self excitation process due to local seismic amplification responsible for the reactivation of the salcito landslide italy on 31 october 2002 1 an integrated numerical and geophysical approach was used to investigate the role of local seismic amplification in the reactivation of the salcito landslide italy after the molise earthquake of 31 october 2002 numerical stress strain analysis with flac 5 0 fdm software performed in dynamic configuration showed that the 1 hz frequency was consistent with landslide instability conditions the fourier spectrum of the triggering earthquake showed two main peaks occurring at 1 and 2 hz respectively which could be related to local effects the analysis of h v spectral ratios of ambient noise records obtained in the landslide area evidenced amplification effects in the 1 3 hz range on the basis of an engineering geology model numerical modeling of both 1 d and 2 d seismic wave propagation was conducted using linear and nonlinear solutions the simulation outputs showed 1 a 1 hz amplification ascribable to 2 d effects due to a landslide mass lying within a basin like geological structure 2 a double peak amplification at about 2 and 3 hz respectively ascribable to 1 d resonance of the landslide mass and 3 1 d plus lateral wave effects within the landslide mass in the 2 5 3 5 hz frequency range these findings suggest that local amplification of ground motion by the salcito landslide mass may generate a self excitation process responsible for its reactivation

a parametric numerical study of the interaction between seismic waves and landslides for the evaluation of the susceptibility to seismically induced displacements this study presents the results of a numerical analysis investigating the influence of the interaction between seismic waves and slopes on seismically induced displacements of existing landslides three step like slope geometries with dip angles varying from 10 degrees to 45 degrees and two landslide mechanisms were considered 54 multi frequential dynamic equivalent signals were applied to the models and were derived according to the lema des approach based on the accelerometric records of the european strong motion and cosmos databases the simulations were performed using a finite difference approach that assumed different viscous rheologies and considered different values for both the dynamic properties and the mechanical parameters the interaction between seismic waves and landslides was analyzed using frequency ratios defined for characteristic periods associated with the landslide dimensions i e thickness and length and the seismic input a regression analysis was also performed to derive correlations between seismically induced displacements and the frequency ratios the values of the arias intensity and the critical accelerations the obtained results reveal that a the seismically induced displacements increase with the seismic amplification induced by the landslide mass b the coupling of a 2d interaction between seismic waves and slope with the 1d resonance of the landslide mass which is strictly related to the high impedance contrasts between the landslide mass and the substratum significantly affects the seismically induced displacements and c the seismically induced displacements increase more intensely with increasing slope angle for a rototranslational mechanism with respect to a translational one moreover the seismically induced displacements that can be expected from the here obtained results can significantly differ from those computed by the sliding block stability analyses based on newmark s method

the great tumaco colombia earthquake of 12 december 1979 southwestern colombia and northern ecuador were shaken by a shal low focus earthquake on 12 december 1979 the magnitude 8 shock located near tumaco colombia was the largest in northwestern south america since 1942 and had been forecast to fill a seismic gap thrust faulting occurred on a 280 by 130 kilometer rectangular patch of a subduction zone that dips east beneath the pacific coast of colombia a 200 kilometer stretch of the coast tectonically subsided as much as 1 6 meters uplift occurred offshore on the continental slope a tsunami swept inland immediately after the earthquake ground shaking intensity vi to ix caused many buildings to collapse and generated liquefaction in sand fills and in holocene beach lagoonal and fluvial deposits

arecibo radar observations of phobos and deimos abstract in november 2005 we observed the moons of mars using the arecibo 2380 mhz 13 cm radar obtaining a result for the oc radar albedo of phobos 0 056 0 014 consistent with its previously reported radar albedo and implying an upper bound on its near surface bulk density of 1 6 0 3 g cm 3 we detected deimos by radar for the first time finding its oc radar albedo to be 0 021 0 006 implying an upper bound on its near surface density of 1 1 0 3 g cm 3 consistent with a high porosity regolith we briefly discuss reasons for these low radar albedos deimos being possibly the lowest of any solar system body yet observed by radar

acoustic fluidization and the extraordinary mobility of sturzstroms 1 sturzstroms are a rare category of rock avalanche that travel vast horizontal distances with only a comparatively small vertical drop in height their extraordinary mobility appears to be a consequence of sustained fluid like behavior during motion which persists even for driving stresses well below those normally associated with granular flows one mechanism that may explain this temporary increase in the mobility of rock debris is acoustic fluidization where transient high frequency pressure fluctuations generated during the initial collapse and subsequent flow of a mass of rock debris may locally relieve overburden stresses in the rock mass and thus reduce the frictional resistance to slip between fragments in this paper we develop the acoustic fluidization model for the mechanics of sturzstroms and discuss the conditions under which this process may sustain fluid like flow of large rock avalanches at low driving stresses

controls of earthquake faulting style on near field landslide triggering the role of coseismic slip 1 we compare the spatial distributions of seven databases of landslides triggered by mw 5 6 7 9 earthquakes using distances normalized by the earthquake fault length we show that the normalized landslide distance distributions collapse i e the normalized distance distributions overlap whatever the size of the earthquake separately for the events associated with dip slip buried faulting earthquakes and surface faulting earthquakes the dip slip earthquakes triggered landslides at larger normalized distances than the oblique slip event of loma prieta we further identify that the surface faulting earthquakes of wenchuan chi chi and kashmir triggered landslides at normalized distances smaller than the ones expected from their mw 7 6 magnitudes these results support a control of the seismic slip through amplitude rake and surface versus buried slip on the distances at which landslides are triggered in terms of coseismic landslide management in mountainous areas our results allow us to propose distances at which 95 and 75 of landslides will be triggered as a function of the earthquake focal mechanism

landslides caused by the m 7 6 tecoman mexico earthquake of january 21 2003 abstract the tecoman mexico earthquake also called the colima earthquake of january 21 2003 m 7 6 triggered several hundreds of landslides in the coastal cordilleras of colima state near the earthquake source and several thousands in the volcanic highlands north and northwest of colima city these landslides mostly shallow and disrupted failures caused minor damage to roads to a railroad and to irrigation systems in one area extensive post earthquake rock fall activity indicates a possible long term instability that could threaten dwellings and other infrastructure located nearby in the coastal cordilleras most of the landslides were generated by failures of artificially cut slopes especially along roads the rocks of the coastal cordilleras are generally well indurated and landslides occurred only where the rocks were made locally susceptible by weathering the presence of prominent discontinuities with unfavorable orientations or intense fracturing or shearing in contrast to the coastal cordilleras the volcanic rocks to the north were more susceptible to the occurrence of seismically triggered landslides the greatest number and concentrations of landslides occurred there and the landslides were larger than those in the coastal cordilleras even though this volcanic terrain was farther from the earthquake source here stretches of river bluffs several hundred meters long had been stripped of vegetation and surficial material by coalescing landslides and several days after the main shock thousands of small rock falls were still occurring each day indicating an ongoing hazard the high susceptibility of volcanic materials to earthquake generated landslides conforms to findings in other recent earthquakes

