied proportionally to antecedent hydrologic conditions these changes are attributed to the expansion of individual macropores with surrounding soil and the lateral extension of macropore networks during wetter conditions

the preservation potential of coastal coseismic and tsunami evidence observed following the 2012 mw 7 8 haida gwaii thrust earthquake abstract we describe near field coseismic and tsunami evidence collected following the 28 october 2012 m w 7 8 thrust earthquake that occurred offshore western haida gwaii british columbia and discuss factors that influence its extent and preservation potential observations indicate minor geomorphic and sedimentological impacts on the rugged and unpopulated west coast of the islands despite widespread coastal coseismic subsidence 0 5 m triggered landslides and tsunami waves exceeding 3 m in runup maximum 13 m along 230 km of coastline evidence left by the tsunami was minimal likely because it occurred during a low tide that restricted its onshore reach its flow depth and its capacity to entrain and transport significant amounts of clastic sediment sources of which are minimal or absent on the dominantly steep rocky coastline it is unlikely that subaerial evidence of coseismic subsidence and tsunami inundation will be recognizably recorded in the coastal stratigraphy of western haida gwaii due to the relatively small magnitude of subsidence a lack of suitable coastal environments such as tidal marshes to record paleoelevation differences sedimentation rates that are too low to bury a paleoseismic or paleotsunami record and long term relative sea level fall leading to erosion and bioturbation a higher preservation potential is likely for tsunami deposits in coastal lakes ponds and bogs as well as coseismic slope failure deposits offshore in lakes and in sheltered fjords our findings imply that large tsunamigenic earthquakes are likely undersampled in the paleoseismic record of haida gwaii and of other plate margins with similar characteristics

transpression between two warm mafic plates the queen charlotte fault revisited the queen charlotte fault is a transpressive transform plate boundary between the pacific and north american plates offshore western canada previous models for the accommodation of transpression include internal deformation of both plates adjacent to the plate boundary or oblique subduction of the oceanic plate the latter has been the preferred model both plates are warm and mafic and have similar mechanical structures new multichannel seismic reflection data show a near vertical queen charlotte fault down to the first water bottom multiple significant subsidence east of the queen charlotte fault a large melange where the fault is in a compressive left step and faulting which involves oceanic basement gravity modeling of profiles indicates that moho varies fairly smoothly across the plate boundary isostatic anomalies indicate that the pacific plate is flexed downward adjacent to the queen charlotte fault upward flexure of north america along with crust thickened relative to crust in the adjacent basin creates topography known as the queen charlotte islands combined with other regional studies these observations suggest that the plate boundary is a vertical strike slip fault and that transpression is taken up within each plate

estimate of tsunami source using optimized unit sources and including dispersion effects during tsunami propagation the 2012 haida gwaii earthquake we apply a genetic algorithm ga to find the optimized unit sources using dispersive tsunami synthetics to estimate the tsunami source of the 2012 haida gwaii earthquake the optimal number and distribution of unit sources gives the sea surface elevation similar to that from our previous slip distribution on a fault using tsunami data but different from that using seismic data the difference is possibly due to submarine mass failure in the source region dispersion effects during tsunami propagation reduce the maximum amplitudes by up to 20 of conventional linear long wave propagation model dispersion effects also increase tsunami travel time by approximately 1 min per 1 300 km on average the dispersion effects on amplitudes depend on the azimuth from the tsunami source reflecting the directivity of tsunami source while the effects on travel times depend only on the distance from the source

spatiotemporal distribution of events during the first week of the 2012 haida gwaii aftershock sequence abstract we systematically relocated the 2012 haida gwaii aftershock sequence by re examining continuous seismic waveforms of the canadian national seismographic network cnsn because of the sparse station density in the source area and the offshore location of the majority of events precise determination of hypocenters is extremely challenging constraints on the back azimuth and incident angle of ray paths were derived from the cross correlation of three component waveforms and incorporated into the locating process to improve the results we located 1228 aftershocks for the first week after the mainshock effectively double the size of the cnsn routine earthquake catalog the distribution of aftershocks tends to form two linear trends roughly parallel to the strike of the plate margin in the northwest southeast direction the trend located updip from the mainshock within the subducting pacific plate appears to have three clusters spanning a lateral distance of 80 km the other trend coincides with the surface trace of the queen charlotte fault qcf spanning the northern two thirds of the main rupture zone the overall area of aftershock distribution is 120 km 40 km aftershocks overlap the southern part of the estimated rupture zone of the 1949 earthquake with no activity in the seismic gap farther to the south therefore it is likely that the 2012 earthquake only partially released the accumulated stress on the strike slip transform fault system in this scenario the possibility of a major strike slip earthquake along the southernmost part of the qcf should not be ignored online material table of source parameters of relocated mainshock and aftershocks

impacts of the october 2012 magnitude 7 8 earthquake near haida gwaii canada on 27 october 2012 a magnitude m w 7 8 earthquake occurred in the sparsely populated region of haida gwaii british columbia canada formerly called the queen charlotte islands this was the second largest recorded earthquake in canadian history it was felt throughout british columbia and as far away as the yukon alberta and montana roughly 1600 km from the epicenter in some locations notably on haida gwaii the perceivable shaking lasted 1 5 2 min with very strong shaking for about 30 s strong ground motions recorded at three locations in the region reached a maximum horizontal acceleration of 0 2 g fortunately this earthquake resulted in very limited damage partly because of the relatively large distance more than 60 km between population centers and the fault rupture and partly because of seismic resistance of the generally low wood frame construction found on the islands we examine the various physical effects from the shaking e g tsunami landslides building damage loss of hot springs cataloged by field crews and reported by the inhabitants of haida gwaii and the surrounding regions these will serve as a guide toward the potential impact from future large earthquakes on the various haida gwaii communities through a community decimal intensity evaluation of people s accounts it was revealed that although intensities were close to expected near the source zone regional intensities were lower than predicted by the conventional western north america theoretical relation finally the october 2012 earthquake may be used as a scenario event for moderate subduction earthquakes in other more populated areas of british columbia canada and the world online material abridged did you feel it reports

dendroclimatic reconstruction of april may temperature fluctuations in the western himalaya of india since a d 1698 abstract ring width chronologies of himalayan cedar cedrus deodara d don g don himalayan pine pinus wallichianaa b jackson and himalayan spruce picea smithiana wall boiss from the western himalayan region india have been used to reconstruct mean april may temperature back to a d 1698 the reconstruction correlates significantly with the average april may instrumental temperature record r 0 62 1876 1988 and is characterized by annual to multiyear fluctuations the most striking feature of the present reconstruction is the absence of any warming trend in the 20th century relationships between the mean april may temperature for the western himalayan region indian summer monsoon rainfall and southern oscillation index indicate that the tree ring chronologies as surrogate temperature records will provide valuable data for climate change studies with regional and global perspectives

