spatial and temporal variation of coda wave attenuation in the faryab region southeast of the sanandaj sirjan zone using aftershocks of the tiab earthquake of 28 february 2006 coda quality factor q c estimates for the faryb region in the southeast zagros have been obtained by using aftershock data of the tiab earthquake of 28 february 2006 recorded within an epicentral distance of 100 km more than 394 earthquakes were recorded by a local temporary network consisting of 9 short period stations installed for one month after 28 february 2006 q c was estimated using the single backscattering model in frequency bands of 0 5 24 hz in this research the spatial and temporal variation of q c in the sanandaj sirjan zone is studied to explore the lateral variation q c is calculated for nine stations and in different parts of the covered area the lowest values are derived in kali station in the southern part and the higher value in baga station in the northern part but generally there is an absence of significant lateral variation in coda q c in the faryab region to investigate the attenuation variation with depth q c value was calculated for eight lapse times the average frequency relation for this region is q c 28 1 1 f 1 14 0 01 at 5 s lapse time window length and q c 105 1 3 f 0 98 0 047 at 30 s lapse time window length q c increases with depth however the rate of increase of q c is not uniform with depth in the study area beneath the faryab region the rate of increase of q c is greater at depths less than 49 km compared to larger depths indicating a low attenuation structure at less than 49 km depth which is the moho depth in this region

tsunami of december 26 2004 on the southwest coast of india post tsunami geomorphic and sediment characteristics this paper discusses the impact of the december 26 2004 tsunami on the geomorphic features and sediment characteristics along the southwest coast of india the data used include field observations made after the tsunami and the inferences drawn from the satellite imagery taken before and after the tsunami sediment samples collected from the inner shelf beach and estuarine environments were analyzed to understand post tsunami changes in grain size characteristics the tsunami eroded and transported landwards significant volumes of distinct black sands rich in heavy minerals from the shelf onto the beaches of the kerala region and up to 500 m inland of the present coast

temporal variations in coda duration of local earthquakes in the wellington region new zealand temporal variations of coda duration relative to event magnitude for local earthquakes near wellington have been investigated the region is one of plate convergence and subduction the data consist of routinely made observations for events from 1978 through 1985 1552 events magnitude 1 6 to 5 2 depth 0 5 to 90 0 km the observed average over time correspondence between duration as measured from the origin time and magnitude is reasonably well predicted by the single backscattering theory of coda formation for events of magnitude 4 or less for larger events the observed durations are longer than predicted this theory predicts that a temporal increase in scattering attenuation will reduce the coda duration relative to magnitude thus any temporal changes in the duration magnitude relation can be interpreted in terms of changes inq however it is necessary to consider spatial biases since the observed durations are relatively long for shallow events and for events of all depths at stations situated in the south eastern half of the region usually believed part of the accretionary border for both these situations other evidence would suggest that the scattering coefficient would be relatively high lowq these observations may be due to a relatively high component of surface wave scattering and the importance of multiple scattering in the later part of the coda in regions of lowq as suggested by finite element studies of coda formation despite the lack of any significant earthquakes during the 1978 1985 period there is nevertheless a significant temporal change in duration observed in the wellington region a change from relatively long to relatively short codas occurred in mid 1981 this change correlates well with changes in the rate of activity b value radon emission and ground tilt as derived from lake levels it is not yet clear how all these parameters are related physically but an episode of aseismic slip or creep along the plate interface below the region may have been the cause

evidence for an earthquake and tsunami about 3100 3400 yr ago and other catastrophic saltwater inundations recorded in a coastal lagoon new zealand abstract okupe lagoon is 2 02 masl brackish and ponded behind two boulder banks at the northern end of kapiti island new zealand the sediments of the lagoon provide a record of late holocene environmental changes such as tectonic uplift catastrophic saltwater inundation and vegetation change five main events were identified over a 5300 yr record with a sixth representing a re evaluation of previous work an uplift event of 1 5 3 0 m and an associated tsunami are recorded and are inferred to have been caused by a local fault rupture possibly the northern extension of the wairau fault about 3360 40 yr bp two additional tsunami generated by ruptures of either the ohariu or wellington faults 1290 and 1220 ad respectively and either the wellington or alpine faults 1450 ad have been tentatively proposed two catastrophic saltwater inundations csis have also been identified one possibly a tsunami generated by either the wairarapa fault 500 ad or taupo eruption 190 ad the other about 4780 150 yr bp may relate to a local fault rupture however further work is needed to determine whether these are tsunami or storm surge related and they are therefore designated csis the sixth event is the 1855 tsunami recorded from a raised shore platform to the west of okupe lagoon

temporal change in coda q before the tangshan earthquake of 1976 and the haicheng earthquake of 1975 a new earthquake precursor called coda q is demonstrated for the tangshan earthquake of 1976 and for the haicheng earthquake of 1975 the precursor is based on the measurement of coda decay rate for small local earthquakes in the general area that is preparing for a major earthquake during the 3 year period preceding the tangshan earthquake the coda q was about 3 times lower than it was before or after this period a comparable change also occured at the time of the haicheng earthquake the observed change cannot be due to the change in the source parameters such as the focal depth or the source spectrum the coda q precursor appears to detect the same physical process detected by other precursors such as b value quiescence radon water quality vp vs and animal behavior but has advantages over them in its clearer physical mechanism easier sampling and better defined anomalous region

signatures of natural catastrophic events and anthropogenic impact in an estuarine environment new zealand the sedimentary record of known natural catastrophic events and anthropogenic activity in an estuarine environment is assessed using sedimentological chemical and geochronological techniques shallow cores collected from intertidal and salt marsh sediments in ahuriri estuary hawke s bay reveal a variety of signatures of natural and human disturbance evidence for the 1931 hawke s bay earthquake which resulted in an uplift of one to two metres in the napier area is given by a change from silt to sand dominated sediment in the lower estuary which is consistent with a shift toward higher energy depositional conditions following uplift however based on physical properties of sediments the 1931 uplift event does not appear to have caused major changes in depositional conditions in the upper estuary similarly no changes were recorded at one site in the lower estuary which seems to represent an area of low energy depositional environment although the 1960 chilean tsunami resulted in structural damage in napier it did not produce any recognisable sedimentological and geochemical signature in the sedimentary record suggesting that the study sites were possibly beyond the limit of sedimentation of the tsunami post european settlement impact is mainly restricted to the lower estuary where increased concentrations of zn cr pb and cu are attributed to industrial discharges evidence of agricultural runoff is shown by an increase in cu concentrations within a fine grained depositional environment that is distal from industrial sources in the town of napier chemical data cl and s suggest a change in the depositional environment in the upper estuary due to increased freshwater influx and or decrease in seawater influence dating by 210pb suggests that this occurred around the middle part of the 19th century and might be attributed to river flooding in the region at that time