earthquake induced ground failures in italy abstract the national catalog of ground failures induced by strong earthquakes in italy cedit is described the catalog holds data on ground failures triggered by the earthquakes that occurred in italy in the last millennium and which had a nominal epicentral intensity equal to or greater than viii in the mercalli cancani sieberg mcs intensity scale the ground effects reported in the catalog are the following landslides fractures liquefaction surface faulting and topographic changes of the ground level subsidence settlements tilting and so on each effect is described in terms of seismological parameters of the triggering earthquake site coordinates and administrative code lithology and kinematic type of the ground failure the catalog represents a tool to assess the susceptibility of geologic materials to ground shaking and to validate predictive models of seismically induced ground displacements scenarios of earthquake induced geologic risks in the context of this study a simple statistical analysis of the database yielded useful relations between the parameters of the triggering earthquakes and the related effects

high cu grades in porphyry cu deposits and their relationship to emplacement depth of magmatic sources observations at several porphyry cu deposits indicate that in those formed above source magma chambers emplaced to relatively shallow levels roofs 3 4 km deep zones of higher cu grade are associated with the oldest intrusions of a central porphyry cluster abundant early a type quartz veins secondary feldspar alteration and usually high fe fe cu low s fe cu sulfide oxide mineral assemblages in deposits for which source magma chambers were deeper roofs 5 km porphyries closest in age to ore are spatially less directly related to mineralization in these higher cu grades in early mineralization comprise swarms of veinlets with alteration halos that include sericite as well as secondary feldspar and biotite sulfide oxide assemblages are usually of lower fe fe cu and higher s fe cu these differences in deposit characteristics appear to correspond with a change from two phase chloride bearing aqueous fluids that would exsolve from magma at shallow depths to one phase fluids deeper

unusually cu rich magmas associated with giant porphyry copper deposits evidence from bingham utah mass balance constraints indicate that formation of giant porphyry copper deposits pcds requires either highly efficient collection of cu from large volumes of magma or unusually cu rich parent magmas support for the second of these possibilities has been discovered in the form of mafic enclaves with abundant bornite and chalcopyrite in the last chance stock one of the parent intrusions of the giant bingham pcd utah united states mineral assemblages and compositions indicate that the last chance enclaves are autoliths consisting of phases that crystallized from the intrusion and that the intrusion was unusually enriched in cu one possible mechanism for generating cu rich magmas is fractional crystallization during pyrrhotite undersaturated conditions the high fo 2 conditions observed for the last chance stock may have allowed such an evolution alternatively if the magma has not undergone significant fractionation early crystallization of chalcopyrite and bornite from the magma would indicate that the lower crustal source region for the magma probably contained cu fe sulfides possible cu rich source regions are a subcrustal mafic intrusion with sulfide cumulates or a deeply buried metamorphic terrane containing cu deposits such as those in the curaca valley brazil or okiep south africa heterogeneous distribution of cu fe sulfides in an okiep type source terrane would produce local pcds such as bingham or large accumulations of cu fe sulfides possibly in the form of cumulates in subcrustal intrusions at convergent margins could produce giant pcd provinces such as those in indonesia papua new guinea and central chile

space weathering trends among carbonaceous asteroids abstract we present visible spectroscopic and albedo data of the 2 3 gyr old themis family and the 15 km and small 15 km themis members suggest these phyllosilicate feature and albedo trends result from regolith variations as a function of diameter observations of the beagle asteroids show a small but notable fraction of members with phyllosilicate features the presence of phyllosilicates and the dynamical association of the main belt comet 133p elst pizarro with the beagle family imply the beagle parent body was a heterogenous mixture of ice and aqueously altered minerals

fluid density control on vapor liquid partitioning of metals in hydrothermal systems hot aqueous fluids both vapor and saline liquid are primary transporting media for metals in hydrothermal magmatic systems despite the growing geological evidence that the vapor phase formed through boiling of magmatic ore bearing fluids can selectively concentrate and transport metals the physical chemical mechanisms that control the metal vapor liquid fractionation remain poorly understood we performed systematic experiments to investigate the metal vapor liquid partitioning in model water salt gas systems h2o nacl kcl hcl at hydrothermal conditions measurements show that equilibrium vapor liquid fractionation patterns of many metals are directly related to the densities of the coexisting vapor and liquid phases despite differences in the vapor phase chemistry of various metals that form hydroxide chloride or sulfide gaseous molecules of contrasting volatile properties water solute interaction is a key factor that controls the metal transfer by vapor like fluids in earth s crust these findings allow quantitative prediction of the vapor liquid distribution patterns and vapor phase metal transport in a wide range of conditions our density model accounts well for the vapor brine distribution patterns of na si fe zn as sb and ag observed in fluid inclusions from magmatic hydrothermal deposits for au and cu the partitioning in favor of the liquid phase predicted in a sulfur free system contrasts with the copper and gold enrichment observed in natural vapor like inclusions the formation of stable complexes of cu and au with reduced sulfur may allow for their enhanced transport by sulfur enriched magmatic hydrothermal vapors

investigating the combined effects of shape density and rotation on small body surface slopes and erosion rates abstract based upon observational evidence and the derived shape models from seven small solar system bodies comets 103p hartley 2 and 9p tempel 1 asteroids 433 eros 243 ida 951 gaspra and 25143 itokawa and the martian moon phobos we explore the existence of a self correcting negative feedback system in which disturbance triggered downslope regolith flow is constantly working to erode the local surface topography of rotating irregularly shaped small bodies towards that of a flat equipotential surface this process is driven by the fact that erosion rates are very non linear with respect to slope becoming quite high as slopes approach the angle of repose but also quite low when slopes are small four conditions are required for this system 1 the mean rotational force is a significant fraction of the mean gravitational force 2 a sufficiently thick low cohesion mobile regolith layer exists over most of the body s surface 3 a downslope flow disturbance source is present such as volatile activity on comets or impact induced seismic shaking and 4 a sufficient amount of time has occurred since the body s last major surface alteration when these conditions are met then the magnitude of the gravitational force for the body and hence its bulk density can be estimated by assuming that the body has reached an erosional saddle point in which either increasing or decreasing the body s rotation rate will increase erosion rates and drive the surface topography back towards a low slope state this technique yields bulk density estimates of 220 140 520 kg m 3 for comet 103p hartley 2 and 1400 930 2800 kg m 3 for asteroid 951 gaspra neither of which have accurate density measurements via other means

giant uranium deposits formed from exceptionally uranium rich acidic brines the athabasca basin canada is home to some of the world s largest uranium deposits analysis of preserved ore forming fluids and experimental measurement of uranium solubility in analogous solutions show that the giant deposits could have formed relatively rapidly from extremely uranium rich brines under acidic conditions

