a large refined catalog of earthquake relocations and focal mechanisms for the island of hawai i and its seismotectonic implications we present high quality focal mechanisms based on a refined earthquake location catalog for the island of hawai i focusing on mauna loa and k lauea volcanoes the relocation catalog is based on first arrival times and waveform data of both compressional and shear waves for about 180 000 events on and near the island of hawai i between 1986 and 2009 recorded by the seismic stations at the hawaiian volcano observatory we relocate all the earthquakes by applying ray tracing through an existing three dimensional velocity model similar event cluster analysis and a differential time relocation method the resulting location catalog represents an expansion of previous relocation studies covering a longer time period and consisting of more events with well constrained absolute locations the focal mechanisms are obtained based on the compressional wave first motion polarities and compressional to shear wave amplitude ratios by applying the hash program to the waveform cross correlation relocated earthquakes overall the good quality defined by the hash parameters focal solutions are dominated by normal faulting in our study area especially in the active ka iki and h lea seismic zones k lauea caldera is characterized by a mixture of approximately equal numbers of normal strike slip and reverse faults whereas its south flank has slightly fewer strike slip events our relocation and focal mechanism results will be useful for mapping the seismic stress and strain fields and for understanding the seismic volcanic tectonic relationships within the magmatic systems

fault controlled soil co2 degassing and shallow magma bodies summit and lower east rift of kilauea volcano hawaii 1997 soil co2 flux measurements were carried out along traverses across mapped faults and eruptive fissures on the summit and the lower east rift zone of kilauea volcano anomalous levels of soil degassing were found for 44 of the tectonic structures and 47 of the eruptive fissures intercepted by the surveyed profiles this result contrasts with what was recently observed on mt etna where most of the surveyed faults were associated with anomalous soil degassing the difference is probably related to the differences in the state of activity at the time when soil gas measurements were made kilauea was erupting whereas mt etna was quiescent although in a pre eruptive stage unlike mt etna flank degassing on kilauea is restricted to the tectonic and volcanic structures directly connected to the magma reservoir feeding the ongoing east rift eruption or in areas of the lower east rift where other shallow likely independent reservoirs are postulated anomalous soil degassing was also found in areas without surface evidence of faults thus suggesting the possibility of previously unknown structures

deep magma body beneath the summit and rift zones of kilauea volcano hawaii a magnitude 7 2 earthquake in 1975 caused the south flank of kilauea volcano hawaii to move seaward in response to slippage along a deep fault since then a large part of the volcano s edifice has been adjusting to this perturbation the summit of kilauea extended at a rate of 0 26 meter per year until 1983 the south flank uplifted more than 0 5 meter and the axes of both the volcano s rift zones extended and subsided the summit continues to subside these ground surface motions have been remarkably steady and much more widespread than those caused by either recurrent inflation and deflation of the summit magma chamber or the episodic propagation of dikes into the rift zones kilauea s magmatic system is therefore probably deeper and more extensive than previously thought the summit and both rift zones may be underlain by a thick near vertical dike like magma system at a depth of 3 to 9 kilometers

volcanic spreading at kilauea 1976 1996 the rift system traversing about 80 km of the subaerial surface of kilauea volcano has extended continuously since the m 7 2 flank earthquake of november 1975 widening across the summit has amounted to more than 250 cm decelerating after 1975 from about 25 to 4 cm yr 1 since 1983 concurrently the summit has subsided more than 200 cm even as the adjacent south flank has risen more than 50 cm the axes of the upper zones about 10 km from the summit subsided before 1983 at average rates of 9 and 4 cm yr 1 respectively and at rates of 4 and 3 cm yr 1 since the middle southwest rift zone is also subsiding and at the other end of kilauea s subaerial rift system subsidence along the lower east rift zone has averaged 1 2 cm yr 1 deformation of kilauea s south flank has been continuous although subject as well to displacements caused by major rift zone seismic swarms whereas horizontal strains across the subaerial south flank seem to have been generally compressive after 1975 they have been extensional since about 1980 or 1981 interrupted only by the east rift zone dike intrusion of 1983 because the magnitudes of these contractions and extensions are much less than the extension across the rift system the subaerial south flank is apparently sliding seaward on its basal decollement more than it is accumulating horizontal strains within the overlying volcanic pile kilauea suffers from gravitational spreading made even more unstable by accumulation of magma along the rift system at depths in excess of about 4 5 km in the presence hot rock incapable of withstanding deviatoric stresses this seismicly quiescent zone decouples the south flank from the rest of hawaii s volcanic edifice the rift zones at lesser depths exhibit a more brittle and therefore sporadic extensional behavior judging from the modern extension record of the summit which both predates the m 7 2 earthquake of 1975 and has outlived its 10 year period of aftershocks kilauea will continue to spread along its rift system as its south flank slips seaward to accommodate the accretion of magma and its relatively dense olivine rich differentiate

an estimate of the absolute stress tensor in kaoiki hawaii the stress tensor orientation was calculated by inversion of 81 fault plane solutions of m 3 5 0 6 earthquakes located in an area 6 by 16 km at depths of 7 2 km this crustal volume is situated on a straight line between the summits of the active volcanoes kilauea and mauna loa the orientation of the greatest principal stress was found to be near horizontal and in the line connecting the two volcanoes this is further evidence supporting the model that magmatic expansion within the feeding conduits of these volcanoes is the source of stress that causes earthquakes in southern hawaii these earthquakes are tectonic earthquakes in the sense that they occur in a brittle elastic crust at distances of a few to several tens of kilometers from the volcanoes and that they are not directly associated with the opening of cracks by intrusions we propose that this model leads to the corollary that the shear stresses responsible for earthquake failure in the shallow hawaiian crust are approximately 3 2 mpa and that the pore pressure of ground water p in the hypocentral volume must be under near lithostatic pressure this result is obtained by arguing that the greatest principal stress 1 is equal to the magma pressure in the volcanic feeder pipe but cannot exceed the least principal stress 3 by more than the tensile strength of the crust because otherwise hydrofracture would occur opening a crack against the least principal stress given the difference between the greatest and least principal stress the fact that the overburden at the 7 km hypocentral depth equals the intermediate principal stress and the ratio r 1 2 1 3 0 4 which is obtained in the inversion of fault plane solutions we estimate that 1 202 mpa 2 200 mpa 3 196 mpa 3 mpa and n 199 mpa with uncertainties on the order of several mpa it follows that for any coefficients of friction larger than 0 15 the pore fluid pressure necessary for faulting on the observed fault planes has to be larger than 90 of the lithostatic pressure these considerations suggest that many earthquakes represent fault ruptures under low ambient shear stresses in the order of the average observed stress drop of 3 mpa

a linear gradient crustal model for south hawaii a new crustal model with linear velocity gradients within layers does as good a job of locating earthquakes on south hawaii as any model yet published incorporating linear gradients means the model can be simpler and free of artificial velocity discontinuities using travel time residuals from local earthquakes and consistency of focal mechanism solutions as tests it is seen that a low velocity zone at the base of the crust is not required

evidence of viscoelastic deformation following the 2011 tohoku oki earthquake revealed from seafloor geodetic observation the gps acoustic seafloor positioning has detected significant postseismic movements after the 2011 tohoku oki earthquake m9 0 just above the source region off the pacific coast of eastern japan in contrast to the coastal global navigation satellite systems sites where trenchward upward movements were reported the offshore sites above the main rupture zone in the northern part of the source region exhibit landward displacements of tens of centimeters with significant subsidence from almost 3 years of repeated observations at the sites above around the edge of the main rupture zone smaller amount of trench normal movements was found although the terrestrial movements were reasonably interpreted by afterslip beneath the coastal area these offshore results are rather consistent with effects predicted from viscoelastic relaxation in the upper mantle providing definitive evidence of its occurrence on the other hand the results in the southern part of the source region imply superposition of effects from viscoelastic relaxation and afterslip