coastal sedimentation associated with the tohoku tsunami of 11 march 2011 in south kuril islands nw pacific ocean sediment deposited by the tohoku tsunami of march 11 2011 in the southern kurils kunashir shikotan zeleniy yuri tanfiliev islands was radically different from sedimentation during local strong storms and from tsunamis with larger runup at the same location sediments from the 2011 tohoku tsunami were surveyed in the field immediately and 6 months after the event and analyzed in the laboratory for sediment granulometry benthos foraminifa assemblages and diatom algae run up elevation and inundation distance were calculated from the wrackline accumulations of driftwood woody debris grass and seaweed marking the distal edge of tsunami inundation run up of the tsunami was 5 m at maximum and 3 4 m on average maximum distance of inundation was recorded in river mouths up to 630 m but was generally in the range of 50 80 m although similar to the local strong storms in runup height the tsunami generally did not erode the coast nor leave a deposit however deposits uncharacteristic of tsunami described as brown aleuropelitic silty and clayey mud rich in organic matter were found in closed bays facing the south kuril strait these closed bays were covered with sea ice at the time of tsunami as the tsunami waves broke the ice the ice floes enhanced the bottom erosion on shoals and destruction of low lying coastal peatland even at modest ranges of runup in the muddy tsunami deposits silt comprised up to 64 and clay up to 41 5 the foraminifera assemblages displayed features characteristic of benthic microfauna in the near shore zone deep sea diatoms recovered from tsunami deposits in two closely situated bays namely krabovaya and otradnaya bays had different requirements for environmental temperature suggesting these different diatoms were brought to the bays by the tsunami wave entraining various water masses when skirting the island from the north and from the south

rupture process of the 2012 mw 7 8 haida gwaii earthquake from an empirical green s function method abstract this article examines rupture processes of the 28 october 2012 m w 7 8 haida gwaii earthquake off the coast of british columbia canada using an empirical green s function egf technique the haida gwaii earthquake was the largest event along the canadian portion of the pacific north american plate boundary since the m s 8 1 queen charlotte earthquake of 1949 it occurred along a potentially blind thrust fault dipping gently to the northeast rather than the main subvertical queen charlotte fault surface waveforms from a 2001 m w 6 3 event located only 15 km from the 2012 epicenter and with similar mechanism are used as an egf and deconvolved from those of the 2012 mainshock the resulting source time functions contain minimal path effects focal mechanism effects and instrument response so the waveforms display only properties of the 2012 mainshock rupture itself by examining azimuthal variations in these source time functions we constrain parameters such as average rupture velocity extent and directivity in addition information is obtained about the possible existence of major subevents and their relative locations results indicate two subevents within this rupture the first 12 km south and updip of the epicenter and the second approximately 28 km from the first along a heading parallel to the queen charlotte terrace 323 overall the rupture front propagated roughly 50 km at an azimuth of 308 5 this evidence for directivity to the northwest is important given that earthquakes with strong directivity such as the 2002 m w 7 9 denali earthquake have been shown to be capable of triggering earthquakes thousands of kilometers away in this case we suggest that northwest directivity of this earthquake is responsible for amplification of surface waves observed at seismic stations in alaska gomberg 2013 and may provide a potential link between this 2012 event and the 2013 craig alaska earthquake online material figure of all relative source time functions used in directivity analysis

a review of geological records of large tsunamis at vancouver island british columbia and implications for hazard abstract large tsunamis strike the british columbia coast an average of once every several hundred years some of the tsunamis including one from alaska in 1964 are the result of distant great earthquakes most however are triggered by earthquakes at the cascadia subduction zone which extends along the pacific coast from vancouver island to northern california evidence of these tsunamis has been found in tidal marshes and low elevation coastal lakes on western vancouver island the tsunamis deposited sheets of sand and gravel now preserved in sequences of peat and mud these sheets commonly contain marine fossils and they thin and fine landward consistent with deposition by landward surges of water they occur in low energy settings where other possible depositional processes such as stream flooding and storm surges can be ruled out the most recent large tsunami generated by an earthquake at the cascadia subduction zone has been dated in washington and japan to ad 1700 the spatial distribution of the deposits of the 1700 tsunami together with theoretical numerical modelling indicate wave run ups of up to 5 m asl along the outer coast of vancouver island and up to 15 20 m asl at the heads of some inlets the waves attenuated as they moved eastward along juan de fuca strait and into puget sound and the strait of georgia no deposits of the 1700 event or for that matter any other tsunami have yet been found in the strait of georgia suggesting that waves were probably no more than 1 m high in this area if a tsunami like the 1700 event were to occur today communities along the outer pacific coast from southern british columbia to northern california would be severely damaged there would be little time to evacuate these communities because the tsunami would strike the outer coast within minutes of the first ground shaking fortunately such tsunamis are infrequent perhaps as few as seven have occurred in the last 3500 yr other tsunamis that are much smaller and more localized although probably more frequent are caused by local crustal earthquakes and landslides along the british columbia coast two such tsunamis have occurred in british columbia in recent years one in 1946 in the strait of georgia and another in 1975 at the head of a fiord on the northern mainland coast

the tsunami of 2007 september 12 bengkulu province sumatra indonesia post tsunami field survey and numerical modelling summary the m w 8 4 earthquake on 2007 september 12 offshore of the bengkulu province of sumatra indonesia generated a moderate tsunami with run up heights of up to 4 m as measured by indonesian and international researchers in the days following the earthquake the tsunami was observed along 250 km of coastline and caused damage at several locations the largest wave heights and most severe inundation were observed about 50 km to the northwest of bengkulu elsewhere the effects were less severe with the exception of substantial inundation at a site 150 km to the south in addition to presenting the field data we conduct a modelling study and compare the run up heights and water level predictions from four different seismic deformation models used to initialize a tsunami propagation and inundation model our comparative results suggest that for this event the estimates of fault parameters available immediately after determination of the earthquake size and location predicted the near field run up heights and distribution and far field wave equally well as estimates obtained using more detailed descriptions of the seafloor deformation as typically available hours or days after an event we conclude that while detailed slip patterns can be important to the near field run up distribution simple fault models can be used to rapidly assess the likely near and far field tsunami effects of a particular earthquake