ti diffusion in quartz abstract we have measured ti diffusion in quartz under dry 1 atm conditions experiments were performed using synthetic and natural quartz and a tio2 powder source with ti profiles obtained by rutherford backscattering spectrometry rbs over the temperature range 700 1150 c the following arrhenius relation was obtained for diffusion parallel to 001 d ti 7 10 8 exp 273 12 kj mol 1 r t m 2 sec 1 similar diffusivities were obtained for both synthetic and natural quartz and for a range of ti source materials including natural titanite powder and rutile quartz single crystal diffusion couples although ti diffusion appears slightly slower in the direction normal to c this difference is not great using these diffusion parameters calculations indicate that distances over which diffusional alteration of ti concentrations in quartz could occur in a million years would be on order of 500 m at 800 c and 15 m at 600 c the arrhenius relation above should be broadly applicable and may find application in constraining metamorphic histories under conditions where the ti in quartz geothermometer can be reasonably applied this relation can also be used to constrain peak temperatures and cooling histories from observations of exsolved rutile needles in quartz and the width of the ti depleted zone that develops around the growing needles finally these findings may find utility in evaluating crystal residence times in magmatic systems when coupled with observations of the sharpness of zoning patterns in quartz

recognition of diagnostic criteria for recent and paleo tsunami sediments from sri lanka uncontaminated sediment from the december 26 2004 tsunami in southern sri lanka was collected from a previously empty arrack bottle stacked in a plastic case at an elevation of about 5 m above mean sea level and from several other localities the sediments were analysed for grain size distribution sediment petrography and microfossil assemblages and were compared with storm surge sediment and nearshore sediment the undiluted tsunami sediment is a brownish silty fine sand it is characterized by a particular grain size distribution and an assemblage of planktonic benthic microfossils consisting of foraminifera radiolarians and spicules storm surge and nearshore sediments are better sorted have fewer microfossils more rounded quartz grains and a higher proportion of heavy minerals influenced by references in sri lankan ancient texts to past tsunamis we searched for paleo tsunami sediments in potential locations such as the coastal depressions in borehole samples and well cuttings from soil profiles in the coastal village of peraliya we were able to recognize two paleo tsunami horizons at 30 and 75 cm below the present ground surface each consisting of brownish silty fine sand that remarkably resembled the recently deposited undiluted tsunami sediment

hydrodynamic implications of textural trends in sand deposits of the 2004 tsunami in sri lanka abstract field observations and sediment samples at a coastal plain setting in southeastern sri lanka were used to document the erosional and depositional impacts of the 2004 indian ocean tsunami and to interpret the hydrodynamic processes that produced an extensive sand sheet deposit tsunami deposit thicknesses ranged from 6 to 22 cm with thickness being controlled partly by antecedent topography the deposit was composed of coarse to medium sand organized into plane parallel laminae and a few laminasets vertical textural trends showed an overall but non systematic upward fining and upward thinning of depositional units with an upward increase in heavy mineral laminations at some locations repeated patterns in the vertical textural trends upward fining upward coarsening uniform were used to subdivide and correlate the deposit into five hydro textural stratigraphic units the depositional units were linked to hydrodynamic processes and upcurrent conditions such as rates of sediment supply and composition of the sediment sources vertical changes in grain size distributions recorded the depositional phases associated with flow acceleration initial unsteady pulsating flow relatively stable and uniform flow flow deceleration slack water and return flow or flow redirection study results suggest that vertical textural trends from multiple cross shore sections can be used to interpret complex tsunami flow histories but at the location examined interpretation of the lateral textural trends did not provide a basis for identifying the correct sediment transport pathways because flow near the landward boundary was multidirectional

kuwae 1425 a d the forgotten caldera in vanuatu tongoa and epi islands once formed part of a larger landmass kuwae which was partly destroyed during a cataclysmic seismo volcanic event that is recorded in local folklore it led to the formation of a 12 kmlong and 6 km wide oval shaped submarine caldera with two distinct basins and a total area of 60 km2 at the level of the rim the age ofthis eniption 1420 1430 a d and the structure of the related collapse are discussed and a composite log 143 m of the pyroclastics surrounding the caldera is presented they comprise thick hydromagmatic deposits belonging to a terminal hydromagmatic phase of the pre caldera edifice which grade upwards into two major sequences of pyroclastic flow deposits clearly related to the caldera event collapse near the caldera edge was at least in the range 650 to 950 m and may have been as much as 800 to 1100 m the volume of rocks engulfed during the caldera formation is 32 39 km3 suggesting the same volume of magma was erupted even if two coalescent collapse structures were formed it is worth noting that the kuwae caldera is not a reactivated structure but the result of a single event of short duration which occurred in the first half of the fifteenth century this event is one of the seven biggest caldera forming events during the last 10 000 years and is comparable with the santorini minoan eruption and the crater lake eruption

