where was south china in the rodinia supercontinent evidence from u pb geochronology and hf isotopes of detrital zircons abstract u pb geochronology and lu hf isotopic studies on detrital zircons from late neoproterozoic sediments of the cathaysia block south china show abundant grenville age 1 0 ga and neoarchaean populations and minor eoarchaean 3 8 ga paleo to mesoarchaean 3 3 3 0 ga mesoproterozoic 1 7 1 4 ga and pan african 0 70 0 54 ga populations this is the first report of 3 8 ga material in the crust of the cathaysia block the presence of euhedral 1 0 ga zircons indicates that a grenville orogenic belt was within or very close to the southern cathaysia block however the provenance containing the 3 8 ga 3 3 3 0 ga 2 5 ga 1 0 ga and 0 70 0 54 ga zircon populations cannot be found in the south china block the combination of zircon age distributions and the rounded strongly abraded shapes of the archean zircons suggesting long transport is consistent with derivation from other continental terranes previously linked with the southern part of the south china block comparison with the tectono magmatic history and compositions of rocks in western laurentia eastern australia and eastern india east antarctica western australia we suggest that these late neoproterozoic sediments may have originated mainly from eastern india east antarctica this indicates that the south china block was linked with the eastern india east antarctica continents in the late neoproterozoic rather than being located between the western laurentia and eastern australia continental blocks u pb and hf isotope studies on detrital zircons provide an important independent constraint on the palaeogeography of the south china block in the context of the breakup of rodinia and the subsequent assembly of gondwana in late neoproterozoic time and insights into the relationship between the cathaysia and yangtze blocks

induced polarization detection and mapping of contaminant plumes several laboratory and scaled model investigations suggest that organic contaminants affect the surface electrical properties of exposed soils rocks and therefore produce measurable induced polarization ip signatures however there is little field evidence of an ip methodology for contaminant mapping a2d time domain ip method is developed for mapping the fs12 contaminant plume at the massachusetts military reservation mmr located in cape cod massachusetts the fs 12 plume consists of approximately 265 m 3 of fuel that erupted from a broken underground pipeline in the early 1970s benzene and ethylene dibromide edb are the primary contaminants at fs 12 with concentrations exceeding the allowed maximum concentration levels mcl while other constituents of the plume did not exceed their mcl therefore the contaminants of interest are benzene and edb partly because of their health risk and partly because they present the highest concentrations 2400 and 1000 g l respectively among the plume constituents and are therefore more likely to be related to the polarization source ip data were acquired along a survey line that partially transects the plume extending over contaminated and uncontaminated zones and were inverted to give 2d resistivity and chargeability plots to 100 m depth and a horizontal extent of 400 m by separately inverting ip data derived from time windows located at short and long decay times a timedomain gross spectral chargeability difference is produced both the chargeability and gross spectral chargeability difference show good agreement with the known location of the plume from monitoring wells with the ip chargeability section suggesting contaminant distribution detail that cannot otherwise be inferred from the sparse borehole distribution

on the leading negative phase of major 2010 2014 tsunamis time series observations from instruments sited in the deep ocean and along coastal margins of the pacific during major tsunami events in the years since 2010 were systematically processed examination of these records during four events 2010 chile maule 2011 east japan tohoku 2012 haida gwaii and 2014 chile iquique show the prevalence of a small negative phase leading the first major positive tsunami wave a phase that is not typically reproduced by current modelling approaches we present leading negative phase signatures in examples from the more than 40 deep ocean bottom pressure and approximately 200 tide gauge records investigated for this study high sampling rate time series 15 s were given greater weight in our investigation than the more readily available 1 min series careful investigation of tsunami arrival at each deep ocean site highlights the role filtering techniques may play in misleading researchers or masking specific tsunami features such as the leading negative phase that is the basis of this study the main focus of this investigation is to characterise the scale and repeatability of the phenomenon in support of recent similar findings rather than to provide a definitive explanation as to the cause in general our findings are in good agreement with and support the theoretical results of watada et al j geophys res solid earth 119 4287 4310 2014

evaluation of intensity of recent seismogenic tsunamis in the world ocean from 2000 to 2014 tsunami intensity on the soloviev imamura scale is one of the most important parameters for characterizing the overall size of a tsunami generated by submarine earthquakes consequently this parameter is included in both global tsunami databases maintained by the national centers for environmental information world data service ncei wds and the novosibirsk tsunami laboratory of the institute of computational mathematics and mathematical geophysics ntl icmmg s soloviev made the initial evaluation of the intensities of a large number of destructive historical tsunamis while compiling his two historical catalogs of tsunamis in the pacific the novosibirsk tsunami laboratory under the expert tsunami database project made further determinations of tsunami intensity for the events after 1975 these intensities have been periodically incorporated into the ncei wds tsunami database under the global tsunami database joint icg itsu iugg tc project in the on line version of the ncei wds tsunami database the data on tsunami intensity are available only for the events prior to 2003 the main purpose of this paper is to extend the temporal coverage of this important parameter for characterizing tsunamigenic events to the present in order to provide researchers with more data for analyzing the temporal and spatial tsunami occurrence however of the 164 tsunamigenic events in the world ocean from 2000 to the present we could determine the intensity value for only 44 events that is less than 27 of the total for the rest of the events that is 73 the intensity value cannot be determined due to the lack of data on wave heights from the nearest coast this shows that despite a great improvement in the tsunami recording network in the pacific and other oceanic basins during the last two decades the data for reliable estimates of tsunami intensity are still problematic

field survey of the 1945 makran and 2004 indian ocean tsunamis in baluchistan iran we report the result of a 2010 survey of the effects on the iranian coastline of the tsunami which followed the earthquake of 27 november 1945 m 0 2 8 1028 dyn cm m w 8 2 the only large event recorded along the makran subduction zone since the onset of instrumental seismology based on the interview of elderly survivors of the event we obtained a database of nine values of run up or splash amplitudes on a segment of shore extending 280 km from souraf in the west to pasabandar near the pakistani border and ranging in vertical amplitude from 2 3 to 13 7 m witness reports are consistent with a significant delay estimated at 2 5 h of the tsunami waves suggesting that they were generated by an ancillary phenomenon such as a landslide triggered by the earthquake none of our witnesses bore ancestral memory of comparable events in the past suggesting that reported predecessors to the 1945 earthquake may have been smaller in size the survey also allowed the compilation of previously unreported data concerning the effects of the 2004 sumatra andaman tsunami

shrimp u pb zircon geochronology of the fuping complex implications for formation and assembly of the north china craton abstract the fuping complex located within the central zone of the north china craton is composed of amphibolite to granulite facies orthogneisses interleaved with minor supracrustal rocks at similar metamorphic grade the oldest components recognised are hornblende gneiss enclaves within the predominant biotite orthogneiss which have a shrimp u pb zircon age of 2708 8 ma we consider these enclaves to represent fragments of 2 7 ga continental materials incorporated in the biotite gneiss the biotite gneiss has a shrimp u pb zircon age of 2513 12 ma interpreted to be time of magmatic crystallisation of the igneous precursor based on the igneous characteristics of the zircons this indicates a major magmatic episode at 2 52 ga in the fuping complex identical to the age of felsic volcanism within the low grade wutai complex which crops out immediately to the west a gneissic granite that intrudes the biotite gneisses has a poorly defined 207pb 206pb age of 2045 64 ma this is within error of the age of 2097 46 ma obtained from a fine grained gneiss interlayered with amphibolite of the wanzi supracrustal suite wss interpreted to be volcanic in origin zircons from both these samples have strong oscillatory zoning and provide the first indication of a palaeoproterozoic magmatic event in the area again similar in age to magmatic events recently recognised in the adjacent wutai complex these data indicate a comparable history for the fuping and wutai complexes and support geochemical evidence that they had a common origin and formed part of a late archaean arc affected by later palaeoproterozoic re activation low uranium zircons without oscillatory zoning separated from a sample of biotite gneiss yield data clustered at 1817 26 ma which is interpreted to reflect a period of new zircon growth during a major metamorphic event these data support the recently proposed tectonic model that amalgamation of the north china craton occurred due to collision of the eastern and western blocks along the central zone at 1 8 ga ago

note on the paper by guochun zhao simon a wilde sanzhong li min sun matthew l grant and xuping li 2007 u pb zircon age constraints on the dongwanzi ultramafic mafic body north china confirm it is not an archean ophiolite

earthquake scenario based tsunami wave heights in the eastern mediterranean and connected seas we identified a set of tsunami scenario input parameters in a 0 5 0 5 uniformly gridded area in the eastern mediterranean aegean both for shallow and intermediate depth earthquakes and black seas only shallow earthquakes and calculated tsunami scenarios using the swan joint research centre swan jrc code mader 2004 annunziato 2007 with 2 arcmin resolution bathymetry data for the range of 6 5 mwmax with an mw increment of 0 1 at each grid in order to realize a comprehensive analysis of tsunami wave heights from earthquakes originating in the region we defined characteristic earthquake source parameters from a compiled set of sources such as existing moment tensor catalogues and various reference studies together with the mwmax assigned in the literature where possible results from 2 415 scenarios show that in the eastern mediterranean and its connected seas aegean and black sea shallow earthquakes with mw 6 5 may result in coastal wave heights of 0 5 m whereas the same wave height would be expected only from intermediate depth earthquakes with mw 7 0 the distribution of maximum wave heights calculated indicate that tsunami wave heights up to 1 m could be expected in the northern aegean whereas in the black sea cyprus levantine coasts northern libya eastern sicily southern italy and western greece up to 3 m wave height could be possible crete the southern aegean and the area between northeast libya and alexandria egypt is prone to maximum tsunami wave heights of 3 m considering that calculations are performed at a minimum bathymetry depth of 20 m these wave heights may according to green s law be amplified by a factor of 2 at the coastline the study can provide a basis for detailed tsunami hazard studies in the region

evolution and assembly of archean gneiss terranes in the godthabsfjord region southern west greenland structural metamorphic and isotopic evidence the godthabsfjord region of southern west greenland comprises several terranes that were assembled between 2750 and 2550 ma and folded during amphibolite facies metamorphism the terranes which are dominated by gneisses of different ages and show different preassembly metamorphic and structural histories are 1 the faeringehavn terrane containing the 3820 3600 ma amitsoq gneisses with granulite facies metamorphism at circa 3600 ma 2 the akia terrane containing the 3070 2940 ma nuk gneisses with granulite amphibolite facies metamorphism at circa 2980 ma 3 the tasiusarsuaq terrane containing circa 2900 ma gneisses with granulite facies metamorphism at circa 2800 ma and 4 the tre brodre terrane containing the 2800 2750 ma ikkattoq gneisses with amphibolite facies metamorphism at 2800 2750 ma metamorphic assemblages and structures formed prior to terrane assembly were variably overprinted during amphibolite facies metamorphism and heterogeneous strain associated with assembly recognition of the region as consisting of several terranes indicates that the anatomy of some archean high grade gneiss complexes may resemble that of orogens of proterozoic and phanerozoic age that formed as a consequence of plate tectonic processes

new tsunami forecast tools for the french polynesia tsunami warning system this paper presents the tsunami warning tools which are used for the estimation of the seismic source parameters these tools are grouped under a method called preliminary determination of focal mechanism 2 pdfm2 that has been developed at the french polynesia warning center in the framework of the seiscomp3 system as a plug in concept the first tool determines the seismic moment and the focal geometry strike dip and slip and the second tool identifies the tsunami earthquakes earthquakes that cause much bigger tsunamis than their magnitude would imply in a tsunami warning operation initial assessment of the tsunami potential is based on location and magnitude the usual quick magnitude methods which use p waves work fine for smaller earthquakes for major earthquakes these methods drastically underestimate the magnitude and its tsunami potential because the radiated energy shifts to the longer period waves since french polynesia is located far away from the subduction zones of the pacific rim the tsunami threat is not imminent and this luxury of time allows to use the long period surface wave data to determine the true size of a major earthquake the source inversion method presented in this paper uses a combination of surface waves amplitude spectra and p wave first motions the advantage of using long period surface data is that there is a much more accurate determination of earthquake size and the advantage of using p wave first motion is to have a better constrain of the focal geometry than using the surface waves alone the pdfm2 method routinely gives stable results at t 0 45 minutes with t 0 being the origin time of an earthquake our results are then compared to the global centroid moment tensor catalog for validating both the seismic moment and the source geometry the second tool discussed in this paper is the slowness parameter theta and is the energy to moment ratio it has been used to identify tsunami earthquakes which are characterized by having unusual slow rupture velocity and release seismic energy that has been shifted to longer periods and therefore have low theta values the slow rupture velocity would indicate weaker material and bigger uplift and thus bigger tsunami potential the use of the slowness parameter theta is an efficient tool for monitoring the near real time identification of tsunami earthquakes