in search of preferential flow paths in structured porous media using a simple genetic algorithm fracture network and preferential flow path images from exposed outcrops of geological formations exposed soil pedon faces and extracted soil columns and rock cores are often used to conceptualize and construct models to predict the fate and transport of subsurface contaminants both the scale resolutions inherent in these observations and the upscaling methods used to obtain macroscopic flow and transport parameters may result in uncertainties in the prediction we present a mechanistic based approach that utilizes a discrete fracture flow and transport model a distributed and high performance computational architecture and a genetic based search algorithm to invert scale representative equivalent fracture networks or the preferential flow paths synthetic breakthrough curves btcs and exposed structural information from known fracture networks in hypothetical soil columns are presented to the search algorithm using three genetic operators a simple genetic algorithm sga is able to invert the correct pictures of simple but not complex fracture networks solute transport experiments using soil columns often assume that the structure of soil columns is laterally uniform with respect to the macroscopic transport direction and the transport process is longitudinally one dimensional this assumption and the one btc thus collected for each injection of solutes even with flow interruptions are not sufficient to guide the search algorithm toward the global optimum additional information e g multiple solute btcs along a cross section of the soil column is necessary for the sga to invert the correct fracture network three sga population statistics fracture network uncertainty informatic entropy and matrix fracture contact area are proposed to measure the uncertainty of sga near optima a positive correlation between the reduction of these statistics and the level of relevant information to better confine the sga search space was found the sga search algorithm is then applied to a laboratory solute transport problem multiple scenarios of search constraints derived from visually traced surface features are examined the hypothesis that variation in fracture aperture may reduce the uncertainty of sga near optima is also tested the results from these applications suggest that there is a certain degree of uncertainty regarding the flowing nature of the exposed fracture segments that are visually traced the uncertainty of sga near optima is not improved by incorporating fracture aperture information into the fracture networks breakthrough curves thus calculated have marginal improvement relative to the uniform aperture sga near optima in fitting the observations the lack of improvement may be caused by the relative uniform structure of the soil and the scale of the problem it is further suggested that in applying the search algorithm to laboratory and field problems one explores only the search scenarios that relevant information and search constraints may warrant

introduction to the special issue on the 2012 haida gwaii and 2013 craig earthquakes at the pacific north america plate boundary british columbia and alaska the 27 october 2012 m w 7 8 haida gwaii thrust earthquake and the 5 january 2013 m w 7 5 craig strike slip earthquake are the focus of this special issue they occurred along the transform boundary between the pacific and north american plates fig 1 the most identifiable feature of the plate boundary the strike slip queen charlotte fault might be viewed as typical of continent ocean transform faults because it separates the continental crust of the north american plate from oceanic crust of the pacific plate for most of its length however the current relative plate motion of about 5 cm yr is highly oblique to the queen charlotte fault causing a transpressive plate boundary in the region figure 1 location map for the 2012 m w 7 8 haida gwaii and 2013 m w 7 5 craig earthquakes which occurred on the pacific north american plate boundary approximate rupture zones for the two events are shown in yellow whereas other significant events on the plate boundary are depicted by their aftershock zones red 1949 queen charlotte fault orange 1970 cape st james blue 1972 sitka the epicentral positions are given by stars and the focal mechanisms are plotted in a lower hemisphere projection the black arrows indicate pacific north american relative motion the queen charlotte terrace is located west of the queen charlotte fault and is interpreted to be a narrow accretionary prism inset the earthquakes occurred offshore the western margin of northern north america barbs indicate subduction of the juan de fuca jdf plate and smaller plates beneath north america at the cascadia subduction zone csz transform plate boundaries between continental and oceanic crust are often depicted as both simple and common in reality such continent ocean transform boundaries are neither for example the san andreas fault in california carries continental crustal fragments along with it on the seaward side

a multiple pore region concept to modeling mass transfer in subsurface media abstract recent studies in soil science literature have strongly indicated the need to incorporate pore structures in near surface mass transport modeling there is increasing evidence suggesting that pore structures such as fractures and macropores facilitate the transport of water and solutes along a preferential flow path while water and solutes are moved into micropores and rock matrices concurrently this study presents a conceptual model a multiple pore region or multi region concept to account for pore structures as well as the resultant widely distributed pore water velocities in macroporous media pore regions can either be physically identified as discrete features such as fractures and rock matrices or be experimentally determined by separation of water retention curves according to pore classification schemes a multi region mechanism is proposed to account for the effect of local scale and field scale heterogeneities on mass transport under variably saturated conditions two numerical codes for subsurface fluid flow and solute transport have been developed with the multi region concept in which a firstorder mass exchange model is adopted to simulate the redistribution of pressure heads and solute concentrations among pore regions the computer codes are used to demonstrate the applicability of the concept to fractured porous media and to test a three pore region hypothesis using laboratory soil column tracer injection data based upon the parameters obtained from fitting multi region and mobile immobile models to these data we successfully demonstrated that the former model has the advantage of maintaining consistent conceptual models over the latter under variably saturated conditions

shear wave velocity structure in the vicinity of the 2012 mw 7 8 haida gwaii earthquake from receiver function inversion abstract the thrust mechanism of the 2012 m w 7 8 haida gwaii earthquake suggests convergence across the transpressive pacific north america plate boundary in the region is accommodated by underthrusting with important consequences for seismic and tsunami hazard analysis this article investigates the crustal structure and extent of subduction beneath haida gwaii by nonlinear inversion of receiver function data processed from teleseismic recordings at five land based seismograph stations three of these stations were deployed since the 2012 earthquake to extend coverage to the southeast and have not been analyzed previously the inversions provide estimates of the shear wave velocity structure beneath much of moresby island results indicate a positive velocity contrast at approximately 18 26 km depth interpreted as a shallow continental moho a 12 17 km thick low shear wave velocity zone is also identified which increases in depth from 25 to 42 km along the direction of plate convergence which is interpreted as subducting oceanic material these results provide the first evidence that the subducting oceanic plate extends beneath the entirety of moresby island

preferential flow in a sandy vadose zone 1 field observation abstract field experiments of water movement in the lower portion of an unsaturated zone i e vadose zone are far more difficult to conduct than those in the root zone thus our concept of the transport mechanism in the vadose zone is still primitive and mainly an extrapolation of our understanding of transport in the root zone recent results from field experiments conducted at the hancock agricultural research station indicated that water and solute applied uniformly to soil surfaces did not flow through the entire vadose zone by using dye tracing and profile excavation field experiments were conducted during the 1987 growing season to examine water flow patterns in the unsaturated zone of the central sand area of wisconsin csaw the results confirmed that preferential flow paths constitute the dominant flow pattern at this location water flowing through the root zone was funneled into concentrated flow paths that occupied only a small portion of the soil matrix in the vadose zone yet accounted for most of the transport the observed phenomena of preferential flow in a sandy vadose zone are discussed in this paper the mechanism and implications of preferential flow are presented in a companion paper