block tectonics of the island of hawaii from a focal mechanism analysis of basal slip the southern third of the island of hawaii is composed of at least three rigid blocks kilauea volcano s south flank mauna loa volcano s southeast flank and mauna loa volcano s west flank analysis of earthquake focal mechanisms suggests that kilauea s south flank the most mobile of these blocks is moving seaward perpendicular to its east rift zone along a southeasterly course at an azimuth of 155 5 mauna loa s southeastern flank is also moving in a southeasterly direction although at a slightly more easterly azimuth of 140 5 although data are sparse on the western flank of mauna loa due to low seismicity and inadequate seismic network station density the available data suggest that this region is translating seaward along a generally westerly azimuth relative differences in these translational azimuths may represent oblique opening across the boundaries between these regions the active rift zones of kilauea and mauna loa volcanoes

deep fault plane geometry inferred from multiplet relative relocation beneath the south flank of kilauea dense microearthquake swarms occur in the upper south flank of kilauea providing multiplets composed of hundreds of events the similarity of their waveforms and the quality of the data have been sufficient to provide accurate relative relocations of their hypocenters a simple and efficient method has been developed which allowed the relative relocation of more than 250 events with an average precision of about 50 m horizontally and 75 m vertically relocation of these events greatly improves the definition of the seismic image of the fault that generates them indeed relative relocations define a plane dipping about 6 northward although corresponding absolute locations are widely dispersed in the swarm a composite focal mechanism built from events providing a correct spatial sampling of the multiplet also gives a well constrained northward dip of about 5 to the near horizontal plane this technique thus collapses the clouds of hypocenters of single event locations to a plane coinciding with the slip plane revealed by previous focal mechanism studies we cannot conclude that all south flank earthquakes collapse to a single plane there may locally be several planes perhaps with different dips and depths throughout the south flank volume the 6 northward dipping plane we found is too steep to represent the overall flexure of the oceanic crust under the load of the island of hawaii this plane is probably an important feature that characterizes the basal slip layer below the upper south flank of kilauea volcano differences in seismicity rate and surface deformations between the upper and lower south flank could be related to the geometry of this deep fault plane the present work illustrates how high precision relative relocations of similar events in dense swarms combined with the analysis of geodetic measurements can help to describe deep fault plane geometry systematic selection and extensive relative relocation of similar earthquakes could be attempted in other well instrumented highly seismic areas to provide reliable basic information especially useful for understanding of earthquake generation processes

seismic hazard in hawaii high rate of large earthquakes and probabilistic ground motion maps the seismic hazard and earthquake occurrence rates in hawaii are locally as high as that near the most hazardous faults elsewhere in the united states we have generated maps of peak ground acceleration pga and spectral acceleration sa at 0 2 0 3 and 1 0 sec 5 critical damping at 2 and 10 exceedance probabilities in 50 years the highest hazard is on the south side of hawaii island as indicated by the m i 7 0 m s 7 2 and m i 7 9 earthquakes which occurred there since 1868 probabilistic values of horizontal pga 2 in 50 years on hawaii s south coast exceed 1 75 g because some large earthquake aftershock zones and the geometry of flank blocks slipping on subhorizontal decollement faults are known we use a combination of spatially uniform sources in active flank blocks and smoothed seismicity in other areas to model seismicity rates of earthquakes are derived from magnitude distributions of the modern 1959 1997 catalog of the hawaiian volcano observatory s seismic network supplemented by the historic 1868 1959 catalog modern magnitudes are m l measured on a wood anderson seismograph or m s historic magnitudes may add m l measured on a milne shaw or bosch omori seismograph or m i derived from calibrated areas of mm intensities active flank areas which by far account for the highest hazard are characterized by distributions with b slopes of about 1 0 below m 5 0 and about 0 6 above m 5 0 the kinked distribution means that large earthquake rates would be grossly underestimated by extrapolating small earthquake rates and that longer catalogs are essential for estimating or verifying the rates of large earthquakes flank earthquakes thus follow a semicharacteristic model which is a combination of background seismicity and an excess number of large earthquakes flank earthquakes are geometrically confined to rupture zones on the volcano flanks by barriers such as rift zones and the seaward edge of the volcano which may be expressed by a magnitude distribution similar to that including characteristic earthquakes the island chain northwest of hawaii island is seismically and volcanically much less active we model its seismic hazard with a combination of a linearly decaying ramp fit to the cataloged seismicity and spatially smoothed seismicity with a smoothing half width of 10 km we use a combination of up to four attenuation relations for each map because for either pga or sa there is no single relation that represents ground motion for all distance and magnitude ranges great slumps and landslides visible on the ocean floor correspond to catastrophes with effective energy magnitudes m e above 8 0 a crude estimate of their frequency suggests that the probabilistic earthquake hazard is at least an order of magnitude higher for flank earthquakes than that from submarine slumps

discussion of results presented by hhndorf and dill some aspects of lead lead model ages of ore mineralizations from the western edge of the bohemian massif f r germany mineral deposita 21 329 336 1986

sediment effect on tsunami generation of the 1896 sanriku tsunami earthquake the 1896 sanriku earthquake was one of the most devastating tsunami earthquakes which generated an anomalously larger tsunami than expected from its seismic waves previous studies indicate that the earthquake occurred beneath the accretionary wedge near the trench axis it was pointed out recently that sediments near a toe of an inner trench slope with a large horizontal movement due to the earthquake might have caused an additional uplift in this paper the effect of the additional uplift to tsunami generation of the 1896 sanriku tsunami earthquake is quantified we estimate the slip of the earthquake by numerically computing tsunamis and comparing their waveforms with those recorded at three tide gauges the estimated slip for the model without the additional uplift is 10 4 m and those with the additional uplift are 5 9 6 7 m this indicates that the additional uplift of the sediments near the trench has a large effect on the tsunami generation

lead isotope and pb pb model age determinations of ores from central europe and their metallogenetic interpretation the paper presents lead isotope data from 211 samples from phanerozoic lead bearing ore occurrences in central europe particularly from the southern part of the former german democratic republic the data are interpreted in terms of amov s dynamic model of continuous lead isotope evolution the relationships between thoro genic and urano genic model ages and the source of lead in different regional units are discussed we observed differences in lead isotope evolution in the hercynian internides and externides within the moldanubian and saxothuringian zones we distinguish five main lead bearing ore associations 1 cambrian stratiform base metal hermsdorf waldsassen 206pb 204pb 17 50 17 70 2 devonian vein type sb bearing metamorphogene neumuhle hartmannsdorf 17 80 18 00 3 upper carboniferous permian polymetallic including tin vein type kutna hora freiberg altenberg 18 00 18 20 4 triassic jurassic pb ba vein type st ibro halsbrucke 18 20 18 60 5 cenozoic polymetallic vein type riftogene roztoky banska stiavnica 18 80 19 10 pb isotope characteristics from ores of the montagne noire and the brioude massiac district correspond to this subdivision ore associations from the rheno hercynian zone display higher 207pb 204pb ratios which can be explained by more evolved and less metamorphosed source rocks mineralizations of the eastern harz strasberg neudorf belong to the permian association those from the western harz clausthal bad grund to the triassic jurassic because of pb isotope agreement the stratabound rammelsberg and the vein bound ramsbeck i mineralization are presumed to be isogenetic pb isotope identity of distinct mineralizations in the basement zone halsbrucke bad grund and in the triassic sediments gorny slask mechernich bleiglanzbanke suggests a strong genetic coherence pb isotope conformity between the upper carboniferous permian triassic ore associations and hercynian postkinematic granitoids and lamprophyric rocks also favours a close relationship pb isotope and other data indicate crustal sources as the age of the ore associations decreases crustal influences generally increase apart from the roztoky mineralization

