seismic moment catalog of large shallow earthquakes 1900 to 1989 we compile a worldwide catalog of shallow depth 70 km and large ms 7 earthquakes recorded between 1900 and 1989 the catalog is shown to be complete and uniform at the 20 sec surface wave magnitude ms 7 0 we base our catalog on those of abe 1981 1984 and abe and noguchi 1983a b for events with ms 7 0 those catalogs however are not homogeneous in seismicity rates for the entire 90 year period we assume that global rates of seismicity are constant on a time scale of decades and most inhomogeneities arise from changes in instrumentation and or reporting we correct the magnitudes to produce a homogeneous catalog the catalog is accompanied by a reference list for all the events with seismic moment determined at periods longer than 20 sec using these seismic moments for great and giant earthquakes and a moment magnitude relationship for smaller events we produce a seismic moment catalog for large earthquakes from 1900 to 1989 the catalog is used to study the distribution of moment released worldwide although we assumed a constant rate of seismicity on a global basis the rate of moment release has not been constant for the 90 year period because the latter is dominated by the few largest earthquakes we find that the seismic moment released at subduction zones during this century constitutes 90 of all the moment released by large shallow earthquakes on a global basis the seismic moment released in the largest event that occurred during this century the 1960 southern chile earthquake represents about 30 to 45 of the total moment released from 1900 through 1989 a frequency size distribution of earthquakes with seismic moment yields an average slope b value that changes from 1 04 for magnitudes between 7 0 and 7 5 to b 1 51 for magnitudes between 7 6 and 8 0 this change in the b value is attributed to different scaling relationships between bounded large and unbounded small earthquakes thus the earthquake process does have a characteristic length scale that is set by the downdip width over which rupture in earthquakes can occur that width is typically greater for thrust events at subduction zones than for earthquakes along transform faults and other tectonic environments

undrained triaxial strength and stress strain characteristics of a glacial till soil undrained triaxial compression tests were carried out on reconstituted and nominally undisturbed tubed samples of a lodgement till from the vale of st albans in hertfordshire england the soil is a matrix dominant chalky boulder clay of anglian age with little discernable engineering fabric electron microscope observations showed the presence of crystalline calcite in tube samples the test results were examined within the general framework of critical state soil mechanics using normalizing procedures to take account of the different states and stress histories of the samples these analyses demonstrate the practical importance of accounting for the current state and stress history in the interpretation of soil test data the present results form a self consistent pattern of behaviour differences between reconstituted and tubed samples were found only at small strain and may be attributed to cementing in tubed samples which is broken down during reconstitution and during relatively large straining in recompression and shearing

long term earthquake prediction in the circum pacific convergent belt investigation of the time dependent seismicity in 274 seismogenic regions of the entire continental fracture system indicates that strong shallow earthquakes in each region exhibit short as well as intermediate term time clustering duration extending to several years which follow a power law time distribution mainshocks however interevent times of the order of decades show a quasiperiodic behaviour and follow the regional time and magnitude predictable seismicity model this model is expressed by the following formulas begin gathered log t t 0 19 m min 0 33 m p 0 39 log m 0 q hfill m f 0 73 m min 0 28 m p 0 40 log m 0 m hfill end gathered which relate the interevent time tt in years and the surface wave magnitude mf of the following mainshock with the magnitude mmin of the smallest mainshock considered the magnitude mp of the preceded mainshock and the moment rate m0 in dyn cm yr 1 in a seismogenic region the values of the parametersq andm vary from area to area the basic properties of this model are described and problems related to its physical significance are discussed

chemical remobilization of volcanic hosted sulphide deposits at rosebery and mt lyell tasmania abstract devonian hydrothermal activity has resulted in localised chemical remobilization of the cambrian massive sulphide deposits at rosebery and mt lyell in the mt read mineral province of western tasmania at rosebery part of the massive pyrite sphalerite galena chalcopyrite quartz phyllosilicate lens has been replaced volume for volume by a pyrite pyrrhotite chalcopyrite magnetite phlogopite tourmaline quartz assemblage with complete removal of cambrian sphalerite and galena the replacement is later than folding of probable devonian age the likely temperature the presence of tourmaline and the relatively reduced nature of the secondary assemblage suggest that the related fluids were derived from devonian granitoids which on independent evidence tourmaline veins pyrrhotite deposits metamorphic biotite and shallow granites nearby appear to extend beneath the rosebery mice lead and zinc dissolved from the cambrian sulphide lens may have been redeposited as veins and replacements in younger rocks the resulting lead is likely to yield anomalous isotopic ages and be associated with sulphur having the isotopic characteristics of cambrian massive sulphide deposits at mt lyell altered felsic volcanics host large disseminated pyrite chalcopyrite quartz phyllosilicate lenses and minor stratabound exhalative massive sulphide bodies all of probable cambrian age in the north lyell fault zone late cambrian early ordovician siliciclastic sediments have been replaced by cherty quartz bornite chalcopyrite chalcocite sericite pyrophyllite ores of likely devonian age this assemblage probably formed from acid pyrophyllite oxidized barite solutions that may have derived high a cu a fe by dissolution of cambrian chalcopyrite disseminated pyrite chalcopyrite ores of cambrian age have a well developed devonian cleavage in which hematite has crystallized thereby indicating circulation of oxidized fluids during or after cleavage development precipitation mechanisms for the bornite ores may have involved fluid sulphide and or fluid sediment reactions the fluids are unlikely to have been derived directly from devonian granitoids but they may have been modified groundwaters circulating either during cleavage growth or as a result of heating by post kinematic devonian granitoid plutons

long term earthquake prediction along the western coast of south and central america based on a time predictable model the repeat times t of strong shallow mainshocks in fourteen seismogenic sources along the western coast of south and central america have been determined and used in an attempt at long term forecasting the following relation was determined log t 0 22 m min 0 21 m p a between the repeat time t and the magnitudes m min of the minimum mainshock considered and m p of the preceding mainshock no dependence of the magnitude m f of the following mainshock on the preceding interevent time t was found these results support the idea that the time predictable model is valid for this region this is an interesting property for earthquake prediction since it provides the ability to predict the time of occurrence of the next strong earthquake a strong negative dependence of m f on m p was found indicating that a large mainshock is followed by a smaller magnitude one and vice versa

the block structure and quaternary strike slip block rotation of central japan central japan is situated on the inflection point of the bow shaped japanese islands numerous nw se trending active faults arranged in parallel at intervals of 20 to 80 km are found in this area these active faults are more than 30 km long with shattered zones from 30 to 300 m wide several active faults constitute a given block boundary which serves as the dividing line for one of the four blocks that make up central japan the block boundaries require careful study since numerous historical earth quakes have occurred along these lines offset measurements of basement rocks created during the quaternary period due to left lateral faulting amount to 1 to 7 km gravity lineaments which link points of sudden change and saddles of bouguer anomalies are clearly found along the block boundaries the nw se trending active faults appearing on the ground surface are associated with motions of the block boundaries block rotational movement caused by left lateral faulting plays an important role in the crustal deformation of central japan rotational angles of the blocks calculated from the amount of displacement of basement rocks initiated during the quaternary period are estimated to be 3 to 7 in a clockwise manner

sunda strait and central sumatra fault sunda strait marks the limit between java trench frontal subduction and sumatra trench oblique subduction the right lateral central sumatra fault accommodates the oblique subduction it does not pass sunda strait but ends between sumatra and java in a complex pattern of dominantly normal faults associated with subsidence seismicity and volcanism we examine the implications of this phenomenon in sunda strait and in the adjacent fore arc basin and accretionary prism which underwent north south compression due to subduction as well as east west extension we propose that the strait is a consequence of the northwestward motion of the southwestern sumatra block along the central sumatra fault we also propose that the extensional zone in the sunda strait widens considerably to the southwest toward the trench and changes into a composite zone of deformation affected by strike slip as well as normal faulting

a revision of blight s model of field vane testing vane shear test data obtained by a number of researchers show that the excess pore pressures generated within the soil surrounding the vane by vane insertion and rotation and their effects on the m

foliation boudinage control on the formation of the rosebery pbzn orebody tasmania abstract the rosebery pb zn ag au massive sulphide deposit occurs within the middle cambrian mount read volcanics of western tasmania it is hosted by a tuffaceous slate lens that is surrounded by felsic volcanics the volcanic belt and its ordovician cover were deformed and metamorphosed during an early to middle devonian orogeny tabberabberan orogeny during this orogeny d 3 e w shortening was partially accommodated by reverse bedding parallel shearing within the slate unit and immediately underlying volcanic rocks this caused reactivation and intensification of an early foliation s 2 and the development of asymmetric chocolate tablet foliation boudinage structures with boudin necks parallel to the x and y directions the mineralization occurs along extensional shear planes that are associated with foliation boudinage mineralogical zoning in the orebody can be directly related to dilational bends in shears associated with foliation boudin necks it is proposed that these structures gaped during the d 3 deformation allowing infiltration of metalliferous hydrothermal fluids along shear plane and cleavage directions into the fractured wall rock progressive metasomatic replacement of the wall rock resulted in the formation of a sulphide sulphate silicate orebody the orebody is completely discordant to folds in the host rock this observation confirms a structurally controlled origin and refutes earlier interpretations of the deposit as a tightly folded chemical sediment isotope data indicate that the orebody was probaby derived from volcanogenic sulphides within the mount read volcanics the rosebery orebody is best regarded as a metamorphogenic deposit that formed by dissolution upward transport concentration and re precipitation of primary sulphides the proposed macroscopic model complements separate microstructural evidence by the author indicating a syn d 3 timing of mineralization