tsunami wave analysis and possibility of splay fault rupture during the 2004 indian ocean earthquake the 2004 indian ocean tsunami was observed by two satellites close in space and time that traversed the indian ocean 2 h after the sumatra andaman earthquake but which observed different tsunami lead wave morphologies the earlier satellite jason 1 recorded a lead wave with two peaks of similar amplitude and wavelength while the later satellite topex poseidon recorded a lead wave with only one longer wavelength uplift to resolve this disparity we examine the travel paths of long wavelength waves over the seafloor bathymetry waves traveling from the margin will traverse significantly different paths to arrive at the two satellite transects the result is that the satellites are sensitive to different parts of the margin jason 1 is highly sensitive to the margin in the area of the epicenter while topex is sensitive to a more northerly section by developing solutions of the ocean gravity wave equations accounting for dispersion we show that the double peak of the jason 1 satellite observations are consistent with coseismic rupture of a splay fault of limited along strike extent located north of simeulue island the doubly peaked morphology can be reproduced with co activation of the subduction zone interface and the splay fault which creates a seafloor uplift pattern with two distinct areas of uplift the jason 1 satellite is sensitive to a splay fault in this portion of the margin whereas the topex satellite would not be significantly affected by this uplift pattern by back projecting satellite observation points to the margin we constrain the location of the proposed splay fault and find that it correlates with a bathymetric high the aftershock locations uplift of corals on simeulue island and a fault scarp on pulau salaut besar are also consistent with the activation of a splay fault in the area delimited by the back projection our work also shows that it is critical to fully capture gravity wave dispersion in order to represent features of the lead wave profile that may not be as well characterized by the shallow water long wavelength model it is also necessary to account for dispersion so as to precisely assess wavefront travel times this leads us to conclude that the rupture must have reached very near to the trench and propagated with an updip rupture velocity of order 2 0 km s or more

distribution of the pacific north america motion in the queen charlotte islands s alaska plate boundary zone 1 we present gps data that constrain the distribution of the relative pacific north america motion across the queen charlotte islands alaska panhandle margin nw north america velocities from a network of 22 campaign and permanent sites indicate that the pacific north america transpressive motion is mostly accommodated along the locked queen charlotte fairweather fault a significant portion 6 7 mm yr of the relative plate motion is taken up by distributed dextral shear across a 200 km wide region of the margin two models have been proposed to describe how the pacific north america convergence is accommodated off the queen charlotte islands internal shortening vs underthrusting of the pacific plate although the gps data cannot discriminate between the models they provide strong constraints on the convergence distribution the significant non transient motion of gps sites along the central british columbia southern alaska margin has implications for seismic hazard and tectonic evolution models of the canadian cordillera

quantifying diffusive mass transfer in fractured shale bedrock a significant limitation in defining remediation needs at contaminated sites often results from an insufficient understanding of the transport processes that control contaminant migration the objectives of this research were to help resolve this dilemma by providing an improved understanding of contaminant transport processes in highly structured heterogeneous subsurface environments that are complicated by fracture flow and matrix diffusion our approach involved a unique long term steady state natural gradient injection of multiple tracers with different diffusion coefficients br he ne into a fracture zone of a contaminated shale bedrock the spatial and temporal distribution of the tracers was monitored for 550 days using an array of groundwater sampling wells instrumented within a fast flowing fracture regime and a slow flowing matrix regime the tracers were transported preferentially along strike parallel fractures with a significant portion of the tracer plumes migrating slowly into the bedrock matrix movement into the matrix was controlled by concentration gradients established between preferential flow paths and the adjacent rock matrix observed differences in tracer mobility into the matrix were found to be a function of their free water molecular diffusion coefficients the multiple tracer technique confirmed that matrix diffusion was a significant process that contributed to the overall physical nonequilibrium that controlled contaminant transport in the shale bedrock the experimental observations were consistent with numerical simulations of the multitracer breakthrough curves using a simple fracture flow model the simulated results also demonstrated the significance of contaminant diffusion into the bedrock matrix the multiple tracer technique and ability to monitor the fracture and matrix regimes provided the necessary experimental constraints for the accurate numerical quantification of the diffusive mass transfer process the experimental and numerical results of the tracer study were also consistent with indigenous contaminant discharge concentrations within the fracture and matrix regimes of the field site these findings suggest that the secondary source contribution of the bedrock matrix to the total off site transport of contaminants is relatively large and potentially long lived

the mw 7 9 denali fault earthquake of 3 november 2002 felt reports and unusual effects across western canada the 3 november 2002 m w 7 9 denali fault earthquake was one of the largest north american earthquakes of the past 100 years this earthquake located 330 km to the west of the yukon alaska border generated 260 reports of shaking and other unusual effects to distances of 3500 km across western canada felt intensity for this earthquake ranged from v at communities in the yukon closest to the epicenter about 350 km distance iv across much of the yukon territory distances of 350 to 750 km iii across much of northern british columbia to ii in southern british columbia and alberta about 2400 km distance in many instances people reported feeling nauseous or seasick and having trouble standing the long period ground motions generated by this earthquake displacements greater than 10 cm were recorded in the yukon caused water to spill from swimming pools generated seiches in lakes and rivers and affected wells instances of dirty well water to distances of 3500 km across western canada

combined effects of tectonic and landslide generated tsunami runup at seward alaska during the mw 9 2 1964 earthquake we apply a recently developed and validated numerical model of tsunami propagation and runup to study the inundation of resurrection bay and the town of seward by the 1964 alaska tsunami seward was hit by both tectonic and landslide generated tsunami waves during the m rm w 9 2 1964 megathrust earthquake the earthquake triggered a series of submarine mass failures around the fjord which resulted in landsliding of part of the coastline into the water along with the loss of the port facilities these submarine mass failures generated local waves in the bay within 5 min of the beginning of strong ground motion recent studies estimate the total volume of underwater slide material that moved in resurrection bay to be about 211 million m3 haeussler et al in submarine mass movements and their consequences pp 269 278 2007 the first tectonic tsunami wave arrived in resurrection bay about 30 min after the main shock and was about the same height as the local landslide generated waves our previous numerical study which focused only on the local landslide generated waves in resurrection bay demonstrated that they were produced by a number of different slope failures and estimated relative contributions of different submarine slide complexes into tsunami amplitudes suleimani et al in pure appl geophys 166 131 152 2009 this work extends the previous study by calculating tsunami inundation in resurrection bay caused by the combined impact of landslide generated waves and the tectonic tsunami and comparing the composite inundation area with observations to simulate landslide tsunami runup in seward we use a viscous slide model of jiang and leblond j phys oceanogr 24 3 559 572 1994 coupled with nonlinear shallow water equations the input data set includes a high resolution multibeam bathymetry and lidar topography grid of resurrection bay and an initial thickness of slide material based on pre and post earthquake bathymetry difference maps for simulation of tectonic tsunami runup we derive the 1964 coseismic deformations from detailed slip distribution in the rupture area and use them as an initial condition for propagation of the tectonic tsunami the numerical model employs nonlinear shallow water equations formulated for depth averaged water fluxes and calculates a temporal position of the shoreline using a free surface moving boundary algorithm we find that the calculated tsunami runup in seward caused first by local submarine landslide generated waves and later by a tectonic tsunami is in good agreement with observations of the inundation zone the analysis of inundation caused by two different tsunami sources improves our understanding of their relative contributions and supports tsunami risk mitigation in south central alaska the record of the 1964 earthquake tsunami and submarine landslides combined with the high resolution topography and bathymetry of resurrection bay make it an ideal location for studying tectonic tsunamis in coastal regions susceptible to underwater landslides