230th 238u radioactive disequilibria in tholeiites from the famous zone mid atlantic ridge 36 50 n th and sr isotopic geochemistry we analyzed u th and230th 232th activity ratios for a few tholeiites from the mid atlantic ridge famous zone at 36 50 n the results show a fairly wide scatter for both th u and 230th 232th ratios seawater contamination appears to be responsible for this scatter and for the uranium produces an increase in content yielding a 234u 238u ratio greater than 1 and for the th an increase of the 230th 232th ratio which is a very sensitive indicator for contamination also the latter often is selective u th and sr are not affected in the same manner when discarding all data for contaminated samples the famous zone appears to be very homogeneous with ath u ratio value of 3 05 and a 230th 232th ratio value of 1 24 comparison with other active volcanic areas reveals a negative correlation between 230th 232th and87sr 86sr ratios for present lavas which is indicative of a consistency in th u and rb sr fractionation in the source regions of these magmas the th isotopic geochemistry can thus provide useful information for the study of present volcanism information as valuable as that from sr pb or nd isotopes

inversion for source parameters from sparse data sets test of the method and application to the 1951 m 6 9 kona hawaii earthquake we have tested a method originally developed by beisser et al 1990 to retrieve the source parameters strike dip rake and depth of sparsely recorded earthquakes from the inversion of teleseismic waveform data the complete wave train of all body waves is modeled using the reflectivity method the parameter space of strike dip and rake is searched to find the source orientation which leads to the minimum misfit between the observed and the synthetic seismogram the 1983 kaoiki hawaii earthquake ms 6 6 was chosen as a test case the inversion of the full data set 16 stations gave a fault plane solution similar to the best double couple moment tensor solution of harvard university and national earthquake information centre these three solutions were averaged to create a standard solution sparse data sets were simulated by decimating the full data set and the resulting fault plane solutions were compared with the standard we found that as few as one to three stations were sufficient to retrieve the focal mechanism of the 1983 kaoiki event we applied this technique to the 1951 kona hawaii earthquake ms 6 9 a total of four stations and nine components were used to model the source parameters of this earthquake the depth was estimated at 13 3 km the fault plane solution was a decollement type with a near horizontal plane dipping at about 15 to the southwest and a near vertical plane striking nw se this observation supports a tectonic model for the kona coast similar to that of kilauea s south flank the upper crust is pushed away from the center of hawaii slipping westward along a near horizontal plane of weakness

a seismotectonic model for western hawaii based on stress tensor inversion from fault plane solutions for 57 fault plane solutions of earthquakes with magnitude ml 3 0 located west of the southwest rift zone of mauna loa volcano in hawaii which occurred between 1972 and 1988 the dominant focal mechanisms 44 events are decollement type with one nodal plane nearly horizontal dip 30 the average slip vector of the upper crust on the decollement plane points in an azimuth of 260 toward the ocean away from mauna loa s southwest rift zone at an angle of about 150 with respect to the ne sw oriented rift two other types of focal mechanisms are present normal faults four events and strike slip faults with normal component nine events the orientation of the principal stresses was derived by minimizing the sum of the misfits between the theoretical and observed fault geometry for each focal mechanism after subdividing the data set into three different regions we found that the stress tensor is not homogeneous in west hawaii the orientation for the stress tensor is best resolved in the area located between latitudes 19 27 n and 19 4 n and longitudes 155 7 and 155 9 w where the greatest principal stress directions within the 95 confidence limits are nearly vertical with some spreading to the west their plunge varies between 53 and 85 the intermediate and least principal stresses are mostly horizontal and have similar magnitudes their plunge varies between 1 and 36 the area between latitudes 19 4 and 19 6 n and longitudes 155 7 and 156 w is characterized partly by near vertical and partly by east west oriented greatest principal stresses the least principal stresses are approximately horizontal and have magnitudes similar to the intermediate principal stresses in the two areas where the stress tensor was well resolved the principal strain directions differed from the principal stress directions by 30 in the plunge suggesting that the faulting in western hawaii takes place on a weak plane but this result could not be established at the 95 confidence level the tectonic model proposed for west hawaii is similar to the model for the kalapana region the strain is accumulated through magmatic intrusions in the southwest rift zone of mauna loa and the earthquakes occur along a zone of weakness composed of oceanic sediment at about 10 km depth the west flank of mauna loa slips in the direction away from the rift

tsunami simulation by tuned seismic source inversion for the great 2011 tohoku earthquake seismic and tsunami waves were the most destructive phenomena during the 2011 tohoku earthquake here we ask whether the same source model can be used to obtain equally good simulations of the observed strong ground motions and the tsunami waves if so we could use the same source modeling technique for predictions of both tsunami waves and strong ground motions long period 20 200 s strong ground motion data were inverted to determine the rupture process of the 2011 tohoku earthquake the inverted slip distribution shows that large slip area was extended around 150 km to north and 120 km to south from hypocenter and stretched between hypocenter and the trench we estimated two slip models without and with additional constraints the first relatively rough slip model reproduced short period tsunami wave 4 5 min due to better constraint by data of other kind and being relatively smooth the second model reproduces long period tsunami wave 15 25 min as well as keeps good fit of the short period tsunami although short period tsunami becomes underestimated we used a fully nonlinear boussinesq water wave model to model tsunami propagation and used the results to tune the slip model finally we developed a tuned slip model that combines the features of both the first and the second slip models and reproduced both the short and long period tsunami waves while maintaining good fit of the seismic waveforms

magma supply and storage at kilauea volcano hawaii 1956 1983 abstract shallow crustal magma reservoirs beneath the summit of kilauea volcano and within its rift zones are linked in such a way that the magma supply to each can be estimated from the rate of ground deformation at the volcano s summit our model builds on the well documented pattern of summit inflation as magma accumulates in a shallow summit reservoir followed by deflation as magma is discharged to the surface or into the rift zones magma supply to the summit reservoir is thus proportional to summit uplift and supply to the rift zones is proportional to summit subsidence the average proportionality constant is 0 33 10 6 m 3 rad this model yields minimum supply estimates because it does not account for magma which escapes detection by moving passively through the summit reservoir or directly into the rift zones calculations suggest that magma was supplied to kilauea during july 1956 april 1983 at a minimum average rate of 7 2 10 6 m3 month roughly 35 of the net supply was extruded the rest remains stored within the volcano s east rift zone 55 and southwest rift zone 10 periods of relatively rapid supply were associated with the large kapoho eruption in 1960 and the sustained mauna ulu eruptions in 1969 1971 and 1972 1974 bursts of harmonic tremor from the mantle beneath kilauea were also unusually energetic during 1968 1975 suggesting a close link between kilauea s deep magma supply region and shallow storage reservoirs it remains unclear whether pulses in magma supply from depth give rise to corresponding increases in shallow supply or if instead unloading of a delicately balanced magma transport system during large eruptions or intrusions triggers more rapid ascent from a relatively constant mantle source

seismic detection of a low velocity layer beneath the southeast flank of mauna loa hawaii the authors have identified seismic phases reflected off the top and bottom of a low velocity layer lvl by analysis of seismograms from six small earthquakes in hawaii these events occurred almost directly beneath station ain of the hawaiian volcano observatory hvo seismic network located within the kaoiki seismic zone on the southeast flank of mauna loa the polarity reversals of the first reflected phases provide clear evidence for the existence of a lvl beneath this station the lvl is estimated to be at a depth of about 11 5 km with a thickness of about 800 m the estimated depth to the top of the lvl is consistent with the depth distribution of low angle thrust faulting events from the aftershock sequence of the 1983 kaoiki earthquake presumably this zone is the marine sediment layer buried beneath the volcanic pile along which the volcanic edifice may slip easily to cause large earthquakes mapping the interface between the volcanic pile and oceanic crust and thus determining the depth and thickness of the buried sediment layer is essential for understanding the tectonics of large earthquakes in hawaii

new insights into kilauea s volcano dynamics brought by large scale relative relocation of microearthquakes 1 we investigated the microseismicity recorded in an active volcano to infer information concerning the volcano structure and long term dynamics by using relative relocations and focal mechanisms of microearthquakes there were 32 000 earthquakes of the mauna loa and kilauea volcanoes recorded by more than eight stations of the hawaiian volcano observatory seismic network between 1988 and 1999 we studied 17 000 of these events and relocated more than 70 with an accuracy ranging from 10 to 500 m about 75 of these relocated events are located in the vicinity of subhorizontal decollement planes at a depth of 8 11 km however the striking features revealed by these relocation results are steep southeast dipping fault planes working as reverse faults clearly located below the decollement plane and which intersect it if this decollement plane coincides with the pre mauna loa seafloor as hypothesized by numerous authors such reverse faults rupture the pre mauna loa oceanic crust the weight of the volcano and pressure in the magma storage system are possible causes of these ruptures fully compatible with the local stress tensor computed by gillard et al 1996 reverse faults are suspected of producing scarps revealed by kilometer long horizontal slip perpendicular lineations along the decollement surface and therefore large scale roughness asperities and normal stress variations these are capable of generating stick slip large magnitude earthquakes the spatial microseismic pattern observed in the south flank of kilauea volcano and hilina type instabilities rupture intersecting the decollement surface causing its large scale roughness may be an important parameter controlling the growth of hawaiian volcanoes