revision of magnitudes of large shallow earthquakes 1897 1912 abstract in previous research trace amplitudes of surface wave maxima recorded by undamped milne seismographs were used to determine the surface wave magnitudes ms of large shallow earthquakes which occurred prior to 1912 for this purpose the effective gain of these instruments was calibrated by using the surface wave magnitudes ms gr which were calculated from the unpublished worksheets for seismicity of the earth of gutenberg and richter in this paper the real quality of ms gr is critically re evaluated by using independent sets of data it is found that ms gr for the period 1904 1909 is considerably overestimated the average excess from the real ms is 0 5 units for 1904 1906 0 4 for 1907 0 3 for 1908 1909 and 0 0 for 1910 1912 this overestimation is so systematic and large that the previous results are all redetermined the average effective gain of milne instruments is revised to be 21 9 previously the gain depended on ms this revision results in systematic reduction in the previously assigned magnitudes the revised values of ms for 264 shallow earthquakes with ms 6 8 and over in the period 1897 1912 inclusive are listed the present revision is large enough to preclude the possibility of the high activity of large shallow earthquakes around the turn of the century the present results have a direct effect on all the magnitude catalogues of shallow earthquakes which occurred prior to 1909

the earthquake deformation cycle recurrence and the time predictable model geodetic and geologic observations from a handful of well studied great plate boundary earthquakes provide a basis for exploring those features of the deformation cycle having the strongest influence on recurrence estimation in ideal circumstances the time predictable model requires knowledge of only the seismic slip and time of the last earthquake and the rate of relative plate motion or fault slip practically indirect measurements must usually suffice local coseismic strain changes rather than seismic slip and local deformation rate rather than slip rate permanent nonrecoverable deformation often roughly half the coseismic strain offset near great thrust earthquakes complicates the inference of interplate seismic slip owing to short and long term postseismic transients commonly 20 40 of the coseismic strain drop deformation rates are variable and not simply related to the plate motion rate at strike slip plate boundaries these complications can sometimes be avoided and seismic slip and slip rate can be obtained more or less directly when these favorable circumstances are absent and when knowledge of the deformation cycle is incomplete recurrence accuracy can be improved by empirically correcting for unknown elements of the cycle systematic features in the spatial distribution of the transients and permanent deformation near subduction zones help identify the regions where these corrections are largest and where the shortcomings of the empirical approach are most severe

a time predictable model for earthquake generation in greece 20th century data have been used to determine repeat times t of main shocks in seven of the most active seismogenic sources of shallow earthquakes in greece it is observed that t depends on magnitude mp of the preceding main shock and not on the magnitude mf of the following main shock this means that the time predictable model and not the slip predictable model is valid for the main shocks of these sources a relation of the form log t cmp a fits the data while the parameter a depends on the seismicity of each source and on the minimum cutoff magnitude of the main shocks considered a representative of all sources value equal to 0 3 is found for parameter c when mp is surface wave magnitude and t is measured in yr

moment tensor summation to derive the active crustal deformation in japan abstract the country of japan and the surrounding area has been divided into 12 seismogenic sources which belong to five belts with an almost uniform orientation of the stress field in each one of these sources the active crustal deformation has been determined using the summation of the seismic moment tensors of mainly post 1964 earthquakes the analysis showed that due to the subduction of the philippine sea plate beneath the eurasian plate the deformation is expressed as compression at a mean direction of n53 w and an average rate of 1 5 cm yr the fault plane solution corresponding to the summed tensor indicates low angle thrust faulting with the following parameters strike 226 dip 21 and rake 98 along the sagami trough dextral strike slip motion is predominant at an average rate of 6 cm yr the summed tensor corresponds to a fault plane solution with strike 291 dip 73 and rake 180 along the districts of fukushima tohoku and the hokkaido island the motion of the pacific plate toward eurasia causes compression at a mean direction of n65 w and an average rate of 4 cm yr the summed tensor corresponds to a fault plane solution with strike 199 dip 18 and rake 81 that is low angle thrust faulting dipping toward the land this pattern resembles the hellenic arc where the deformation is also taken up by motion on low angle 18 thrust faults dipping to the north in the tohoku district the rate of motion reaches a value of 8 cm yr which is the highest calculated in the whole japan area in the inner part of the japanese islands along western honshu and niigata the mean p axis is almost horizontal trending nearly e w in western honshu the deformation is mainly expressed as dextral strike slip motion at an average rate of 5 cm yr in a n59 e direction the representative fault plane solution for this area has strike 240 dip 81 and rake 173 at niigata the western coast of hokkaido and further north at okushiri the deformation is taken up as compression at a mean direction of n96 e at an average rate of 2 cm yr the summed tensor corresponds to a fault plane solution with strike 5 dip 41 and rake 90 the calculated directions and rates of motion along the japanese islands are in good agreement with the expected values from plate motion models

k o ocr relationships in soil the relationships between k o and ocr are investigated for primary loading unloading reloading conditions the study reviews laboratory data from over 170 different soils and presents an approach common to clays silts and sands simple empirical methods for predicting k o for normally consolidated and overconsolidated soils are evaluated the validity of the methods is supported by statistical analyses on the basis of the findings only the effective stress friction angle o and prior stress history ocr and ocrmax are needed to predict approximate values of k o

long term earthquake prediction in central america and caribbean sea based on the time and magnitude predictable model abstract instrumental and historical information on strong mainshocks for 12 seismogenic sources in central america and caribbean sea has been used to show that the interevent time t t in years between two strong earthquakes and the magnitude m f of the following mainshock are given by the relations log t t 0 30 m m i n 0 48 m p 0 69 log m 0 13 70 m f 0 98 m m i n 0 31 m p 0 28 log m 0 4 55 where m min is the surface wave magnitude of the smallest mainshock considered m p the magnitude of the preceding mainshock and m 0 the moment rate per year in each source on the basis of these relations the probability of the occurrence of a mainshock during the decade 1993 to 2002 as well as the magnitude of this expected mainshock in each seismogenic source has been calculated the highest probability p 10 0 67 was estimated for the seismogenic source of el salvador a 1 for the occurrence of a large earthquake with expected magnitude m f 7 5 and high probabilities p 10 0 55 were estimated for the seismogenic sources of jamaica c 3 and puerto rico c 5 for earthquakes with expected magnitudes m f 7 5 in both sources

integration of geological and seismological data for the analysis of seismic hazard a case study of japan seismic hazard analyses are associated with large uncertainties when historical data are insufficient to define secular rates of seismicity such uncertainties may be decreased with geological data in areas where seismicity is shallow and produced by quaternary faulting to illustrate we examine intraplate japan large intraplate earthquakes in japan characteristically produce surface ruptures along mappable quaternary faults and show a systematic relation between seismic moment m 0 and rupture length i log m 0 23 5 1 94 log i it is observed that within the bounds placed by geologically assessed slip rates the mean regional moment release rate m 0 resulting from slip on mapped quaternary faults is in accord with estimates of m 0 determined with the 400 yr record of seismicity recent work also shows that when the repeat time t of earthquakes on quaternary faults in southwest japan is assumed to equal m 0 m 0 g where m 0 is estimated for rupture extended over the entire fault length and m 0 g is the geologically assessed moment release rate of each fault the moment frequency distribution of earthquakes predicted from the geologic record is virtually identical to that seen with the 400 yr record of seismicity these observations indicate that the geologic record of quaternary fault offsets contains sufficient information to predict both the spatial and size distribution of intraplate earthquakes in japan a contour map of the average recurrence time of ground shaking of jma intensity v is thus computed using an empirical relation between seismic moment and the areal distribution of seismic intensity and assuming that the repeat time t of earthquakes on each quaternary fault equals m 0 m 0 g the map demonstrates how quaternary fault data may be used to assess long term seismic hazard in areas of active faulting where historical records of seismicity are relatively short or absent another shortcoming of conventional seismic hazard analysis is that hazard is not considered a function of the time since each fault in a region last ruptured a simple procedure is used to demonstrate how the time dependent nature of the earthquake cycle affects the evaluation of seismic hazard the distribution of seismic shaking characteristic of large interplate earthquakes offshore of japan is estimated from published isoseismal maps the observed average repeat times of ruptures along specific segments of the plate boundaries then provide the basis to make probabilistic estimates of the next expected time of seismic shaking due to plate boundary earthquakes when data are too few to document the average repeat times of rupture the estimates of probability are calculated with data relating to the relative coseismic slip during past earthquakes and the rate of interseismic strain accumulation interpreted within the framework of the time predictable model of earthquake occurrence results are displayed as maps of instantaneous seismic hazard the probability that seismic shaking will occur conditional to knowledge of where in time each fault in a region presently resides with respect to the earthquake cycle