scale up of two dimensional conductivity tensor for heterogenous fracture networks abstract an approach is developed to scale up the two dimensional conductivity tensor for highly heterogenous fracture networks based on a numerical modelling approach that was proposed previously by zhang et al j rock mech min sci 33 17 37 1996 in that approach it was assumed that the fractured rock mass was statistically uniform and only a unit square of sample rock was needed to work out the conductivity tensor hence its application was limited where the heterogenous characteristics of a fracture network was not negligible in the present paper the local conductivity tensors both magnitude and direction either calculated based on small fracture networks or samples measured on separate exposures are scaled up to estimate the overall nature of conductivity for a relatively large region the approach developed is used to estimate the two dimensional conductivity tensor of naturally fractured rock masses for two types of fracture networks constant aperture and variable aperture under stress the effects of sample number and sample size of local sub areas were examined against the totally sampled area finally field data were used to predict the overall conductivity tensor of a large region based on four fracture networks sampled on separate exposures within the region

introduction to tsunami science ten years after the 2004 indian ocean tsunami volume i twenty papers on the study of tsunamis and respective tsunamigenic earthquakes are included in volume ii of the pageoph topical issue tsunami science ten years after the 2004 indian ocean tsunami the papers presented in this second of two special volumes of pure and applied geophysics reflect the state of tsunami science during this time including five papers devoted to new findings specifically in the indian ocean two papers compile results from global observations and eight papers cover pacific ocean studies focusing mainly on the 2011 tohoku earthquake and tsunami remaining papers in this volume describe studies in the atlantic ocean and mediterranean sea and tsunami source studies overall the volume not only addresses the pivotal 2004 indian ocean and 2011 tohoku tsunamis but also examines the tsunami hazard posed to other critical coasts in the world

further studies on the focal mechanism and source rupture process of the 2012 haida gwaii canada 7 8 moment magnitude earthquake the 28 october 2012 haida gwaii british columbia canada earthquake with a moment magnitude mw of 7 8 occurred along an east dipping poorly known thrust fault beneath the queen charlotte terrace it was the largest thrust event ever recorded in this dominated by strike slip motion region we studied the focal mechanism and the source rupture process for the event the retrieved geometric parameters of the fault plane were a strike of 329 dip of 24 and slip of 114 the isotropic moment was negative and its value was about one fifth of the total seismic moment released the earthquake ruptured an area of about 160 km 60 km and major slip occurred in an area of about 100 km 60 km the maximum slip was about 5 8 m the slip distribution on the fault plane was highly heterogeneous with four slip patches the main slip lay on a large zone above the hypocentre to the sea floor the maximum and average stress drops calculated using the brune model were 16 5 and 4 6 mpa respectively the major rup

tsunami data assimilation of cascadia seafloor pressure gauge records from the 2012 haida gwaii earthquake we use tsunami waveforms recorded on a dense array of seafloor pressure gauges offshore oregon and california from the 2012 haida gwaii canada earthquake to simulate the performance of two different real time tsunami forecasting methods in the first method the tsunami source is first estimated by inversion of recorded tsunami waveforms in the second method the array data are assimilated to reproduce tsunami wavefields these estimates can be used for forecasting tsunami on the coast the dense seafloor array provides critical data for both methods to produce timeliness 30 min lead time and accuracy in both timing and amplitude 94 confidence tsunami forecasts real time tsunami data on dense arrays and data assimilation can be tested as a possible new generation tsunami warning system

streamflow variability for the aksu river on the southern slopes of the tien shan inferred from tree ring records gauged river flow records from china generally span only a few decades which hampers the detection of long term decadal to centennial scale cycles and trends in streamflow variability new and updated tree ring chronologies help reconstructed the water year october september streamflow for the aksu river which is an important river at the edge of the taklimakan desert that drains into the tarim basin the reconstruction dates back to 1692 and has an adjusted r 2 of 0 61 1957 2006 based on frequency intensity and duration of droughts and pluvial events the lowest streamflows occurred in the 1920s since then streamflow has continuously increased and was exceptionally rapidly after the 1960s until today the start and end of the 20th century to the present were the highest streamflow periods the mid 20th century was the longest and driest period over the past 300 yr the reconstructed streamflow series has a strong positive correlation with the north atlantic oscillation index changes in mid latitude circulation patterns influencing precipitation may have indirectly resulted in streamflow variations along the aksu river over the past 300 yr the rapid increase and the exceptional streamflows of the 1960s are likely linked with global warming and mid latitude atmospheric circulation changes c 2016 university of washington published by elsevier inc all rights reserved

tectonics and structure of the queen charlotte fault zone haida gwaii and large thrust earthquakes abstract this article provides a summary of the structure and tectonic history of the queen charlotte transform fault zone off western canada as background to understanding the 2012 m w 7 8 thrust earthquake off haida gwaii there was margin subduction prior to the eocene the fault zone then became the mainly transcurrent pacific north america boundary there was mid tertiary oblique extension then 15 20 oblique convergence from 6 ma to the present that resulted in underthrusting and subduction initiation the total underthrusting has been too small for benioff wadati seismicity or arc volcanics but is indicated by 1 a trench the queen charlotte trough into which the oceanic plate bows downward and an offshore flexural bulge the oshawa rise 2 the queen charlotte terrace an accretionary sedimentary prism 3 seismic receiver function delineation of the underthrusting pacific plate 4 heat flow decreasing landward as predicted for underthrusting 5 low gravity offshore and high onshore consistent with underthrusting and 6 late tertiary uplift and erosion of the west coast of the islands oblique convergence is partitioned into nearly margin normal underthrusting i e m w 7 8 event relative to the terrace which is moving along the margin and margin parallel on the queen charlotte strike slip fault just off the coast that produced the 1949 m s 8 1 earthquake landward on the mainland global positioning system data suggest slow coast parallel shear with no historical seismicity the convergence rate decreases to the north of haida gwaii off dixon entrance but large thrust earthquakes are possible to the south underthrusting of the winona basin margin also could generate large earthquakes