lead isotope systematics of epigenetic lead zinc mineralization in the western part of the rheinisches schiefergebirge germany in the western part of the rheinisches schiefergebirge three different types of epigenetic lead zinc vein mineralization in paleozoic rocks can be distinguished 1 syntectonic variscan veins 2 post variscan saxonian veins mainly in paleozoic siliceous clastic rocks 3 post variscan carbonate hosted mineralization in the aachen stolberg area ore impregnations occur in the triassic buntsandstein bunter sandstone and muschelkalk of the maubach mechernich triangular depression covering the paleozoic rocks data points define two distinct populations in both lead isotope diagrams and thus indicate two major variscan and post variscan mineralization events the lead isotope pattern of the paleozoic sedimentary rocks bears good evidence that this thick rock sequence may be the main source of metals for the mineralization the metals were mobilized at deeper levels by saline fluids at different times there are no direct indications for remobilization of the older variscan vein ore deposits the sandstone and carbonate hosted ore impregnations of maubach mechernich have a similar lead isotope pattern to the post variscan mineralization in the paleozoic sedimentary basement

growth and persistence of hawaiian volcanic rift zones hawaiian volcanic rift zones are modeled by representing the rifts and adjacent volcano flanks as long ridges with the geometry of flattened triangular prisms the intrusion of dikes along the axis of a rift requires a mechanism to generate the appropriate dike trapping stress field within the prism possible factors that affect the state of stress in the prism include multiple dike intrusion along the ridge axis faulting and gravitational sagging of the topography in extreme models with very steep slopes and high poisson s ratio corresponding to the gelatin models of rift zones by fiske and jackson 1972 results of finite element calculations indicate that gravity induced stresses are sufficient to trap a dike into propagating within the prism and parallel to the rift zone as proposed by fiske and jackson however the mechanism does not work for gently sloping flanks or a more acceptable poisson s ratio of about 0 25 additionally trapping stresses in the gravity loading and density stratification models will not persist after a few dike injection episodes therefore in mature hawaiian rift zones with possibly thousands of dikes additional processes must act to control the stresses that permit continued dike intrusion and rift persistence it is proposed that accommodation to dike emplacement occurs by slip on deep faults possibly of the type proposed for the 1975 kalapana hawaii earthquake as suggested by others for this earthquake the faults could coincide with the contact of the volcano with the seafloor within the weak seafloor sediments such faulting not only provides a means for the flanks to adjust continuously to intrusions but also generates the stress patterns needed to constrain future dikes to propagate along the rift axis other possible faulting mechanisms such as shallow gravity slides and normal faulting of the flanks do not appear to favor rift zone persistence in this model the horizontal stress generated by a standing column of magma at the time of dike emplacement the stresses in the ridges and the fault strength are coupled this results in a feedback between the maximum height that magma can rise along the rift fault friction and fault width through this feedback the slope of the volcano flank is controlled by the fault friction when applied to kilauea volcano the model yields an estimate for the coefficient of fault friction as high as 0 39 assuming normal hydrostatic pore fluid pressure an implication of this model supported by other studies is that rift intrusion and lateral spreading could be major contributors to volcano growth

focal mechanisms and locations of earthquakes in the vicinity of the 1975 kalapana earthquake aftershock zone 1970 1979 implications for tectonics of the south flank of kilauea volcano island of hawaii the november 29 1975 kalapana earthquake of magnitude 7 1 on the south flank of kilauea volcano hawaii represents a major rift tectonic event it is generally understood that the earthquake resulted from movement on a nearly horizontal fault plane with the crustal block south of kilauea s east rift zone moving south southeastward up to several meters well recorded earthquakes on the south flank of kilauea from 1970 to 1979 were analyzed and focal mechanisms determined to obtain a better understanding of the details of south flank tectonics included are a large number of earthquakes from the aftershock sequence of the 1975 earthquake hypocenters are distributed in a subplanar zone that dips 2 to 3 to the west at a depth of about 8 9 km depth we interpret this pattern to coincide with a portion of the slip plane of the kalapana earthquake and to be consistent with the notion of the slip plane occurring in a weak layer at the top of the old oceanic crust focal mechanisms are remarkably constant throughout this time period both before and after the 1975 event and closely agree with the mainshock mechanism p axis azimuths and slip vectors for the low angle fault planes are normal to the middle and lower east rift zones of kilauea there is suggestion of a change in the orientation of p axes from shallower to steeper plunge at the time of the kalapana earthquake such a change is consistent with a general reduction in the horizontal compressional stress normal to the rift zone at the time of the large earthquake no other evidence of precursory reorientation of the stress field was found and the precise predictability of this event remains in doubt however a general model of the tectonics of the volcanic rift system is now available that satisfies a number of geological and geophysical observations

volcanotectonic interactions between mauna loa and kilauea insights from 2 d discrete element simulations abstract numerical simulations using the discrete element method dem are carried out to examine the dynamics and internal deformation of overlapping volcanoes constructed upon a weak decollement horizon as analogs to the kilauea mauna loa system of volcanoes in hawaii employing a frictional rheology the dem simulations capture much of the complex deformation behavior of mauna loa and kilauea volcanoes here referred to as the primary and secondary edifices respectively the models demonstrate incremental displacements of the outer flanks of the volcanoes and concurrent summit subsidence leading to characteristic low slopes and inward dipping strata slip discontinuities that develop within the piles define steeply dipping normal faults along the upper flanks and beneath the edifice summits that accommodate subsidence and flank spreading edifice overlap influences dynamic behavior significantly even small topographic perturbations restrict the internal deformation and spreading of the confined flanks the degree of buttressing depends on the relative positions of the two edifices if the secondary edifice grows high upon the flanks of the primary edifice outward spreading of the underlying flank is enhanced if the secondary edifice is built low upon the primary flanks spreading of the underlying flank is effectively prevented or possibly reversed furthermore as the second edifice grows it subsides into the underlying flank partitioning it into a mobile downslope region entrained by spreading of the second edifice and a comparatively stable upper flank region these results suggest that much of the mass of kilauea volcano may lie deeply buried within the underlying flank of mauna loa while older mauna loa rocks may lie far from their source beneath the mobile flank of the younger volcano

evolution of uranogenic and thorogenic lead 1 a dynamic model of continuous isotopic evolution a dynamic model of the continuous isotopic evolution of uranogenic and thorogenic lead based on the minimum possible number of assumptions is proposed here the model is based on the simple assumption that the rate of change of the ratios 238 u 204 pb and w 232 th 204 pb present day values increased initially and after attaining a maximum started decreasing because of surface cooling of the earth the time t m when the and w rates of change attained their maximums is a model parameter depending on the age of formation of the different layers of the crust or in mixing processes on the participation of materials from the older or younger crust and mantle mathematically this is suitably described by a two parameter function which is the product of a linear and an exponential function the deduced equations of the model are calibrated according to the isotopic data on ore lead from the isotopic ratios of a lead sample it is possible to determine the two model ages uranogenic and thorogenic and the model parameter t m or another parameter t related to t m the values of the model parameters t m or t indicate the time of the enrichment ancient or younger in u pb which is an extremely important index for identifying the pb source type the use of these model parameters provide the possibility of a better theoretical description of the pb isotopic characteristics in the different types of sources

the 2011 tohoku oki earthquake displacement reaching the trench axis we detected and measured coseismic displacement caused by the 11 march 2011 tohoku oki earthquake moment magnitude mw 9 0 by using multibeam bathymetric surveys the difference between bathymetric data acquired before and after the earthquake revealed that the displacement extended out to the axis of the japan trench suggesting that the fault rupture reached the trench axis the sea floor on the outermost landward area moved about 50 meters horizontally east southeast and 10 meters upward the large horizontal displacement lifted the sea floor by up to 16 meters on the landward slope in addition to the vertical displacement