delineation of saltwater intrusion into the freshwater aquifer of lekki peninsula lagos nigeria recently the deterioration of water quality in the coastal zones of lekki peninsula area of lagos due to saltwater infiltration into the freshwater aquifer has become a major concern with the aim of providing valuable information on the hydrogeologic system of the aquifers the subsurface lithology and delineating the groundwater salinity vertical electrical resistivity ves sounding survey was carried out utilizing surface schlumberger electrode arrays and electrode spacing varying between 1 and 150m the dc resistivity surveys revealed significant variations in subsurface resistivity also the ves resistivity curves showed a dominant trend of decreasing resistivity with depth thus increasing salinity in general the presence of four distinct resistivity zones were delineated viz the unconsolidated dry sand a having resistivity values ranging between 125 and 1 028 m represent the first layer the fresh water saturated soil zone b having resistivity values which correspond to 32 256 m is the second layer the third layer zone c is interpreted as the mixing transition zone of fresh with brackish groundwater the resistivity of this layer ranges from 4 to 32 m while layer four zone d is characterized with resistivities values generally below 4 m reflecting an aquifer possibly containing brine the rock matrix salinity and water saturation are the major factors controlling the resistivity of the formation moreover this investigation shows that saline water intrusion into the aquifers can be accurately mapped using surface dc resistivity method

petrochemistry and sr pb and nd isotopic geochemistry of early precambrian rocks wutaishan and taihangshan areas china abstract in the wutaishan and taihangshan region china the lowermost high grade metamorphic complex of grey gneiss and amphibolite the fuping complex gives a 2 2 0 2 ga pb pb isochron age with a first stage growth 7 73 and a 2 37 0 07 ga sm nd isochron age with 143nd 144nd 0 0 50963 0 00005 or nd t 1 50 nd depleted mantle model dates tdm of amhibolites 2 48 to 2 60 ga those of gneisses are 2 43 to 2 46 ga the unconformably overlying medium to low grade metavolcanic complex the wutai complex gives a 2 0 0 1 ga rb sr isochron age with 87 86sr 0 0 7025 2 a 2 27 0 02 ga pb pb isochron date with afirst stage growth 7 73 and a 2 26 0 06 ga sm nd isochron first stage 143nd 144nd 0 0 5097 2 or nd t 1 08 individual sample nd depleted mantle model date are 2 5 ga metavolcanic samples from low grade metasedimentary rocks of the hutuo group all lie close to a 2 3 ga reference line on a rb sr isochron plot have nd tdm 2 32 2 34 and 2 62 ga from previous geological work published u pb zircon dating and ourisotopic and geochemical results we infer that the fuping rocks formed 2 6 ga ago in an environment like a modern island arc the wutai complex formed by 2 5 ga ago mostly formed in a tectonic setting similar to that of the fuping complex with the exception that one volcanic cycle formed in an environment like a modern mor and one unit formed in an environment transitional between modern within plate and plate margin settings the hutuo group formed 2 4 ga ago in a within plate tectonic environment there is no evidence for continental crust before 2 6 ga in the wutaishan and taihangshan region this contradicts previous assignment of the fuping complex to 2 8 ga ol older the fuping complex is not an early nucleus of the sino korean craton the new data also confirm that the wutai complex is older than its original assignment as early proterozoic the sm nd systems for metabasaltic rocks in the region either in amphibolite facies or in greenschist facies are all significantly disturbed in contrast with the undisturbed sm nd reported in previous studies of the sino korea craton this study provides further evidence that the archean igneous rocks in china formed at different times from heterogeneous and depleted mantle sources

new insights into the source of the makran tsunami of 27 november 1945 from tsunami waveforms and coastal deformation data we constrain the source of the 27 november 1945 tsunami in the makran subduction zone msz using available tsunami waveforms recorded on tide gauges at mumbai india and karachi pakistan and that inferred at port victoria seychelles and coseismic deformation data along the makran coast spectral analysis of the tsunami waveforms shows that the tsunami governing period was 40 50 min at karachi whereas it was around 22 min at mumbai the inferred tsunami waveform at port victoria also indicated a period of around 21 min for the tsunami tsunami numerical simulations from the previously proposed source models failed in reproducing the observed tsunami waveforms and coseismic deformation data sensitivity analysis showed that the source fault needs to be extended offshore into deep water in order to reproduce the first 22 min signal at mumbai based on the inversion of the observed tsunami waveforms we propose a four segment fault with varying slip amounts as the final source this source includes a slip of 4 3 m onshore near ormara pakistan and a slip of 10 m offshore at water depth of around 3 000 m the total fault length is 220 km and the average slip is 6 1 m this source first reproduces fairly well the observed tide gauge records at mumbai and karachi second produces 1 m of uplift at ormara and 1 m of subsidence at pasni and third gives a moment magnitude of 8 3 for the earthquake which is in the acceptable range of seismic data the computed 1 m uplift at ormara is in the uplift range of 1 3 m reported in the literature as the tide gauge stations were located in the far field our proposed source explains mainly the tectonic source of the tsunami

validating velocities in the geoclaw tsunami model using observations near hawaii from the 2011 tohoku tsunami the ability to measure predict and compute tsunami flow velocities is of importance in risk assessment and hazard mitigation substantial damage can be done by high velocity flows particularly in harbors and bays even when the wave height is small moreover advancing the study of sediment transport and tsunami deposits depends on the accurate interpretation and modeling of tsunami flow velocities and accelerations until recently few direct measurements of tsunami velocities existed to compare with model results during the 11 march 2011 tohoku tsunami 328 current meters were in place around the hawaiian islands usa that captured time series of water velocity in 18 locations in both harbors and deep channels at a series of depths we compare several of these velocity records against numerical simulations performed using the geoclaw numerical tsunami model based on solving the depth averaged shallow water equations with adaptive mesh refinement to confirm that this model can accurately predict velocities at nearshore locations model results demonstrate tsunami current velocity is more spatially variable than waveform or height and therefore may be a more sensitive variable for model validation

integrated earth resistivity tomography ert and multilevel sampling gas a tool to map geogenic and anthropogenic methane accumulation on brownfield sites soil gas emissions of methane and carbon dioxide on brownfield sites are usually attributed to anthropogenic activities however geogenic sources of soil gas are often not considered during site investigation and risk management strategies this paper presents a field study at a redeveloped brownfield site on a flood plain to identify accumulations of methane biogas trapped in underlying sediments the investigation is based on a multidisciplinary approach using direct multi level sampling measurements and earth resistivity tomography resistivity imaging was applied to evaluate the feasibility of identifying the size and spatial continuity of soil gas accumulations in anthropogenic and naturally occurring deposits as a result biogas accumulations are described within both anthropogenic deposits and pristine organic sediments this result is important to identify the correct approaches to identify and manage risks associated with soil gas emissions on brownfield and pristine sites the organic rich sediments in quaternary fluvial environments of sao paulo basin in particular the tiete river biogas reservoirs can be generated and trapped beneath geogenic and anthropogenic layers potentially requiring the management of brownfield developments across this region

the 2004 sumatra tsunami in the southeastern pacific ocean new global insight from observations and modeling the 2004 sumatra tsunami was an unprecedented global disaster measured throughout the world oceans the present study focused on a region of the southeastern pacific ocean where the westward circumferentially propagating tsunami branch converged with the eastward branch based on data from fortuitously placed chilean dart 32401 and tide gauges along the coast of south america by comparison of the tsunami and background spectra we suppressed the influence of topography and reconstructed coastal spectral ratios that were in close agreement with a ratio at dart 32401 and spectral ratios in other oceans findings indicate that even remote tsunami records carry spectral source signatures birth marks the 2004 tsunami waves were found to occupy the broad frequency band of 0 25 10 cph with the prominent ratio peak at period of 40 min related to the southern fast slip source domain this rupture hot spot of 350 km was responsible for the global impact of the 2004 tsunami data from dart 32401 provided validation of model results the simulated maximum tsunami wave height of 2 25 cm was a conservative approximation to the measured height of 2 05 cm the computed tsunami travel time of 25 h 35 min to dart 32401 although 20 min earlier than the actual travel time provided a favorable result in comparison with 24 h 25 min estimated from classical kinematic theory the numerical simulations consistently reproduced the wave height changes observed along the coast of south america including local amplification of tsunami waves at the northern stations of arica 72 cm and callao 67 cm

crosshole ip imaging for engineering and environmental applications induced polarization ip imaging is a promising tool in engineering and environmental studies application of this technique for near surface investigations has previously been limited by incomplete understanding of the physicochemical controls on the ip response together with a lack of appropriate methods for data inversion as laboratory studies have shown description of ip in terms of complex electrical conductivity enables access to various structural characteristics pertinent to practical issues such as subsurface lithology definition hydraulic permeability estimation or hydrocarbon contaminant mapping in particular analysis in terms of real and imaginary conductivity components offers improved lithological characterization since surface polarization effects are separated from electrolytic and surface conduction effects an occam type ip inversion algorithm based on complex algebra is described which accounts for these advances in ip interpretation by directly solving for complex conductivity results from crosshole applications at two case study sites demonstrate the suitability of the ip imaging approach for subsurface characterization in the first case study the imaging results correlate with the observed complex sequence of quaternary sediments at a waste disposal site characterization of the polarizability of these sediments offers significant value in lithological differentiation in the second case study the results of ip imaging at a hydrocarbon contaminated site illustrate the potential of the method in environmental studies the hydrocarbon location is clearly evident from the ip image and a markedly different response is observed at an uncontaminated region of the site by adopting empirical structural electrical relationships images of textural and hydraulic properties are estimated as a step toward improved quantitative characterization the success of the method for these contrasting applications supports further investigation into understanding the physical and chemical processes that control observed ip

tsunami forerunner of the 2011 tohoku earthquake observed in the sea of japan during the march 11 2011 tohoku tsunami some japanese and russian tide gauges in the sea of japan recorded sea level disturbances with periods of several to 10 min and amplitudes of several to a few tens of centimeters starting immediately after the earthquake tsunami travel times computed from the 2011 source in the pacific ocean to these stations are 1 2 h to examine the cause of the observed tsunami forerunners and to reproduce them we carried out tsunami numerical computations from three kinds of coseismic seafloor deformation the vertical displacement in the tsunami source area in the pacific ocean the vertical displacement extending in the sea of japan and the vertical displacement including the effects of the horizontal displacement and the seafloor slope in both the pacific ocean and the sea of japan only the last source reproduced the observed tsunami forerunners this indicates that the tsunami forerunners were produced by the horizontal displacement of fault motion and the seafloor slope in the sea of japan for the tide gauge records in japan the forerunners with periods longer than 2 min were well reproduced by the tsunami simulation the shorter period components may be induced by seismic ground shakings for the tide gauge records in russia the agreement between the observed and computed waveforms was less satisfactory probably because of less accurate and coarser bathymetry data

remnants of an archean oceanic plateau belingwe greenstone belt zimbabwe stratigraphic and structural data from the archean zimbabwe craton suggest that a major detachment surface exists within the belingwe greenstone belt the surface separates ultramafic and mafic magmatic rocks of the upper greenstones in the hanging wall from an ancient gneiss complex older volcanic sedimentary rocks and a shallow water sedimentary sequence in the footwall rocks dated at ca 2 7 ga above the detachment surface form the proposed mberengwa allochthon the regionally extensive upper greenstone succession represents tectonically emplaced allochthonous sheets not indigenous magmas erupted within autochthonous continental rifts magmatic rocks of the mberengwa allochthon resemble oceanic plateaus preserved in younger mountain belts comparison of the zimbabwe craton with the proterozoic birrimian terranes of west africa leads us to suggest that precambrian continental growth may have been characterized by intense structural imbrication related to the difficulty of subduction of buoyant oceanic lithosphere