cathodoluminescence imaging and titanium thermometry in metamorphic quartz cathodoluminescence cl of quartz from metamorphic rocks representing a range of conditions from the garnet grade to the migmatite grade reveals a variety of textures that is a function of metamorphic grade and deformation history ti concentrations determined by electron microprobe and ion microprobe generally correlate with cl intensity blue wavelengths and application of the ti in quartz thermometer titaniq reflects the temperature of quartz growth or recrystallization and in some settings modification by diffusion quartz from garnet grade samples is not visibly zoned records temperatures of 425 475 c and is interpreted to have recrystallized during fabric formation quartz grains from staurolite grade samples are zoned in cl with markedly darker cores and brighter rims some of which are interpreted to have been produced by the dominant staurolite producing reaction whereas others are interpreted as having formed by diffusion of ti into quartz rims quartz from the matrix of kyanite and sillimanite grade samples are generally unzoned although locally displays slightly brighter rims higher ti quartz inclusions within garnet and staurolite have distinctly brighter rims which are interpreted as having been produced by diffusive exchange with the host mineral quartz from migmatite grade samples displays highly variable cl intensity which is dependent on the location of the grain matrix grains in melanosomes are largely unzoned or rarely zoned with darker cores leucosome quartz is strongly zoned with bright cores and dark rims and is interpreted as having formed during crystallization of the melt locally within the leucosome is observed oscillatory zoned quartz which is interpreted as a subsolidus recrystallization to achieve strain relaxation quartz inclusions within garnet or plagioclase crystals often show bright domains separated by zones of dark cl these enigmatic textures possibly reflect local melting fluxed by fluid inclusions temperatures calculated from the ti in quartz thermometer are a function of the metamorphic grade of the sample the textural setting of the quartz the reaction history and the deformation history of the rock the titaniq temperatures can be used to constrain the conditions at which various metamorphic processes have occurred

chemical signatures of palaeotsunamis a forgotten proxy article i nfo article history a range of diagnostic criteria are required to help identify palaeotsunami deposits although chemical signatures have long been used as indicators of palaeosalinity in sedimentary sequences their use in the studies of palaeotsunami deposits is rarely applied and is yet to be widely recognised the chemical composition of interstitial water in coastal ponds and sedimentary sequences in coastal marshes and lagoons has been used successfullyasanindicatoroftsunamiinundation chemicalsignaturescanalsoprovidecluesaboutthelandward limit of runup of a tsunami beyond the area of sediment deposition like most palaeotsunami proxies however the preservation of chemical signatures varies with environmental conditions

reverse tracing of short term earthquake precursors abstract we introduce a new approach to short term earthquake prediction named reverse tracing of precursors rtp since it considers precursors in reverse order of their appearance first we detect the candidates for the short term precursors in our case these are newly introduced chains of earthquakes reflecting the rise of an earthquake correlation range then we consider each chain one by one checking whether it was preceded by an intermediate term precursor in its vicinity if yes we regard this chain as a precursor in prediction it would start a short term alarm the chain indicates the narrow area of possibly complex shape where an intermediate term precursor should be looked for this makes possible to detect precursors undetectable by the direct analysis rtp can best be described on an example of its application we describe retrospective prediction of two prominent californian earthquakes landers 1992 m 7 6 and hector mine 1999 m 7 3 and suggest a hypothetical prediction algorithm this paper descripes the rtp methodology which has potentially important applications to many other data and to prediction of other critical phenomena besides earthquakes in particular it might vindicate some short term precursors previously rejected as giving too many false alarms validation of the algorithm per se requires its application in different regions with a substantial number of strong earthquakes first and positive retrospective results are obtained for 21 more strong earthquakes in california m 6 4 japan m 7 0 and the eastern mediterranean m 6 5 these results are described elsewhere the final validation requires as always prediction in advance for which this study sets up a base we have the first case of a precursory chain reported in advance of a subsequent strong earthquake tokachi oki japan 25 september 2003 m 8 1 possible mechanisms underlying rtp are outlined

intensity of quartz cathodoluminescence and trace element content in quartz from the porphyry copper deposit at butte montana textures of hydrothermal quartz revealed by cathodoluminescence using a scanning electron microscope sem cl refl ect the physical and chemical environment of quartz formation variations in intensity of sem cl can be used to distinguish among quartz from superimposed mineralization events in a single vein in this study we present a technique to quantify the cathodoluminescent intensity of quartz within individual and among multiple samples to relate luminescence intensity to specific mineralizing events this technique has been applied to plutonic quartz and three generations of hydrothermal veins at the porphyry copper deposit in butte montana analyzed veins include early quartz molybdenite veins with potassic alteration pyrite quartz veins with sericitic alteration and main stage veins with intense sericitic alteration cl intensity of quartz is diagnostic of each mineralizing event and can be used to fingerprint quartz and its fluid inclusions isotopes trace elements etc from specific mineralizing episodes furthermore cl intensity increases proportional to temperature of quartz formation such that plutonic quartz from the butte quartz monzonite bqm that crystallized at temperatures near 750 c luminesces with the highest intensity whereas quartz that precipitated at 250 c in main stage veins luminesces with the least intensity trace element analyses via electron microprobe and laser ablation icp ms indicate that plutonic quartz and each generation of hydrothermal quartz from butte is dominated by characteristic trace amounts of al p ti and fe thus in addition to cl intensity each generation of quartz can be distinguished based on its unique trace element content aluminum is generally the most abundant element in all generations of quartz typically between 50 and 200 ppm but low temperature main stage quartz containing 400 to 3600 ppm al is enriched by an order of magnitude relative to all other quartz generations phosphorous is present in abundances between 25 and 75 ppm and p concentrations in quartz show little variation among quartz generations iron is the least abundant of these elements in most quartz types and is slightly enriched in cl dark quartz in pyrite quartz veins with sericitic alteration titanium is directly correlated with both temperature of quartz precipitation and intensity of quartz luminescence such that bqm quartz contains hundreds of ppm ti whereas main stage quartz contains less than 10 ppm ti our results suggest that ti concentration in quartz is controlled by temperature of quartz precipitation and that increased ti concentrations in quartz may be responsible for increased cl intensities