ground ruptures of the 1974 and 1983 kaoiki earthquakes mauna loa volcano hawaii the november 30 1974 ml 5 5 and november 16 1983 ml 6 6 earthquakes generated left stepping en echelon ground cracks within the kaoiki seismic zone on the southeast flank of mauna loa volcano hawaii the general trend of the ruptures n48 55 e parallels a nodal plane of the main shocks focal mechanisms the ruptures themselves consist of short predominantly extension cracks which are up to 20 m long and strike roughly e w 30 50 clockwise from the overall trend of the zones some of the cracks are linked by secondary fractures and rubble breccia to form left stepping crack arrays which are themselves linked to form longer en echelon systems of ground rupture geologic maps and field observations indicate that these features emerge from an underlying strike slip fault and they form a fracture process zone above its tip the maximum displacement measured across cracks in the 1983 rupture zone is 0 5 m trilateration data however suggests that the overall shear displacement was about 1 5 m at depth elastic solutions indicate that a region of significant tensile stress can exist above buried strike slip faults we suggest that these stresses generated the extensional ground cracks and that shear displacements were transmitted to the earth s surface by subsequent growth and linkage of these cracks into the observed arrays we infer that the crack arrays accommodate increased displacement with depth and they merge downward into the parent strike slip fault at an estimated 1 2 km depth where strike slip displacement was probably more or less continuous along the 7 km length of the rupture in the kaoiki region only three major ground ruptures traverse a series of basaltic lava flows that date back 1500 years this suggests that the recent 10 year periodicity of moderate magnitude kaoiki strike slip events may not have extended far into the past the tectonic significance of strike slip faulting on mauna loa volcano remains enigmatic

crustal structure of mauna loa volcano hawaii from seismic refraction and gravity data abstract in october 1978 the u s geological survey established a 100 km long seismic refraction profile normal to the kona coast of hawaii island analysis of these data along with available gravity data suggest that the oceanic crust dips about 3 landward under the submerged flank of the island increasing to 8 5 under the kona coast maximum vertical deflection of the base of crust from beneath the deep ocean to a point beneath the summit of mauna loa is about 9 km high velocity high density rocks vp about 7 1 km sec density about 2 9 gm cm 3 comprise the bulk of the volcanic edifice and reach to within a few kilometers of the surface beneath the north flank of mauna loa the data also suggest that an elongate high velocity high density body lies parallel to the kona coast just below the surface this body probably represents an extinct buried rift zone

isotopic evolution of the mantle the role of magma mixing trace element and isotopic data for magmas from the two major mantle reservoirs appear to be inconsistent the incompatible elements and sr and nd isotopes show that abyssal tholeiities morb are form a reservoir that has current and time integrated depletions of the elements that are fractionated into a melt morb however have206pb 204pb and207pb 204pb ratios suggesting long term enrichment in u pb i e future single stage ages alkali basalts and tholeiities from continents and oceanic islands are derived from lile and u pb enriched reservoirs sr and nd isotopic ratios however appear to indicate that some of these basalts are derived from unfractionated reservoirs and others from reservoirs with time integrated depletions the apparent stages of the mantle reservoirs are much younger than the ages of continental shields these inconsistencies can be reconciled by assuming that oceanic and continental basalts are mixtures of magmas from depleted and enriched reservoirs morb are slightly contaminated depleted magmas while ocean island and continental basalts are mixtures of morb or a depleted picritic parent magma and an enriched end member having trace element patterns similar to high k magmas such as kimberlites or nephelinites the mixing relations are such that mixtures can be enriched in u pb rb sr nd sm 206pb 204pb relative to primitive mantle yet appear to have time integrated depletions in143nd 144nd and87sr 86sr a small amount of contamination by material from an enriched reservoir can explain the pb results for morb depleted basalts are more sensitive to pb than to rb or nd contamination the238u 204pb of uncontaminated morb may be about 7 compared to 7 9 for the primary growth curve and 10 for the enriched reservoirs similarly continental and ocean island basalts may represent mixtures of enriched and depleted magmas if so the ages of mantle reservoirs have been underestimated we propose that both of the major mantle magmas source are in the upper mantle and that both are global in extent the shallower one 200 km depth is inhomogenous having been enriched metasomatised at various time by fluids from the depleting layer it may also be the sink of subducted sediments and hydrothermally altered oceanic crust the deeper source 220 670 km depth is more homogenous more garnet rich and provides depleted magmas which however become contaminated as they rise through the shallow encriched layer partial melting and diapiric ascent originated in the thermal boundary layer between the two chemically distinct layers magma mixing prior to eruption is an inevitable consequence of a chemically layered mantle with depleted magmas rising through an enriched uppermost mantle this allows quantification of the heretofore nebolous concept of mantle metasomatism

flexure and seismicity beneath the south flank of kilauea volcano and tectonic implications we present a refined model for the tectonic behavior of kilauea volcano s south flank including flexure calculations and microearthquake data supportive of the model in our model the south flank moves seaward over the downwardly flexed ocean crust in a manner analogous to an accretionary prism in a subduction zone the flank is driven seaward by the gravitational stresses inherent in its shape this driving force is augmented by high density material in kilauea s rift zones elastic flexure calculations predict a configuration for the downwardly flexed crust which agrees with previous seismic refraction and gravity modeling this configuration in turn is consistent with the hypothesis that many earthquakes occur along the volcanic pile ocean crust interface focal mechanisms for these events predominantly indicate southeastward directed overthrusting we also propose a relationship between rift zone intrusion and south flank displacement including a suggestion that the decollement configuration controls the relative activity of kilauea s east and southwest rift zones

did a submarine landslide contribute to the 2011 tohoku tsunami many studies have modeled the tohoku tsunami of march 11 2011 as being due entirely to slip on an earthquake fault but the following discrepancies suggest that further research is warranted 1 published models of tsunami propagation and coastal impact underpredict the observed runup heights of up to 40 m measured along the coast of the sanriku district in the northeast part of honshu island 2 published models cannot reproduce the timing and high frequency content of tsunami waves recorded at three nearshore buoys off sanriku nor the timing and dispersion properties of the waveforms at offshore dart buoy 21418 3 the rupture centroids obtained by tsunami inversions are biased about 60 km nne of that obtained by the global cmt project based on an analysis of seismic and geodetic data together with recorded tsunami waveforms we propose that while the primary source of the tsunami was the vertical displacement of the seafloor due to the earthquake an additional tsunami source is also required we infer the location of the proposed additional source based on an analysis of the travel times of higher frequency tsunami waves observed at nearshore buoys we further propose that the most likely additional tsunami source was a submarine mass failure smf i e a submarine landslide a comparison of pre and post tsunami bathymetric surveys reveals tens of meters of vertical seafloor movement at the proposed smf location and a slope stability analysis confirms that the horizontal acceleration from the earthquake was sufficient to trigger an smf forward modeling of the tsunami generated by a combination of the earthquake and the smf reproduces the recorded on near and offshore tsunami observations well particularly the high frequency component of the tsunami waves off sanriku which were not well simulated by previous models the conclusion that a significant part of the 2011 tohoku tsunami was generated by an smf source has important implications for estimates of tsunami hazard in the tohoku region as well as in other tectonically similar regions