dc resistivity mapping of internal landfill structures two pre excavation surveys geophysical investigations using 2 d dc resistivity were carried out on old parts of two similar landfills with waste of different ages the data sets which included high data density in both vertical and horizontal directions were interpreted with 2 d smoothness constrained inversion the landfills were excavated after the surveying the objective was to test the capability of the resistivity method as a pre characterization technique the objectives were only partially fulfilled first the moisture content was the parameter that appeared to exert the dominant control over the resistivity distribution of the landfill the most important potential information that can be recovered is therefore an indication of the waste piles hydraulics second it was neither possible to estimate the amount of recoverable soils nor to correlate the type of waste with the resistivity models however discrete anomalies were identified and if specific materials are searched for the resistivity models indicate possible places to search

energy decay of the 2004 sumatra tsunami in the world ocean the catastrophic indian ocean tsunami generated off the coast of sumatra on 26 december 2004 was recorded by a large number of tide gauges throughout the world ocean this study uses gauge records from 173 sites to examine the characteristics and energy decay of the tsunami waves from this event in the indian atlantic and pacific oceans findings reveal that the decay e folding time of the tsunami wave energy within a given oceanic basin is not uniform as previously reported but depends on the absorption characteristics of the shelf adjacent to the coastal observation site and the time for the waves to reach the site from the source region in general the decay times for island and open ocean bottom stations are found to be shorter than for coastal mainland stations decay times for the 2004 sumatra tsunami ranged from about 13 h for islands in the indian ocean to 40 45 h for mainland stations in the north pacific

upb zircon geochronology of late archaean metamorphic rocks in the taihangshan wutaishan area north china abstract a geochronological study has been made in the taihangshan wutaishan area shanxi province on a sequence of precambrian supracrustal rocks and stratigraphically related intrusives these constitute part of the north china basement block the oldest rocks of the fuping group consist predominantly of mafic granulites paragneisses quartzites and amphibolites this group was always considered archaean and early k ar measurements yielded some minimum ages as old as 2300 ma and others as young as 1500 1900 ma the unconformably overlying wutai group is considered as the base of the proterozoic succession and consists of amphibolite grade paragneisses carbonates and amphibolites in its lower part and greenschist grade clastic sediments and volcanics in its upper part it has given apparent k ar mineral ages between 1500 and 2000 ma present investigations have employed the u pb zircon approach on selected parts of the sequences to provide direct depositional ages or age constraints for the fuping and wutai groups and to find the age s of subsequent metamorphic processes a minimum age for the fuping group and maximum age for the wutai group has been derived from zircon age measurements on the lanzhishan granite 2560 9 ma which intrudes the fuping group and is unconformably overlain by the wutai group this late archaean result can be interpreted as the age of an igneous crystallization event and therefore a maximum for the depositional age of the wutai group the above result is well substantiated by zircon dating of the wutai group itself zircons from a low grade metamorphosed keratophyric lava in the upper part of the group give a volcanic crystallization age of 2520 17 ma this provides close constraints for the age of deposition of the wutai group at between 2560 and 2520 ma ago if the wutai group is indeed basal proterozoic the archaean proterozoic boundary in this part of china is also dated at between 2560 and 2520 ma further evidence as to the antiquity of the wutai group comes from a u pb zircon age of 2520 30 ma for the ekou granite which intrudes the wutai group sequence the age of the underlying late archaean rocks in the tainhangshan wutaishan area the fuping group could not be directly determined because of the paucity of volcanic markers and the higher grade of metamorphism its minimum age is 2560 ma see above but only an approximate maximum age can be gleaned from the zircon systematics in granulite and amphibolite grade paragneiss samples these data indicate a degree of pb inheritance which combined with metamorphic disturbance and more recent pb loss inhibit any further interpretation other than that they indicate an approximate maximum age of around 2800 ma several of the paragneisses and one amphibolitic schist contain zircon systems which are interpreted as having completely responded to a well defined amphibolite facies metamorphic event at 2500 ma ago a younger but less well defined metamorphism caused complete pb loss from zircon and recrystallization in the amphibolite and granulite facies terrains at between 2000 and 1800 ma ago rocks which show evidence of this younger metamorphic event were not recognized from the field or structural data base but from the distribution of the few such samples analyzed it seems possible that this younger terrain may now be interpretable as a cross cutting proterozoic mobile belt this proterozoic metamorphic province is also reflected by k ar mica ages between 1600 and 2000 ma and some preliminary rb sr total rock ages at 1700 ma on nearby paragneisses whose u pb zircon age is 2500 ma

determining precambrian crustal evolution in china a case study from wutaishan shanxi province demonstrating the application of precise shrimp u pb geochronology

interrogation of the megathrust zone in the tohoku oki seismic region by waveform complexity intraslab earthquake rupture and reactivation of subducted normal faults results from the 2011 mw 9 1 tohoku oki megathrust earthquake display a complex rupture pattern with most of the high frequency energy radiated from the downdip edge of the seismogenic zone and very little from the large shallow rupture current seismic results of smaller earthquakes in this region are confusing due to disagreements among event catalogs on both the event locations 30 km horizontally and mechanisms here we present an in depth study of a series of intraslab earthquakes that occurred in a localized region near the downdip edge of the main shock we explore the validity of 1d velocity model and refine earthquake source parameters for selected key events by performing broadband waveform modeling combining regional networks these refined source parameters are then used to calibrate paths and further simulate secondary source properties such as rupture directivity and fault dimension calculation of stress changes caused by the main event indicate that the region where these intraslab events occurred are prone to thrust events this group of intraslab earthquakes suggest the reactivation of a subducted normal fault and are potentially useful in enhancing our understanding on the downdip shear zone and large outer rise events

two and three dimensional electrical resistivity imaging at a heterogeneous remediation site geometrically complex heterogeneities at a decommissioned sour gas plant could not be adequately characterized with drilling and 2d electrical resistivity surveys alone in addition 2d electrical resistivity imaging profiles produced misleading images as a result of out of plane resistivity anomalies and violation of the 2d assumption accurate amplitude and positioning of electrical conductivity anomalies associated with the subsurface geochemical distribution were required to effectively analyze remediation alternatives forward and inverse modeling and field examples demonstrated that 3d resistivity images were needed to properly reconstruct the amplitude and geometry of the complex resistivity anomalies problematic 3d artifacts in 2d images led to poor inversion fits and spurious conductivity values in the images at depths close to the horizontal offset of the off line anomaly three dimensional surveys were conducted with orthogonal sets of wenner and dipole dipole 2d resistivity survey lines the

osl dating and gpr mapping of palaeotsunami inundation a 4000 year history of indian ocean tsunamis as recorded in sri lanka to evaluate and mitigate tsunami hazard as long as possible records of inundations and dates of past events are needed coastal sediments deposited by tsunamis tsunamites can potentially provide this information however of the three key elements needed for reconstruction of palaeotsunamis identification of sediments dating and finding the inundation distance the latter remains the most difficult the existing methods for estimating the extent of a palaeotsunami inundation rely on extensive excavation which is not always possible here by analysing tsunamites from sri lanka identified using sedimentological and paleontological characteristics we show that their internal dielectric properties differ significantly from surrounding sediments the significant difference in the value of dielectric constant of the otherwise almost indistinguishable sediments is due to higher water content of tsunamites the contrasts were found to be sharp and not to erode over thousands of years they cause sizeable electromagnetic wave reflections from tsunamite sediments which permit the use of ground penetrating radar gpr to trace their extent and morphology in this study of the 2004 boxing day indian ocean tsunami we use gpr in two locations in sri lanka to trace four identified major palaeotsunami deposits for at least 400 m inland investigation inland was constrained by inaccessible security zones the subsurface extent of tsunamites not available without extensive excavation provides a good proxy for inundation the deposits were dated using the established method of optically stimulated luminescence osl this dating partly corroborated by available historical records and independent studies contributes to the global picture of tsunami hazard in the indian ocean the proposed method of combined gpr osl based reconstruction of palaeotsunami deposits enables estimates of inundation recurrence and therefore tsunami hazard for any sandy coast with identifiable tsunamite deposits the method could be also used for anchoring and synchronizing chronologies of ancient civilisations adjacent to the ocean shores

the wutaishan orogenic belt within the shanxi province northern china a record of late archaean collision tectonics abstract the archaean crust of northeastern shanxi province northern china is dominated by three distinct terranes the high grade gneiss terranes hengshan in the north and fuping in the southeast and the intervening low grade terrane of the wutaishan belt the 2 5 ga beitai arc complex which constitutes the major part of the wutaishan belt is interpreted as a pre collision magmatic arc there was a marginal sea basin between the beitai arc and the fuping terrane at the fore arc collision stage the passive margin deposits which occurred along the western margin of the fuping terrane became a foreland fold thrust belt after the closure of the marginal sea basin the remnants of sea floor occur as a melange zone along the suture zone between the beitai arc and fuping terrane nearly at the same time at 2 5 ga the back arc oceanic lithosphere started to subduct beneath the hengshan terrane then the hengshan terrane came into collision with the arc and the fuping terrane some dismembered sea floor rocks are preserved as a back arc melange zone between the hengshan terrane and the beitai arc the term wutaishan orogeny should be reserved for the processes which lasted from 2600 to 2450 ma

quantification of tsunami bathymetry effect on finite fault slip inversion the strong development of tsunami instrumentation in the past decade now provides observations of tsunami wave propagation in most ocean basins this evolution has led to the wide use of tsunami data to image the complexity of earthquake sources in particular the 2011 mw9 0 tohoku oki earthquake is the first mega event for which such a tsunami instrumentation network was available with an almost complete azimuthal coverage source inversion studies have taken advantage of these observations which add a lot of constrain on the solutions especially in the shallow part of the fault models where other standard data sets tend to lack resolution while on land data are quite insensitive to slip on the often distant shallow part of a subduction fault interface tsunami observations are directly sensitive to the shallowest slip and it is in this shallow portion that steep bathymetry combined with horizontal motion the so called bathymetry effect can contribute to the tsunami excitation in addition to the direct vertical sea bottom deformation in this study we carefully investigate the different steps involved in the calculation of this bathymetry effect from the initial sea floor deformation to the prediction of the tsunami records and evaluate its contribution across the main subduction zones of the world we find that the bathymetry effect locally exceeds 10 of the tsunami excitation in all subduction zones and 25 in those known to produce the largest tsunami either from mega or tsunami earthquakes we then show how the bathymetry effect can modify the tsunami wave predictions with time shifts of the wavefront and amplitudes sometimes varying by a factor of two if the bathymetry effect can have a strong impact on the simulated tsunami it will also affect the solution of the finite fault slip inversion we illustrate this later aspect in the case of the tohoku oki earthquake we find that not accounting for the bathymetry effect will not necessarily cause strong variations in the spatial extent of the inferred coseismic rupture but can severely distort the solution we also find that the bathymetry effect improves the consistency of the slip model inverted from tsunami data with seafloor geodesy observations implying that taking the bathymetry effect into account reduces the epistemic uncertainties on tsunami modeling implementing this easily quantifiable effect in the tsunami early warning system could thus lead to improved estimates of the tsunami impact across ocean basins

sedimentology of coastal deposits in the seychelles islands evidence of the indian ocean tsunami 2004 the seychelles an archipelago in the indian ocean at a distance of 4 500 5 000 km from the west coast of sumatra were severely affected by the december 26 2004 tsunami with wave heights up to 4 m since the tsunami history of small islands often remains unclear due to a young historical record it is important to study the geological traces of high energy events preserved along their coasts we conducted a survey of the impact of the 2004 indian ocean tsunami on the inner seychelles islands in detail we studied onshore tsunami deposits in the mangrove forest at old turtle pond in the curieuse marine national park on the east coast of curieuse island it is thus protected from anthropogenic interference towards the sea it was shielded until the tsunami in 2004 by a 500 m long and 1 5 m high causeway which was set up in 1909 as a sediment trap and assuring a low energetic hydrodynamic environment for the protection of the mangroves the causeway was destroyed by the 2004 indian ocean tsunami the tsunami caused a change of habitat by the sedimentation of sand lobes in the mangrove forest the dark organic rich mangrove soil 1 9 was covered by bimodal fine to medium carbonate sand 1 7 2 2 containing coarser carbonate shell fragments and debris intertidal sediments and the mangrove soil acted as sources of the lobe deposits the sand sheet deposited by the tsunami is organized into different lobes they extend landwards to different inundation distances as a function of the morphology of the onshore area the maximum extent of 180 m from the shoreline indicates the minimum inundation distance to the tsunami the top parts of the sand lobes cover the pneumatophores of the mangroves there is no landward fining trend along the sand lobes and normal grading of the deposits is rare occurring only in 1 of 7 sites the sand lobe deposits also lack sedimentary structures on the surface of the sand lobes numerous mostly fragmented shells of bivalves and molluscs were distributed up to 150 m from the coastline intact bivalve shells were mostly found positioned with the convex side upwards on small ledges of a granitic body at 130 150 m from the shore mostly fragmented and gravel sized shells were deposited at different elevations up to 4 m above sea level this implies a run up height of at least 4 m above sea level up to 150 m from the present shoreline