evidences of landslide earthquake triggering due to self excitation process the basin like setting of stiff bedrock combined with pre existing landslide masses can contribute to seismic amplifications in a wide frequency range 0 10 hz and induce a self excitation process responsible for earthquake triggered landsliding here the self excitation process is proposed to justify the far field seismic trigger of the cerda landslide sicily italy which was reactivated by the 6th september 2002 palermo earthquake ms 5 4 about 50 km far from the epicentre the landslide caused damage to farm houses roads and aqueducts close to the village of cerda and involved about 40 106 m3 of clay shales the first ground cracks due to the landslide movement formed about 30 min after the main shock a stress strain dynamic numerical modelling performed by fdm code flac 5 0 supports the notion that the combination of local geological setting and earthquake frequency content played a fundamental role in the landslide reactivation since accelerometric records of the triggering event are not available dynamic equivalent inputs have been used for the numerical modelling these inputs can be regarded as representative for the local ground shaking having a pga value up to 0 2 m s2 which is the maximum expected in 475 years according to the italian seismic hazard maps a 2d numerical modelling of the seismic wave propagation in the cerda landslide area was also performed it pointed out amplification effects due to both the structural setting of the stiff bedrock at about 1 hz and the pre existing landslide mass in the range 3 6 hz the frequency peaks of the resulting amplification functions a f fit well the h v spectral ratios from ambient noise and the h h spectral ratios to a reference station from earthquake records obtained by in situ velocimetric measurements moreover the fourier spectra of earthquake accelerometric records whose source and magnitude are consistent with the triggering event show a main peak at about 1 hz this frequency value well fits the one amplified by the geological setting of the bedrock in correspondence with the landslide area which is constituted of marly limestones and characterised by a basin like geometry

unconventional pseudostatic stability analysis of the diezma landslide granada spain based on a high resolution engineering geological model abstract a novel unconventional pseudostatic analysis is proposed here to infer on the sensitivity of a landslide to earthquakes characterized by different physical properties several sine waves with different amplitudes frequencies and phases were applied to the landslide mass assuming limit equilibrium conditions the unconventional approach was used for the diezma landslide case study the landslide is located 25 km from the city of granada spain although the slope had repeatedly suffered small scale stability problems since the construction of the a 92 highway a larger failure occurred on 18 march 2001 and damaged the highway between kilometers 272 6 and 272 8 the landslide had an estimated volume of 1 2 mm 3 and involved a disordered deposit of silt and clay with heterometric blocks within the numidoide formation which outcrops along the contact between the malaguide and dorsal domains of the betic cordillera mountain range despite the 18 million euros spent since 1999 on geotechnical investigations and stabilization solutions the numerous reactivations that occurred through 2010 and 2013 demonstrate the persistent activity of the landslide the geometry of the large slope failure corresponding to the first activation of the diezma landslide was used to back analyze the stability of the slope based on a high resolution engineering geological model the model was developed from the analysis of numerous borehole logs as well as from geophysical investigations consisting of seismic noise measurements the results demonstrate that the safety factor sf of the diezma landslide varies significantly for frequencies less than 1 hz moreover unstable conditions are reached at frequency values between 0 5 and 1 hz for water pressure distributions corresponding to bishop factors r u between 0 and 0 36 to estimate the co seismic displacements the geometrical and mechanical properties of the landslide mass were used to derive its characteristic periods for thickness t s and length t l which were compared with the characteristic period of the earthquake t m the results indicate that the maximum expected co seismic displacements are up to 2 m for an earthquake with a t m value close to 1 s and an arias intensity on the order of 1 m s

volatile transport in a convecting magma column implications for porphyry mo mineralization we propose that convection in a column of silicic magma allows transport of volatile components from large 50 km3 magma chambers to the sites of shallow 3 km porphyry type mo deposits using constraints from the henderson and pine grove systems we show that even at temperatures as low as 700 c a granitic magma with 30 vol phenocrysts can flow through a magma column with a 150 m radius at a rate 10 km3 yr enough magma to contribute the mo necessary to form an ore deposit in a geologically reasonable time frame this process requires an efficient mechanism for bubble separation at the top of the magma column to produce degassed magma that can descend down through the column it also requires slow rates of crystallization in the silicic magma consistent with experimental studies hydrothermal fluids released from the convecting magma column can explain many geologic features of the deposits

earthquake induced chains of geologic hazards patterns mechanisms and impacts large earthquakes initiate chains of surface processes that last much longer than the brief moments of strong shaking most moderate and large magnitude earthquakes trigger landslides ranging from small failures in the soil cover to massive devastating rock avalanches some landslides dam rivers and impound lakes which can collapse days to centuries later and flood mountain valleys for hundreds of kilometers downstream landslide deposits on slopes can remobilize during heavy rainfall and evolve into debris flows cracks and fractures can form and widen on mountain crests and flanks promoting increased frequency of landslides that lasts for decades more gradual impacts involve the flushing of excess debris downstream by rivers which can generate bank erosion and floodplain accretion as well as channel avulsions that affect flooding frequency settlements ecosystems and infrastructure ultimately earthquake sequences and their geomorphic consequences alter mountain landscapes over both human and geologic time scales two recent events have attracted intense research into earthquake induced landslides and their consequences the magnitude m 7 6 chi chi taiwan earthquake of 1999 and the m 7 9 wenchuan china earthquake of 2008 using data and insights from these and several other earthquakes we analyze how such events initiate processes that change mountain landscapes highlight research gaps and suggest pathways toward a more complete understanding of the seismic effects on the earth s surface

landslides and other surface effects induced by the 1997 umbria marche seismic sequence abstract this paper both describes and discusses landslides and other ground effects induced by the september october 1997 seismic sequence which struck the umbria and marche regions central italy three main events occurred on 26 september at 00 33 and 09 40 gmt and 14 october with magnitude m w equal to 5 8 6 0 and 5 4 respectively furthermore hundreds of minor but significant events were also recorded the authors examined an area of some 700 km 2 around the epicentre colfiorito primary and secondary effects were observed including surface faulting phenomena landslides ground fractures compaction and various hydrological phenomena surface evidence of faulting reactivation was found along the well known capable faults to a total length of ca 30 km landslides which were the most recurrent among the phenomena induced consisted mainly of rock falls and subordinately of rotational and translational slides which were generally mobilised by the inertia forces during the seismic motion the percentage of reactivated old landslides decreased as the distance from the epicentral zone increased a similar decrease had been observed for the 1980 irpinia earthquake southern italy the ground fracture distribution was consistent with the regional structural setting and the general pattern of macroseismic field numerous episodes of hydrological changes were observed within the most severely damaged area all this evidence confirms the relevance of the study of ground surface effects for achieving a more complete evaluation of seismic hazard