an application of the time and magnitude predictable model for the long term prediction of strong shallow earthquakes in the japan area the country of japan and its surrounding area has been divided into 12 seismogenic sources on the basis of certain seismotectonic and geomorphological criteria in each of these sources interevent times between successive mainshocks with magnitudes equal to or larger than certain cutoff magnitudes were considered these interevent times as well as the magnitudes of the mainshocks have been used to determine the following relations log t t 0 30 m min 0 19 m p 0 18 log m 0 2 41 m f 0 88 m min 0 25 m p 0 46 log m 0 9 06 where tt is the interevent time measured in years m min is the surface wave magnitude of the smallest mainshock considered mp is the magnitude of the preceding mainshock mf is the magnitude of the following mainshock and m is the yearly released seismic moment in each source on the basis of these two relations and taking into account the time of occurrence and the magnitude of the last mainshock in each source time dependent conditional probabilities for the occurrence of the next large ms 7 5 shallow mainshocks in the 12 seismogenic sources during the next 10 yrs 1993 to 2002 and the magnitudes of the expected mainshocks are determined for seismogenic sources 5 fukushima 9 western honshu 7 southern hokkaido 1 ryukyu islands and 12 okushiri island relatively high probabilities p 10 0 5 were assigned it is of interest to note that in seismogenic source 12 okushiri for which an expected magnitude of 7 5 was calculated an earthquake with a magnitude of 7 6 national earthquake information center occurred on 12 july 1993

seismicity of the sunda strait evidence for crustal extension and volcanological implications the sunda strait is located in the transitional zone between two different modes of subduction the java frontal subduction and the sumatra oblique subduction this setting implies that the sunda strait region is a key to the understanding of the geodynamic processes involved in order to study the shallow seismicity a microearthquake survey was carried out in that region twelve stations accurately located by the aim of satellite positionning recorded about 300 local events in the summer 1984 from this set 174 shallow earthquakes have been precisely located the results of this study reveal that the crustal earthquakes in the sunda strait area occurs in three main areas 1 beneath the krakatau complex where earthquakes are generated by double couples and are of tectonic origin 2 inside a graben in the western part of the strait and 3 in a more diffused zone to the south of sumatra the individual and composite focal mechanisms from the events inside the strait show an extensional regime a stress tensor which have been deduced from the individual focal mechanisms of earthquakes of the krakatau group shows that the tensional axis is oriented n130oe this study confirms that the sunda strait is in an extensional tectonic regime as a result of the northwestward movement of the sumatra sliver plate along the semangko fault zone

magnitudes of large shallow earthquakes from 1904 to 1980 abstract in order to obtain a uniform magnitude catalogue surface wave magnitudes ms and broad band body wave magnitudes mb have been determined for large shallow earthquakes from 1904 to 1980 in making the catalogue homogeneous the author consistently adheres to the original definitions of ms and mb given by gutenberg 1945 and gutenberg and richter 1956 the determinations of ms and mb are all based on the amplitude and period data listed in gutenberg and richter s unpublished notes bulletins from stations worldwide and other basic information mb is measured on broad band instruments in periods of 8 s consistency of the magnitude determinations from these different sources is carefully checked in detail more than 900 shallow shocks of magnitude 7 and over are catalogued the meaning of the magnitude scales in various catalogues is examined in terms of ms and mb most of the magnitudes listed by gutenberg and richter 1954 in their seismicity of the earth are basically ms for large shocks shallower than 40 km but are basically mb for large shocks at depths of 40 60 km the surface wave magnitudes given by earthquake data reports are higher than ms by 0 2 unit whether the combined horizontal amplitude or the vertical amplitude is used mb and the currently used 1 s body wave magnitude are measured at different periods and should not be directly compared

effective stress vane shear strength correction factor correlations a recent effective stress model of vane shear strength testing in soils can relate measured torques to vane shear strengths using theoretical analysis in terms of effective stress parameters the strength estimates are based on known in situ stresses and soil parameters derived from laboratory testing the model may be applied for example in obtaining theoretical estimates of conventional undrained vane shear strengths for comparison with field data and for use in stability analyses however the model incorporates a correction factor v analogous to bjerrum s field vane shear strength correction factor intended to compensate for pore pressure and shearing rate effects this correction factor must be evaluated before reliable torque or shear strength estimates can be made in any given case to facilitate this the paper presents correlations of v with both liquid limit and plasticity index based on world wide data from clays and silts the correlations are compared with independent data from norwegian clays

pyrite composition and ore genesis in the prince lyell copper deposit mt lyell mineral field western tasmania australia the prince lyell copper gold silver deposit occurs in the late cambrian mt read volcanics at queenstown tasmania steeply plunging broadly conformable lenses of disseminated and stringer pyrite chalcopyrite mineralisation occur in quartz sericite chlorite rocks derived from intense alteration of predominantly felsic lavas and volcaniclastic rocks middle devonian deformation has substantially modified primary sulphide textures although extensively fractured pyrite grains in the ore have retained their original pre deformation internal structure and chemistry which are revealed by etching and electron microprobe analysis earliest sulphide mineralisation produced oscillatory zoned cobalt rich pyrite pyrite i coeval with chalcopyrite mineralisation cobalt rich pyrite is commonly associated with cambrian volcanic rocks in western tasmania and suggests a volcanogenic origin for the ore fluids at prince lyell pyrite i was corroded by later hydrothermal fluids and reprecipitated as unzoned trace element poor pyrite pyrite ii commonly as overgrowths on pyrite i cores minor amounts of a second cobalt rich pyrite pyrite iii occurs with pyrite ii in composite pyrite overgrowths sulphur isotope ratios from all pyrite generations fall within a small range 3 to 11 in situ isotopic analyses showed no consistent 34s variation between the various pyrite generations suggesting recycling of sulphur derived from a single cambrian volcanogenic source hematite alteration derived from oxidised fluids possibly from the adjacent hematitic owen conglomerate occurs in the structural footwall volcanics and the great lyell fault zone hematite inclusions in pyrite ii and iii indicate that these pyrite generations occurred after or during deposition of the conglomerate it is postulated that pyrite ii and iii were deposited during waning volcanism contemporaneous with owen conglomerate sedimentation in the late cambrian or early ordovician the great lyell fault would have acted as a growth fault margin between a terrestrial basin filling rapidly from the east and the volcanic terrane to the west the scenario raises the possibility that the concentration of mineral deposits and hematitic alteration along the great lyell fault resulted from the subsurface interaction of reduced volcanogenic fluids and oxidised basin waters along the growth fault contact

long term earthquake prediction along the north and east anatolian fault zones based on the time and magnitude predictable model summary the north and east anatolian fault zones have been separated into 10 seismogenic sources on the basis of certain seismological and geomorphological criteria in each of these sources the interevent times between successive main shocks with magnitudes equal to or larger than a certain magnitude threshold were considered these times and the magnitudes of the main shocks have been used to determine the following empirical relations log tt 0 27 mmin 0 19 mp a mf 0 76 mmin 0 48mp m where tt is the interevent time measured in years m min the surface wave magnitude of the smallest main shock considered mp is the magnitude of the preceding main shock and mf is the magnitude of the following main shock multiple correlation coefficients equal to 0 83 and 0 70 and standard deviations equal to 0 16 and 0 34 were calculated for the first and second of these relations respectively on the basis of these relations and taking into account the time of occurrence of the last main shock the probabilities of occurrence of main shocks in each seismogenic source during the next decade were determined

microstructural timing of the rosebery massive sulphides tasmania evidence for a metamorphic origin through mobilization of disseminated base metals microstructural timing relationships indicate that the rosebery massive sulphide ore western tasmania australia formed by metasomatic replacement of sericite schist during a devonian deformation event d3 this interpretation is contrary to earlier volcanogenic based interpretations but accords with the discordant position and inferred structurally controlled emplacement of the orebody the main timing criteria are overprinting of s3 by the late ore minerals replacement textures in undeformed mineral parageneses and a d3 structural control from the microscopic to the macroscopic scales the consistent observation of these criteria in the orebody and the complete lack of pre d3 ore argue against in situ dissolution of a primary orebody and local redeposition of sulphides by replacement d3 deformation at rosebery is inferred to have been characterized by heterogeneous cleavage parallel extension which resulted in localized microfracturing and selective replacement of zones of maximum strain rate continuous shifts in the strain rate distribution pattern during progressive mineralization led to the compositional ore banding published pb isotope data point towards a cambrian source rock for the orebody this suggests a metamorphogenic origin by regional scale dissolution of dispersed volcanogenic metals focused solution transfer and concentrated redeposition in a structural trap