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

south american tsunamis in lyttelton harbor new zealand at 2347 utc on april 1 2014 12 47 pm april 2 2014 nzdt an earthquake with a moment magnitude of 8 2 occurred offshore of iquique in northern chile the temblor generated a tsunami that was observed locally and recorded on tide gauges and deep ocean tsunameters close to the source region while real time modeling based on inverted tsunameter data and finite fault solutions of the earthquake rupture suggested that a damaging far field tsunami was not expected and later confirmed this event nevertheless reminded us of the threat posed to new zealand by tsunami generated along the west coast of south america and from the peru chile border region in particular in this paper we quantitatively assess the tsunami hazard at lyttelton harbor from south american tsunamis through a review of historical accounts numerical modeling of past events and analysis of water level records a sensitivity study for tsunamis generated along the length of the south american subduction zone is used to illustrate which section of the subduction zone would generate the strongest response at lyttelton while deterministic scenario modeling of significant historical south american tsunamis i e 1868 1877 and 1960 provide a quantitative estimate of the expected effects from possible future great earthquakes along the coast of south america

accretion of japanese island arcs and implications for the origin of archean greenstone belts the present day region of arc arc collision between the izu bonin arc and mainland japan honshu arc in the western pacific called the izu collision zone or icz provides a useful kinematic model for the development of many archean greenstone belts the compositional assemblage thermal structure and structural style of the crust in the icz are very similar to those inferred for many archean greenstone belts in both cases thick young and flaky arc crust with a high heat flux is in collision with another crustal block the icz has resulted in the imbrication of very thick slices of crust and associated sediments juxtaposed against older accretionary prisms many archean greenstone belts show similar geological features and we suggest that the incremental imbrication of the crust was a common tectonic style in some archean convergent margins

tsunami impact computed from offshore modeling and coastal amplification laws insights from the 2004 indian ocean tsunami the 2004 indian ocean tsunami gave the opportunity to gather unprecedented tsunami observation databases for various coastlines we present here an analysis of such databases gathered for 3 coastlines among the most impacted in 2004 in the intermediate and far field thailand myanmar se india sri lanka and se madagascar non linear shallow water tsunami modeling performed on a single 4 coarse bathymetric grid is compared to these observations in order to check to which extent a simple approach based on the usual energy conservation laws either green s or synolakis laws can explain the data the idea is to fit tsunami data with numerical modeling carried out without any refined coastal bathymetry topography to this end several parameters are discussed namely the bathymetric depth to which model results must be extrapolated using the green s law or the mean bathymetric slope to consider near the studied coast when using the synolakis law using extrapolation depths from 1 to 10 m generally allows a good fit however a 0 1 m is required for some others especially in the far field madagascar possibly due to enhanced numerical dispersion such a method also allows describing the tsunami impact variability along a given coastline then using a series of scenarios we propose a preliminary statistical assessment of tsunami impact for a given earthquake magnitude along the indonesian subduction conversely the sources mostly contributing to a specific hazard can also be mapped onto the sources providing a first order definition of which sources are threatening the 3 studied coastlines

deformation history of the hengshan complex implications for the tectonic evolution of the trans north china orogen structural analysis indicates that the hengshan complex underwent five distinct episodes of deformation d1 d5 the d1 episode formed small isoclinal folds f1 penetrative axial planar foliations s1 and mineral stretching lineations l1 d1 fabrics were reworked by following d2 deformation associated with d2 was the development of nw verging asymmetric folds and accompanying thrust faults both d1 and d2 resulted from crustal thickening and coherent with prograde and peak metamorphism d2 deformation was followed by transpressional dextral shearing d3 including top to nw oblique slip shearing and nne ssw dextral strike slip shearing ongoing collision led to development of the zhujiafang ductile shear zone d4 a near e w trending high strain belt across the hengshan complex d5 deformation is characterized by f5 open folds and associated normal faults probably related to exhumation of the complex structural patterns of the hengshan complex can place important insights into a recently proposed tectonic model suggesting that an ocean between the eastern and western blocks underwent eastward directed subduction beneath the western margin of the eastern block and closure of this ocean finally led to collision between the two blocks to form the coherent north china craton

nd isotopic and geochemical constraints on the provenance and tectonic setting of the low grade meta sedimentary rocks from the trans north china orogen north china craton abstract in the trans north china orogen tnco of the north china craton low grade supracrustal successions extensively occur in the wutai luliang zanhuang zhongtiao and dengfeng complexes from north to south meta sedimentary samples from the wutai and zhongtiao complexes were collected for geochemical and nd isotopic studies and several samples from the zanhuang and dengfeng complexes were also analyzed for nd isotopic studies for comparative purpose most of the meta siltstones and meta sandstones from the wutai and zhongtiao complexes are characterized by depletions in mobile elements like cao sr and na2o high chemical index of weathering ciw values and strong positive correlation between al2o3 and tio2 indicating intense weathering conditions significant post depositional k metasomatism is indicated in the a cn k diagrams for most of the analyzed samples and the relatively high pre metasomatized chemical index of alteration cia values 43 87 also imply a high degree of source weathering depleted transitional trace elements ni cr co and sc fractionated light rare earth elements patterns mild negative eu anomalies in the majority of these meta sedimentary samples point toward felsic source rocks including the 2 5 ga granitics ttg gneisses and the paleoproterozoic granitics in the tnco minor contribution from mafic rocks is evidenced from relative high contents of mgo fe 2 o 3 t sc and lower la ybn ratios in some older sequence set samples from the zhongtiao complex our geochemical and nd isotopic data combined with previous studies in the lithostratigraphic sequence provenance and depositional age suggest that the older and younger sequence sets of the low grade supracrustal successions in the tnco were deposited in the different depositional environments the older sequence set was deposited in a back arc basin between the andean type continental margin arc and the eastern block after 2 1 ga whereas the younger sequence set formed in a foreland basin between 1 88 and 1 80 ga which is consistent with the model that the collision between the eastern and western blocks to form the trans north china orogen occurred at 1 85 ga

investigation of tsunami hydrodynamic parameters in inundation zones with different structural layouts in this study we analyze the tsunami parameter hydrodynamic demand hd using advanced numerical modeling the hd can be defined as the square of the froude number which represents the relative value of the drag force damage level of tsunami waves in the inundation zone the other key hydrodynamic parameters investigated in this study include maximum flow depth inundation depth maximum current velocity and its direction and maximum water elevation and discharge flux occurring during tsunami inundation the analyses are performed on regular shaped basins with various orientations and distribution of coastal and land structures in order to provide comparisons of the results in a number of different case studies we also provide information for defining damage levels in residential areas and for testing the performance of coastal protection structures

late archaean terrane accretion in the godthab region southern west greenland tectono stratigraphic terranes fault bounded blocks of the earth s crust characterized by a geological history distinct from that of adjacent terranes1 are now widely recognized in phanerozoic and proterozoic orogenic belts and their present configurations are thought to result from plate tectonic processes similar to those in operation today2 4 there has been much debate about whether such processes operated in archaean times5 6 here we present new data from the archaean high grade gneiss complex of the godthab now nuuk region of southern west greenland which show that discrete tectonic units recognized in the south of the region7 can be more widely identified at least four terranes are recognized each of which evolved separately until their juxtaposition in the late archaean this suggests that at least some archaean high grade gneiss complexes may resemble more recent orogenic belts formed by plate tectonic processes

precambrian tectonic evolution of part of gondwana southwestern australia southwestern australia has a long dynamic precambrian history of crustal fragmentation and aggregation by continental collision and accretion this interpretation contrasts with the widely held belief that most of australia was part of a proterozoic supercontinent in which all tectonic magmatic and metamorphic activity was intracontinental the pilbara and yilgarn cratons are two quite different fragments of archean continental crust that collided to form the capricorn orogen between 2000 and 1600 ma the albany fraser orogen formed along the southern margin of the yilgarn craton during another major continental collision at 1300 to 1100 ma rifting removed the northeastern part of these combined cratons and orogens between 1100 and 700 ma subsequent continental collision along this rifted margin formed the paterson orogen at 700 to 600 ma therefore the assembly of this considerable part of gondwana may not have been completed until about 600 ma

tsunami simulation using sources inferred from various measurement data implications for the model forecast model forecast applications use various models of tsunami sources inferred from different measurement data even the same type of observation data can produce substantially different tsunami source models during a real time forecast when more data are obtained during the real time analysis improved tsunami observations enable investigation of the influence of such model source variability on the final forecast using different source data sets of several events the 2010 maule chile and 2011 tohoku japan tsunamis were two recent events that provide ample observations throughout the pacific and were thus used here to study the sensitivity of different model inputs for forecasting the sources for these events were derived using the following three different methods 1 real time or post event inversion of tsunameter water level data 2 prediction of sea floor deformations via analysis of seismic wave forms and application of a finite fault model and 3 prediction of sea floor deformation using real time gps data for the march 11 2011 tohoku tsunami two examples of each method are used while for the february 27 2010 maule event only one tsunameter inversion and one finite fault model method were used due to a much more limited data set observed data from the deep ocean assessment and reporting for tsunamis dart network japan gps buoys and select tide gauges across the pacific were compared with forecasts to assess the sensitivity of these three methods using root mean square error analysis we divided the analysis by the type of data and the distance from the source this sensitivity analysis showed that increasing the resolution of a tsunami source model does not necessarily improve tsunami forecast quality even in the near field instead the findings suggest that when forecasting coastal impact defining the overall energy characteristic of a tsunami source may be more important than refining small source details source models based on direct tsunami observations are better at reproducing a tsunami signal this finding is not very surprising but has implications for tsunami forecasting and warning operations

tsunami generation above a sill the generation of surface waves by seafloor displacement is a classic problem that arises in the study of tsunamis the generation of waves in a two dimensional domain of uniform depth by uplift or subsidence of a portion of a flat bottom boundary has been elegantly studied by hammack tsunamis a model of their generation and propagation ph d thesis california institute of technology 1972 for idealized motions the physical problem of tsunami generation is more complex even when the final displacement is known from seismic analysis the deforming seafloor includes relief features such as mounts and trenches here following kajiura j oceanogr soc jpn 28 260 277 1972 we investigate analytically the effect of bathymetry on the surface wave generation by solving the forced linear shallow water equation while kajiura s geometry consisted of a step type bottom bathymetry with a rectangular uplift to understand the effect of the continental shelf on tsunami generation our model bathymetry consists of an uplifting cylindrical sill initially resting on a flat bottom a geometry which helps evaluate the effect of seamounts on tsunami generation we find that as the sill height increases partial wave trapping reduces the wave height in the far field while amplifying it above the sill

parallel implementation of dispersive tsunami wave modeling with a nesting algorithm for the 2011 tohoku tsunami because of improvements in offshore tsunami observation technology dispersion phenomena during tsunami propagation have often been observed in recent tsunamis for example the 2004 indian ocean and 2011 tohoku tsunamis the dispersive propagation of tsunamis can be simulated by use of the boussinesq model but the model demands many computational resources however rapid progress has been made in parallel computing technology in this study we investigated a parallelized approach for dispersive tsunami wave modeling our new parallel software solves the nonlinear boussinesq dispersive equations in spherical coordinates a variable nested algorithm was used to increase spatial resolution in the target region the software can also be used to predict tsunami inundation on land we used the dispersive tsunami model to simulate the 2011 tohoku earthquake on the supercomputer k good agreement was apparent between the dispersive wave model results and the tsunami waveforms observed offshore the finest bathymetric grid interval was 2 9 arcsec approx 5 m along longitude and latitude lines use of this grid simulated tsunami soliton fission near the sendai coast incorporating the three dimensional shape of buildings and structures led to improved modeling of tsunami inundation