slope failures associated with the 1988 saguenay earthquake quebec canada nine case records of slope failure during the saguenay earthquake are documented including five in granular embankments two in natural slopes in granular material with small embankments at the top and two in sensitive clay the bedrock motion during the earthquake is well documented each failure is related to the most probable bedrock motion at the site 0 05 to 0 15 g for the seven cases of failure in granular slopes the reserve of stability under static conditions was relatively low before the earthquake and only a small additional undrained loading was necessary to develop failure two slope failures occurred in extrasensitive clay deposits containing no visible lens or layer of silt or sand silty or sandy materials have been identified only at the clay till contact it is believed that in at least one of the sites a portion of the failure surface developed at the inclined clay till contact key words slope failure earthquake sensitive clays embankment fill stability granular material

rates of magma differentiation and emplacement in a ballooning pluton recorded by u pb tims tea adamello batholith italy abstract geochemical structural field and geochronological data have been used to arrive at very different models for the construction of upper crustal batholiths models for pulsed intrusion of small magma batches over long timescales 1 ma versus transfer of larger magma bodies on shorter timescales predict a different thermal metamorphic and rheological state of the crust highlighting the importance of robust time constraints this study focuses on a well characterized upper crustal intrusion the 15 km2 lago della vacca complex lvc adamello batholith n italy previous studies used structural and petrologic data to argue that the lvc was emplaced through pulsed magma injection and in situ expansion or ballooning of a short lived 105 yr magma chamber we test this model using a dense sampling strategy and high precision id tims u pb geochronology of zircon and titanite combined with hafnium isotope and trace element analyses of the same volume of dated mineral u pb tims tea these data show that the marginal mafic pulses of magma crystallized zircon with primitive hf isotopes and negligible eu anomalies during fractional crystallization and ascent through the crust on 10 30 ka timescales subsequent more felsic pulses yield individual zircon dates spanning as much as 200 ka within single handsamples and restrict the total construction time of the lvc to

space weathering on airless bodies space weathering refers to alteration that occurs in the space environment with time lunar samples and to some extent meteorites have provided a benchmark for understanding the processes and products of space weathering lunar soils are derived principally from local materials but have accumulated a range of optically active opaque particles oaopq that include nanophase metallic iron on in rims formed on individual grains imparting a red slope to visible and near infrared reflectance and larger iron particles which darken across all wavelengths such as are often found within the interior of recycled grains space weathering of other anhydrous silicate bodies such as mercury and some asteroids produce different forms and relative abundance of oaopq particles depending on the particular environment if the development of oaopq particles is minimized such as at vesta contamination by exogenic material and regolith mixing become the dominant space weathering processes volatile rich bodies and those composed of abundant hydrous minerals dwarf planet ceres many dark asteroids outer solar system satellites are affected by space weathering processes differently than the silicate bodies of the inner solar system however the space weathering products of these bodies are currently poorly understood and the physics and chemistry of space weathering processes in different environments are areas of active research

evaluation of factors controlling earthquake induced landslides caused by chi chi earthquake and comparison with the northridge and loma prieta events over 10 000 landslides were triggered by the september 21 1999 chi chi earthquake a large number of these landslides have been mapped from spot images and a smaller number were described in a detailed field investigation geographic information systems gis was used to conduct a spatial characterization of the slope failures including distribution of type size slope angle bedrock geology ground motion and distance from earthquake source the most abundant landslides were shallow disaggregated rock and soil slides landslides occurred primarily in tertiary sedimentary rocks which are well known for their susceptibility to landsliding in many parts of the world landslide concentration values diminish beyond epicentral distances of 40 and 70 km from the epicenter and the surface projection of the fault plane respectively ground motion was found to be the most significant factor in triggering the shallow landslides in the chi chi earthquake overall 74 of all slope failures occurred in regions with vertical ground motions greater than 0 2g and 81 of all slope failures occurred in the region with mean horizontal peak ground accelerations pga greater than 0 15g these factors were used to compare landslides generated by the chi chi earthquake to the landslides triggered by the 1989 loma prieta earthquake and the 1994 northridge earthquake the major difference in distribution of landslides between the chi chi earthquake and the two california earthquakes was the distribution of slope angles in the chi chi earthquake 90 of the failures occurred on slopes steeper than 45 while more than 80 of failures occurred on slopes less than 50 in california apparently reflecting much steeper and tectonically more active geologic setting in taiwan

seismically induced landslides by a low magnitude earthquake the mw 4 7 ossa de montiel event central spain this work has been funded by spanish ministry of economy and competitiveness research project cgl2011 30153 c02 02 and by the research groups rnm 374 junta de andalucia tectac ucm 910368 and vigrob 184 universidad de alicante mr loffredo acknowledges funding of the universita di roma la sapienza post graduate grant concorso a n 480 area cun 04

application of a characteristic periods based cpb approach to estimate earthquake induced displacements of landslides through dynamic numerical modelling the authors would like to thank the european union erdf for financial support via the monitorizacion sismica de deslizamientos criterios de reactivacion y alerta temprana project of the programa operativo feder de andalucia 2007 2013

contribution of mafic melt to porphyry copper mineralization evidence from mount pinatubo philippines and bingham canyon utah usa mount pinatubo in the philippines known for its cataclysmic eruption in 1991 hosts several porphyry copper deposits and active geothermal systems an underlying mafic melt supplied much of the sulphur for the dacitic magma and its injection into the dacitic magma chamber triggered the eruption the eruption caused purging of the sulphur rich fluid from the dacite to the atmosphere and extensive fracturing similar events took place at bingham canyon utah site of the largest copper and gold deposit in north america at 38 ma the bingham canyon mineralization took place beneath an active stratovolcano and pyroclastic flows contemporaneous with the mineralization show evidence for magma mingling ascent of mafic melt supplied sulphur and chalcophile elements to the felsic magma which consolidated to form the bingham stock and its underlying magma chamber injections of the mafic melt caused periodic eruptions of felsic magma to form the stratovolcano and deposition of sulphide minerals in highly fractured rocks in and around the stock

metal fractionation between magmatic brine and vapor determined by microanalysis of fluid inclusions the major and trace element compositions of individual fluid inclusions from a range of magmatic hydrothermal ore deposits were analyzed by laser ablation inductively coupled plasma mass spectrometry to explore the behavior of ore forming components during fluid phase separation boiling in high temperature saline fluid systems data from 13 samples showing unambiguous evidence for coeval trapping of a liquid brine and a coexisting vapor phase identify two groups of elements with drastically different geochemical behavior na k fe mn zn rb cs ag sn pb and tl preferentially partition into the brine probably as cl complexes whereas cu as au probably as hs complexes and b selectively partition into the vapor fluid phase separation is probably a major previously underestimated process in the chemical differentiation that contributes to the extreme range of selective element enrichments in magmatic hydrothermal systems from deep plutons through porphyry style and greisen deposits to epithermal mineralization and volcanic fumaroles