mechanism of the 1975 kalapana hawaii earthquake inferred from tsunami data we investigated the source mechanism of the 1975 kalapana hawaii earthquake m s 7 2 by modeling the tsunamis observed at three tide gauge stations hilo kahului and honolulu we computed synthetic tsunamis for various fault models the arrival times and the amplitudes of the synthetic tsunamis computed for ando s fault model fault length 40 km fault width 20 km strike n70 e dip 20 se rake 90 fault depth 10 km and slip 5 6 m are 10 min earlier and 5 times smaller than those of the observed respectively we tested fault models with different dip angles and depths models with a northwest dip direction yield larger tsunami amplitudes than those with a southeast dip direction models with shallower fault depths produce later first arrivals than deeper models we also considered the effects of the hilina fault system but its contribution to tsunami excitation is insignificant this suggests that another mechanism is required to explain the tsunamis one plausible model is a propagating slump model with a 1 m subsidence along the coast and a l m uplift offshore this model can explain the arrival times and the amplitudes of the observed tsunamis satisfactorily an alternative model is a wider fault model that dips 10 nw with its fault plane extending 25 km offshore well beyond the aftershock area of the kalapana earthquake these two models produce a similar uplift pattern offshore and kinematically are indistinguishable as far as tsunami excitation is concerned the total volume of displaced water is estimated to be 2 5 km 3 from the comparison of slump model and the single force model suggested earlier from seismological data we prefer a combination of faulting and large scale slumping on the south flank of kilauea volcano as the most appropriate model for the 1975 kalapana earthquake two basic mechanisms have been presented for explaining the deformation of the south flank of kilauea 1 pressure and density variation along the rift zone caused by magma injection and 2 gravitational instability due to the steep topography of the south flank of kilauea in either mechanism large displacements on the south flank are involved that are responsible for the observed large tsunamis

along arc structural variation of the plate boundary at the japan trench margin implication of interplate coupling 1 at the japan trench convergent margin many large interplate earthquakes of greater than m7 5 frequently occur their epicenters have uneven distribution mostly located in the northern area to investigate the relationship between this distribution and tectonic structures we have conducted multichannel seismic surveys since 1996 our data show two kinds of interplate sedimentary units a wedge shaped unit and a channel like unit both units have a lower p wave velocity than the basal part of the overriding island arc crust the wedge shaped unit having a velocity of 2 3 km s is widely distributed over the forearc region in the northern area its thickness decreases with depth becoming several hundred meters at a depth of 12 km the channel like unit having a velocity of 3 4 km s is observed in the southern area extending in the downdip direction its thickness reaches 2 km at a depth of 12 km if the low velocity of these units results from the existence of fluid as many authors assume the units being thick implies higher fluid content assuming constant porosity considering that fluid reduces basal friction and with an assumption that fluid available at a specific interface is proportional to the total fluid content in the sediment the thickness variation of the units would cause different degrees of coupling at the plate boundary along the arc this may provide one explanation for the regional disparity in the interplate earthquake occurrence in the margin furthermore we attempt to call attention to the possibility that the channel like sediment works as a shear stress releaser

lithospheric flexure under the hawaiian volcanic load internal stresses and a broken plate revealed by earthquakes several lines of earthquake evidence indicate that the lithospheric plate is broken under the load of the island of hawai i where the geometry of the lithosphere is circular with a central depression the plate bends concave downward surrounding a stress free hole rather than bending concave upward as with past assumptions earthquake focal mechanisms show that the center of load stress and the weak hole is between the summits of mauna loa and mauna kea where the load is greatest the earthquake gap at 21 km depth coincides with the predicted neutral plane of flexure where horizontal stress changes sign focal mechanism p axes below the neutral plane display a striking radial pattern pointing to the stress center earthquakes above the neutral plane in the north part of the island have opposite stress patterns t axes tend to be radial the m6 2 honomu and m6 7 kiholo main shocks both at 39 km depth are below the neutral plane and show radial compression and the m6 0 kiholo aftershock above the neutral plane has tangential compression earthquakes deeper than 20 km define a donut of seismicity around the stress center where flexural bending is a maximum the hole is interpreted as the soft center where the lithospheric plate is broken kilauea s deep conduit is seismically active because it is in the ring of maximum bending a simplified two dimensional stress model for a bending slab with a load at one end yields stress orientations that agree with earthquake stress axes and radial p axes below the neutral plane a previous inversion of deep hawaiian focal mechanisms found a circular solution around the stress center that agrees with the model for horizontal faults the shear stress within the bending slab matches the slip in the deep kilauea seismic zone and enhances outward slip of active flanks

survey of 2011 tohoku earthquake tsunami inundation and run up 1 at 14 46 local time on march 11 2011 a magnitude 9 0 earthquake occurred off the coast of northeast japan this earthquake generated a tsunami that struck japan as well as various locations around the pacific ocean with the participation of researchers from throughout japan joint research groups conducted a tsunami survey along a 2000 km stretch of the japanese coast more than 5300 locations have been surveyed to date generating the largest tsunami survey dataset in the world on the sendai plain the maximum inundation height was 19 5 m and the tsunami bore propagated more than 5 km inland along the ria coast from about 50 to 200 km north of sendai the narrow bays focused the tsunami waves generating the largest inundation heights and run ups the survey data clearly show a regional dependence of tsunami characteristics

evolution of uranogenic and thorogenic lead 2 some differences in the variations of the206pb 204pb and208pb 204pb ratios abstract on the basis of a dynamic model of a continuous pb isotope evolution the variations in the isotopic ratios of uranogenic and thorogenic pb in a number of young ore deposits ocean sediments and volcanic rocks from mid ocean ridges oceanic islands island arcs and continents are evaluated the deviations in the th u ratio from its model values are calculated a model parameter t which indicates a more ancient enrichment in u pb crustal type pb sources or younger enrichment in u pb mantle type pb sources is also calculated the relative change in the th u ratio is close to 1 for mantle type pb sources lower t values and decreases for crustal type pb sources higher t values an interpretation of these changes could be connected with the differences in the u and th geochemical behaviours in metamorphic processes under the conditions of a deeper mantle or crustal source owing to the differences in their valence states in some cases they have similar u 4 and th 4 migration abilities in others u 6 and th 4 considerably different

estimate of the stress field in kilauea s south flank hawaii summary we estimated stress and seismic strain tensors for the kilauea volcano s south flank the stress orientation inversion and the seismic strain calculation were performed using fault plane solutions the principal stress and seismic strain directions are approximately uniformly distributed in space and time during the interval covered by the data however the 01 03 plane is approximately orthogonal to the plane therefore a weak layer may exist beneath the south flank o1 has a plunge of 59 and an azimuth of 152 with a 10 95 per cent confidence range we also developed a stress magnitude inversion to estimate magnitudes of boundary and interior stresses in this inversion the principal stress directions were taken as constraints in the seismic volume and surface geodetic observations were used as data the maximum magmatic pressure in kilauea s rift zone is about 160 mpa the direction of o1 can be interpreted as the superposition of hydrostatic stress pgh and magmatic pressure without the constraint imposed by the direction of ol the estimated pressure is only 60 mpa the distribution of magmatic pressure may be similar to that of pgh in contrast the upper rift zone may be in tension the shear stress in the rift zone is about one order of magnitude smaller than the maximum compressive stress supporting the interpretation of magmatic flow as fluid in dikes or channels the combination of stress orientation inversion seismic strain calculation and stress magnitude inversion performed in this study provides a means by which to estimate the stress state in seismic areas

trench normal variation in observed seafloor displacements associated with the 2011 tohoku oki earthquake 1 seafloor geodetic measurements using the gps acoustic technique just above the rupture area of the 2011 tohoku oki earthquake revealed strong trench normal variation in the horizontal crustal displacement associated with the earthquake one set of observations at a site only 50 km away from the trench yielded the most trench ward data ever reported with an accuracy better than 1 m it showed a coseismic displacement of up to 31 m whereas another set of observations 100 km away from the trench showed a 15 m displacement these horizontal data as well as vertical data from pressure gauges and tsunami observations strongly indicate that the seismic slip reached the trench they are also likely to contribute quantitatively to further investigations that reveal the coseismic behavior of the frontal wedge of the overriding plate in the source region along the japan trench