case study a 3d resistivity and induced polarization imaging from downstream a waste disposal site in brazil a contaminated site from a downstream municipal solid waste disposal site in brazil was investigated by using a 3d resistivity and induced polarization ip imaging technique this investigation purpose was to detect and delineate contamination plume produced by wastes the area was selected based on previous geophysical investigations and chemical analyses carried out in the site indicating the presence of a contamination plume in the area resistivity model has successfully imaged waste presence 31 mv v water table depth and groundwater flow direction a higher chargeability zone m 31 mv v outside wastes placement and following conductive anomaly was interpreted as a contamination plume normalized chargeability mn m confirmed polarizable zone which could be an effect of a salinity increase contamination plume and the clay presence in the environment

new tsunami forecast tools for the french polynesia tsunami warning system part ii numerical modelling and tsunami height estimation tsunami warning is classically based on two fundamental tools the first one concerns the source parameters estimations and the second one is the tsunami amplitude forecast we presented in the first companion paper how the seismic source parameters are evaluated and this second article describes the operational aspect and accuracy of the estimation of tsunami height using tsunami numerical modelling on a dedicated supercomputer 2 5 t flops the french polynesian tsunami warning centre developed two new tsunami forecast tools for a tsunami warning context based on our tsunami propagation numerical model named taitoko the first tool named merit that is very rapid provides a preliminary forecast distribution of the tsunami amplitude for 30 sites located in french polynesia in less than 5 min in this case the coastal tsunami height distribution is calculated from the numerical simulation of the tsunami amplitude in deep ocean using an empirical transfer function inspired by the green law this method which does not take into account resonance effects of bays and harbour is suitable for rapid and first estimation of the tsunami danger the second method named coaster which uses 21 nested grids of increasing resolutions gives more information about the coastal tsunami effects about the flow velocities the arrival time of the maximal amplitude and the maximal run up height for five representative sites in 45 min the historical tsunamis recorded over the last 22 years in french polynesia have been simulated with these new tools to evaluate the accuracy of these methods the results of the 23 historical tsunami simulations have been compared to the tide gauge records of three sites in french polynesia the results which are quite encouraging shows standard errors of generally less than a 2 factor the maximal standard error is 0 38 m for the tahauku bay of hiva oa marquesas islands

rb sr and sm nd isotopic dating of an early precambrian spilite keratophyre sequence in the wutaishan area north china preliminary evidence for nd isotopic homogenization in the mafic and felsic lavas during low grade metamorphism the spilite keratophyre sequence in the wutaishan area north china has been dated by zircon from the quartzkeratophyre and a volcanic crystallization age of 2522 ma liu dunyi et al 1985 was obtained this volcanic rock sequence experienced a low grade metamorphism of greenschist facies during 1800 2000 ma however combined sm nd whole rock data from the volcanic rock sequence if interpreted in terms of an isochron gives a younger age of 2250 182 ma if separately calculated sm nd isochrons for quartz keratophyre and spilite yield two consistently younger ages of 1977 385 ma and 1981 178 ma these sm nd isochron ages are consistent with a rb sr age of 1871 98 ma and with the time of regional greenschist facies metamorphism consequently we interpret the 2250 ma alignment on the sm nd diagram as an errorchron the two sm nd metamorphic ages suggest that partial homogenization of nd isotopic composition in water rich spilite keratophyric meta volcanics can be achieved during low grade metamorphism as a result of ree mobility using the nd values at the time of metamorphism and the average 147sm 144nd ratios of the spilite and the quartzkeratophyre initial nd values of 2 6 3 5 and 3 0 6 1 respectively are estimated at the time of volcanic eruption 2522 ma similar positive initial nd values for the spilites and quartz keratophyres suggest that they might have been derived from the same depleted mantle source or that the quartz keratophyres are derived from a short lived mafic source

estimation of extreme sea levels for the russian coasts of the kuril islands and the sea of okhotsk extreme sea levels arising from the combination of tides storm surges seasonal oscillations and tsunamis were estimated by the joint probability method for the coast of the sea of okhotsk and the pacific coast of the kuril islands the sea level observations at 10 coastal tide gauges were examined the tidal heights at most stations are about 1 5 2 m and only at magadan are they much larger about 5 m storm surges have the largest heights for the central kuril islands matua and iturup islands while at the north and south kuril islands the surge heights are the smallest the recurrence of tsunami heights of various probabilities was estimated for each station the influence of tides and storm surges on the tsunami risk assessment for the pacific coast of the kurile islands was found to be relatively small for the coast of the sea of okhotsk the contribution of tides and surges is the primary influence especially for return periods less than 100 years for longer return periods tsunamis play the major role in forming the extreme levels similar to the russian coast of the sea of japan e g rabinovich et al 1992

shrimp u pb zircon ages of the fuping complex implications for late archean to paleoproterozoic accretion and assembly of the north china craton the fuping complex is situated in the central part of the north china craton and consists of four major lithological assemblages fuping tonalitic trondhjemitic granodioritic gneisses longquanguan augen gneisses wanzi supracrustal assemblage and nanying granitic gneisses shrimp u pb geochronology combined with u th and cathodoluminescence cl imaging of zircon enables resolution of magmatic and metamorphic events that can be directed towards understanding the late archean to paleoproterozoic history of the fuping complex cl images reveal the coexistence of magmatic and metamorphic zircons in nearly all rock types of the fuping complex the metamorphic zircons occur as either single grains or overgrowth or recrystallization rims surrounding and truncating oscillatory zoned magmatic zircon cores and are all characterized by nebulous zoning or being structureless with extremely high luminescence and very low th contents these features make them distinct from magmatic zircons that are characterized by concentric oscillatory zoning comparatively low luminescence and high th and u contents shrimp u pb analyses on magmatic zircons reveal that the tonalitic trondhjemitic and granodioritic plutons of the fuping gneisses were emplaced at 2523 14 ma 2499 10 ma and 2486 8 ma respectively whereas the monzogranitic and granitic plutons of the longquanguan augen gneisses were intruded respectively at 2510 22 ma and 2507 11 ma prismatic and oscillatory zoned zircons dominate in the pelitic rocks of the wanzi supracrustal assemblage and are interpreted as detritus from igneous source rocks the concordant and discordant u pb ages of 2502 5 ma and 2507 14 ma obtained from two pelitic rock samples indicate these rocks must have been deposited no earlier than 2507 ma ago in addition a zoned zircon grain in one pelitic rock sample has a near concordant age of 2109 5 1 ma which may provide a maximum depositional age for the wanzi supracrustal rocks shrimp results also reveal that granitic magmatism assigned to the nanying granitic gneisses occurred over a protracted interval from 2077 13 ma to 2024 21 ma the nebulously zoned zircon grains and overgrowth recrystallization zircon rims from different rocks yielded similar concordant 207pb 206pb ages in the range 1875 to 1802 ma interpreted as approximating the age of regional metamorphism of the fuping complex timing of primary zircon crystallization and regional metamorphism of the fuping complex is in general agreement with recent u pb zircon ion probe results for the wutai and hengshan complexes that bound the fuping complex to the northwest these areas are characterized by the emplacement of major granitoid bodies at around 2 50 ga to 2 48 ga ago deposition of supracrustal rocks in the paleoproterozoic intrusion of paleoproterozoic granitic bodies at 2 1 to 2 0 ga and regional metamorphism at 1 875 to 1 802 ga these data indicate that the fuping and hengshan complexes do not represent an older crystalline basement to the wutai complex as suggested in previous tectonic models but together with the wutai complex represent elements of a single late archean to paleoproterozoic magmatic arc system that has been subsequently tectonically disrupted and juxtaposed during the collision of the eastern and western north china blocks at 1 85 ga which resulted in the final assembly of the north china craton

tsunami squares approach to landslide generated waves application to gongjiafang landslide three gorges reservoir china we have developed a new method named tsunami squares for modeling of landslides and landslide generated waves the approach has the advantages of the previous tsunami ball method for example separate special treatment for dry and wet cells is not needed but obviates the use of millions of individual particles simulations now can be expanded to spatial scales not previously possible the new method accelerates and transports squares of material that are fractured into new squares in such a way as to conserve volume and linear momentum the simulation first generates landslide motion as constrained by direct observation it then computes induced water waves given assumptions about energy and momentum transfer we demonstrated and validated the tsunami squares method by modeling the 2008 three gorges reservoir gongjiafang landslide and river tsunami the landslide s progressive failure the wave generated and its subsequent propagation and run up are well reproduced on a laptop computer tsunami square simulations flexibly handle a wide variety of waves and flows and are excellent techniques for risk estimation

3d behaviour of contamination in landfill sites using 2d resistivity ip imaging case studies in portugal aiming at defining a valid spatial contamination model resistivity and induced polarization ip measurements were used to investigate contamination plumes in the vicinity of two municipal landfills ovar and ilhavo previous geophysical surveys and underground water samples confirmed the contamination however 2d resistivity ip surveys enabled in obtaining a more accurate spatial model the ovar survey consisted of two profiles with nine wenner soundings each the ilhavo survey was carried out along two individual lines using a wenner standard pseudo section in both situations negative ip values were found associated with positive ip values which can be explained mainly by 2d or 3d geometric effects caused by the presence of the conductive plumes the data were modelled using a 2d inversion program res2dinv and the resulting resistivity and chargeability distributions were displayed as pseudo sections the resistivity and chargeability pseudo sections define the contamination plumes and the sedimentary structure these case studies illustrate the advantages of 2d resistivity ip surveys for the mapping of shape and dimension of contamination associated with landfills

geochemical changes in baslts and andesites across the archean proterozoic boundary identification and significance abstract to identify accurately changes in rock composition across the archean proterozoic boundary it is necessary to compare rocks from similar lithologic associations to constrain the effect of tectonic setting most basalts and andesites from the greenstone association volcanic dominated submarine supracrustal rocks possess a geochemical subduction zone component similar to their counterparts from modern arc systems basalts with island arc geochemical affinities dominate in archean greenstones while those with calc alkaline affinities are most abundant in proterozoic greenstones basalts with morb or oceanic within plate geochemical characteristics are rare in precambrian greenstones of all ages preserved early archean greenstone basalts 3500 ma reflect mantle sources less depleted than late archean greenstone basalts 2500 3500 ma proterozoic greenstone basalts are derived from relatively enriched mantle sources compared to all archean sources a feature which may be due to recycling of continental sediments into the mantle following rapid late archean continental growth precambrian andesites are geochemically similar to andesites from modern arcs but archean andesites are unique in that they are depleted in heavy ree and y results are consistent with archean andesite production by partial melting of descending mafic crust with amphibole garnet remaining in the residue while proterozoic and younger andesites are produced by fractional crystallization of basalts

characterization of active and closed landfill sites using 2d resistivity ip imaging case studies in penang malaysia an interpretation approach for analysis of electrical resistivity and chargeability inverse models generated at two upgraded semi aerobic landfill sites was developed the inverse models produced from a 2d inversion program res2dinv were used to set up a grid of electrical resistivity and chargeability imaging at the landfill sites the investigations confirmed a high chargeability unit 70 ms depicting waste deposits and a saturated clayey layer while the leachate plume showed low resistivity 10 m and weak chargeability zone 20 ms moreover the ip responses of a diffused leachate plume downstream of a separate semi aerobic landfill site in a similar geological setting were evaluated obtaining an analogous result the ion dominated plume that exhibited a weak chargeability promoted membrane polarization rather than electrode polarization in its ip responses however the high concentration of ions in the diffused leachate restrained the ionic polarization diminishing the ip effects in host sediments the interpretation of the resistivity and chargeability profiles at the characterization sites allowed delineating the different zones of the subsurface strata in particular comparison of the leachate zones at the two locations revealed that the active landfill with a lesser proportion of waste deposits contained a greater accumulation of leachate than the closed site the results in this study support the effectiveness of contaminant plume monitoring through the joint application of resistivity and ip methods these non invasive rapid and cost effective geophysical techniques could lead to a promising reconnaissance tool for remediation or reclamation of solid waste disposal sites