a new method to determine the grain size of planetary regolith abstract airless planetary bodies are covered by a dusty layer called regolith the grain size of the regolith determines the temperature and the mechanical strength of the surface layers thus knowledge of the grain size of planetary regolith helps to prepare future landing and or sample return missions in this work we present a method to determine the grain size of planetary regolith by using remote measurements of the thermal inertia we found that small bodies in the solar system diameter less than 100 km are covered by relatively coarse regolith grains with typical particle sizes in the millimeter to centimeter regime whereas large objects possess very fine regolith with grain sizes between 10 m and 100 m

space weathering from mercury to the asteroid belt the variety of evidence bearing on the nature of space weathering is reviewed the effects of space weathering include spectral darkening reddening and subdued absorption bands and the distinctive magnetic electron spin resonance caused by single domain metallic iron particles ever since the apollo missions two paradigms have dominated the thinking of the planetary science community concerning space weathering 1 the optical effects are caused by impact vitrified glass in agglutinates and 2 the submicroscopic metallic iron results from the reduction of ferrous iron by the impact melting of minerals whose surfaces have been saturated with hydrogen from the solar wind however studies carried out since the apollo program showed that both of these paradigms are invalid a hypothesis first suggested by the author and his colleagues 26 years ago but not generally accepted at that time now appears to be essentially correct both the optical and magnetic effects are caused by metallic iron particles smaller than the wavelength in ubiquitous vapor deposited coatings on soil particle surfaces and inside agglutinates the vapor is generated by both solar wind sputtering and micrometeorite impact vaporization and injected preferentially downward into the porous regolith the iron is reduced by a physical process the selective loss of oxygen that occurs during deposition of the vapor and does not require heating melting or a reducing environment a mathematical theory that describes the optical effects of the submicroscopic iron quantitatively is derived and applied to the regoliths of the moon mercury and an s asteroid

analysis of topographic amplification of inclined shear waves in a steep coastal bluff abstract the effect of inclined shear waves on the seismic response of a steep bluff is analyzed using generalized consistent transmitting boundaries the results of the frequency domain analysis of a stepped half space subjected to incident shear waves inclined from 0 to 30 show that the motion at the crest of the slope is amplified for waves traveling into the slope and attenuated for waves traveling away from the slope as compared to the motion in the free field behind the crest of the slope this amplification can be as much as twice that observed for vertically propagating waves a time domain analysis of bluffs at seacliff state beach california is used to estimate the effect of topography using realistic conditions taking into account wave inclination and site effects the analysis of the site shows that although topographic amplification does in fact nearly double the amplitude of the motion in some cases this amplification is offset by reduced site amplification and by wave splitting at material interfaces thus the actual peak acceleration occurring at the crest of the slope changes little with incident angle as compared to the amplification of the free field motion and actually decreases in many cases though a more general study is recommended these results suggest that wave orientation and inclination substantially increase topographic amplification however it may be adequate to only account for vertically propagating waves for site response and slope stability analyses where only the magnitude of acceleration is considered

the interaction of seismic waves with step like slopes and its influence on landslide movements abstract the interaction of seismic waves with slopes is a major factor influencing landslide movements that involve slope stability local site seismic amplification and topographic effects affecting ground motion the results of a numerical study of landslide movements induced by the interaction of seismic waves with step like slopes are presented here to investigate this input slope interaction a dynamic analysis was performed using the finite difference stress strain numerical code flac 6 0 under visco plastic conditions the dynamic signals were selected to be representative of different peak ground accelerations pgas arias intensities and frequency contents and they were used in a parametric study of different step like slopes with different geometrical configurations in terms of dip height and thickness of geological strata the derived outputs were processed for a seismic amplification analysis and to evaluate the induced stress strain effects in terms of progressive failure and resulting displacements the obtained results i describe a fundamental role of topography in amplifying or de amplifying the seismic ground motion ii demonstrate that the progressive failure of unsheared slopes influences the seismic amplification iii show that the strain effects on unsheared slopes in terms of progressive failure are more intense with increasing arias intensity and slope dip iv prove that amplification or de amplification processes can justify the values of displacements involving pre existing landslide masses which are significantly different with respect to those expected on the basis of sliding block approaches i e newmark s and flexible sliding block methods v highlight that in the geological setting considered here the seismically induced displacements arising from the reactivation of pre existing landslide masses can be significantly underestimated by sliding block approaches in the case of low angle slopes characterised by high k values i e the ratios between the critical pseudostatic threshold ky of the landslide and pgas of the applied seismic input

giant ore deposits formed by optimal alignments and combinations of geological processes giant ore deposits are priority targets for mining companies a review of the characteristics of several giant porphyry and epithermal deposits worldwide suggests that they formed from ordinary processes that were fortuitously operating at maximum efficiency

surface refreshing of martian moon phobos by orbital eccentricity driven grain motion the surface of the martian moon phobos exhibits two distinct geologic units red and blue characterized by their spectral slopes the provenance of these units is uncertain yet crucial to understanding the origin of the martian moon and its interaction with the space environment here we present a combination of dynamical analyses and numerical simulations of particle dynamics to show that periodic variations in dynamic slopes driven by orbital eccentricity can cause surface grain motion for regions with steep slopes that vary substantially over one phobos orbit the surface is excavated at a faster rate than the space weathering timescale our model predicts that this new mechanism is most effective in regions that coincide with blue units therefore space weathering is the likely driver of the dichotomy on the moon s surface reddening blue units that represent pristine endogenic material the distribution of two distinct geologic units on mars s moon phobos red and blue units can be explained by surface grain motion triggered by orbital variations in slope steepness according to dynamical analyses and numerical simulations

solar wind as the origin of rapid reddening of asteroid surfaces a comparison of the laboratory reflectance spectra of meteorites with observations of asteroids revealed that the latter are much redder with the spectral difference explained by space weathering though the actual processes and timescales involved have remained controversial a recent study of young asteroid families concluded that they suffered only minimal space weathering here we report additional observations of those families revealing that space weathering must be a very rapid process the final colour of a silicate rich asteroid is acquired shortly after its birth within 10 6 years of undergoing a catastrophic collision this rapid timescale favours solar wind implantation as the main mechanism of space weathering as laboratory experiments have shown that it is the most rapid of several competing processes we further demonstrate the necessity to take account of composition when evaluating weathering effectiveness as both laboratory and asteroid data show an apparent dependence of weathering on olivine abundance the rapid colour change that we find implies that colour trends seen among asteroids are most probably due to compositional or surface particle size properties rather than to different relative ages apparently fresh surfaces most frequently seen among small near earth asteroids may be the result of tidal shaking that rejuvenates their surfaces during planetary encounters

landslides triggered by the avaj iran earthquake of june 22 2002 abstract the 2002 avaj iran earthquake mw 6 5 triggered many landslides over an area of about 3600 km 2 in this paper we describe a ground based field study conducted during several days immediately after the earthquake and pre and post earthquake landslide inventory maps that were prepared the landslides due to earthquake include 47 fall and topple zones 9 slides and 3 lateral spreads the largest slide is a rockslide 150 100 m which occurred southeast of the village of changureh the main results of this study are the density of earthquake triggered landslides decreases away from the fault zone in a manner that is asymmetric with respect to direction although several slides and lateral spreads were seen the most common types of triggered landslides are falls and topples the area throughout which landslides occurred and maximum epicentral and fault zone distances of landslides are comparable to similar data from other historical earthquakes landslides mostly occurred in the most susceptible geologic units in which there were many landslides before the earthquake new disrupted slides and falls generally occurred in ancient fall zones but no information about reactivation of coherent slides is available