a single force model for the 1975 kalapana hawaii earthquake a single force mechanism is investigated as the source of long period seismic radiation from the 1975 kalapana hawaii earthquake m s 7 1 the observed love wave radiation pattern determined from the spectra of world wide standard seismograph network and high gain long period records at 100 s is two lobed with azimuth consistent with a near horizontal single force acting opposite strike 330 to the observed displacement direction of the earthquake this pattern is inconsistent with the expected double couple pattern assuming a form of the force time history of a one cycle sinusoid the total duration of the event estimated from rayleigh waves at two international deployment of accelerometers stations is approximately 180 s the peak amplitude f o of the time function is 1 10 15 n from amplitudes of love and rayleigh waves the interpretation is that the bulk of the seismic radiation was produced by large scale slumping of a large area of the south flank of kilauea volcano the single force is a crude representation of the effect on the earth of the motion of a partially decoupled large slide mass using the mass estimated from the tsunami generation area 10 15 10 16 kg the peak acceleration of the slide block 0 1 1 m s 2 inferred from the seismic force is comparable with the acceleration due to gravity on a gently inclined plane the slump model for the kalapana earthquake is also more qualitatively consistent with the large horizontal deformation 8 m on land and tsunami associated with the earthquake which are difficult to explain with the conventional double couple source model the single force source has been used previously to model the long period seismic waves from the landslide accompanying the eruption of mount st helens volcano and may explain other anomalous seismic events as being due to massive slumping of sediments or unconsolidated material and not to elastic dislocation

an increment of volcano collapse kinematics of the 1975 kalapana hawaii earthquake abstract earthquakes on kilauea volcano can be even more hazardous than volcanic eruptions the most recent large earthquake was the 1975 kalapana quake which generated a locally damaging tsunami over 8 m of horizontal surface displacement and 3 m of subsidence at the coast the seismic magnitude estimates for this earthquake range from ms 7 2 to mw 7 7 the complexity of the seismic data is matched by the complex surface deformation that was observed with a combination of leveling tilt and electronic distance measurements edm the geodetic data shows evidence of collapse of the caldera due to magma withdrawal localized subsidence over the rift zone normal faulting associated with shallow slumping along the hilina pali and displacement on the basal detachment fault we model the summit caldera rift zones and basal detachment fault as dislocations in an elastic half space to better quantify the sources of deformation related to this devastating event using inversion techniques that allow us to let the data constrain the geometry and magnitude of these sources we find 0 04 km3 of magma withdrawal at the summit between 3 5 m of opening along the rift zone and 7 1 m of slip along the basal detachment at 8 3 km depth models that allow for finer spatial resolution of slip on the detachment show that the largest slip occurred west of the seismically recorded earthquake hypocenter along the region of the fault below the coast and that the majority of the fault slip occurred south of the region of microseismicity our best fitting model has a geodetic moment of 4 1 1020 nm mw 7 7 which is consistent with tsunami models and recent analysis of long period seismic data the residual displacements of sites located in the hanging wall of the hilina pali slump system which were not used in the inversion of the other sources suggest that triggered shallow slumping contributed several meters of horizontal displacement to the coseismic displacement at these sites

structure of the mobile south flank of kilauea volcano hawaii how do huge landslides occur in hawaii we can begin to address this question by examining an incipient landslide structure on the mobile south flank of kilauea volcano between 1970 and 1989 this part of the south flank moved in a southeast direction seaward by 4 m on its eastern end and by 10 m on its western end parallel to the western boundary of a large oifshore topographic bench we show that abrupt decreases in cumulative flank movement correspond to abrupt decreases in hypocenter concentration most of the earthquakes occur in a 7 to 10 km deep band beneath the south flank and relative relocation of a subset of these events shows that they are derived from a single horizontal plane which appears to be a decollement focal mechanisms for this deep seismicity are dominated by thrust fault mechanisms with the overlying block moving seaward a comparison of south flank bathymetry with decollement structures on other volcanoes suggests that the distal end of this decollement coincides with the distal end of the offshore topographic bench 30 50 km from shore and 5 km below sea level the fault system forming the hilina pali is connected with this decollement so that slip on the hilina pali s normal faults coincides with slip of the decollement and with reverse faulting of the distal end of the bench this interpretation is supported by studies of the events associated with the m7 2 kalapana earthquake in 1975 when the hilina pali is connected to the outer bench with a decollement inferred from seismicity a wedge 8 km thick adjacent to kilauea s magma system and 1 2 km thick along the edge of the outer bench an area over 3000 km2 is defined the thickness adjacent to the magma system decreases eastward along kilauea s east rift zone and southwestward from kilauea caldera whereas the thickness of the lip of the outer bench decreases only eastward geologic observations and geophysical studies of the subaerial flank reveal an extensive magma system beneath the koae fault system as well as beneath kilauea caldera and its east rift zone we infer that the boundary of the proximal end of the mobile flank is the southern boundary of this magma system and that this boundary coincides with the southern boundaries of both the koae fault system and kilauea s east rift zone

displacement above the hypocenter of the 2011 tohoku oki earthquake the moment magnitude m w 9 0 2011 tohoku oki mega thrust earthquake occurred off the coast of northeastern japan combining global positioning system gps and acoustic data we detected very large sea floor movements associated with this event directly above the focal region an area with more than 20 meters of horizontal displacement that is four times larger than those detected on land stretches several tens of kilometers long along the trench the largest amount reaches about 24 meters toward east southeast just above the hypocenter furthermore nearly 3 meters of vertical uplift occurred contrary to observed terrestrial subsidence

motion of kilauea volcano during sustained eruption from the puu oo and kupaianaha vents 1983 1991 kilauea erupted almost continuously from january 1983 through 1991 although the summit began subsiding during the rift zone dike intrusion that initiated this eruption remarkably steady ground surface motions began in late 1983 after a magnitude 6 6 earthquake beneath the slopes of nearby mauna loa volcano and continued until the onset of brief upper east rift zone earthquake swarms in late 1990 during these 7 years the summit and upper rift zones subsided up to 10 11 and 4 8 cm yr 1 respectively and summit baselines contracted up to 6 cm yr 1 baselines directed northward from the summit to stations on mauna loa extended at rates up to 7 cm yr 1 and a baseline from south of the summit to mauna loa extended 4 cm yr 1 much of this extension is inconsistent with deformation caused solely by summit magma reservoir collapse and more likely reflects rifting as the south flank of the volcano moved seaward from the summit and rift zones farther from the summit baselines crossing the south flank extended up to 2 cm yr 1 and a south flank tide gauge rose 2 cm yr 1 the lower east rift zone 40 50 km from the summit subsided about 2 cm yr 1 motion on kilauea then is broadly consistent with slip along low angle south flank faults generating subsidence that is focused at the summit and along the rift system behind the faulting and uplift along the coastal south flank ahead of it dislocation models that combine these elements show that much of kilauea s edifice migrated seaward producing ground surface motions along the south flank of up to about 6 cm yr 1 the magnitude 6 1 earthquake of 1989 punctuated these motions along the eastern south flank producing more than 25 cm of seaward displacement and 15 km east of the epicenter up to 24 cm of subsidence south of the lower east rift zone unlike the magnitude 7 2 south flank earthquake of 1975 the 1989 event was preceded neither by summit magma reservoir inflation nor by rift zone dike intrusions and accompanying compression of the south flank deformation was probably caused by the weight of the volcanic overburden and by ongoing dilation and slip within the rift system

a possible triggering mechanism for large hawaiian earthquakes derived from analysis of the 26 june 1989 kilauea south flank sequence abstract examination of short period seismic data from the m l 6 1 kilauea south flank earthquake and aftershock sequence indicates that the rupture process in large hawaiian earthquakes is more complex than previously modeled in contrast to the low angle thrust solution determined for the mainshock from long period teleseismic body waves by other workers i find an intermediate to high angle reverse solution i find however that focal mechanisms for coastal aftershocks of m l 3 0 are similar to the teleseismic mechanism for the mainshock a difference in focal mechanisms determined from short period local network seismic data and from long period teleseismic data has been noted for other recent large hawaiian earthquakes both the mapping of surface cracks and the focal mechanism derived from short period seismic data for the m l 6 6 1983 kaoiki earthquake show strike slip motion whereas the centroid moment tensor solution shows low angle thrusting the focal mechanism calculated from short period seismic data for the m l 7 2 1975 kalapana mainshock shows low angle thrusting according to some workers but intermediate to high angle reverse faulting according to others whereas focal mechanisms calculated from long period seismic data show low angle thrusting this result suggests that rupture initiation in large hawaiian earthquakes as represented by the short period focal mechanisms differs significantly from the overall rupture process as represented by the teleseismic mechanisms i propose that small earthquakes trigger the large scale energy release at the bases of the volcanic edifices the type of energy release often observed in large hawaiian earthquakes these triggering events may occur along rupture surfaces that differ from those along which the long period moment release occurs and thus may represent release of a local stress concentration superposed upon the regional stress field