archean geodynamics in the central zone north china craton constraints from geochemistry of two contrasting series of granitoids in the fuping and wutai complexes abstract the archean to paleoproterozoic central zone of the north china craton is situated between the eastern and western archean continental blocks and contains two contrasting series of neoarchean granitoids the 2523 2486 ma tonalite trondhjemite granodiorite ttg gneisses in the fuping complex and the 2555 2525 ma calc alkaline granitoids tonalite granodiorite granite and monzogranite in the wutai complex the fuping ttg gneisses most likely formed from partial melting of 2 7 ga basalts at 50 km with an involvement of 3 0 ga crustal material the wutai granitoids have higher k 2 o lile and rb sr but lower sr y and la n yb n than the fuping ttg gneisses are characterized by nd t dm from 2 5 to 2 8 ga and e nd t from 0 49 to 3 34 and are derived from partial melting of a juvenile source at the geochemistry of these two contrasting series of neoarchean granitoids provides further evidence that the wutai complex originated and evolved separately from the fuping complex the wutai complex most likely formed as an oceanic island arc with volcanism and synvolcanic granitoid intrusions at 2555 2525 ma the wutai complex was subsequently accreted onto the eastern archean continental block and was probably responsible for crustal thickening and ttg magmatism at 2523 2486 ma in the fuping complex as part of the taihangshan hengshan block at the western margin of the eastern archean continental block

traveltime delay and initial phase reversal of distant tsunamis coupled with the self gravitating elastic earth systematic tsunami traveltime delays of up to 15 min relative to the numerically simulated long waves from the 2010 chilean and 2011 tohoku oki earthquakes were widely observed at deep ocean tsunamimeters enigmatic small negative phases appearing before the main peak were commonly found only at the trans oceanic locations the frequency dependence of the measured tsunami phase velocities shows reverse dispersions at long periods i e the tsunami speed becomes slower at periods beyond 1000 s this is consistent with the phase velocities of a tsunami mode coupled with a self gravitating elastic earth suggesting that the effects of compression and dilatation of seawater elastic tsunami loadings on a solid earth and the geopotential variations associated with the motion of mass during tsunami propagation are responsible for the traveltime delays and the initial negative phases simple 1 d tsunami propagation tests confirm that the reverse dispersion creates a small negative phase that precedes the main peak at large distances a new method to simulate tsunami waveforms on real ocean bathymetry that takes into account seawater compressibility the elasticity of the earth and geopotential perturbations has been developed by applying a phase correction to the simulated long waves the simulated waveforms in which phase corrections are applied for the dispersion effects accurately reproduce the observed waveforms including a small initial negative phase that appears at distant locations the traveltime difference between the observed and simulated waveforms has been decreased to less than 5 min and the waveform difference between them remarkably diminishes

a late archean foreland fold and thrust belt in the north china craton implications for early collisional tectonics abstract the archean north china craton is divided into the western and eastern blocks along the central orogenic belt a 1600 km long archean foreland basin and thrust belt fringes the eastern side of the central orogenic belt rocks in the orogen form tectonically stacked east vergent fold and thrust sheets including foreland basin sediments 2 50 ga ophiolitic melange and an island arc complex foreland basin sediments overlie a passive margin sequence and include a 2 50 ga deep water turbidite sequence that grades upward and westward into shallow water molasse now disposed in structurally imbricated east verging thrusts and asymmetric folds that gradually migrated craton ward with deformation uplift and erosion of the orogen there is a strong linked relationship of the formation of the foreland basin to collision of the east and west blocks of the north china craton along the central orogenic belt at 2 50 ga the qinglong foreland basin and central orogenic belt of the north china craton represents one of the best preserved archean orogen to craton transitions in the world its classic internal to external zonation and flexural response to loading demonstrate that convergent tectonics in the archean were broadly similar to phanerozoic convergent margin processes

formation of an archaean continent about 30 of the earth is covered by continents but only about 10 small kernels of these continentsae known as archaean cratonsae are continental fragments formed before 2 5 gyr ago the kaapvaal craton of south africa which formed and stabilized between 3 7 and 2 7 gyr ago is one of the oldest reasonably sized examples of these continental fragments it consists of a mosaic of subdomains that have been welded together by processes similar to those of modern day plate tectonics the earliest subdomains may have owed their origin to the onset of efficient recycling from the earth s hydrosphere into the mantle

far field tsunami impact in the north atlantic basin from large scale flank collapses of the cumbre vieja volcano la palma in their pioneering work ward and day suggested that a large scale flank collapse of the cumbre vieja volcano cvv on la palma canary islands could trigger a mega tsunami throughout the north atlantic ocean basin causing major coastal impact in the far field while more recent studies indicate that near field waves from such a collapse would be more moderate than originally predicted by ward and day lovholt et al j geophy res 113 c09026 2008 abadie et al j geophy res 117 c05030 2012 these would still be formidable and devastate the canary island while causing major impact in the far field at many locations along the western european african and the us east coasts abadie et al j geophy res 117 c05030 2012 simulated tsunami generation and near field tsunami impact from a few cvv subaerial slide scenarios with volumes ranging from 20 to 450 km 3 the latter representing the most extreme scenario proposed by ward and day they modeled tsunami generation i e the tsunami source using thetis a 3d navier stokes ns multi fluid vof model in which slide material was considered as a nearly inviscid heavy fluid near field tsunami impact was then simulated for each source using funwave tvd a dispersive and fully nonlinear long wave boussinesq model shi et al ocean modell 43 44 36 51 2012 kirby et al ocean modeling 62 39 55 2013 here using funwave tvd for a series of nested grids of increasingly fine resolution we model and analyze far field tsunami impact from two of abadie et al s extreme cvv flank collapse scenarios i that deemed the most credible worst case scenario based on a slope stability analysis with a 80 km 3 volume and ii the most extreme scenario similar to ward and day s with a 450 km 3 volume simulations are performed using a one way coupling scheme in between two given levels of nested grids based on the simulation results the overall tsunami impact is first assessed in terms of maximum surface elevation computed along the western european and african and us east coasts usec strong wave elevation decay is predicted over the wide usec shelf which is shown to be essentially due to bottom friction effects we then show more detailed results for the usec which is the object of high resolution tsunami inundation mapping under the auspices of the us national tsunami hazard mitigation program in this context we compare the maximum surface elevation predicted along the coastline for each cvv scenario and show that besides the initial directionality of the sources coastal impact is mostly controlled by focusing defocusing effects resulting from the shelf bathymetric features a simplified ray tracing analysis confirms this controlling effect of the wide usec shelf for incident long waves finally we perform high resolution 10 m inundation mapping for the most extreme cvv scenario and show results at one of the most vulnerable and exposed communities in the mid atlantic us states in and around ocean city maryland such maps are being generated for all exposed areas of the usec to be used in tsunami hazard assessment and mitigation work

a 3 d resistivity investigation of a contaminated site at lernacken sweden a contaminated site at lernacken in southern sweden formerly used for sludge disposal was investigated using a 3 d resistivity imaging technique the data acquisition was carried out using a roll along technique for 3 d data acquisition that allows using standard multielectrode equipment designed for engineering and environmental applications the technique allows for the measurement of large true 3 d resistivity data sets and data were measured using two perpendicular electrode orientation directions with only one layout of the cables the data were plotted as two sets of pseudo depth slices using the two electrode orientation directions which resulted in markedly different plots the complete data set was inverted to form a resistivity depth model of the ground using a 3 d least squares smoothness constrained inversion technique the results obtained were compared to other geophysical and background data and a good agreement was found the results show that the 3 d roll along technique in combination with 3 d inversion can be highly useful for engineering and environmental applications however multichannel measurement equipment is necessary to speed up the data acquisition process for routine application

tsunami observations in rivers from a perspective of tsunami interaction with tide and riverine flow the observations of the 2011 tohoku tsunami and the 2010 chilean tsunami in several rivers in japan and in the columbia river in the usa are analyzed for patterns of tsunami behavior in river environments tsunamis in rivers exhibit actions very different from those observed on an open coast but very similar among different rivers though the action scale in different rivers varies greatly we describe two tsunami effects in rivers as observed in field data first the river tide modulates the tsunami wave in a very specific way common to all rivers second a strong near field tsunami can cause significant prolonged water accumulation in lower river reaches both effects are inherent in tidal river environments and have been reproduced numerically in a simplified 1 d river using a non linear shallow water model with bottom friction the numerical experiments highlight the indispensable role of a tsunami s interaction with tide and riverine flow

assessment of groundwater contamination around active dumpsite in ibadan southwestern nigeria using integrated electrical resistivity and hydrochemical methods investigation of groundwater contamination due to leachate migration in a solid waste disposal site was done using both geophysical and hydrochemical methods the main goals were to delineate groundwater contamination due to leachate percolation and thus assessment of quality of groundwater from nearby hand dug wells bordering the dumpsite for drinking purpose a total of ten resistivity traverses were acquired within and outside the dumpsite using wenner configuration with constant electrode separation ranging from 5 to 25 m the 2d resistivity data were processed and inverted using res2dinv and res3dinv softwares respectively geochemical assessment of groundwater samples were carried out according to apha standards while hydrochemical facies of the sampled groundwater was evaluated using piper trilinear software the inverse resistivity models of the subsurface from 2d and 3d imaging revealed low resistivity value less than 10 m suspected to be leachate while 3d inverse sections allowed delineation of leachate weathered layer bedrock and seepage path from the dumpsite the extent of migration was more pronounced in the southern part of the dumpsite hence possible contamination of shallow groundwater system as dumpsite ages the results of physico chemical analyses showed the groundwater samples to be within the limits of who nsdwq for drinking purpose however higher values of concentrations of most analyzed parameters were noticed in well 1 due to its nearness to dumpsite and well 10 due to agricultural activities respectively interpretation of piper diagram showed cahco3 to be dominant facie in the area while alkaline earth metals text ca 2 text mg 2 and weak acids hco3 co3 are dominant cations and anions during both climatic seasons groundwater in the study area is of hard fresh and alkaline in nature

evaluation of the relationship between coral damage and tsunami dynamics case study 2009 samoa tsunami on september 29 2009 an mw 8 1 earthquake at 17 48 utc in tonga trench generated a tsunami that caused heavy damage across samoa american samoa and tonga islands tutuila island which is located 250 km from the earthquake epicenter experienced tsunami flooding and strong currents on the north and east coasts causing 34 fatalities out of 192 total deaths from this tsunami and widespread structural and ecological damage the surrounding coral reefs also suffered heavy damage the damage was formally evaluated based on detailed surveys before and immediately after the tsunami this setting thus provides a unique opportunity to evaluate the relationship between tsunami dynamics and coral damage in this study estimates of the maximum wave amplitudes and coastal inundation of the tsunami are obtained with the most model titov and synolakis j waterway port coast ocean eng pp 171 1998 titov and gonzalez noaa tech memo erl pmel 112 11 1997 which is now the operational tsunami forecast tool used by the national oceanic and atmospheric administration noaa the earthquake source function was constrained using the real time deep ocean tsunami data from three dart deep ocean assessment and reporting for tsunamis systems in the far field and by tide gauge observations in the near field we compare the simulated run up with observations to evaluate the simulation performance we present an overall synthesis of the tide gauge data survey results of the run up inundation measurements and the datasets of coral damage around the island these data are used to assess the overall accuracy of the model run up prediction for tutuila and to evaluate the model accuracy over the coral reef environment during the tsunami event our primary findings are that 1 most simulated run up correlates well with observed run up for this event r 0 8 it tends to underestimated amplitudes over coral reef environment around tutuila for 15 of 31 villages run up is underestimated by more than 10 in only 5 was run up overestimated by more than 10 and 2 the locations where the model underestimates run up also tend to have experienced heavy or very heavy coral damage 8 of the 15 villages whereas well estimated run up locations characteristically experience low or very low damage 7 of 11 villages these findings imply that a numerical model may overestimate the energy loss of the tsunami waves during their interaction with the coral reef we plan future studies to quantify this energy loss and to explore what improvements can be made in simulations of tsunami run up when simulating coastal environments with fringing coral reefs

resistivity and induced polarization monitoring of salt transport under natural hydraulic gradients we demonstrate the use of resistivity induced polarization ip monitoring of salt transport under natural hydraulic loads electrical monitoring of saline tracer transport during forced injection has been demonstrated previously detection of tracer transport under natural hydraulic loading is difficult because neither the hydraulic load nor the tracer resistivity can be controlled in one study we identify the electrical response to salt transport in a dynamic beach environment resistivity ip imaging resolved the structure of the saltwater freshwater interface and evidence for tide induced groundwater transport resistivity increases in the near surface and at depth upbeach of the high tide mark accompanied by tidal transgression we attribute this to desaturation and decreasing salinity in the near surface and to decreasing salinity at depth despite tidal transgression monitoring of groundwater levels indicates a phase lag between the tide level and groundwater level supporting the electrical da