wall rock alteration and metamorphism of a volcanogenic massive sulfide deposit at que river tasmania petrology and mineralogy the rocks in the alteration halo surrounding the polymetallic massive sulfide deposit at que river preserve primary hydrothermal mineral textures and assemblages despite the imprint of later prehnite pumpellyite facies regional metamorphism their textural preservation is attributed to the mechanical strength of many of the hydrothermal minerals such as pyrite carbonates except calcite and quartz the competency of some of the host rocks and the low strain that has affected many rocks at the margin of the halo assemblages include quartz white mica carbonates albitized plagioclase pyrite and chlorite closer to the ore as intensity of alteration increases albite disappears pyrite apatite rutile and anatase become more common white mica quartz carbonates and chlorite vary in abundance and are distributed irregularly these minerals also occur in hydrothermal veins throughout the stockwork zone several generations of veins are commonly developed with each generation having its own distinctive hydrothermal assemblage both hydrothermal and metamorphic phases are compositionally variable despite some overlap there appear to be systematic differences in composition x ray diffraction and microprobe analyses show that the hydrothermal white micas are variable in composition ranging from illites or muscovites to fuchsites their metamorphic counterparts contain less pyrophyllite and more celadonite the hydrothermal carbonates are most commonly ferroan dolomite magnesian siderite and ferroan magnesite the latter two are more abundant than dolomite where alteration is intense calcite and ferroan dolomite formed during metamorphism and the composition of the hydrothermal and metamorphic carbonates may be different in individual specimens both hydrothermal and metamorphic chlorites are ferro clinochlores and magnesio chamosites metamorphic chlorites outside the halo are more fe rich and more al vi deficient than those within the hydrothermal chlorites exhibit fe mg and al iv al vi si iv mg fe vi tschermakite substitutions and contain al iv contents suggesting temperatures of crystallization of 290 degrees to 320 degrees c similar to the temperature of 280 degrees c inferred from fluid inclusions the chemistry of the hydrothermal phases varies throughout the halo overall fe and mg do not show a systematic trend toward mineralization however fe enrichment of hydrothermal phases in the ore is apparent as is mg enrichment of locally developed chlorite carbonate rocks na and celadonite in white micas and ca in carbonates on the other hand decrease with increasing alteration mg only became an important component in the fluid when seawater infiltrated into the hydrothermal system the heterogeneous distribution of the hydrothermal phases is attributed to successive influxes of hydrothermal fluids of varying composition into the alteration pipe variable water rock ratios and seawater entrainment

geochemistry of wallrock alteration rosebery tasmania australia the rosebery ore deposit consists of two adjacent massive sulphide bodies hosted in an easterly dipping lens of sedimentary rocks within a pile of acid pyroclastic rocks of cambrian age both orebodies are underlain by zones of intense alteration which mark the path of the metal bearing fluids the southern vent is exposed on the surface its alteration zone extends for up to 2 km in a n s direction and has a maximum e w width of 700 m the footwall and to a minor degree the hanging wall have been subjected to hydrothermal alteration in the field this alteration is marked by plagioclase free quartz sericite chlorite schists which exhibit two different facies siliceous augen schists and thinly cleaved k feldspar bearing schists samples can be grouped geochemically into altered and unaltered volcanics despite the large variation in chemical composition within each group this classification is supported by cluster analysis in the vicinity of the deposit concentrations of sio2 k2o and rb are anomalously high while contents of al2o3 na2o tio2 cao sr zr y and nb show a significant depletion at the outer limit of the alteration halo the hydrothermal influence is more easily detected geochemically than geologically

microstructural observations of shear zones in sensitive clay abstract the present work assesses the structure and evolution of shear zones in sensitive quick clays from the initiation to the well established state this assessment is done by utilizing laboratory and small scale field experiments combined with the analysis of thin sections in light microscopy and sem high resolution x ray tomography micro ct is also applied in combination detailed 2d and 3d visualization of the shear zones is achieved shear zones are suggested to be formed in mm thick continuous fields of displacement with increasing shear displacement sets of micron sized minor shears develop within the main shear zone these initiate terminate and merge both in the plane and out of the plane directions the minor shears are characterized by distinct particle reorientation where the flaky clay particles and mica grains are aligned parallel to the direction of shear a porosity reduction is observed in the minor shears this is a direct observation of material contractancy and implies migration of water from the shear zone into the undisturbed matrix the width of the main shear zone is considered to be related to the applied rate of shear while the minor shears have a width determined by the micro texture of the sediment the observed multi scale structure of the shear zones which is governed by complex inner mechanics is challenging the smooth shear zone concept that is commonly applied in numerical simulations this is motivating a further improvement of such tools and the testing of other types of clay sediments

a time and magnitude predictable model for generation of shallow earthquakes in the aegean area repeat times of strong shallow mainshocks have been determined by the use of instrumental and historical data for 68 seismogenic sources in the aegean and surrounding area 34 n 43 n 18 e 30 e for 49 of these sources at least two interevent times three mainshocks are available for each source by using the repeat times for these 49 sources the following relation has been determined log t t 0 36m min 0 35m p a wheret t is the repeat time measured in years m p the surface wave magnitude of the preceding mainshock mmin the magnitude of the smallest earthquake considered and a parameter which varies from source to source a multilinear correlation coefficient equal to 0 89 was determined for this relation

the effect of local drainage in shear zones on the undrained strength of overconsolidated clay in soil mechanics undrained loading of saturated soil implies constant volume and constant water content so that in the measurement and application of undrained strength it is assumed that the water content at failure is the same as the initial water content during shearing of overconsolidated soils shear zones occur in which there are large strains and any small flow of water into these shear zones from the neighbouring soil has the consequence that the soil is no longer strictly undrained as a result the undrained strength measured in laboratory and field tests will depend on the degree of local drainage as well as on several other factors such as the test conditions and sample size to examine the effect of local drainage on undrained strength triaxial compression tests were carried out on reconstituted london clay at various overconsolidation ratios and loaded at different speeds where shear zones occurred their geometry was found to be consistent with volumetric straining due to local drainage a

long term earthquake prediction of large shallow mainshocks along the tonga kermadec new zealand seismic zone based on a time and magnitude predictable model abstract repeat times of large shallow mainshocks in thirteen seismogenic sources along the tonga kermadec new zealand seismic zone have been used to establish the validity of the time and magnitude predictable model for earthquake occurrence this model is expressed for this region by the relations logtt 0 09mmin 0 43mp 0 41 logmo 8 08 and mf 0 71mmin 0 20mp 0 47 logmo 8 37 where tt is the inter event time measured in years mmin the surface wave magnitude of the smallest mainshock considered mp the magnitude of the preceding mainshock mf the magnitude of the following mainshock m o the moment rate in each source per year given that the log normal distribution is more appropriate to fit the t tt data where t is the observed repeat time and tt that given by the first of these relations as well as the date and the magnitude of the last mainshock in each seismogenic source conditional probabilities are determined for the next 10 years 1993 2002 on the other hand the second of these relations has been applied to calculate the magnitude mf of the expected large ms 7 0 and 7 5 mainshock in each seismogenic source at present six of these seismogenic sources tafahi island tongatapu islands the north and central kermadec islands north island of new zealand and macquarie island exhibit relatively high p10 0 50 probabilities for the occurrence of a mainshock with ms 7 0 in two of these sources tafahi island and north island the probability is also high p10 0 53 and 0 50 respectively for the occurrence of a mainshock with ms 7 5

a laboratory study of post rupture strength stiff intact clays exhibit rapid loss of strength after failure with the formation of slip surfaces and the development of a well defined post rupture strength envelope this paper describes an experimental study of the influence of a number of factors on the post rupture strength of initially intact samples of vallericca clay these include changes in confining pressure after the formation of a slip surface the magnitude of the relative displacement across the surface comparison between the post rupture strength envelopes in triaxial compression and extension and the influence of existing slip surfaces on the formation and strength of subsequent rupture planes formed by rotation of the principal stresses the results show that the post rupture strength envelope is well defined repeatable and not very sensitive to stress history or the rotation of the principal stresses little reduction in shearing resistance takes place for relative displacements up to about 10 mm the results are believed to be

long term behaviour of reconsolidated clay around a driven pile extensive in situ testing and undisturbed sampling were carried out near two steel piles to determine the long term state of a clay in which these piles had been driven 7 years before results show that this material exhibits a rigidity that varies with the distance from the pile the average rigidity in the zone of study is representative of a slightly destructured clay the shear strength of this clay is in most cases equal to the shear strength of the intact material except in the zone located at depth greater than 3 5 m and within 30 cm of the pile wall where lower shear strength values were consistently monitored it is believed that reconsolidation after driving took place in this last case under relatively low stresses key words piles clays ageing destruction reconsolidation shear strength rigidity limit state