rutile inclusions in quartz crystals record decreasing temperature and pressure during the exhumation of the su lu uhp metamorphic belt in donghai east china donghai county in the jiangsu province of east china is known for its large scale production of high quality quartz crystals the quartz crystals are hosted within the su lu ultrahigh pressure uhp metamorphic belt they form in quartz veins hosted by eclogite and gneiss or along contacts between eclogite and gneiss and are mined as placer deposits in the quaternary sediments backscattered electron imaging of the rutile in rutile bearing euhedral quartz crystals from this region reveal three compositionally and texturally distinct generations of rutile encapsulated within the host quartz crystal the earliest generation of rutile r1 is brightest in bse reflecting enrichment in fe2o3 0 75 2 08 wt nb2o5 0 37 0 93 wt wo3 0 48 2 99 wt and zro2 0 005 0 105 wt relative to r2 and r3 r2 rutile overgrows r1 rutile and contains 0 66 1 11 wt fe2o3 0 45 0 74 wt nb2o5 0 09 0 20 wt wo3 and 0 001 0 013 wt zro2 r3 rutile which is the only rutile generation in contact with the host quartz crystals is darkest in bse and always overgrows r1 and rounded aggregates of r2 r3 rutile contains 0 40 0 68 wt fe2o3 0 13 0 37 wt nb2o5 0 03 0 12 wt wo3 and 0 001 wt zro2 oxygen isotopes decrease progressively from 0 6 to 1 5 in r1 rutile to 0 1 in r2 rutile to 5 1 to 0 3 in r3 rutile consistent with decreasing temperature of rutile crystallization combined application of the zr in rutile and ti in quartz thermobarometers indicate that these rutile generations precipitated at progressively lower pressures and temperatures consistent with previously determined retrograde metamorphic conditions of the su lu uhp belt r1 grew after peak metamorphism during retrograde eclogite facies metamorphism at temperatures between 720 and 800 c and pressures between 21 7 and 26 6 kbar during subsequent retrograde metamorphism r1 was fractured and partially brecciated and overgrown by r2 during epidote amphibolite facies retrograde metamorphism in the range of 400 to 500 c and 5 kbar zirconium concentrations of 14 ppm in r3 rutile and ti concentrations of 1 ppm in the co precipitated host quartz suggest that they both grew at low temperatures of 300 and pressures 2 kbars oscillatory growth zones in quartz revealed by cathodoluminescence suggest that no subsequent metamorphism or hydrothermal activity occurred after the formation of the host euhedral quartz crystals and is consistent with a low temperature of quartz crystallization the random distribution of rutile crystals in the quartz and the lack of evidence for rutile transport by hydrothermal fluids indicate that the host quartz formed by a dissolution replacement process whereby the original host mineral likely omphacite or garnet was replaced by quartz but the rutile was not significantly replaced or dissolved due to the low solubility of ti in low temperature hydrothermal fluids

titaniq a titanium in quartz geothermometer titanium is one of many trace elements to substitute for silicon in the mineral quartz here we describe the temperature dependence of that substitution in the form of a new geothermometer to calibrate the titaniq thermometer we synthesized quartz in the presence of rutile and either aqueous fluid or hydrous silicate melt at temperatures ranging from 600 to 1 000 c at 1 0 gpa the ti contents of quartz in ppm by weight from 13 experiments increase exponentially with reciprocal t as described by text log left x text qtz text ti right 5 69 pm 0 02 frac 3765 pm 24 t k application of this thermometer is straightforward typically requiring analysis of only one phase quartz this can be accomplished either by epma for crystallization temperatures above 600 c or by sims for temperatures down to at least 400 resulting temperature estimates are very precise usually better than 5 c potentially allowing detailed characterization of thermal histories within individual quartz grains although calibrated for quartz crystallized in the presence of rutile the thermometer can also be applied to rutile absent systems if tio2 activity is constrained

lagoon subsidence and tsunami on the west coast of new zealand abstract sediment core and trench data from a coastal lagoon on the west coast of the south island new zealand are used to investigate evidence for co seismic subsidence and associated tsunami inundation physical data are used to document a salt marsh soil buried 80 cm below the modern sediment surface that is locally covered by a gravelly sand bed the sediment record also contains geochemical and biological diatom and foram evidence for abrupt changes in salinity of lagoon waters that link to subsidence tsunami flooding and to the open versus closed state of the lagoon tidal entrance at the local scale these relationships allow for separation of tsunami evidence from other agents of environmental change in the lagoon we also propose a conceptual connection between these local changes and regional drivers of landscape development most notably major earthquakes and resultant pulses in sediment supply to the coast

sheet gravel evidence for a late holocene tsunami run up on beach dunes great barrier island new zealand abstract a semi continuous sheet of granule to cobble size clasts forms a distinctive deposit on sand dunes located on a coastal barrier in whangapoua bay great barrier island new zealand the gravel sheet extends from the toe of the foredune to 14 3 m above mean sea level and 200 m landward from the beach clasts are rounded to sub rounded and comprise lithologies consistent with local bedrock terrestrial sources for the gravel are considered highly unlikely due to the isolation of the dunes from hillslopes and streams the only source for the clasts is the nearshore to inner shelf of whangapoua bay where gravel sediments have been previously documented the mechanism for transport of the gravel is unlikely to be storm surge due to the elevation of the deposit maximum recorded storm surge on this coast is 0 8 m above mean high water spring tide aeolian processes are also discounted due to the size of clasts and the elevation at which they occur tsunami is therefore considered the most probable mechanism for gravel transport minimum run up height of the tsunami was 14 3 m based on maximum elevation of gravel deposits optical ages on dune sands beneath and covering the gravel allow age bracketing to 0 4 7 ka within this time frame numerous documented regional seismic and volcanic events could have generated the tsunami notably submarine volcanism along the southern kermadec arc to the east southeast of great barrier island where large magnitude events are documented for the late holocene radiocarbon ages on shell from maori middens that appear to have been reworked by tsunami run up constrain the age of this event to post ca 1400 ad regardless of the precise age of this event the well preserved nature of the whangapoua gravel deposit provides for an improved understanding of the high degree of spatial variability in tsunami run up