queen charlotte fault zone microearthquakes from a temporary array of land stations and ocean bottom seismographs a temporary array of land and ocean bottom seismograph stations was used to accurately locate microearthquakes on the queen charlotte fault zone which occurs along the continental margin of wester

geomorphological effects of tsunami run up and backwash abstract geomorphological processes associated with tsunami run up and backwash are highly complex to date most studies have considered the sedimentology of palaeo tsunamis while almost no detailed studies have been undertaken in areas known to have been affected by tsunamis in recent times research on contemporary tsunamis show that coastal landscapes may be greatly altered not only by direct tsunami run up orthogonal to the shoreline but also by episodes of vigorous backwash and by water flow sub parallel to the coastline the combined effect of these processes produces hitherto unrecognised coastal landforms that are dominated by the effects of high magnitude erosion and deposition deposition of large boulders is also associated with severe tsunamis while in adjacent areas run up processes often result in the deposition of continuous and discontinuous sediment sheets in many instances the upper limit of sediment deposition lies well below the upper limit of wave run up which is frequently marked by a well defined zone of stripped vegetation and soil the processes described have considerable implications for models of coastal evolution it may even be the case that the evolution of particular stretches of coastline are dominated by such high magnitude low frequency events

twenty five years of progress in the science of geological tsunamis following the 1992 nicaragua and flores events we review a set of 47 tsunamis of geological origin triggered by earthquakes landslides or volcanoes which have occurred over the past 25 years and provided significant new insight into theoretical experimental field or societal aspects of tsunami science among the principal developments in our command of various aspects of tsunamis we earmark the development of the w phase inversion for the low frequency moment tensor of the parent earthquake the abandonment of the concept of a maximum earthquake magnitude for a given subduction zone controlled by simple plate properties the development and implementation of computer codes simulating the interaction of tsunamis with initially dry land at beaches thus introducing a quantitative component to realistic tsunami warning procedures and the recent in situ investigation of current velocities in addition to the field of surface displacements during the interaction of tsunamis with harbors continued research remains warranted notably in the field of the real time identification of tsunami earthquakes whose tsunamis are larger than expected from their seismic magnitudes especially conventional ones the recent tragedy during the 2018 krakatau flank collapse along a scenario which had been quantitatively forecast also emphasizes the need for a continued effort in the education of the populations at risk

hydrologic mechanisms governing fluid flow in a partially saturated fractured porous medium in contrast to the saturated zone within which fluid moves rapidly along fractures the fractures with apertures large relative to the size of matrix pores will desaturate first during the drainage process and the bulk of fluid flow would be through interconnected pores in the matrix within a partially drained fracture the presence of a relatively continuous air phase will produce practically an infinite resistance to liquid flow in the direction parallel to the fracture the residual liquid will be held by capillary force in regions around fracture contact areas where the apertures are small normal to the fracture surfaces the drained portion of the fractures will reduce the effective area for liquid flow from one matrix block to another matrix block a general statistical theory is constructed for flow along the fracture and for flow between the matrix blocks to the fractures under partially saturated conditions results are obtained from an aperture distribution model for fracture saturation hydraulic conductivity and effective matrix fracture flow areas as functions of pressure the effects of distortion of flow paths by the air pockets are taken into account by a phase separation constriction factor in a generalized cubic law for fracture flow under a partially saturated condition the reduction of matrix fracture flow area is taken into account by summing the aperture distribution function to a saturation cutoff aperture which is inversely proportional to the suction head drainage from a column of fractured tuff is simulated using available parameters for the densely welded tuff of the topopah spring member at yucca mountain southern nevada the column is bounded by discrete vertical fractures and dissected by horizontal fractures with the fracture spacings determined by the frequencies and orientations of fractured cores the fraction of fracture surfaces with coatings is assumed to correspond to the fraction of in situ fracture contact area the characteristic curves for the matrix are based on laboratory measurements of tuff samples from the cases simulated for the fractured porous columns with discrete vertical and horizontal fractures and porous matrix blocks explicitly taken into account it is observed that the highly transient changes from fully saturated conditions to partially saturated conditions are extremely sensitive to the fracture properties however the quasi steady changes of the fluid flow of a partially saturated fractured porous system could be approximately simulated without taking the fractures into account

porosity of natural fracture networks volumetric imaging is used to determine the three dimensional topology of natural fracture networks in coal subjected to reservoir conditions computerized x ray tomographic data and bulk porosity measurements are combined with image processing techniques to quantify the porosity distribution of three dimensional fracture networks in two coal cores under in situ conditions the porosity of the fracture networks in the cores is less than one tenth of a percent in addition the porosity varies by 10 over depth intervals of approximately 16 mm 11 refs 4 figs 3 tabs

gps observations of crustal deformation associated with the 2012 mw 7 8 haida gwaii earthquake abstract on 28 october 2012 an m w 7 8 earthquake occurred off the west coast of haida gwaii british columbia although past large events at this margin reflect strike slip motion between the pacific and north american plates e g 1949 m s 8 1 this earthquake involved low angle thrust faulting with a slip direction almost perpendicular to the margin a consequence of slip partitioning at this obliquely convergent margin to refine regional source models we investigated the coseismic and postseismic displacements using a network of global positioning system gps sites coseismic movement at the campaign site closest to the coast and about 30 km from the epicenter is 115 cm to the south southwest with 30 cm of subsidence the only continuously recording gps station on haida gwaii at the time of the earthquake about 80 km from the epicenter provides a robust coseismic displacement estimate of 22 cm to the south southwest the coseismic results are consistent with a shallow dipping thrust rupture underlying the queen charlotte terrace immediately seaward of the queen charlotte fault these results allowed us to update rupture models that were originally derived from seismic waveforms and tsunami data estimates of cumulative postseismic horizontal displacements over about one year from seven sites are up to 6 cm with a systematic along strike variation in azimuth from south southwest to southeast from north to south in the study area besides viscoelastic stress relaxation these postseismic trends may indicate afterslip on the deeper plate interface beneath northern moresby island and possibly aseismic slip along the queen charlotte or subparallel faults offshore of southern moresby island online material figures of three component daily position estimates from bernese analysis at global positioning system tracking stations on haida gwaii and the adjacent mainland