probabilities of occurrence of large plate rupturing earthquakes for the san andreas san jacinto and imperial faults california 1983 2003 the san andreas san jacinto and imperial faults in california are divided into 19 segments conditional probabilities are calculated that a particular segment will be the site of a large plate rupturing earthquake i e an event that breaks the entire down dip extent of the seismogenic zone during the next 20 years the sizes of such events which account for most of the slip that occurs seismically appear to vary greatly for different segments of these faults repeat time of large shocks coseismic displacement moment release rupture length and seismic magnitude appear to correlate with one another and to be a function of the tectonic style of different parts of those fault zones tectonic inhomogeneities on a scale of about 1 to 100 km are much larger than displacement in any single seismic event and may be regarded as being invariant in their effects upon earthquake generation over many cycles of large shocks it is this invariance that appears to lead to a given segment of a fault rupturing repeatedly in events of nearly the same size since repeat time varies however for a given segment of a fault a simple probabilistic approach is used to forecast the likelihood of large future earthquakes for each segment using as input the time of the last large shock the average recurrence time and the standard deviation of time intervals between events dates of the last large shocks are available for most of the segments investigated repeat times are estimated from times of historic and prehistoric events tectonic similarity and times calculated from coseismic displacement in the last large shock divided by a rate of fault motion or strain buildup the standard deviation of time intervals divided by the average repeat time is close to 1 3 for three fault segments in california for which data are available on historic and prehistoric earthquakes that normalized value is adopted for all calculations of conditional probability magnitudes and seismic moments of future plate rupturing events are estimated for each fault segment several of the segments have well constrained probabilities for rupture during the next 20 years whereas others have large uncertainties eight of the segments constituting about 40 of the total lengths of the three faults have moderate to high probability and thus should be instrumented and studied extensively so as to provide shorter time warnings in some cases two adjacent segments may be nearly in phase in their loading history and may break in a single event the segment of the san andreas fault from opposite san jose to san juan bautista which ruptured less than 1 5 m in 1906 and which probably also broke in 1838 is calculated to have a moderate to high probability of an earthquake of magnitude 6 to during the next 20 years a 325 km section of the southern san andreas between tejon pass and the salton sea has about a 25 chance of rupturing in a shock of magnitude near 8 during the next 20 years all the other segments have only a small chance i e less than 5 to 10 of rupturing in an event of magnitude near 8 during that interval

insights into the liquid bismuth collector model through analysis of the bi au stormont skarn prospect northwest tasmania the liquid bismuth collector model has previously been proposed to explain the common association between gold and bismuth seen in many ore deposits and involves the scavenging of gold from hydrothermal fluid by liquid bismuth here textural relationships and temperature and chemical conditions of mineralization at the stormont bi au skarn prospect in northwestern tasmania are analyzed to investigate whether the liquid bismuth collector model can explain gold accumulation at this prospect the calc silicate skarn assemblage containing grandite hedenbergite actinolite magnetite epidote quartz and calcite suggests that initial metasomatism involved temperatures 400 to 500 c visible gold is associated with native bismuth bismuthinite maldonite galena and an unknown bi te s mineral native bismuth is directly associated with grandite which formed during initial stages of metasomatism this implies that bismuth would have precipitated from a hydrothermal fluid as a liquid heating experiments showed that bismuth alloy inclusions in garnet melt between temperatures of 250 and 288 c the mineralization setting at stormont and textural relationships suggest that gold was scavenged from hydrothermal fluids by liquid bismuth rhythmically zoned grandite crystals provide evidence for fluctuating hydrothermal fluid conditions which may have contributed to dissolution and reprecipitation of gold thus facilitating an ore zone refining process within the prospect this refining process is made possible by the tendency of liquid bismuth to scavenge gold from significantly under saturated fluids infiltrating gold undersaturated fluids can dissolve gold not in contact with bismuth which can then be preferentially redeposited upon encountering a bismuth droplet enhancing the correlation between the two elements a long lived and focused fluid flow system would maximize the efficiency of this ore zone refining process which is likely to be relevant to gold deposition at a range of deposit types

stratigraphy and mineralization in the mt read volcanics western tasmania most of the known sulfide mineralization in the mt read volcanics occurs within a central belt of rhyolitic dacitic andesitic volcanics 9 to 12 km wide and roughly 90 km long in which felsophyric lavas and ash flows are common but sediments are rare the volcanics resemble rhyolitic caldera complexes in part and large sections appear to be subaerial sediments and tuffs which probably represent marine embayments are also present and the exhalative massive sulfides tend to coincide with local marine units preliminary radiometric dating indicates a middle cambrian age for the belt at queenstown the central belt is flanked on the western side by folded volcano sedimentary marine sequences partly of middle cambrian age in which volcanic lithic turbidites and quartz phyric tuffs are common contacts with the central belt range from abrupt and faulted to conformable and possibly interfingering and interpretation of the relationship is difficult some evidence suggests that the mineralized belt may represent a volcano tectonic rift structure superimposed on a larger marine basin overlying the central belt in the queenstown mt darwin area is an unmineralized sequence of volcaniclastic conglomerates and quartz phyric volcanics of late middle cambrian to late cambrian age deposition of this sequence occurred largely in local graben structures and was accompanied by considerable erosion of the earlier volcanics some mineralization in the darwin mt lyell area was probably removed at this stage

time dependent seismicity in the indonesian region the indonesian region was divided in 23 seismogenic sources and the interevent times of strong shallow mainshocks were determined and used for each source in an attempt at long term forecasting the following relations have been obtained log tt 0 15mmin 0 34mp 0 34 log mo 6 54 and m 0 92mmin 0 34mp 0 53 log mo 10 60 where tt is the interevent time measured in years mmin the surface wave magnitude of the smallest mainshock considered mp the magnitude of the preceding mainshock m the magnitude of the following mainshock and mo the moment rate in each source per year on the basis of these relations and taking into account the time of occurrence and the magnitude of the last mainshock in each seismogenic source time dependent conditional probabilities for the occurrence of the next large ms 7 0 shallow mainshocks during the next 10 years as well as the magnitudes of the expected mainshocks are determined

high precision u pb zircon chronostratigraphy of the mount read volcanic belt in western tasmania australia implications for vhms deposit formation the middle cambrian mount read volcanics of western tasmania australia host several world class volcanic hosted massive sulfide vhms deposits representing a wide range of deposit styles although the deposits and their host sequences are variably deformed and locally preserve spectacular examples of primary textures and structures rapid lateral and vertical facies changes and faults with uncertain sense and magnitude of displacement have made it impossible to correlate stratigraphy across the belt previous dating studies in the area have yielded relatively imprecise crystallization ages we have employed the chemical abrasion isotope dilution thermal ionization mass spectroscopy id tims u pb zircon method to obtain highly precise crystallization ages for a total of 18 samples of volcanic and intrusive rock units from throughout the mount read volcanics and underlying mafic ultramafic complexes the new data permit detailed resolution of age relationships within the belt the study establishes an age of 516 0 0 9 ma for the mcivor hill gabbro which is part of a mafic ultramafic complex interpreted to underlie the mount read volcanics magmatism in the central mount read volcanics lasted at least 12 7 m y from 506 8 1 0 ma for a massive dacite unit in the lower part of the central volcanic complex to 496 0 0 9 ma for a welded ignimbrite in the lower tyndall group together with previous age constraints results of the study provide a precise chronostratigraphic framework for magmatism and vhms deposit formation within the mount read volcanics the precise age data indicate that north of the henty fault magmatism occurred in three discrete pulses at least two of which were separated by periods of sedimentation we demonstrate that vhms deposits in the mount lyell roseberry hercules and que hellyer districts comprising the majority of the known significant vhms deposits in the belt formed within a narrow time interval at 500 1 ma at a relatively late stage in the evolution of the belt some of the larger intrusions in the belt e g the bonds range porphyry 500 4 0 8 ma were emplaced contemporaneously with vhms deposit formation however other bodies such as the murchison granite 497 3 0 9 ma are younger than the deposits and are unlikely to have been involved in their genesis as has previously been suggested these conclusions will aid explorers in targeting vhms mineralization in the mount read volcanics

tectonic setting of cambrian rifting volcanism and ophiolite formation in western tasmania abstract in western tasmania small precambrian regions are surrounded by a ramifying system of troughs filled with cambrian sedimentary and volcanic rocks and ophiolite complexes the volcanic associations include a rift related olivine tholeiite association dacite rhyolite and andesite associations and a low ti high mg andesite tholeiite ophiolite association and may have formed during a long lived period of crustal thinning punctuated by episodes of crustal rupturing magmatism and small scale rifting such extensional tectonism could occur in an active continental margin associated with strike slip faulting of regional scale and the volcanic associations may together constitute an igneous assemblage characteristic of magmatism in a transcurrent tectonic regime within an active continental margin undergoing break up the western tasmanian cambrian palaeogeography and volcanism preserve a transitional stage between the late proterozoic kanmantoo regime of sedimentary basins with little volcanism developed at the rifting margin of the proterozoic craton and the tectonic regime of the palaeozoic lachlan fold belt where the cambrian volcanic rocks are dominated by island arc associations and the rift related olivine tholeiite association is absent eastern australian lithosphere may have grown by the insertion of newly formed igneous complexes within the stretched and rifted continental margin as well as by the accretion of terrenes and the addition of packets of subduction complexes which developed off shore

subaqueous pyroclastic flows and ignimbrites an assessment an assessment of the literature on subaqueous pyroclastic flows and their deposits shows that the term pyroclastic flow is frequently used loosely to describe primary hot gas rich pyroclastic flows mass flows which resulted from the transformation of gassupported flows into water supported ones and secondary mass flows carrying redeposited pyroclastic debris based on subaerial pyroclastic flows the term pyroclastic flow should be restricted to demonstrably hot gas rich mass flows of pyroclastic debris using this definition very few examples of subaqueous pyroclastic deposits with evidence for hot emplacement and of having been wholly submerged have been described in the majority of these cases the evidence for a hot state of emplacement and for the subaqueous nature of the host depositional environment is inadequate the only unequivocal cases of hot pyroclastic flow deposits with adequate supporting evidence are the ordovician nearshore shallow marine ignimbrites of ireland and wales and miocene ignimbrites of southwest japan resulting from the passage of subaerially erupted pyroclastic flows into shallow water other possible examples are near vent dense clast deposits in the donzurobo formation of japan possible submarine intra caldera ponded ignimbrite successions in california and wales and near vent pumiceous deposits of ramsay island wales all other purported cases are either clearly the result of water supported mass flow transportation and deposition debris avalanches debris flows turbidity currents or lack adequate supporting evidence regarding the heat state or the palaeoenvironment only the shallow marine ignimbrites of ireland and wales show adequate evidence of welding but even these could have been nearly wholly exposed above sea level when welding occurred we conclude that when pyroclastic flows enter water they are generally disrupted explosively and or ingest water and transform into water supported mass flows and we suggest the various scenarios in which this occurs there is no evidence to suggest that welding in wholly subaqueous environments is common