spatial and temporal correlation between coda q 1 and seismicity and its physical mechanism from the analysis of local earthquake coda waves recorded by the benioff short period vertical seismograph at riverside california we found a surprisingly large and systematic temporal variation in coda q 1 in the southern california during the 55 year period from 1933 to 1987 comparison of the coda q 1 variation with the b value obtained for earthquakes with m 3 occurred in the area within 180 km from riverside corresponding to the area for which q 1 is estimated by the coda method led to an extraordinary result that coda q 1 correlates positively with b value with the correlation coefficient of 0 79 the significance of correlation cannot be rejected at the confidence level of 0 974 since the data used for measuring q 1 namely the coda part of seismograms and the data used for measuring b namely the seismicity catalog are totally independent the observed correlation supports strongly the physical reality of temporal change in both coda q 1 and b value the correlation between coda q 1 and b value has been reported for several other cases but the correlation was positive in some cases and negative in others our current preferred model for explaining the observed correlation is the following aseismic creep is going on from time to time over various sizes of cracks in the ductile part and in some cases in the brittle part of lithosphere at and near the plate boundary creep activities tend to increase the crack density and coda q 1 observed in the region if the creek occurs over distributed cracks with a certain predominant scale length spatial stress concentration may enhance seismicity for earthquakes with a similar size if this characteristic size is in the lower part of the magnitude range for which the b value is estimated the enhanced seismicity will increase b on the other hand if it is in the upper part of the magnitude range it will decrease b thus we can explain the observed strong correlation between coda q 1 and b value for both positive and negative cases the existence of such a characteristic crack size in a seismic region has been supported by various observations on earthquake scaling

distinguishing tsunami and storm deposits an example from martinhal sw portugal abstract geological identification of past tsunamis is important for risk assessment studies especially in areas where the historical record is limited or absent the main problem when using the geological evidence is to distinguish between tsunami and storm deposits both are high energy events that may leave marine traces in coastal stratigraphic sequences at martinhal sw portugal both storm surge and tsunami deposits are present at the same site within a single stratigraphic sequence which makes it suitable to study the differences between them excluding variations caused by local factors the tsunami associated with the lisbon earthquake of november 1st 1755 ad had a major impact on the geomorphology and sedimentology of martinhal it breached the barrier and laid down an extensive sheet of sand as described in eyewitness reports besides the tsunami deposit the stratigraphy of martinhal also displays evidence for storm surges that have breached and overtopped the barrier flooding the lowland and leaving sand layers both marine derived flood deposits show similar grain size characteristics and distinctive marine foraminifera the most important differences are the rip up clasts and boulders exclusively found in the tsunami deposit and the landward extent of the tsunami deposit that everywhere exceeds that of the storm deposits identification of both depositional units was only possible using a collection of different data and extensive stratigraphical information from cores as well as trenches

constraining ultrahigh pressure uhp metamorphism and titanium ore formation from an infrared microthermometric study of fluid inclusions in rutile from donghai uhp eclogites eastern china eclogites in the donghai area of the sulu ultrahigh pressure uhp metamorphic belt in eastern china contain both disseminated rutile and rutile deposits the rutile occurs as small inclusions in garnet omphacite phengite and quartz as larger euhedral to subhedral grains in equilibrium with garnet omphacite phengite and kyanite and as discrete veinlets aggregates and megacrysts in cracks and along grain boundaries to investigate the processes of rutile mineralization and its relationship to the evolution of the sulu uhp metamorphic belt we sampled the exposed maobei deposit at donghai and drill core between 100 and 2000 m in the nearby chinese continental scientific drilling project ccsd main hole to carry out a detailed infrared microthermometric fluid inclusion study three types of fluid inclusions were identified aqueous type i co 2 h 2 o type ii and ch 4 type iii type i and type ii inclusions are the most common primary and pseudosecondary type i inclusions which were trapped during recrystallization of the eclogite or early amphibolite facies retrograde metamorphism have a narrow range of homogenization temperatures but a wide range of salinities in contrast secondary type i inclusions which formed entirely during retrograde amphibolite facies metamorphism associated with exhumation of the uhp rocks have higher and more varied homogenization temperatures but medium to low salinities type ii inclusions formed contemporaneously with the type i variety and are characterized by having small amounts of co 2 and n 2 in addition to h 2 o in addition some of the rutile grains contain sparse inclusions composed of ch 4 type iii our results combined with those of previous studies suggest a great diversity of fluid composition in the peak metamorphic to early retrograde stages implying very limited fluid rock interaction during syn to post peak high pressure hp and uhp metamorphism this study shows that infrared microthermometric investigation of fluid inclusions can provide information not only on the composition of titanium ore forming fluids but also on the relationship between mineralization and the evolution of uhp metamorphic belt

temporal un correlations between coda q and seismicity multiscale trend analysis this paper introduces a statistical technique based on the recently developed multiscale trend analysis mta for quantifying correlations between non stationary processes observed at irregular non coincident time grids we apply this technique to studying the temporal correlation between the dynamics of the ductile and brittle layers in the lithosphere our results confirm the previously reported strong positive correlation between the coda q 1 and seismicity and its drop before major earthquakes observed in california the proposed technique has significant advantages over the conventional correlation analysis 1 mta allows one to work directly with non coincident time series without preliminary resampling the data 2 the correlation is defined via the stable objects trends rather than noisy individual observations hence it is highly robust 3 the correlations are quantified at different time scales the suggested technique seems promising for the wide range of applied problems dealing with coupled time series

scale dependence in earthquake phenomena and its relevance to earthquake prediction abstract the recent discovery of a low velocity low q zone with a width of 50 200 m reaching to the top of the ductile part of the crust by observations on seismic guided waves trapped in the fault zone of the landers earthquake of 1992 and its identification with the shear zone inferred from the distribution of tension cracks observed on the surface support the existence of a characteristic scale length of the order of 100 m affecting various earthquake phenomena in southern california as evidenced earlier by the kink in the magnitude frequency relation at about m3 the constant corner frequency for earthquakes with m below about 3 and the sourcecontrolled fmax of 5 10 hz for major earthquakes the temporal correlation between coda q 1 and the fractional rate of occurrence of earthquakes in the magnitude range 3 3 5 the geographical similarity of coda q 1 and seismic velocity at a depth of 20 km and the simultaneous change of coda q 1 and conductivity at the lower crust support the hypotheses that coda q 1 may represent the activity of creep fracture in the ductile part of the lithosphere occurring over cracks with a characteristic size of the order of 100 m the existence of such a characteristic scale length cannot be consistent with the overall self similarity of earthquakes unless we postulate a discrete hierarchy of such characteristic scale lengths the discrete hierarchy of characteristic scale lengths is consistent with recently observed logarithmic periodicity in precursory seismicity