evidence for underthrusting beneath the queen charlotte margin british columbia from teleseismic receiver function analysis summary the queen charlotte fault zone is the transpressive boundary between the north america and pacific plates along the northwestern margin of british columbia two models have been suggested for the accommodation of the 20 mm yr 1 of convergence along the fault boundary 1 underthrusting 2 internal crustal deformation strong evidence supporting an underthrusting model is provided by a detailed teleseismic receiver function analysis that defines the underthrusting slab forward and inverse modelling techniques were applied to receiver function data calculated at two permanent and four temporary seismic stations within the queen charlotte islands the modelling reveals a 10 km thick low velocity zone dipping eastward at 28 interpreted to be underthrusting oceanic crust the oceanic crust is located beneath a thin 28 km eastward thickening 10 continental crust

attenuation relations of strong ground motion in japan using site classification based on predominant period a spectral acceleration attenuation model for japan is presented in the present study the data set includes a very large number of strong ground motion records up to the 2003 off tokach main and aftershocks site class terms instead of individual site correction terms are used the site classes of recording stations are from a recent study on site classification for strong motion recording stations in japan according to a classification scheme that has been used in japanese engineering design the use of site class terms enables tectonic source type effects to be identified and accounted for in the present model the effects of a faulting mechanism for crustal earthquakes also are accounted for for crustal and interface earthquakes a simple form of an attenuation model with respect to distance is able to capture the main strong motion characteristics and achieves unbiased estimates for subduction slab events a simple distance modification factor is employed to achieve plausible and unbiased predictions the effects of source depth tectonic source type and faulting mechanism of crustal earthquakes are significant the need for magnitude squared terms is evaluated and the use of magnitude squared terms reduces the interevent error further

probabilistic tsunami hazard assessment at seaside oregon for near and far field seismic sources 1 the first probabilistic tsunami flooding maps have been developed the methodology called probabilistic tsunami hazard assessment ptha integrates tsunami inundation modeling with methods of probabilistic seismic hazard assessment psha application of the methodology to seaside oregon has yielded estimates of the spatial distribution of 100 and 500 year maximum tsunami amplitudes i e amplitudes with 1 and 0 2 annual probability of exceedance the 100 year tsunami is generated most frequently by far field sources in the alaska aleutian subduction zone and is characterized by maximum amplitudes that do not exceed 4 m with an inland extent of less than 500 m in contrast the 500 year tsunami is dominated by local sources in the cascadia subduction zone and is characterized by maximum amplitudes in excess of 10 m and an inland extent of more than 1 km the primary sources of uncertainty in these results include those associated with interevent time estimates modeling of background sea level and accounting for temporal changes in bathymetry and topography nonetheless ptha represents an important contribution to tsunami hazard assessment techniques viewed in the broader context of risk analysis ptha provides a method for quantifying estimates of the likelihood and severity of the tsunami hazard which can then be combined with vulnerability and exposure to yield estimates of tsunami risk

source models of the 2012 haida gwaii canada and 2015 illapel chile earthquakes and numerical simulations of related tsunamis seismological observations provide essential input parameters for numerical tsunami simulations here we present source mechanism parameters finite fault source rupture models and numerical tsunami simulation results for the destructive october 28 2012 haida gwaii canada mw 7 7 and september 16 2015 illapel chile mw 8 3 earthquakes and resulting tsunamis these two earthquakes were controlled by active tectonic features along the subduction zones that had developed in response to the convergent movements of lithospheric plates the faulting geometry strike dip and rake angles focal depth fault dimensions average and maximum slip values on the fault planes and seismic moments of the earthquakes are estimated by analyzing teleseismic long period p and sh waves and broadband p waveforms and using waveform inversion and hybrid back projection methods the obtained slip models of the earthquakes reveal heterogeneous slip distributions on fault planes with long source durations 80 s and 150 s and low stress drop values 10 15 bars numerical simulations of tsunami wave propagation are further performed using the uniform and non uniform slip models and nonlinear long wave equations in spherical coordinates the shape and arrival times of leading tsunami waves are adequately constrained particularly with the heterogeneous slip distribution models the general characteristics of synthetic tsunami waveforms e g amplitude shape arrival time calculated using the non uniform slip model are more consistent with the observed tsunami records than those of a uniform slip model it is further seen that simulation results using preliminary and fast slip models for both earthquakes give only approximate early tsunami estimates tsunami wave heights and arrival times to the coasts are mostly not well simulated the results indicate that tsunami simulations based on finite fault source slip models likely contribute to the determination of tsunamigenic coastal regions by revealing locations arrival times amplitudes and directions of tsunami waves within a close approximation to observed records off shore and far from the source region they provide sufficient information to facilitate tsunami warning and mitigation challenges after the destructive earthquakes we further suggest that joint inversions of gps tsunami teleseismic and strong ground motion records and higher resolution bathymetry data are needed in order to obtain better correlations between observed and synthetic tsunami data especially for the later arriving waves

an overview of the 28 october 2012 m w 7 7 earthquake in haida gwaii canada a tsunamigenic thrust event along a predominantly strike slip margin the boundary between the pacific and north america plates along canada s west coast is one of the most seismically active regions of canada and is where canada s two largest instrumentally recorded earthquakes have occurred although this is a predominantly strike slip transform fault boundary there is a component of oblique convergence between the pacific and north america plates off haida gwaii the 2012 mw 7 7 haida gwaii earthquake was a thrust event that generated a tsunami with significant run up of over 7 m in several inlets on the west coast of moresby island several over 6 m with a maximum of 13 m damage from this earthquake and tsunami was minor due to the lack of population and vulnerable structures on this coast

field survey following the 28 october 2012 haida gwaii tsunami this article documents the near field effects of the largest tsunami of 2012 globally which occurred following canada s second largest recorded earthquake on a thrust fault offshore western haida gwaii on october 28 utc despite a lack of reported damaging waves on the coast of british columbia largest amplitudes were recorded in hawaii three field surveys in the following weeks and months reveal that much of the remote unpopulated uninstrumented coastline of western haida gwaii was impacted by significant tsunami waves that reached up to 13 m above the state of tide runup exceeded 3 m at sites spanning 200 km of the coastline greatest impacts were apparent at the heads of narrow inlets and bays on western moresby island where natural and manmade debris with a clear oceanward origin was found on the forest floor and caught in tree branches inferring flow depths up to 2 5 m bays that see regular exposure to storm waves were generally less affected at these sites a storm origin cannot be ruled out for the debris surveyed logs disturbed from their apparent former footprints on the forest floor at the head of pocket inlet provide evidence of complex runup backwash and oblique flow patterns as noted in other tsunamis discontinuous muddy sediments were found at a few sites sedimentation was not proportional to runup lessons learned from our study of the impacts of the haida gwaii tsunami may prove useful to future post tsunami and paleotsunami surveys as well as tsunami hazard assessments