circum pacific seismic potential 1989 1999 the seismic potential for 96 segments of simple plate boundaries around the circum pacific region is presented in terms of the conditional probability for the occurrence of either large or great interplate earthquakes during the next 5 10 and 20 years i e 1989 1994 1989 1999 and 1989 2009 this study represents the first probabilistic summary of seismic potential on this scale and involves the comparison of plate boundary segments that exhibit varying recurrence times magnitudes and tectonic regimes presenting these data in a probabilistic framework provides a basis for the uniform comparison of seismic hazard between these differing fault segments as well as accounting for individual variations in recurrence time along a specific fault segment and uncertainties in the determination of the average recurrence time

deformation of an island arc rates of moment release and crustal shortening in intraplate japan determined from seismicity and quaternary fault data the historical record of large m 6 9 earthquakes and geologically determined rates of slip on quaternary faults in intraplate japan honshu and shikoku are used to estimate the average rate of seismic moment release m for the last 400 years and during the late quaternary respectively values of m estimated from the two data sets are similar in regions where seismic activity is concentrated on land we interpret this observation to suggest that m in intraplate japan has been constant during the late quaternary and is relatively free from secular variation when averaged over periods of several hundreds of years m in shikoku may be attributed almost solely to right lateral slip of the median tectonic line mtl the easterly strike of the mtl is consistent with a compressive stress field that trends northwest crustal shortening of the izu peninsula taken up on a set of strike slip faults that show north by northwest compression is 1 mm yr northeast honshu is characterized by a set of reverse type faults that trend northerly conversion of m in northeast japan to strain rates suggests that about 5 of the relative plate motion between japan and the pacific plate 9 7 cm yr is accommodated as a permanent east west shortening 5 mm yr of northeast honshu the predominant deformation in central and western honshu takes place as slip on a conjugate system of strike slip faults that strike northeast and southeast and show right lateral and left lateral motion respectively crustal shortening resulting from slip on faults in central and western honshu is 5 and 0 5 mm yr respectively in an easterly direction central and western honshu are in closest proximity to the nankai trough and hence the stress field in these regions cannot simply be attributed to the accommodation of the relative northwesterly convergence of the philippine sea plate the northward impingement of the izu peninsula into honshu may influence stresses in central and western japan but a conclusive explanation of the stress field in central and western honshu remains an enigma

test and application of the time and magnitude predictable model to the intermediate and deep focus earthquakes in the subduction zones of the circum pacific belt abstract the test and application of the time and magnitude predictable model in the subduction zones around the circum pacific belt is performed each subduction zone was separated in several seismogenic regions on the basis of tectonic and geometrical features of the subducting lithosphere and for three different depth ranges the data derived from these seismogenic regions were used in order to check the suitability of the regional time and magnitude predictable model as this model was defined for shallow events the results obtained in the present study confirm that this model appropriately describes the behavior of deep seismicity in these regions since a positive c 0 31 0 003 and a negative c 0 13 0 047 dependence were found for the logarithm of the interevent times and the magnitude of following mainshock respectively on the magnitude of the preceding mainshock moreover the slip predictable model was rejected since a negative dependence was found e 0 19 between the interevent times and the magnitudes of the following mainshock probabilities of occurrence of the future strong m 7 0 events in each seismogenic region have been determined for the next decade conditioned on the previous occurrence of such events the magnitudes of the expected events have also been estimated statistical tests for the estimated probabilities exhibit a good correlation with the occurrence rate of such events furthermore the statistical significance of the model has been studied through additional tests the results of this study demonstrate the validity of the regional time and magnitude predictable model in the areas examined

earthquakes and ophiolite emplacement in the molucca sea collision zone indonesia the molucca sea in eastern indonesia is the site of an active arc arc collision and among its interesting features is the exposure of ophiolitic rocks on islands of the talaud mayu ridge tmr a largely submarine ridge formed of highly deformed rocks that bisects the collision zone to explore the relationship between earthquakes and uplift of the ophiolite the centroid depths and fault plane solutions of 18 large earthquakes occurring in the past 20 years beneath the tmr are constrained by inversion of their teleseismic long period p and sh waveforms centroid depths range from 16 to 36 km but uncertainties allow a range of 10 to 45 km all events show thrust faulting nodal planes strike parallel to the nne trending tmr and dip 40 9 to the ese and 53 9 to the wnw published seismic refraction and gravity data support the inference that the wnw dipping steeper nodal planes are the fault planes dips do not change with depth indicating either that the fault flattens below 40 km depth or that the steeply dipping fault penetrates the entire thickness of the lithosphere i conclude that the molucca sea ophiolite is being lifted by high angle thrust faults 45 to 60 that extend at least 15 km into the upper mantle summing seismic moment tensors and assuming uniformly distributed deformation suggest that the closure across the molucca sea collision zone may account for 14 to 59 of the pacific eurasia convergence vector or 15 to 63 of the philippine eurasia convergence moment tensor sums provide estimates of crustal thickening rates beneath the tmr of 7 to 20 mm yr and these imply uplift rates of 2 to 6 mm yr if the increase in crustal thickness is isostatically compensated hence the ophiolite and an enormous volume of melange are being lifted higher than the flanks of the island arcs and will be emplaced on them by gravity i suggest that ophiolites occur in this tectonic setting because the concave down shape of the subducted oceanic lithosphere beneath the molucca sea increases its effective buoyancy preventing it from sinking out of the way of the encroaching island arcs this case suggests a family of convergent margin settings in which normal oceanic lithosphere is buoyed up so that ophiolites can be stripped from it and emplaced on a continental margin or island arc these settings include those where 1 slab geometry restricts asthenospheric flow away from the convergent margin 2 subduction of younger less dense lithosphere decreases its negative buoyancy 3 a passive continental margin resists subduction or 4 the presence of a thick thermal boundary layer beneath a passive continental margin inhibits asthenospheric flow necessary to accommodate the sinking oceanic lithosphere

non linear soil stiffness in routine design soil stress strain behaviour is highly non linear and this has an important influence on the selection of design parameters for simple routine geotechnical calculations non linear behaviour can be characterized by rigidity and degree of non linearity and these can be determined from measurements of very small strain stiffness peak strength and failure strain very small strain stiffness can be found from measurements of shear wave velocity in situ or in laboratory tests peak strength and failure strain can be measured in routine laboratory tests but are strongly influenced by initiation of shear bands the important non linear stiffness parameters for soil are related to its composition and to its current state back analyses of the load settlement behaviour of full scale and model foundations demonstrate the influence of non linear soil behaviour variations of stiffness with settlement calculated from full scale and model foundations agree well with non linear soil stiffnesses based on rigidity and d

probabilistic seismic hazard assessment for japan a probabilistic seismic hazard assessment was performed for the japanese islands and surrounding areas seismic hazard parameters characteristic of the seismic history of the regions were obtained the probability of occurrence of a large m 7 earthquake within a 10 and 50 year period was also calculated regions of very high levels of hazard occur where the pacific phillipine and eurasian plates meet high probabilities of occurrence of a large m 7 earthquake within a 10 and 50 year period occur within the region where the pacific plate subducts with the eurasian plate

time dependent seismicity in china precise zonation of the territory of china has been performed based on the active known faults type of faulting and seismicity level one hundred and forty seven seismogenic regions were defined forming 10 larger seismic areas and the seismotectonic characteristics in each one of them were investigated in detail after checking for data accuracy and completeness of the shallow earthquakes h 60 km the regional time and magnitude predictable model was applied and the model parameters were estimated based on the model applicability in the studied area probabilities for the occurrence of strong m 6 0 earthquakes during the next 10 years were calculated for each seismogenic region statistical tests have been used proving the superiority of the model in comparison with the time independent one as well as in comparison with the actual earthquake occurrence q 2001 elsevier science ltd all rights reserved

long term earthquake prediction in iran based on the time and magnitude predictable model abstract the region of iran has been divided into 21 seismogenic source areas on the basis of certain seismological and geomorphological criteria in each of these source areas the inter event times between successive main shocks with magnitudes equal to or larger than certain cut off magnitudes were considered these inter event times as well as the magnitudes of the main shocks have been used to determine the following relationships by a multilinear regression technique log t t 0 10m min 0 36m p 0 33 log m 0 6 97 m f 0 66m min 0 29m p 0 61 log m 0 10 69 where tt is the calculated inter event time measured in years mmin is the magnitude of the smallest main shock considered mp and mf are the magnitudes of the preceding and following main shocks and m 0 is the annual seismic moment release in each source area these relationships express the basic idea of the time and magnitude predictable model from which given the time of occurrence and the magnitude of the last main shock in a certain seismogenic source area one can calculate the time of occurrence and the magnitude of the next main shock in that area by using the first and second of the equations respectively however as there is considerable scatter in the observations conditional probabilities for the occurrence of a main shock during the next 10 years 1993 2002 as well as the magnitude of the expected main shock in each seismogenic source area were determined