nd isotopic constraints on crustal formation in the north china craton abstract recent tectonic analysis suggests that the north china craton consists of two archean continental blocks called the eastern and western blocks separated by the paleoproterozoic trans north china orogen although the published geochronological data are not sufficient to constrain the detailed tectonothermal evolution of the craton the available nd isotopic data show some important differences in nd model ages between the tectonic units the eastern block shows two main nd model age peaks one between 3 6 and 3 2 ga and the other between 3 0 and 2 6 ga limited nd isotopic data from the western block show a large range of model ages between 3 2 and 2 4 ga these differences are consistent with the recently proposed model the nd isotopic data from mantle derived mafic rocks indicate that the mantle beneath the north china craton was depleted in the archean consistent with major crustal growth during this period in the paleoproterozoic however the mantle derived mafic rocks show negative end t values implying crustal contamination this may have resulted from subduction and collision between the eastern and western block implying that the mechanisms of crustal formation and evolution may have been different between the archean and paleoproterozoic the north china craton was re activated by addition of mantle derived magma into the lower crust in the late mesozoic resulting in rejuvenation of the lower crust this indicates that underplating is also an important mechanism for continental addition although in this case it may not equate to crustal growth since it was preceded by removal of lithospheric mantle and possible some lower crust

the tsunami phenomenon abstract with human activity increasingly concentrating on coasts tsunamis from japanese tsu harbour nami wave are a major natural hazard to today s society stimulated by disastrous tsunami impacts in recent years for instance in south east asia 2004 or in japan 2011 tsunami science has significantly flourished which has brought great advances in hazard assessment and mitigation plans based on tsunami research of the last decades this paper provides a thorough treatise on the tsunami phenomenon from a geoscientific point of view starting with the wave features tsunamis are introduced as long shallow water waves or wave trains crossing entire oceans without major energy loss at the coast tsunamis typically show wave shoaling funnelling and resonance effects as well as a significant run up and backflow tsunami waves are caused by a sudden displacement of the water column due to a number of various trigger mechanisms such are earthquakes as the main trigger submarine and subaerial mass wastings volcanic activity atmospheric disturbances meteotsunamis and cosmic impacts as is demonstrated by giving corresponding examples from the past tsunamis are known to have a significant sedimentary and geomorphological off and onshore response so called tsunamites form allochthonous high energy deposits that are left at the coast during tsunami landfall tsunami deposits show typical sedimentary features as basal erosional unconformities fining upward and landward a high content of marine fossils rip up clasts from underlying units and mud caps all reflecting the hydrodynamic processes during inundation the on and offshore behaviour of tsunamis and related sedimentary processes can be simulated using hydro and morphodynamic numerical models the paper provides an overview of the basic tsunami modelling techniques including discretisation guidelines for appropriate temporal and spatial resolution as well as the nesting method furthermore the boussinesq approximation a simplification of the three dimensional navier stokes equations is presented as a basic theory behind numerical tsunami models which adequately reflects the non linear dispersive wave behaviour of tsunamis the fully non linear boussinesq equations allow the simulation of tsunamis e g in the form of n waves based on the various subtopics presented recommendations for future multidisciplinary tsunami research are made it is especially discussed how the combination of sedimentary and geomorphological tsunami field traces and numerical modelling techniques can contribute to derive locally relevant tsunami sources and to improve the assessment of tsunami hazards considering the individual pre history and physiogeographical setting of a specific region

application of induced polarization and resistivity to the environmental investigation of an old waste disposal area waste disposal in dumpsites or even in sanitary landfills can generate contamination plumes in the subsurface the detection and delineation of the shape of the contaminant plume can be assessed using monitoring systems or different site investigation methods including geophysical methods this paper presents the results of a geophysical survey conducted to map the soil contamination produced by a waste disposal site located at a geological vulnerable area characterized by a trench that resulted from the collapse of sandy soils due to erosion this paper aims to show the improvement in mapping a waste deposit and the contamination produced in sandy soils by integrating resistivity and induced polarization methods the results of three survey lines performed to map the site are presented two across the deposit and one external to it and resistivity chargeability and normalized chargeability sections were generated the geoelectrical sections interpretation was integrated with information from monitoring wells to help the characterization of the waste area and to evaluate soil and groundwater contamination the results show that resistivity identifies the wastes the contaminated soil and the contamination plume but it does not distinguish these zones normalized chargeability on the other hand is more effective in distinguishing the areas with wastes from the areas impacted by the contamination plume

introduction to historical and recent catastrophic tsunamis in the world volume ii tsunamis from 1755 to 2010 eighteen papers on past and recent destructive tsunamis are included in volume ii of the pageoph topical issue historical and recent catastrophic tsunamis in the world three papers discuss deep sea dart and coastal tsunami observations warning systems and risk management in the pacific ocean four papers examine the 1755 lisbon 1964 alaska 2003 algeria and 2011 haiti tsunamis four more papers as well as some papers in volume i report on various aspects of the 2010 chile tsunami two papers present some results of field survey and modelling investigation of the 2010 mentawai indonesia tsunami three papers report on modelling efforts of tsunami generation by earthquake and landslide and of tsunami propagation finally two papers discuss hazard assessment using a probabilistic approach

tectonic evolution in the archaean and proterozoic kre high heat flow probably favoured global hotspot activity with crustal growth of iceland type through vertical magmatic accretion the tectonic environment for the generation of about 3 9 2 5 ga granite gneiss greenstone terrains with volurnlnous production of tonalite trondhjemite granodlorite magmas is still uncertain and both piate ma and intrapiate scenarios arc possible deformanon atylea in greenstones and adjacent high grade orthognersses with intercalated shallow water supracrustal assemblages suggest extensive horizontal shortening and crustal interstacking this probably resulted from collisional and or rotational motion and produced significant intracrustal melting as early as 3 9 ga by the end of the archaean and locally much earlier crustal thicknesses reached 35 50 km or more and the cxtl aordinary hhlding to erogenic deformation may have been due to delamination and crustal subduction towards the end of the proterozoic evidence for modern style plate tectonics becomes abundant through the recognition of laland a16 accretion ophiolite obducdon foreland thrust and fold belts and exotic terranes one of the best documented example for this tectonic environment is the arabian nubian shield 4lthough it is doubtful whether modern plate tectonic settings can serve as analogues for all precambrian tectonic styles it i clear that global crustal evolution since the early archaean was governed by the motion of plates which repeatedly came togethel tv fotm supercontinents and then dlspersetl again we shall not understand the detailed mechanism of precambrian crustal itlton cs before we learn horn lo irltejpret recent large scale crustal deformation and its causes

far field tsunami hazard in new zealand ports we present the results of a numerical modeling study investigating the effects of far field tsunamis in new zealand ports four sites marsden point tauranga harbor port taranaki and lyttelton harbor were selected based on a combination of factors such as economic importance and the availability of historical and or instrumental data numerical models were created using the commit tsunami modeling tool and the method of splitting tsunami most hydrodynamic model comparison of model results to measured data from recent historical events showed that for particular sites and events the model correlated well with the timing and amplitude of the observed tsunami and in most cases there was generally good agreement between the and modeled tsunami heights and current speeds a sensitivity analysis for tsunami heights and current speeds was conducted using a suite of large m w 9 tsunamigenic earthquake sources situated at regular 15 intervals in azimuth along the pacific rim while another set of scenarios focused on regional tsunami sources in the southwest pacific model results were analyzed for tsunami heights and current speeds as a function of the source region in terms of currents the analysis identified where speeds were greatest and which source was responsible results suggested that tsunamis originating from central america produced the strongest response in new zealand the modeling was also used to determine the timing and duration of potentially dangerous current speeds as well as minimum safe depths for vessel evacuation offshore this study was motivated by the desire to reduce damage and operational losses via improved forecasting of far field tsunamis at new zealand ports it is important that forecasts are accurate since tsunami damage to ships and facilities is expensive and can be mitigated given timely warnings and because preventable false alarms are also costly in terms of lost productivity the modeling presented here will underpin efforts to produce port specific guidance and information in the event of future pacific tsunamis

introduction to global tsunami science past and future volume ii twenty two papers on the study of tsunamis are included in volume ii of the pageoph topical issue global tsunami science past and future volume i of this topical issue was published as pageoph vol 173 no 12 2016 eds e l geist h m fritz a b rabinovich and y tanioka three papers in volume ii focus on details of the 2011 and 2016 tsunami generating earthquakes offshore of tohoku japan the next six papers describe important case studies and observations of recent and historical events four papers related to tsunami hazard assessment are followed by three papers on tsunami hydrodynamics and numerical modelling three papers discuss problems of tsunami warning and real time forecasting the final set of three papers importantly investigates tsunamis generated by non seismic sources volcanic explosions landslides and meteorological disturbances collectively this volume highlights contemporary trends in global tsunami research both fundamental and applied toward hazard assessment and mitigation

the great 2006 and 2007 kuril earthquakes forearc segmentation and seismic activity of the central kuril islands region we present a structural study of the central kuril islands forearc region where the great megathrust tsunamigenic earthquake m w 8 3 occurred on november 15 2006 based on new bathymetry and seismic profiles obtained during two research cruises of r v akademik lavrentiev in 2005 and 2006 ten crustal segments with along arc length ranging from 30 to 100 km separated by ns and nw trending transcurrent faults were identified within the forearc region the transcurrent faults may serve as barriers impeding stress transfer between the neighboring segments so that stress accumulated within separate forearc segments is usually released by earthquakes of moderate to strong magnitudes however the great november 15 2006 earthquake ruptured seven of the crustal segments probably following a 226 year gap since the last great earthquake in 1780 the geographic extent of earthquake rupture zones aftershock areas and earthquake clusters correlate well with forearc crustal segments identified using the geophysical data based on segmented structure of the central kuril islands forearc region we consider and discuss three scenarios of a great earthquake occurrence within this area although the margin is segmented we suggest that a rupture could occupy the entire seismic gap with a total length of about 500 km in such a case the earthquake magnitude m w might exceed 8 5 and such an event might generate tsunami waves significantly exceeding in height to those produced by the great 2006 2007 kuril earthquakes

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

probabilistic tsunami hazard in the northeast atlantic from near and far field tectonic sources in this article we present the first study on probabilistic tsunami hazard assessment for the northeast ne atlantic region related to earthquake sources the methodology combines the probabilistic seismic hazard assessment tsunami numerical modeling and statistical approaches we consider three main tsunamigenic areas namely the southwest iberian margin the gloria and the caribbean for each tsunamigenic zone we derive the annual recurrence rate for each magnitude range from mw 8 0 up to mw 9 0 with a regular interval using the bayesian method which incorporates seismic information from historical and instrumental catalogs a numerical code solving the shallow water equations is employed to simulate the tsunami propagation and compute near shore wave heights the probability of exceeding a specific tsunami hazard level during a given time period is calculated using the poisson distribution the results are presented in terms of the probability of exceedance of a given tsunami amplitude for 100 and 500 year return periods the hazard level varies along the ne atlantic coast being maximum along the northern segment of the morocco atlantic coast the southern portuguese coast and the spanish coast of the gulf of cadiz we find that the probability that a maximum wave height exceeds 1 m somewhere in the ne atlantic region reaches 60 and 100 for 100 and 500 year return periods respectively these probability values decrease respectively to about 15 and 50 when considering the exceedance threshold of 5 m for the same return periods of 100 and 500 years