new insights of tsunami hazard from the 2011 tohoku oki event we report initial results from our recent field survey documenting the inundation and resultant deposits of the 2011 tohoku oki tsunami from sendai plain japan the tsunami inundated up to 4 5 km inland but the 0 5 cm thick sand deposit extended only 2 8 km 62 of the inundation distance the deposit however continued as a mud layer to the inundation limit the mud deposit contained high concentrations of water leachable chloride and we conclude that geochemical markers and microfossil data may prove to be useful in identifying the maximum inundation limit of paleotsunamis that could extend well beyond any preserved sand layer our newly acquired data on the 2011 event suggest that previous estimates of paleotsunamis e g 869 ad j gan earthquake and tsunami in this area have probably been underestimated if the 2011 and 869 ad events are indeed comparable the risk from these natural hazards in japan is much greater than previously recognized

observations and numerical modeling of the 2012 haida gwaii tsunami off the coast of british columbia a major mw 7 7 earthquake occurred on october 28 2012 along the queen charlotte fault zone off the west coast of haida gwaii formerly the queen charlotte islands the earthquake was the second strongest instrumentally recorded earthquake in canadian history and generated the largest local tsunami ever recorded on the coast of british columbia a field survey on the pacific side of haida gwaii revealed maximum runup heights of up to 7 6 m at sites sheltered from storm waves and 13 m in a small inlet that is less sheltered from storms leonard and bednarski2014 the tsunami was recorded by tide gauges along the coast of british columbia by open ocean bottom pressure sensors of the neptune facility at ocean networks canada s cabled observatory located seaward of southwestern vancouver island and by several dart stations located in the northeast pacific the tsunami observations in combination with rigorous numerical modeling enabled us to determine the physical properties of this event and to correct the location of the tsunami source with respect to the initial geophysical estimates the initial model results were used to specify sites of particular interest for post tsunami field surveys on the coast of moresby island haida gwaii while field survey observations leonard and bednarski2014 were used in turn to verify the numerical simulations based on the corrected source region

assessment of ground motion models for use in the british columbia north coast region canada abstract the 28 october 2012 m w 7 8 haida gwaii earthquake was the second largest earthquake instrumentally recorded in canada s territory and was strongly felt across the british columbia north coast bcnc region data from the haida gwaii sequence and other events in the region are compiled for 56 earthquakes between moment magnitude m w 4 6 and 7 8 that occurred between 1996 and 2014 pseudospectral accelerations psa at 5 damping are calculated and compared against several modern ground motion models gmms using different binning criteria e g distance magnitude mechanism source to site azimuth and event chronology overall no single model is found to be appropriate for the bcnc region with gmms generally overestimating recorded near source i e earthquake motions recorded prior to and including the 2012 m w 7 8 earthquake were generally more comparable with some gmms at longer spectral periods but still possessed significant biases based on residual analyses additionally earthquakes with normal mechanisms gave less short to mid period shaking relative to strike and reverse slip events online materials summary of the candidate ground motion prediction equations indicating their distance metrics and conditions of use

towards a reconstruction of blue nile baseflow from ethiopian tree rings most of the water in the river nile originates from monsoonal rainfall over the ethiopian highlands despite warnings of future climate change little is known about the historical variability in this supply particularly at annual resolution development of tree ring records in this region has been limited by the occurrence of bi or multimodal rainfall regimes causing the development of multiple growth rings that cannot be dated with confidence in this study we identified annual rings in 30 juniperus procera trees from northwest ethiopia by dendrochronology and ams radiocarbon dating carbon isotope ratios 4 series and ring widths 73 series were measured the carbon isotope series did not contain strong trends possibly attributable to increased anthropogenic atmospheric co2 concentrations or the juvenile effect both carbon isotope values and ring widths were strongly correlated with blue nile baseflow and from composite chronology indices r 0 75 p 0 01 a preliminary reconstruction of blue nile baseflow back to ad 1836 was developed subsample signal strength remained above 0 85 for most of the reconstruction uncertainty bands were relatively narrow and the reliability of the preliminary reconstruction was confirmed by correspondence with reported years of drought and famine the preliminary reconstruction is characterized by an exceptional decline in baseflow during the late ad 1960s flows recovered during the late 1990s additional sampling is advised to increase replication spatial coverage and length of the preliminary reconstruction

reconstructing discharge of beas river basin kullu valley western himalaya based on tree ring data abstract tree ring data of cedrus deodara deodar growing within the beas river basin kullu valley himachal pradesh in western himalaya have been analyzed in relation to streamflow reconstruction the correlation between deodar tree ring chronology and river discharge data from various gauge stations of the beas river basin showed positive relationships with early summer months march april streamflow of these months has been reconstructed using a simple linear regression transfer function model which goes back to ad 1834 explained variances during the calibration period are 43 7 and 60 6 for two gauge stations bhuntar and thalout respectively in the reconstructed data ad 1834 1984 the periods of highest streamflow were during ad 1840 1843 1893 1897 1922 1926 1935 1940 and 1942 45 and lowest were during the years ad 1847 1851 1863 66 1927 1929 1960 1962 and 1972 1974 spatial coherence analysis between the reconstructed series with regional gridded precipitation and nearby longest instrumental precipitation records showed coincidence with drought and wet periods through the spatial correlation analysis between reconstructed march april runoff and gridded palmer drought severity index pdsi a common regional moisture variation was identified

source characteristics of the 2012 haida gwaii earthquake sequence abstract all the significant m l 4 events in the 2012 haida gwaii earthquake sequence are systematically relocated and their moment tensor solutions are determined from waveform inversion the focal mechanism of the mainshock shows low angle thrust faulting along a shallowly dipping plane with a strike parallel to the queen charlotte fault qcf consistent with the inference of pacific plate underthrusting beneath the overriding north american plate the epicenter of the mainshock is located 5 km landward northeast of the surface trace of the qcf suggesting the nucleation of the rupture was near the bottom of the seismogenic locked interface significant aftershocks appear to cluster on the periphery of the main rupture zone with most events located immediately seaward of the deformation front the majority of these events show normal faulting mechanisms that are probably associated with the bending stress within the pacific plate near the deformation front several normal and strike slip events at greater depths within the subducted pacific slab show a consistent pattern of t axis in the down dip direction implying the subducted plate is under a stress regime of down dip extension only a few strike slip events were observed along or near the qcf the limited size and distribution of these events suggest that most of the elastic strain accumulated along the qcf was not released during the 2012 haida gwaii sequence major strike slip earthquakes are likely to occur along the southernmost part of the qcf system in the future