lithospheric deformation within the molucca sea arc arc collision evidence from shallow and intermediate earthquake activity this paper presents the results of a local earthquake survey in the molucca sea arc arc collision zone of eastern indonesia although intermediate depth earthquakes define zones dipping to the west beneath the sangihe arc and to the east beneath the halmahera volcanic arc only shallow activity less than 60 km depth occurred beneath the central part of the collision zone where the majority of activity is observed the concentration of earthquake foci in the 10 to 50 km depth range in a limited region beneath the talaud mayu ridge suggests that convergence between the arcs proceeds by shortening within basement of the intervening molucca sea plate rather than by slip along shallow dipping planes between the arcs and the subducted slabs published focal mechanism solutions suggest that high angle reverse faulting beneath the talaud mayu ridge generates almost all of the seismic energy release within the collision zone the predominance of shallow reverse and strike slip faulting at the axis of the bilaterally subducting molucca sea lithosphere suggests that stresses are not due to bending alone and have a large horizontal regional component perpendicular to the island arcs the geometry and state of stress within the molucca sea lithosphere requires an external driving force for the convergence between the two arcs and a strong degree of coupling between the island arcs and the subducting molucca sea plate at least at the present stage of collision

microearthquake seismicity and fault plane solutions related to arc continent collision in the eastern sunda arc indonesia the collision of australia with the eastern sunda and banda arcs of indonesia represents a modern example of the early stages of arc continent collision in order to obtain a more detailed view of the tectonics of the collision zone a microearthquake survey was conducted around the savu sea the region that encompasses the transition from subduction of indian ocean lithosphere on the west to collision or subduction of australian continental litho sphere on the east intermediate depth earth quakes were concentrated near pantar island the easternmost active volcano of the sunda arc and outline a northwest dipping zone that strikes n65oe from 70 to 150 km depth the seismic zone probably marks the western edge of the collision zone and its more northerly strike and the orientations of nodal planes from fault plane solutions indicate a 25 o bend in the subducted slab to a depth of at least 150 km because the convergence rate and the timing of collision from geologic observations on timor suggest that the oart of the slab now at 150 km depth was at the trench when australia first collided with timor we infer that continental crust or at least rifted continental margin crust caused the bend in the convergent margin and has been subducted to 150 km depth fault plane solutions of several events show nearly vertical nodal planes that trend parallel to the strike of the seismic zone along which a northwest side down sense of dis placement is indicated these events are concentrated at the southern top side of the seismic zone and suggest that the subducted lithosphere is presently detaching in the 50 100 km depth range beneath the eastern savu sea fault plane solutions for earthquakes within the upper part of the detaching slab 70 100 km depth have p and t axes whose trends lie parallel to the strike of the seismic zone and horizontal southeast trending b axes these earthquakes are interpreted as due to stresses caused by the bend in the subducting plate

time independent and time dependent seismic hazard in greece based on seismogenic sources abstract an improved procedure is followed to assess time independent andtime dependent hazard for 144 broad sites cities towns villages of greece in termsof expected macroseismic intensities at each one of these sites in this procedureseveral new results are taken into account source parameters based on new researchwork on seismicity and on other relative information new regionalization and im proved seismicity data parameters and anisotropic radiation at the seismic source anew relation for the attenuation of macroseismic intensities and the effect of localconditions site effects on the strong ground motion analytic relations and tables determined by this procedure permit the reliableassessment of time independent hazard in terms of macroseismic intensity in mmscale peak horizontal ground acceleration and velocity at each one of these 144sites and at any probability level time dependent hazard has been also assessed for these 144 broad sites in greece in terms of the probability for the occurrence of strong ground motion with macro seismic intensity i vii in mm scale at each one of these sites during the period1996 2010 comparison of the assessed time dependent hazard with observed ma croseismic intensities of the period 1950 1995 indicates that the time dependentmodel gives very reasonable results introduction

metallogeny and tectonic development of the tasman fold belt system in tasmania abstract in western tasmania precambrian sedimentary sequences form the basement for narrow trough accumulations of eocambrian and younger sequences the main trough the meridional dundas trough is flanked to the west by the rocky cape region of precambrian rocks within which major apparently stratiform exhalative magnetite pyrite deposits are intercalated with metabasaltic volcanics and ultramafic bodies the eocambrian cambrian troughs apparently developed during extension of precambrian continental crust early shallow water deposition includes thick dolomite units in some troughs deepening of the troughs was accompanied by turbidite sedimentation with minor limestone and submarine basaltic volcanism with associated minor disseminated native copper ultramafic and related igneous rocks were tectonically emplaced in some troughs during a mild compressional phase they contain only minor platinoids copper nickel sulphides and asbestos but are source rocks for tertiary secondary deposits of platinoids chromite and lateritic nickel in the dundas trough eocambrian early cambrian rocks are separated by an inferred erosional surface from structurally conformable overlying middle to late cambrian fossiliferous turbidite sequences the structural conformity continues through overlying ordovician to early devonian terrestrial and shallow marine stable shelf deposits a considerable pile of probable middle cambrian felsic volcanics accumulated between the sedimentary deposits of the dundas trough and the tyennan region of precambrian rocks to the east a lava dominated belt within the volcanics hosts major volcanogenic massive sulphide deposits including those of the exhalative type which in the south are enriched in copper gold and silver whereas in the north they are rich in zine lead copper gold and silver cambrian movements along faults near the margin of the tyennan region resulted in erosion of the mineralized volcanics locally exposing sub volcanic granitoids above the local unconformities occur unmineralized volcaniclastic sequences that pass conformably into ordovician to early devonian shelf deposits ordovician limestone locally hosts stratabound disseminated and veined base metal sulphide deposits pre middle devonian rocks of western tasmania differ for most part from those in the northeast where deeper marine turbidite quartz wacke sequences were deposited during the ordovician and early devonian the eocambrian to early devonian rocks of tasmania were extensively deformed in the mid devonian the precambrian regions of western tasmania behaved as relatively competent blocks controlling early fold patterns in northeastern tasmania folding is of similar age but resulted from movements inconsistent with those affecting rocks of equivalent age in western tasmania the final metallogenic event is associated with high level granitoid masses emplaced throughout tasmania during the middle to late devonian in northeastern tasmania extensive i type granodiorite and s type granite with alkali feldspar granites are associated with mainly endogranitic stanniferous grelsens and wolframite cassiterite vein deposits in contrast scheelite bearing skarns and cassiterite stannite pyrrhotite carbonate replacement deposits are dominant in western tasmania associated mainly with s type granites several argentiferous lead zinc vein deposits occur in haloes around tin tungsten deposits a number of gold deposits are apparently associated with i type granodiorite but some have uncertain genesis the contrasting regions of western and northeastern tasmania have probably been brought together by lateral movement along an inferred fracture flat lying late carboniferous and younger deposits rest on the older rocks and the only known post devonian primary mineralization is gold associated with creta ceous syenite

western irian jaya the end product of oblique plate convergence in the late tertiary abstract the island of new guinea is the surface expression of the deformed northern margin of the australian continental block to the south undeformed continental crust is overlain by flat lying platform sediments that form a conformable sequence from late palaeozoic to late tertiary along the new guinea cordillera these platform sediments have been tightly folded and overthrust to the south as a result of crustal shortening caused by convergence between the australian plate and the pacific plate the earth movements resulting from this convergence started at the end of the miocene and continue to the present day it is postulated that all the major structures of western irian jaya were caused by this orogeny and can be explained by the convergence directed southwest northeast between the australian and pacific plates it is further postulated that the convergence has remained essentially constant since the start of the earth movements this convergence is consistent with that postulated in the circum pacific plate tectonic map aapg 1981 of 12 5 cm yr directed about 15 south of west only if the effects of the sorong yapen fault system are taken into account this complex east west trending fault system forms the southern boundary of the pacific plate and has responded to the convergence by left lateral strike slip displacement of at least 370 km since the late miocene as a consequence south of the sorong yapen fault system the convergence has been directed more to the south i e at least 45 south of west in this region south of the fault zones the north south component of the convergence has been accommodated in the east by folding and overthrusting over a wide zone of interaction called the new guinea mobile belt dow 1977 in the west on the other hand the australian continental crust has been a stable buttress kepala burung fig 2 which following convergence has protruded into the pacific plate its northeastern margin has therefore been exposed to the full brunt of collision with the pacific plate and large segments of continental crust have been broken off and rafted westwards in order to accommodate the difference in crustal shortening between the new guinea mobile belt and kepala burung two fundamental crustal fractures formed in the intervening region the waipoga and wandamen faults these fractures make angles of about 65 with the regional structural trend fig 2 and they were the focus of most of the resulting differential crustal displacement two of the more spectacular examples of this differential movement have been the thrusting of large slabs of crustal rocks tens of kilometres southwards over the australian continental crust weyland overthrust and lengguru fold belt