coda q before and after the 1983 misasa earthquake of m 6 2 tottori prefecture japan to detect any temporal change in coda q associated with an earthquake of m 6 2 digitized data from analog magnetic records of microearthquakes for a small confined region just around its hypocenter have been processed with special attention to measuring errors the m 6 2 earthquake took place at the misasa town tottori prefecture in southwest japan with preceding anomalous seismicity changes theq values were elevated 20 around three years before the m 6 2 event for frequencies of 5 to 20 hz and tended to decrease around two years before data with high quality show undulated temporal variation with a period of 5 6 years before the earthquake which is correlated with the regional seismic activity there is a possibility that the observedq change stands for precursory effect of the medium scale earthquake the aftershock sequence also shows an undulated temporal variation ofq with a period of 150 days for around 10hz correlating also with the seismic activity the fracturing processes by numerous microearthquakes may be responsible for the attenuation property of randomly scattered seismic waves

distribution and sedimentary characteristics of tsunami deposits along the cascadia margin of western north america abstract tsunami deposits have been found at more than 60 sites along the cascadia margin of western north america and here we review and synthesize their distribution and sedimentary characteristics based on the published record cascadia tsunami deposits are best preserved and most easily identified in low energy coastal environments such as tidal marshes back barrier marshes and coastal lakes where they occur as anomalous layers of sand within peat and mud they extend up to a kilometer inland in open coastal settings and several kilometers up river valleys they are distinguished from other sediments by a combination of sedimentary character and stratigraphic context recurrence intervals range from 300 1000 years with an average of 500 600 years the tsunami deposits have been used to help evaluate and mitigate tsunami hazards in cascadia they show that the cascadia subduction zone is prone to great earthquakes that generate large tsunamis the inclusion of tsunami deposits on inundation maps used in conjunction with results from inundation models allows a more accurate assessment of areas subject to tsunami inundation the application of sediment transport models can help estimate tsunami flow velocity and wave height parameters which are necessary to help establish evacuation routes and plan development in tsunami prone areas

submarine silicic volcanism of the healy caldera southern kermadec arc sw pacific i volcanology and eruption mechanisms the submarine healy volcano southern kermadec arc with a 2 2 5 km wide caldera is pervasively mantled with highly vesicular silicic pumice within a water depth of 1 150 1 800 m pumices comprise type 1 white light grey pumice with 30 mm vesicles and weak moderate foliation type 2 grey pumice with millimetre scale laminae flow banded foliation including stretched vesicles 55 mm in length and a minor finely vesicular type 3 pumice all types are sparsely porphyritic with undevitrified glassy groundmass 68 70 sio2 which is microlite and lithic free coexisting pyroxenes yield magma temperatures of 950 c pumice density is 0 5 g cm 3 and vesicularity is 78 83 vesicle size distributions for types 1 and 2 pumice range from 20 m to 20 mm with a strong power law relation with d 2 5 0 4 for vesicles 9 mpa will limit vesicularity to less than the observed 78 83 whereas pressure 6 mpa require a more shallower reconstruction of the edifice and larger volume syn eruptive collapse uniformly high vesicularity is interpreted as evidence of insulation within an eruption column comprising steam and hot pyroclasts most pyroclasts cool condensing and ingesting water into steam inflated vesicles and then sink progression into pyroclastic mode would expand the eruption column displace ambient water reduce the hydrostatic load and further promote vesiculation and fragmentation pyroclasts within the column would quench at these reduced pressures we argue that healy eruptions deeper than 1 000 m cannot be pyroclastic volumes for the lower and upper bounds of edifice size are 2 36 and 3 58 km3 respectively but do not account for intra caldera pumice fill these volumes are considered to be predominantly primary eruption output as shown by a dearth of accessory lithics in all pumice yielding at an average 81 vesicularity eruptive pumice volumes of between 10 and 15 km3 some pyroclasts may have risen to the sea surface and be a correlative of the sea rafted loisels pumice the latter occurs in some new zealand holocene beach sequences and has a estimated age of 590 80 calendar years

new multibeam mapping and geochemistry of the 30 35 s sector and overview of southern kermadec arc volcanism new multibeam mapping and whole rock geochemistry establish the first order definition of the modem submarine kermadec arc between 30 degrees and 35 degrees s twenty two volcanoes with basal diameters 5 km are newly discovered or fully mapped for the first time giggenbacb macauley havre haungaroa kuiwai ngatoroirangi sonne kibblewhite and yokosuka for each large volcano edifice morphology and structure surficial deposits lava fields distribution of sector collapses and lava compositions are determined macauley and havre are large silicic intra oceanic caldera complexes for both concentric ridges on the outer flanks are interpreted as recording mega bedforms associated with pyroclastic density flows and edifice foundering other stratovolcanoes reveal complex histories with repeated cycles of tectonically controlled construction and sector collapse extensive basaltic flow fields and the development of summit craters and or small nested calderas combined with existing data for the southernmost arc segment we provide an overview of the spatial distribution and magmatic heterogeneity along similar to 780 km of the kermadec arc at 30 degrees 36 degrees 30 s coincident changes in arc elevation and lava composition define three volcano tectonic segments a central deeper segment at 32 degrees 20 34 degrees 10 s has basement elevations of 3200 m water depth and relatively simple stratovolcanoes dominated by low k series basalt basaltic andesite in contrast the adjoining arc segments have higher basement elevations typically 3 km coincide with the shallower arc segments the dominant mode of large caldera formation is interpreted as mass discharge pyroclastic eruption with syn eruptive collapse hence the shallower arc segments are characterized by both the generation of volatile enriched magmas from crustal melting and a reduced hydrostatic load allowing magma vesiculation and fragmentation to initiate and sustain pyroclastic eruptions proposed initiation parameters for submarine pyroclastic eruptions are water depths 70 wt sio2 and a high discharge rate c 2005 elsevier b v all rights reserved