development of a tsunami inundation map in detecting tsunami risk in gulf of fethiye turkey namidance tsunami simulation and visualization tool is used to create tsunami inundation maps showing quantitative maximum tsunami flow depths in fethiye the risk of an extreme but likely earthquake generated tsunami is estimated at fethiye bay for 14 probabilistic earthquake scenarios the bay is located 36 39 5 n 29 7 23 e southwestern turkey which has coastline to the eastern mediterranean sea the tsunami simulation and inundation assessment are performed in three stages 1 formation of a digital elevation model of the region from the best available topography bathymetry dataset 2 estimation of a maximum credible tsunami scenario for the region and determination of related earthquake parameters 3 high resolution tsunami simulation and computation of near shore and overland tsunami dynamics in the study area using tsunami simulation and visualization code namidance 4 determination of spatial distributions of tsunami characteristics maximum water elevations water velocities flow depths under the critical tsunami condition the results are based on the most recent descriptions of potential tsunami sources topographic and bathymetric databases and tsunami numerical models we present an innovative study concentrating on preparation of quantitative flow depths and inundation maps with a very high resolution bathymetry topographic dataset in the eastern mediterranean inundation maps will be used to analyze the effects of possible tsunamis the presented research is crucial to raising the awareness of government officials the public and other stake holders about the high probability of a tsunami event in turkey moreover the results of this study will help to plan for evacuation routes establish safe zones and assist in preparation for the tsunami creating public awareness and planning evacuation routes before the actual tsunami event happens

deformation history of the hengshan wutai fuping complexes implications for the evolution of the trans north china orogen abstract the trans north china orogen separates the north china craton into two small continental blocks the eastern and western blocks as one of the largest exposure in the central part of the orogen the hengshan wutai fuping complexes consist of four lithotectonic units the wutai hengshan and fuping complexes and the hutuo group the hengshan complex contains high pressure mafic granulites and retrograded eclogites structural analysis indicates that most of the rocks in these complexes underwent three distinct episodes of folding d 1 to d 3 and two stages of ductile thrust shearing stz 1 between d 1 and d 2 and stz 2 after d 3 the d 1 deformation formed penetrative axial planar foliations s 1 mineral stretching lineations l 1 and rarely preserved small isoclinal folds f 1 in the hengshan and fuping complexes in the wutai complex however large scale f 1 recumbent folds with sw vergence are displayed by sedimentary compositional layers penetrative transposition resulted in stacking of thrust sheets which are separated by ductile shear zones stz 1 the kinematic indicators of stz 1 in the hengshan and wutai complexes show top to the s230 w thrusting likely related to northeastward oblique pre collisional subduction d 1 resulted in crustal thickening with resultant prograde peak metamorphism the hutuo group did not undergo the d 1 deformation either because sedimentation was coeval with the d 1 deformation or because it was at a high structural level and was not influenced directly by the early deformation the d 2 deformation produced nw verging asymmetric and recumbent folds the d 2 deformation is interpreted to have resulted from collision between the eastern and western blocks of the north china craton in the hutuo group and the fuping complex the development of ese verging asymmetric tight folds is associated with d 2 the structural pattern resulting from superimposition of d 1 and d 2 is a composite synform in the hengshan wutai fuping complexes all four lithotectonic units were superposed during the later d 3 deformation the d 3 deformation developed nw trending open upright folds ongoing collision led to development of transpressional ductile shearing stz 2 forming the transpressional zhujiafang dextral ductile shear zone between the northern hengshan complex and the southern hengshan complex and generating the sinistral longquanguan ductile shear zone between the fuping complex and the wutai complex respectively the stz 1 and d 2 deformation were possibly responsible for fast syn collisional exhumation of the high pressure mafic granulites and retrograded eclogites the structural patterns and elucidation of the deformation history of the hengshan wutai fuping complexes places important constraints on the tectonic model suggesting that an oceanic lithosphere between the eastern and western blocks underwent northeastward directed oblique subduction beneath the western margin of the eastern block and that the final closure of this ocean led to collision between the two blocks to form the coherent basement of the north china craton

thermal evolution of two textural types of mafic granulites in the north china craton evidence for both mantle plume and collisional tectonics mafic granulites from the north china craton can be divided into two textural types referred to as a and b types a type mafic granulites display garnet quartz symplectic coronas and outcrop in the eastern and western zones of the craton whereas b type mafic granulites exhibit orthopyroxene plagioclase clinopyroxene symplectites or coronas and are mainly exposed in the central zone of the craton most a type mafic granulites preserve the prograde m 1 peak m 2 and post peak near isobaric cooling m 3 assemblages which are represented respectively by inclusions of hornblende plagioclase quartz a peak mineralogy of orthopyroxene clinopyroxene plagio clase quartz garnet and overprinted by garnet quartz symplectic coronas these mineral assem blages and their p t pressure temperature estimates define anticlockwise p t evolutionary paths the b type mafic granulites preserve the peak m 1 post peak near isothermal decompression m 2 and cooling m 3 assemblages which are represented by the peak assemblage of orthopyroxene clinopyroxene plagioclase quartz garnet hornblende post peak orthopyroxene plagioclase clinopyroxene symplectites or coronas and later hornblende plagioclase magnetite symplectites respectively these mineral assemblages and their p t estimates define clockwise p t paths the anticlockwise p t paths of the a type mafic granulites in the eastern and western zones of the north china craton are consistent with a model of underplating and intrusion of mantle derived magmas in combination with lithological structural and geochronological data the eastern and west ern zones of the north china craton are considered to represent two continental blocks that devel oped through the interaction of mantle plumes with the lithosphere from the palaeoarchaean to the neoarchaean era the b type mafic granulites and associated rocks in the central zone represent a magmatic arc that was metamorphosed and deformed during amalgamation of the eastern and west ern continental blocks in the late palaeoproterozoic era the mineral reaction relations and clockwise p t paths of the b type mafic granulites from the central zone record the tectonothermal history of the collision that resulted in the final assembly of the north china craton at c 1800 ma

rapidness and robustness of finite source inversion of the 2011 mw 9 0 tohoku earthquake by an elliptical patches method using continuous gps and acceleration data the kinematic rupture process of the 2011 mw 9 0 tohoku earthquake is inverted with an elliptical patches method using a genetic algorithm for the purpose of rapid and robust estimation of the source parameters of a mega earthquake we use the ground displacement field provided by a continuous gps network and the ground velocity field recorded by acceleration networks in addition to the typical inversion procedure in which a data duration long enough to cover the whole rupture process is used inversions based on shorter signals giving an incomplete view over the ground shaking sequence are also carried out how fast can a robust estimation of the source parameters be obtained using the elliptical approximation we find that robust solutions of mw 9 0 earthquakes are rather quickly obtained regardless of the frequency band and the elliptical patch description it is also confirmed that because of the absence of off shore recording stations on the east side of the fault some uncertainties in the rupture process cannot be completely removed in fact at the very low frequencies considered the western part of the fault deeper portion contributes more significantly to the recorded signals than does the other end close to the trench this problem also prevents refinement of the description of the rupture process in particular when using more than one ellipse

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

investigation of hydrodynamic parameters and the effects of breakwaters during the 2011 great east japan tsunami in kamaishi bay the march 2011 great east japan tsunami was one of the most disastrous tsunami events on record affecting the east coast of japan to an extreme degree extensive currents combined with flow depths in inundation zones account for this devastating impact video footage taken by the eyewitnesses reveals the destructive effect and dragging capability of strong tsunami currents along the coast this study provides a numerical modeling study in kamaishi bay calculating the damage inflicted by tsunami waves on structures and coastlines in terms of the square of the froude number fr2 and also other calculated hydrodynamic parameters such as the distribution of instantaneous flow depths maximum currents and water surface elevations that occurred during this catastrophic tsunami analyses were performed by using the tsunami numerical modeling code nami dance with nested domains at a higher resolution the effect of the kamaishi breakwater on the tsunami inundation distance and coastal damage was tested by using the conditions of with breakwater without breakwater and damaged breakwater results show that the difference between the hydrostatic pressure on the seaward side of the breakwater and the leeward side of the breakwater is quite high clarifying conditions contributing to failure of the breakwater lower water surface elevations were calculated in the case of a breakwater existing at the entrance a partly valid condition for the damaged breakwater case the results are different for current velocities and fr hbox max 2 in the with breakwater condition due to the concentration of energy through the breakwater gaps

the 2004 sumatra earthquake and tsunami lessons learned in subduction zone science and emergency management for the cascadia subduction zone the 26 december 2004 mw 9 3 sumatra earthquake and tsunami was a pivotal turning point in our awareness of the dangers posed by subduction zone earthquakes and tsunamis this earthquake was the world s largest in 40 years and it produced the world s deadliest tsunami this earthquake ruptured a subduction zone that has many similarities to the cascadia subduction zone in this article i summarize lessons learned from this tragedy and make comparisons with potential rupture characteristics slip distribution deformation patterns and aftershock patterns for cascadia using theoretical modeling and interseismic observations both subduction zones are approximately 1 100 1 300 km in length both have similar convergence rates and represent oblique subduction slip along the subduction fault during the 26 december earthquake is estimated at 15 25 m similar to values estimated for cascadia the width of the rupture 80 150 km estimated from modeling seismic and geodetic data is similar to the width of the locked and transition zone estimated for cascadia coseismic subsidence of up to 2 m along the sumatra coast is also similar to that predicted for parts of northern cascadia based on paleoseismic evidence in addition to scientific lessons learned the 2004 tsunami provided many critical lessons for emergency management and preparedness as a result of that tragedy a number of preparedness initiatives are now underway to promote awareness of earthquake and tsunami hazards along the west coast of north america and plans are underway to develop prototype tsunami and earthquake warning systems along cascadia lessons learned from the great sumatra earthquake and tsunami tragedy both through scientific studies and through public education initiatives will help to reduce losses during future earthquakes in cascadia and other subduction zones of the world

the proterozoic ophiolite problem continental emergence and the venus connection to account for the lack of preservation of ophiolites fragments of oceanic crust and mantle in old orogenic belts age 1000 to 2500 million years a hypothesis proposes that the magmatic oceanic crust formed during sea floor spreading was thicker during the cited time interval this thickening led to reduced contrast between the elevation of continental and oceanic regions and to greater average flooding of the continents the resultant distribution of elevation may have resembled modern venus more than modern earth

source models and near field impact of the 1 april 2007 solomon islands tsunami within weeks of the solomon islands earthquake of 1 april 2007 international tsunami survey teams discovered important biomarkers of crust rupture and tsunami heights along the islands coastlines deep ocean tsunameters recorded the tsunami waves of this event enabling a real time inversion of the tsunami source and model evaluation of near field tsunami impact the survey measurements provide valuable datasets for further confirmation of the tsunami source of the 1 april 2007 solomon earthquake these survey results also aided investigation of the correlation between sources determined by use of tsunameter records and those derived from seismometer records or crust rupture measurements in this study to assess the near field tsunami impact we developed tsunami inundation models for the solomon islands including tsunami waveforms co seismic land level changes and tsunami height distributions on individual islands compared with seismic derived tsunami sources modeling results based on the tsunameter derived tsunami sources were a good match with field survey measurements these results highlight the accuracy and efficiency of the tsunameter derived tsunami source in modeling the near field tsunami impact along a complex archipelago we show that the source models although derived by use of different methods are all suited to initiation of inundation models developed for solomon islands as these source models become available in real time or near real time they can be implemented immediately in the inundation models to provide rapid guidance on tsunami hazard assessment focused search and rescue operations and post event recovery and reconstruction

granitoid evolution in the late archean wutai complex north china craton abstract two temporally discrete episodes of granite magmatism have been identified in the wutai complex of the north china craton based on shrimp u pb zircon dating of all major granitoid bodies in the area the older period is latest archean and ranges in age from 2560 to 2515 ma whereas the younger episode is paleoproterozoic with magmatism at 2170 and 2120 ma archean magmatism can be further separated into two pulses based on geochemistry and the association of the younger plutons with extensive coeval volcanic activity in the wutai complex the early phase of archean activity is represented by the lanzhishan ekou and portions of the chechang betai granites with ages ranging from 2560 to 2540 ma the lanzhishan granite is the only one at wutaishan that contains inherited zircon with a number of cores and individual grains giving ages in excess of 2700 ma these are relatively evolved granitoids interpreted to be derived from older basement of the eastern block of the north china craton the shifo guangmingshi the main grey phase of the wangjiahui granite and the major components of the chechang betai granite have ages of 2540 2515 ma and are coeval with felsic volcanism in the wutai complex which is a consequence of subduction and related arc magmatism the dawaliang granite and pink phase of the wangjiahui granite are considerably younger with paleoproterozoic ages of 2170 and 2120 ma respectively these are also evolved granitoids most likely derived by partial melting of the older basement although we have found no evidence of inheritance the petrogenesis of the granitoids reflects the precambrian amalgamation history of the north china craton indicating derivation along the western edge of the eastern block during development and amalgamation of the wutai arc and prior to collision with the western block of the craton 1 8 ga ago