seismic potential for large and great interplate earthquakes along the chilean and southern peruvian margins of south america a quantitative reappraisal the seismic potential of the chilean and southern peruvian margins of south america is reevaluated to delineate those areas or segments of the margin that may be expected to experience large or great interplate earthquakes within the next 20 years 1984 2004 long term estimates of seismic potential or the conditional probability of recurrence within a specified period of time are based on 1 statistical analysis of historic repeat time data using weibull distributions and 2 deterministic estimates of recurrence times based on the time predictable model of earthquake recurrence both methods emphasize the periodic nature of large and great earthquake recurrence and are compared with estimates of probability based on the assumption of poisson type behavior the estimates of seismic potential presented in this study are long term forecasts only as the temporal resolution or standard deviation of both methods is taken to range from 15 to 25 of the average or estimated repeat time at present the valparaiso region of central chile 32 35 s has a high potential or probability of recurrence in the next 20 years coseismic uplift data associated with previous shocks in 1822 and 1906 suggest that this area may have already started to rerupture in 1971 1973 average repeat times also suggest this area is due for a great shock within the next 20 years flanking segments of the chilean margin coquimbo illapel 30 32 s and talca concepcion 35 38 s presently have poorly constrained but possibly quite high potentials for a series of large or great shocks within the next 20 years in contrast the rupture zone of the great 1960 earthquake 37 46 s has the lowest potential along the margin and is not expected to rerupture in a great earthquake within the next 100 years in the north the seismic potentials of the mollendo arica 17 18 s and arica antofagasta 18 24 s segments which last ruptured during great earthquakes in 1868 and 1877 are also high but poorly constrained

effects of temporal variations in seismicity on seismic hazard the accuracy of stationary mathematical models of seismicity for calculating probabilities of damaging shaking is examined using the history of earthquakes in china from 1350 a d to 1949 a d during this time rates of seismic activity varied periodically by a factor of 10 probabilities of damaging shaking are calculated in 62 cities in north china using 50 yr of earthquake data to estimate seismicity parameters the probabilities are compared to statistics of damaging shaking in the same cities for 50 yr following the data window these comparisons indicate that the seismic hazard analysis is accurate if 1 the maximum possible earthquake size in each seismogenic zone is determined from the entire seismic history rather than from a short time window and 2 the future seismic activity can be estimated accurately the first condition emphasizes the importance of realistically estimating the maximum possible size of earthquakes on faults the second indicates the need to understand possible trends in seismic activity where these exist or to develop an earthquake prediction capability with which to estimate future activity without the capability of estimating future seismicity stationary models provide less accurate but generally conservative indications of seismic ground shaking hazard in the united states the available earthquake history is brief but gives no indication of changing rates of activity the rate of seismic strain release in the central and eastern united states has been constant over the last 180 yr and the geological record of earthquakes on the southern san andreas fault indicates no temporal trend for large shocks over the last 15 centuries both observations imply that seismic activity is either stationary or of such a long period that it may be treated as stationary for seismic hazard analyses in the united states

the regional time and magnitude predictable model and its application to the alpine himalayan belt abstract the regional time and magnitude predictable model has been introduced and has been shown to be appropriate to describe the behaviour in the occurrence of mainshocks the model implies that the magnitude of the preceding mainshock in a seismogenic region that is the largest earthquake during a seismic excitation governs the time of occurrence and the magnitude of the expected mainshock in this region this model has been applied in 149 seismogenic regions of the alpine himalayan seismic belt the model probability for the occurrence of the next very strong main shock ms 6 5 during the decade 1993 2002 as well as the magnitude of this shock in each of these regions have been calculated furthermore two tests have been performed to check the validity of this model these tests have shown the reliability of the model and its superiority compared to the classical time independent model

seismotectonics of the hida region central honshu japan abstract seismotectonic features of the northern hida region central honshu japan have been investigated in some detail mainly on the basis of the last 6 years of observations of seismicity and focal mechanism of a large number of earthquakes with reference to the geological and tectonic setting and evidence of a large earthquake in the past it was found that high seismicity is concentrated with a remarkably clear lineation but with a relatively low activity in the central section along the atotsugawa fault extending for about 70 km this is one of major quaternary faults in this region the high seismicity with spatially nonuniform distribution may be related to postseismic stress concentration after the 1858 hida earthquake m 7 0 and to heterogeneous fault strength seismicity is also high with belt like extension beneath the hida mountain range which is the highest mountain system in the japan islands the depth distribution of seismicity is clearly bounded at 15 km below the atotsugawa fault and 8 km beneath the hida mountains the local variations can be interpreted as being due to the difference in the brittle ductile transition depth which suggests higher temperature beneath the mountains involving active volcanoes the focal mechanism solutions indicate that the maximum compressive stress is oriented in an ese wnw direction which is more consistent with the direction of motion of the pacific plate relative to the eurasian plate rather than the suggested relative motion between the north america and eurasian plates the magnitude of the shear stress working in this region is estimated to be less than 700 bar

tectonic stress state in ne japan as part of the okhotsk plate abstract an existing geodetic flow velocity model obtained by using an internal free network adjustment technique is used to derive estimates for various strain rates parameters in ne japan the greatest shortening rates of the principal strains trending e w are located in regions where much steady internal frame invariant plastic flow deformation is observed to be taking place the internal geodetic adjustment technique yielded the internal deformation in the tohoku arc most of the intraplate deformations including the much folding deformations observed in the inner zone are produced from within an interseismic transient elastic loading at a strongly coupled locked japan trench would not be needed the observed ongoing extensive ductile folding deformation in the inner zone of tohoku may mean that the geodetic strain rates causing shortening at 2 3 cm yr probably reflect the more correct level of the deformation which is steady permanent in ne japan as compared with seismic faulting data which indicate 0 5 cm yr shortening the calculated principal strain rates are used to make an interpretation for the origin of the deviatoric principal stresses within the greater regional plate tectonic framework the tectonic stress state in ne japan as part of the okhotsk plate could mostly be influenced by the okhotsk plate which is extruding southward to lessen the significant accumulated contractional deformation in ne asia in the verkhoyansk cherskii mountains the principal strain rates are n s extensional essentially everywhere in ne japan as a result of the southerly extrusion except in its southernmost leading edge in the uetsu fossa magna province where the japan alps rampart rises in front of the extrusion here an e w compressional stress state prevails a second e w contractional zone is found in north central tohoku extending from the sanriku province in the outer zone to the inner zone in the japan sea side being more prevalent in the latter zone the calculated rotation rates from the geodetic flow model are clockwise cw in both of the e w contractional regions ne japan extruding southward faces buttresses in 1 the oga ojika line ool and or a crustal weakness zone between the northern and the southern halves of tohoku approx at 38 5 n latitude and especially 2 the japanese alps rampart these obstacles cause the northern and southernmost tohoku to veer to its right and rotate cw thereby setting up the e w trending compressional deformation in their respective inner zones between the ool or the 38 5 n boundary and the kanto tectonic line ktl the sense of the differential rotations is counterclockwise ccw towards the ocean to the se the northern tohoku north of the ool and the southernmost tohoku south of the ktl cannot rotate ccw towards the ocean because of the izu block s collision in the south and the relatively strong coupling along the subduction interface beneath the japan trench in the north off sanriku the relatively stronger long term coupling between the northern tohoku and the pacific plate at the sanriku coast with respect to that in off fukushima is due to a flatter subduction of the pacific slab there increasing the plates interface contact area the flattening of the subduction dip angle was caused by ccw rotation and shifting of the northern tohoku along the dextral honjo matsushima line roughly corresponding to the ool towards the pacific and overriding of the subduction zone during the formation of the japan sea

evaluation of undrained shear strength of swedish fine grained sulphide soils in swedish practice there is a long tradition of evaluating undrained shear strength from fall cone tests and field vane tests during the last 20 years cone penetration tests have also become wid

fixed recurrence and slip models better predict earthquake behavior than the time and slip predictable models 1 repeating earthquakes 1 the behavior of individual events in repeating earthquake sequences in california taiwan and japan is better predicted by a model with fixed inter event time or fixed slip than it is by the time and slip predictable models for earthquake occurrence given that repeating earthquakes are highly regular in both inter event time and seismic moment the time and slip predictable models seem ideally suited to explain their behavior taken together with evidence from the companion manuscript that shows similar results for laboratory experiments we conclude that the short term predictions of the time and slip predictable models should be rejected in favor of earthquake models that assume either fixed slip or fixed recurrence interval this implies that the elastic rebound model underlying the time and slip predictable models offers no additional value in describing earthquake behavior in an event to event sense but its value in a long term sense cannot be determined these models likely fail because they rely on assumptions that oversimplify the earthquake cycle we note that the time and slip of these events is predicted quite well by fixed slip and fixed recurrence models so in some sense they are time and slip predictable while fixed recurrence and slip models better predict repeating earthquake behavior than the time and slip predictable models we observe a correlation between slip and the preceding recurrence time for many repeating earthquake sequences in parkfield california this correlation is not found in other regions and the sequences with the correlative slip predictable behavior are not distinguishable from nearby earthquake sequences that do not exhibit this behavior