geological and historical records of tsunami in australia abstract the indian ocean tsunami iot of 2004 has resulted in significant interest within australia about the record of tsunami for the continent because an understanding of tsunami hazard begins with a catalogue of past events here a preliminary catalogue of tsunami affecting australia is presented the catalogue contains entries for 57 tsunami events the oldest event is dated at 3 47 ga the most recent is the july 17th 2006 forty four tsunami were recorded on the new south wales coast although the nw coast of western australia records a significant number of events forty seven events have affected australia since ad1858 maximum run up for an historic event is 6 m asl whilst the maximum run up for a palaeotsunami event is reported at an elevation of at least 100 m asl twenty three percent of historic australian tsunami were generated by unknown causes and papua new guinea the solomon islands and indonesia collectively represent the most important source area of historic tsunami for australia geological records for palaeo and historic tsunami are identified and summarised the geological record of tsunami represents a potentially important source of information for australian tsunami however at the present time the geological record is both limited and controversial and future research should seek to re examine proposed geological evidence of tsunami from an analysis of this preliminary catalogue of australian tsunami a series of key research priorities have been identified to guide future research in the region

seismic driving of nationwide changes in geomorphology and prehistoric settlement a 15th century new zealand example abstract we propose a model for the seismic driving of environmental changes and illustrate it using a case study from new zealand dated to the 15th century ad a seismic staircase shows a chronological progression of environmental outcomes that includes tsunami rock avalanches vegetation disturbance rapid coastal dune building river aggradation and abandonment of prehistoric coastal settlements the 15th century event appears to be unique in the past millenium and is most notable for its period of rapid coastal dune building the coincidence of a catastrophic el nino episode in the mid 15th century ad may have served to move sediments rapidly through the terrestrial system thus delimiting clearly separate geomorphological after effects we contend that seismic driving is a major factor in determining paleoenvironmental change in tectonically active areas during the holocene and provides the palaeoenvironmental context within which smaller scale events operate

provenance interpretation of quartz by scanning electron microscope cathodoluminescence fabric analysis we used a cathodoluminescence cl detector attached to a scanning electron microscope sem to study patterns of variable intensity cl in quartz grains from a variety of igneous metamorphic sedimentary and shock deformed meteorite impact rocks distinctive fabrics in quartz grains revealed by sem imaged differential cl include zoning healed fractures complex shears planar features shocked quartz dark cl streaks and patches indistinct mottled texture and nondifferential low contrast cl zoning is common in volcanic quartz and some plutonic quartz zoned plutonic quartz is distinguished from volcanic quartz by the presence of closed fractures and dark cl streaks and patches metamorphic quartz displays either an indistinct mottled texture or nearly uniform nondifferential cl quartz from rocks severely deformed by tectonism displays a complex pattern of multiple small scale shears quartz from meteorite impact sites and some system boundaries is characterized by intricate patterns of planar features presumably created by shock metamorphism thus the sem cl fabric analysis technique provides a rapid method for distinguishing quartz from a variety of source rocks

tsunami and palaeotsunami depositional signatures and their potential value in understanding the late holocene tsunami record in recent years much research on modern and palaeotsunami deposits has been published from these studies a range of signature types has been identified identifying and dating such deposits is an important element in understanding late holocene tsunami hazard and risk however important questions such as do modern and palaeotsunami leave similar or dissimilar traces do tsunami leave the same signatures all around the world or are there significant variations and what is the actual record of tsunami in different parts of the world still remain answering these questions is not an easy task but examining megatsunami flood deposits should shed some light on these questions because such high magnitude events should leave very clear and detailed traces within the coastal landscape the coast of se australia is reported to have been affected by numerous palaeomegatsunami in the late holocene as such the coast of new south wales offers an important natural laboratory to examine in detail deposits associated with such events here we summarize the published characteristics of modern and palaeotsunami deposits globally and within australia we briefly outline the tsunami risk to australia before examining a site called minnamurra point on the coastline of se australia south of sydney that has previously been described as containing evidence for a palaeomegatsunami of an unknown age we describe the results of a detailed coastal survey field stratigraphic investigation and various standard laboratory analyses surprisingly we are unable to replicate the previously reported findings of tsunami deposits whilst we prefer the interpretation that the sequence is an in situ soil the sediment sequence examined contains none of the usually reported lines of evidence to demonstrate tsunami provenance we recognize and discuss the significance and difficulty of identifying tsunami deposits in the field and consider the implications of our findings to the wider debate about the preservation of tsunami deposited sediments

relationships between sem cathodoluminescence response and trace element composition of hydrothermal vein quartz laser ablation icp ms data of hydrothermal vein quartz with zonation in scanning electron microscope cathodoluminescence reveal two groups of trace elements one that co varies in concentration with luminosity and another that remains uniform throughout bright luminosity correlates with a high total abundance of trace elements in early quartz including al up to 410 g g ti up to 240 g g k up to 330 g g li up to 8 g g na up to 36 g g and fe up to 20 g g up to 20 times lower concentrations of these elements are associated with dark luminosity in late quartz concentrations of p 21 g g ga 0 3 g g ge 1 3 g g sn 1 5 g g cu 0 3 g g and ag 0 1 g g demonstrate no relationship with luminosity charge balance cannot be achieved for bright luminescent quartz unless the presence of up to 6 g g h not analyzed by la icpms or interstitial al3 is invoked interestingly the inferred 6 g g h remains constant for quartz containing more than 10 mol total trace elements and might represent the solubility of h in hydrothermal quartz at temperatures between 450 and 700 c la icpms results indicate that the fluid chemistry determines the quartz trace element pattern which may serve as a monitor for the chemical environment from which quartz crystallized ratios of na al and ti al are uniform whereas k al evolves toward lower values with decreasing luminosity combined evidence including quartz vein textures silica solubility data and estimates of the temperature of quartz growth suggest that early quartz crystallized fast but late quartz grew more slowly at 350 to 425 c it is speculated that the higher the quartz growth rate is the more trace elements are incorporated into quartz besides the temperature dependence known from the literature clearly growth rate temperature and fluid chemistry are important parameters affecting luminosity however their relative importance may vary from case to case