complete miscibility between silicate melts and hydrous fluids in the upper mantle experimental evidence and geochemical implications the phase relationships between silicate melts and hydrous fluids were studied by direct visual observation in an externally heated diamond anvil cell complete miscibility of silicate melt and water was observed for a wide range of melt compositions including nepheline jadeite dacite haplogranite and ca bearing granite some evidence for complete miscibility was also observed in the system basalt h2o the critical temperatures in all systems decrease rapidly with pressure at 15 kbar the critical temperature for nepheline is around 550 c for jadeite around 800 c and for granitic compositions it is close to 900 c in general the critical temperatures appear to increase with silica content in the system our results suggest that there is complete miscibility between silicate melts and water in most of the upper mantle except at very shallow depths this means that a water saturated solidus cannot be defined any more in the deeper parts of the upper mantle very silica rich melt inclusions found in spinel lherzolites associated with fluid inclusion are probably the result of the unmixing of a supercritical fluid containing comparable amounts of water and silicate components the decomposition of amphibole in a subducted slab occurs at conditions where the miscibility gap between fluid and silicate melt is not yet closed while the decomposition of phengite and lawsonite occurs far beyond the critical curve accordingly the fluids released by the breakdown of these minerals should have very different properties highly mobile hydrous fluids containing little dissolved silicate should be produced by amphibole breakdown while the decomposition of lawsonite and phengite will lead to much more silicate rich and less mobile fluid phases

can low magnitude earthquakes act as a triggering factor for landslide activity examples from the western carpathian mts poland abstract there are numerous examples of the impact of strong earthquakes on landslide activity there is however very little information about the ability of low magnitude earthquakes m

how fast does gold trickle out of volcanoes the enormous hydrothermal gold ore deposit on lihir island papua guinea may have formed in less than 55 000 years

the database of individual seismogenic sources diss version 3 summarizing 20 years of research on italy s earthquake geology abstract this paper describes the main characteristics the evolution and the structure of the database of individual seismogenic sources diss and particularly of its release of early 2007 the database contains the results of the investigations of the active tectonics in italy during the past 20 years the first two sections of this paper document the recent evolution in mapping and archiving italian active fault data in relation to important achievements in the understanding of italian tectonics some of which were spurred by significant earthquakes the central sections describe the current structure of the database the reasons for its assumptions and data categories its current contents its evolution through several years of improvements the last section describes how the current contents of the database correspond with the existing strain and stress data available from focal mechanism borehole breakout and gps data for the whole of italy the database supplies a fresh and unified view of active and seismogenic processes in italy by building on basic physical constraints concerning rates of crustal deformation on the continuity of deformation belts and on the spatial relationships between adjacent faults both at the surface and at depth

from andesitic volcanism to the formation of a porphyry cu au mineralizing magma chamber the farallon negro volcanic complex northwestern argentina abstract the geological relations and geochemical composition of extrusive and subvolcanic intrusive rocks of the upper miocene farallon negro volcanic complex nw argentina were studied to reconstruct the evolution of a deeply eroded andesitic volcano over most its life history of some 3 5 my this paper is part of an integrated study of the processes that generate magmatic hydrothermal fluids responsible for the formation of porphyry cu au deposits here we present new data on bulk rock chemical and nd sr and pb isotopic compositions of unaltered volcanic and subvolcanic intrusive rocks for which geological relations and ages are constrained by field based stratigraphy and extensive ar ar geochronology the combined results indicate that voluminous volcanism started at ca 9 7 ma with the eruption of basaltic andesite to andesite lava flows and pyroclastic deposits this basic to intermediate volcanism persisted until 7 5 ma and was followed at 7 35 ma by the eruption of dacites as the last recorded major extrusive event the oldest andesitic intrusions emplaced at 9 0 ma were followed by hypabyssal intrusions of basaltic andesite andesite and dacite composition which intruded the volcanic sequence between 8 3 and 6 1 ma intrusions at 6 8 0 2 ma led to the formation of over 800 mt of porphyry cu au ore at bajo de la alumbrera it was formed by a large flux of magmatic hydrothermal fluids channeled through several phases of fractured dacitic porphyry which together with immediately following barren andesitic intrusions make up a composite stock after this magmatic hydrothermal event only minor rhyodacitic to rhyolitic intrusions were emplaced until magmatic activity ceased at 6 1 ma geochemical data for the magmatic rocks indicate that the evolution of the system was dominated by mixing of a mafic magma with a felsic magma that contained a component of crustal material as indicated by linear compositional correlations between compatible and incompatible elements initial strontium isotopic ratios vary between 0 7047 and 0 7118 while 143nd 144nd range from 0 5127 to 0 5124 and both isotopic variations correlate with each other and with sio2 content of the rocks after 8 5 ma a continuous increase in the silica content of intrusive rocks suggests the gradual formation of a magma chamber a substantial magma reservoir 7 km3 must have been established by the time of porphyry cu au mineralization to allow rapid release of a large volume of ore forming magmatic brine as a result of wholesale crystallization and de volatilization of the magma chamber

the global effects of impact induced seismic activity on fractured asteroid surface morphology abstract impact induced seismic vibrations have long been suspected of being an important surface modification process on small satellites and asteroids in this study we use a series of linked seismic and geomorphic models to investigate the process in detail we begin by developing a basic theory for the propagation of seismic energy in a highly fractured asteroid and we use this theory to model the global vibrations experienced on the surface of an asteroid following an impact these synthetic seismograms are then applied to a model of regolith resting on a slope and the resulting downslope motion is computed for a full range of impactor sizes next this computed downslope regolith flow is used in a morphological model of impact crater degradation and erasure showing how topographic erosion accumulates as a function of time and the number of impacts finally these results are applied in a stochastic cratering model for the surface of an eros like body same volume and surface area as the asteroid with craters formed by impacts and then erased by the effects of superposing craters ejecta coverage and seismic shakedown this simulation shows good agreement with the observed 433 eros cratering record at a main belt exposure age of 400 200 myr including the observed paucity of small craters the lowered equilibrium numbers loss rate production rate for craters less than 100 m in diameter is a direct result of seismic erasure which requires less than a meter of mobilized regolith to reproduce the near observations this study also points to an upper limit on asteroid size for experiencing global surface modifying seismic effects from individual impacts of about 70 100 km depending upon asteroid seismic properties larger asteroids will experience only localized regional seismic effects from individual impacts