time and space distribution of coseismic slip of the 2011 tohoku earthquake as inferred from tsunami waveform data a multiple time window inversion of 53 high sampling tsunami waveforms on ocean bottom pressure global positioning system coastal wave and tide gauges shows a temporal and spatial slip distribution during the 2011 tohoku earthquake the fault rupture started near the hypocenter and propagated into both deep and shallow parts of the plate interface a very large slip approximately 25 m in the deep part off miyagi at a location similar to the previous 869 jogan earthquake model was responsible for the initial rise of tsunami waveforms and the recorded tsunami inundation in the sendai and ishinomaki plains a huge slip up to 69 m occurred in the shallow part near the trench axis 3 min after the rupture initiation this delayed shallow rupture extended for 400 km with more than a 10 m slip at a location similar to the 1896 sanriku tsunami earthquake and was responsible for the peak amplitudes of the tsunami waveforms and the maximum tsunami heights measured on the northern sanriku coast 100 km north of the largest slip the average slip on the entire fault was 9 5 m and the total seismic moment was 4 2 1022 n m m w 9 0 the large horizontal displacement of seafloor slope was responsible for 20 40 of tsunami amplitudes the 2011 deep slip alone could reproduce the distribution of the 869 tsunami deposits indicating that the 869 jogan earthquake source could be similar to the 2011 earthquake at least in the deep plate interface the large tsunami at the fukushima nuclear power station is due to either the combination of a deep and shallow slip or a triggering of a shallow slip by a deep slip which was not accounted for in the previous tsunami hazard assessments online material table of estimated slip for all subfaults at 0 5 min invervals

isotopic composition of lead in proterozoic anoxic metasedimentary and volcanogenic rocks from the bohemian massif czech republic with metallogenetic implications abstract the isotopic composition of lead in normal and metal rich black shales and associated volcanogenic rocks has been studied in the barrandian upper proterozoic of the bohemian massif which is a part of the central european variscan belt these rocks played an important role in the metallogeny of the bohemian massif the late proterozoic age of metamorphism is evidenced by the slope of the secondary isochron of the uranogenic lead corresponding to the age of 635 45 ma and by the model age of 540 590 ma of thorogenic lead in the samples with low th u ratios in most of the samples the leached pb is less radiogenic than the residual pb no correlation was established between the presence of more radiogenic samples and the distance towards variscan granitoids the samples are mostly associated with the upper proterozoic volcano sedimentary sequences far from variscan intrusions and only some occur in the exocontacts of variscan plutons this suggest that most of the uranium was introduced into rocks during cadomian metamorphism rather than variscan tectonomagmatic phases however a possible contribution of radiogenic lead in connection with the latter events as well as some heterogeneity in u pb and th pb ratios from the time between sedimentation and metamorphism cannot be excluded the comparatively low 208 pb 204 pb ratios indicate that thorium was not mobilized by the metamorphic fluids and testifies that th is less mobile under metamorphic conditions the 207 pb 204 pb values 15 57 15 63 of less radiogenic lead in the rocks are close to those of galenas from different variscan polymetallic mineralizations in the bohemian massif which suggests a common source from a well mixed reservoir as observed in ore leads in mature island arcs or at active boundaries between continental and oceanic plates

profile of discontinuities beneath hawaii from s to p converted seismic waves we present new seismological evidence for the depth of depression of the volcano crust and crust mantle moho boundaries and the nature of the volcano crust interface beneath the southeast flank of mauna loa volcano hawaii from a profile of s to p converted waves from deep local earthquakes three component seismic array observations of these converted waves indicate the presence of a low velocity layer lvl at a depth of about 10 km corresponding to the base of the volcanic pile the thickness of the lvl is estimated to be approximately 1 km the lvl and the moho both deepen significantly from southwest to northeast beneath mauna loa s southeast flank the observed polarity reversal of the lvl conversion compared to the moho conversion strongly supports the existence of a buried sediment layer at the volcano ocean crust interface at a depth that is consistent with the depth distribution of thrust earthquakes our results conflict with models of lithosphere flexure at hawaii indicating a depression of the lithosphere greater than that predicted by flexure models the thickness of underlying oceanic crust is observed to be relatively constant so this discrepancy cannot be accounted for by crustal underplating alone

type of faulting and orientation of stress and strain as a function of space and time in kilauea s south flank hawaii earthquake focal mechanisms of events occurring between 1972 and 1992 in the south flank of kilauea volcano hawaii are used to infer the state of stress and strain as a function of time and space we have determined 870 fault plane solutions from p wave first motion polarities for events with magnitudes m l 2 5 and depth ranging between 6 and 12 km faulting is characterized by a mixture of decollement reverse and normal faults most large earthquakes with magnitude m 7 rupture the decollement plane since it is the only surface large enough to generate magnitude 7 or larger earthquakes the percentage of reverse faulting events is high compared to the decollement and normal faulting mechanisms for the period 1972 1983 the percentage of decollement type focal mechanisms becomes dominant after 1983 this pattern of faulting activity suggests that pressure was building up within kilauea s rift zone prior to the 1983 puu oo eruption overall a single stress orientation with the maximum compressive stress oriented se perpendicular to the rift and dipping at 45 is compatible with the coeval existence of decollement reverse and normal faults however in a crustal volume east of longitude 155 10 w we find a change of the orientation of 1 from nearly horizontal to plunging 45 se occurring in 1979 this stress rotation suggests magma movements within the aseismic part of kilauea s east rift zone the strain and stress orientations are coaxial in the south flank except within the volume where the stress rotation is observed we observe a change in the relationship between stress and strain directions caused either by the shifting of seismic activity from reverse faults to decollements while stress stays constant or by a rotation of stress while strain remains constant assuming that the model of a noncohesive coulomb wedge is appropriate for kilauea s south flank we find that high pore pressures are prevalent along the decollement and within the wedge for a coefficient of friction equal to 0 85

tsunami source uncertainty estimation the 2011 japan tsunami this article was published in the journal of geophysical research solid earth 2016 american geophysical union and the definite version is available at http dx doi org 10 1002 2015jb012764 the journal s website is at http onlinelibrary wiley com doi 10 1002 2015jb012764 abstract jsessionid bf5813b61924fb094f31bc8f213840a1 f02t04

relocation of seismicity preceding the 1984 eruption of mauna loa volcano hawaii delineation of a possible failed rift abstract waveform cross correlation based repicking of p arrival times and subsequent relocation of 187 earthquakes that occurred near the summit of mauna loa hawaii prior to the march 1984 eruption has illuminated a previously obscured structure beneath the northwestern flank simultaneous inversion for hypocenters and velocity model parameters using the refined arrival times resulted in well constrained relative earthquake locations with very low arrival time misfits average rms 0 041 s pre eruption seismicity from this time period occurred in two groups a shallow group located near mauna loa s summit at depths of 1 3 km and a deeper group 5 10 km located 4 6 km northwest of the summit after relocation we found that most of the northwest flank earthquakes occurred along a 3 km long planar feature striking about 60 west of north in a thin band about 1 km thick there is a temporal migration of epicenters from the northwestern edge of the zone migrating towards the summit focal mechanisms in this zone reveal a change in faulting from strike slip in the southeast to a mix of strike slip and normal faulting in the northwest this feature we interpret to be related to a rift zone that was stunted by the buttressing of the adjacent volcanoes hualalai and mauna kea previous gravity and magnetic studies provide supporting evidence for the existence of a rift zone there was only a modest increase in clustering of the summit events after relocation hypocenters that were previously located within a diffuse zone 4 5 km were reduced to a 2 5 km wide zone they extend from a depth of 6 km to about sea level trending toward the summit the focal mechanisms from the summit events are mix of faulting types without a consistent pattern