temporal change in scattering and attenuation associated with the earthquake occurrence a review of recent studies on coda waves the study of coda waves has recently attracted increasing attention from seismologists this is due to the fact that it is viewed as a new means by which the stress accumulation stage preceding a large earthquake can be measured since the scattering paths nearly uniformly cover a fairly large region around the focus and observation stations compared with the direct ray paths to date we have had many reports on the temporal variation of the relation between coda duration and amplitude magnitude and that of the coda attenuationq 1 which is estimated from coda amplitude decay some of these have shown a precursor like behavior however others seem to have shown a coseismic change we have critically reviewed these reports and discussed what these observational facts tell us about the change in the heterogeneous crust we found significant temporal variations not only in the mean but also in the scatter ofq 1 associated with the mainshock occurrence the formation of new cracks the reopening and growing of existing cracks the interaction of these cracks and the pore water movement through these cracks might correspond to such variations in addition we may expect an inhomogeneous distribution of crack clusters in a fairly large region compared with the aftershock region the gradual appearance of such crack clusters seems to be the most plausible mechanism by which coda decay gradients are caused to largely scatter in the stress accumulation stage

tsunami sediments and their foraminiferal assemblages abstract tsunami hazard assessment begins with a compilation of past events that have affected a specific location given the inherent limitations of historical archives the geological record has the potential to provide an independent dataset useful for establishing a richer chronologically deeper time series of past events recent geological studies of tsunami are helping to improve our understanding of the nature and character of tsunami sediments wherever possible geologists should be working to improve the research tool kit available to identify past tsunami events marine foraminifera single celled heterotrophic protists have often been reported as present within tsunami deposited sediments but in reality little information about environmental conditions and by analogy the tsunami that deposited them has been reported even though foraminifera have an enormous capacity to provide meaningful palaeo environmental data here we review what foraminifera are describe their basic form and significance summarise where they have been reported in tsunami sediments and identify what can be learnt from them we review the gaps in our understanding and make recommendations to assist researchers who examine foraminiferal assemblages in order to enhance their use within tsunami geology

a tsunami ca 6300 years bp and other holocene environmental changes northern hawke s bay new zealand abstract sediment cores collected in a coastal lagoon a few kilometres east of wairoa northern hawke s bay new zealand were examined using sedimentological geochemical palynological and micropaleontological analyses a distinct short lived catastrophic saltwater inundation csi about 6300 years bp and possibly other minor marine incursions are preserved in the coastal estuarine to lagoonal freshwater sedimentary sequences which have been deposited in the last 6500 years the csi is characterised by a gravel unit that thins landward and decreases in particle size to sand within a sequence consisting mainly of brackish estuarine muds diatom assemblages indicate a marked change from the shallow brackish estuarine muds to marine gravels and sands to brackish estuarine muds the marine influence in the gravel and sand is also shown by the presence of marine dinoflagellates and a peak in na rb sedimentological chemical and paleontological in particular diatoms evidence indicates it is a csi we conclude that this was a tsunami and propose the most likely propagating mechanisms marine influence decreases upcore and totally freshwater conditions are evident in the upper section of the cores the geochemistry of the sediments mainly reflects the change in stratigraphy with distinct signatures for tephra na fe cr organic rich and peat units as br and the coarse gravel sand csi unit na rb cr fe but it is also indicative of changes in depositional environment the change in chemistry na rb in the csi event is indicative of a saltwater influence whereas a marked change in s content suggests a sudden change from brackish to freshwater conditions shortly after 4800 years bp another peak in s and br content about 3200 years bp may indicate another temporary change to brackish conditions

a late holocene record of environmental changes from coastal wetlands abel tasman national park new zealand abstract article size organic content loss on ignition loi geochemistry radiocarbon and 137cs analyses were carried out on paired cores taken from wainui totaranui and awaroa inlets abel tasman national park a 1700 year record of long and short term environmental changes was produced representing a sedimentary and geochemical sequence from tidal flat to mature salt marsh the sequence is punctuated by a series of short term environmental changes namely tsunami establishment of salt marsh and european settlement long term environmental changes include fluctuating accretion rates and relative sea level rise tsunami signatures include i a peak in fines ii contemporaneous or delayed peak in organic content and or loi iii contemporaneous peaks in fe and or s iv dilution of anthropogenic contaminants and v visible change in the sediments ruptures of the wellington and west wairarapa faults are considered to be the tsunamigenic sources pre european sediment accretion rates in abel tasman national park range from 0 5 to 1 7 mm a with post european settlement rates increasing to 1 6 2 7 mm a in the past 30 years rates have increased to 2 3 3 3 mm a the component of relative sea level rise is estimated to be about 1 3 2 2 mm a which compares favourably with the nearest tidal records from wellington

multi proxy records of regionally sourced tsunamis new zealand abstract a multi proxy study of sediment cores from kaituna bay mimiwhangata in northern new zealand has produced a record of three palaeotsunamis dated to around 6500 cal yr bp 2800 cal yr bp and 1450 ad these events punctuate a coastal palaeoenvironmental history spanning the last 8000 years or more in which the site progressed from a semi open lagoon to a freshwater swamp proxies used included stratigraphy geochemistry palynology diatoms foraminifera geomorphology and a regional palaeotsunami synthesis the identification of tsunamigenic sources for these events is tentative we propose that the two oldest events are associated with a source in the tonga kermadec trench region with the most recent possibly associated with the kuwae caldera collapse in 1452 1453 ad palaeotsunami deposits contemporaneous with the estimated age of the three events identified in this study were used to assist in identifying possible source regions the development of regional and national palaeotsunami databases is in its infancy but as more data become available the ability to determine the source magnitude and frequency of past events will improve this will greatly enhance our understanding of the regional risk from tsunamis

palaeotsunami deposits a new zealand perspective abstract over the past few years geological investigations of coastal sediments in new zealand have provided evidence of past tsunami the identification of palaeotsunami deposits is helping to increase our knowledge about the sources magnitude and frequency of these events this paper briefly outlines both the key diagnostic characteristics used in new zealand to identify palaeotsunami deposits and the emerging findings related to recent research