mass wasting on phobos triggered by an evolving tidal environment the martian moon phobos is experiencing orbital decay increasing tidal forces and possible disruption in the near future we suggest that this changing dynamic tidal environment has contributed to re surfacing of the odd shaped small moon we investigated mass wasting features in craters using high resolution images acquired by the mars express onboard high resolution stereo camera we model the evolving dynamical environment of phobos by reconstructing dynamic slopes on its surface with phobos at different distances to mars we note that the increase in slope by tidal effect correlates with most of the observed landslides which is particularly obvious for craters near the sub mars and anti mars points we suggest that the effect has triggered mass displacements that are responsible for observed asymmetries of some craters the most recent landslides are likely to be geologically young and occurred within the past few hundred million years

a seismic landslide susceptibility rating of geologic units based on analysis of characteristics of landslides triggered by the 17 january 1994 northridge california earthquake abstract one of the most significant effects of the 17 january 1994 northridge california earthquake m 6 7 was the triggering of thousands of landslides over a broad area some of these landslides damaged and destroyed homes and other structures blocked roads disrupted pipelines and caused other serious damage analysis of the distribution and characteristics of these landslides is important in understanding what areas may be susceptible to landsliding in future earthquakes we analyzed the frequency distribution and geometries of triggered landslides in the santa susana 7 5 quadrangle an area of intense seismic landslide activity near the earthquake epicenter landslides occurred primarily in young late miocene through pleistocene uncemented or very weakly cemented sediment that has been repeatedly folded faulted and uplifted in the past 1 5 million years the most common types of landslide triggered by the earthquake were highly disrupted shallow falls and slides of rock and debris far less numerous were deeper more coherent slumps and block slides primarily occurring in more cohesive or competent materials the landslides in the santa susana quadrangle were divided into two samples single landslides 1502 and landslide complexes 60 which involved multiple coalescing failures of surficial material we described landslide morphologies by computing simple morphometric parameters area length width aspect ratio slope angle to quantify and rank the relative susceptibility of each geologic unit to seismic landsliding we calculated two indices 1 the susceptibility index which is the ratio given as a percentage of the area covered by landslide sources within a geologic unit to the total outcrop area of that unit and 2 the frequency index given in landslides per square kilometer ls km2 which is the total number of landslides within each geologic unit divided by the outcrop area of that unit susceptibility categories include very high 2 5 landslide area or 30 ls km2 high 1 0 2 5 landslide area or 10 30 ls km2 moderate 0 5 1 0 landslide area or 3 10 ls km2 and low

advances and problems in understanding the seismic response of potentially unstable slopes abstract the influence of site effects on landslide triggering during earthquakes has been inferred in several studies but its evaluation is made difficult by the complexity of factors controlling the dynamic response of potentially unstable slopes and also by the lack of local ground motion instrumental observations this work explores this problem and reports new findings based on an ongoing long term accelerometric monitoring conducted on a landslide prone test area in the apennine mountains italy where the presence of site effects enhancing seismic susceptibility of local slopes has been invoked on the basis of historic accounts of landsliding triggered at large epicentral distance the recordings relative to low to moderate magnitude earthquakes showed significant amplifications affecting hillslope portions covered by thick 5 m colluvia and pronounced amplification maxima oriented along the local maximum slope direction on a recent deep seated landslide while the amplifications seem most likely linked to high impedance contrast between surface materials and underlying substratum the causes of directivity are less clear the case of the monitored test site together with evidence of site response directivity identified on other hillslopes suggest that the directivity phenomena can result from a combination of topographic lithological and structural factors that act together to re distribute shaking energy focusing it on site specific directions thus it is difficult to single out the critical factors controlling such phenomena and no general criterion for the identification of sites affected by directivity is proposed here nevertheless the presence and orientation of site response directivity can be revealed through reconnaissance techniques by using recordings of seismic weak motion and or ambient microtremors and calculating azimuthal variation of shaking energy and horizontal to vertical ground motion spectral ratios a comparison with the recordings obtained during the recent m w 6 3 earthquake that hit the abruzzo region in april 2009 demonstrated that analysis relying on data from low energy events can furnish valid indications for slope behaviour also under stronger shaking provided the data are well differentiated in terms of distance azimuth and source characteristics furthermore the comparative analysis of the abruzzo earthquake recordings at a landslide and reference sites showed that directivity properties of strong shaking had been correctly anticipated using earlier weak motion observations however under the complex slope conditions the identification of resonance frequencies from horizontal to vertical spectral ratios estimated from weak motion accelerometric recordings does not seem reliable and better results have been obtained by velocimetric microtremor recordings

magnitude distance relations for earthquake induced landslides in greece a data set of 47 earthquake induced landslides occurring in greece from ad 1650 to 1995 has been compiled and the landslide distribution has been examined the spatial distribution indicates landslides occurrence almost everywhere in greece with the exception of the north greek mainland which is likely due to the low occurrence frequency of large earthquakes the earthquake magnitude m s ranges between 5 3 and 7 9 while the main bulk of events falls within the range 7 5 m s 5 3 with peaks at m s 6 4 and 6 7 the upper bound of the maximum epicentral distance r e from a reported landslide has been approximated by the line log r e 2 98 0 75m s for m s 5 3 which is compatible with curves proposed world wide and constitutes a realistic solution at least for hazard assessment purposes we discuss the importance of the results for assessing hazards from earthquake induced landslides and for calculating focal parameters of historical earthquakes 2000 elsevier science b v all rights reserved

tidal disruption of phobos as the cause of surface fractures phobos the innermost satellite of mars displays an extensive system of grooves that are mostly symmetric about its sub mars point phobos is steadily spiraling inward due to the tides it raises on mars lagging behind phobos orbital position and will suffer tidal disruption before colliding with mars in a few tens of millions of years we calculate the surface stress field of the deorbiting satellite and show that the first signs of tidal disruption are already present on its surface most of phobos prominent grooves have an excellent correlation with computed stress orientations the model requires a weak interior that has very low rigidity on the tidal evolution time scale overlain by an 10 100 m exterior shell that has elastic properties similar to lunar regolith as described by horvath et al 1980

statistical analysis of an earthquake induced landslide distribution the 1989 loma prieta california event the 1989 loma prieta california earthquake moment magnitude m 6 9 generated landslides throughout an area of about 15 000 km2 in central california most of these landslides occurred in an area of about 2000 km2 in the mountainous terrain around the epicenter where they were mapped during field investigations immediately following the earthquake the distribution of these landslides is investigated statistically using regression and one way analysis of variance anova techniques to determine how the occurrence of landslides correlates with distance from the earthquake source slope steepness and rock type the landslide concentration defined as the number of landslide sources per unit area has a strong inverse correlation with distance from the earthquake source and a strong positive correlation with slope steepness the landslide concentration differs substantially among the various geologic units in the area the differences correlate to some degree with differences in lithology and degree of induration but this correlation is less clear suggesting a more complex relationship between landslide occurrence and rock properties

large rock avalanches triggered by the m 7 9 denali fault alaska earthquake of 3 november 2002 the moment magnitude m 7 9 denali fault alaska earthquake of 3 november 2002 triggered thousands of landslides primarily rock falls and rock slides that ranged in volume from rock falls of a few cubic meters to rock avalanches having volumes as great as 20 10 6 m 3 the pattern of landsliding was unusual the number and concentration of triggered slides was much less than expected for an earthquake of this magnitude and the landslides were concentrated in a narrow zone about 30 km wide that straddled the fault rupture zone over its entire 300 km length despite the overall sparse landslide concentration the earthquake triggered several large rock avalanches that clustered along the western third of the rupture zone where acceleration levels and ground shaking frequencies are thought to have been the highest inferences about near field strong shaking characteristics drawn from interpretation of the landslide distribution are strikingly consistent with results of recent inversion modeling that indicate that high frequency energy generation was greatest in the western part of the fault rupture zone and decreased markedly to the east d 2005 elsevier b v all rights reserved

the effect of topography on earthquake ground motion a review and new results a brief review of experimental and theoretical results about the effect of topography on seismic motion shows that they are consistent only on a qualitative basis amplification at mountain tops for wavelengths comparable with mountain widths is predicted and observed but the numerical simulations often underestimate the actual observed effects we propose that this disagreement is because current models are not complex enough we therefore computed the response to incident sh waves of a set of different complex configurations that include two dimensional surface topography with or without periodic ridges and subsurface layering the results show that 1 the topographic effect in itself is difficult to isolate from other effects like surface layering and therefore the amplification on top of geomorphologically complex sites cannot be predicted by a priori estimations based solely on topography and 2 the high crest base amplification ratio observed in the field cannot usually be matched even with complex two dimensional structures with incident plane sh waves which suggests that more complex models are needed to incorporate more complex wave fields e g sv surface and three dimensional geologic configurations

comprehensive analysis of the local seismic response in the complex buyukcekmece landslide area turkey by engineering geological and numerical modelling multi risk management requires a strong comprehension of possible effects induced by natural hazardous events in this regard landslides triggering due to earthquakes results from complex interactions between seismic waves and slopes multidisciplinary approaches can significantly contribute to better understand such interactions the large buyukcekmece landslide about 1500 m wide and 1830 m long located in turkey avcilar peninsula about 15 km northward from the north anatolian fault zone nafz was selected as case study in the framework of the european project marsite marmara supersite new directions in seismic hazard assessment through focused earth observation in the marmara supersite the avcilar area was recently affected by the 17th august 1999 mw 7 4 kocaeli and by the 12th november mw 7 2 duzce earthquakes the buyukcekmece landslide involves upper oligocene to lower miocene deposits consisting of silty clays tuffs and sands no earthquake induced re activations are testified so far but the landslide area was interested by a very intense urbanization during the last decade a detailed engineering geological model for the local seismic response of the buyukcekmece landslide slope was constructed based on geophysical measurements data from a multisensor in hole monitoring system and stress strain numerical modelling several tens of earthquakes were recorded from october 2014 to may 2015 in the landslide site by considering in hole and surface data the reliability of the local seismic response obtained by numerical modelling respect to the empirically derived one was checked in terms of both site to reference spectral ratios and transfer function between surface and downhole sites inside the landslide mass the 2d numerical amplification functions confirm that the local seismic response is a consequence of the complex geological setting of the landslide slope while no relevant amplification effects can be referred to topographic features based on these results the interaction between seismic waves and the buyukcekmece landslide slope cannot be neglected to evaluate the possibility of future landslide re activations

on far field occurrence of seismically induced landslides abstract earthquakes may induce landslides at large distances from the epicentral area in the last two decades there have been many studies of this phenomenon to determine the causes that contribute to the occurrence of landslides at very long distances from earthquake epicenter in this study which is based on previously published works a worldwide database comprising 270 earthquakes including 150 during the instrumental period was compiled to analyse the features of those landslides that occur at much further distances than maximum expected distances from the analysis of the compiled data it was observed that susceptible slopes can be grouped into five broad geological categories jointed rock marly clayey cohesive soils granular alluvial and or colluvial sediments volcanic soils and residual soil slopes these categories were equally likely to be associated with far field disrupted landslides whereas far field coherent landslides were more frequent on cohesive soil slopes other factors along with slope susceptibility may also contribute to far field landslides and increase the size of the area affected among these factors site effects antecedent rain and occurrence of seismic series have been cited the analysis of available data also showed that for events of the same magnitude far field disrupted landslides may occur at greater distances than coherent ones the same database has also been employed to determine for the first time the upper bound curves for the maximum observed epicentral distances of several types of landslides and the maximum area observed to be affected by landslides both based on the epicentral intensity of the events

time scales of pluton construction at differing crustal levels examples from the mount stuart and tenpeak intrusions north cascades washington deciphering the magmatic history of continental magmatic arcs in general and the growth history of individual intrusions in particular is key to understanding the complex history of magma generation segregation and transport that define the dynamics of crustal growth we utilize high precision u pb geochronology to resolve a detailed magmatic history from two composite intrusions the 2 4 kbar mount stuart batholith and the 7 10 kbar tenpeak pluton emplaced in the cretaceous north cascades arc this temporal framework provides a way to evaluate models of pluton growth that explain common features of intrusions such as concentric compositional zoning and internal magmatic contacts u pb zircon crystallization ages were obtained from 12 samples of the mount stuart batholith and 8 samples of the tenpeak intrusion representing the range of compositional diversity and geographical extent these dates indicate that the mount stuart batholith was constructed over a 5 5 m y time period that was punctuated by four intervals of high magma flux the durations of the high flux periods are short a few hundred thousand years relative to the duration of the batholith the consistent pattern of magmatic fabrics and the lack of distinct contacts in the batholith may be explained by the juxtaposition of melt rich and mush zones with subtle contacts between mineralogically and texturally similar tonalite and time transgressive magma fabrics in contrast the tenpeak intrusion was constructed over a 2 6 m y time period with magma influx distributed throughout the intrusive history and texturally distinct magma bodies the tenpeak intrusion lacks distinct age domains which suggests that any magma reservoir was smaller in size and potentially more ephemeral although the distinct age domains and discrete compositional and textural phases indicate that pluton growth occurred incrementally neither pluton bears resemblance to a purely end member incremental growth model whereby a pluton is constructed from hundreds to thousands of discrete magma pulses that have little if any interaction in particular ages from the youngest domain of the mount stuart batholith indicate that a melt rich magma reservoir of 520 km 3 existed over a 170 90 k y time span

the 2003 lefkada earthquake field observations and preliminary microzonation map based on liquefaction potential index for the town of lefkada abstract a strong earthquake mw 6 2 occurred offshore the island of lefkada or lefkas on august 14 2003 the maximum intensity has been evaluated io viii ems at lefkada municipality while vi to vii intensities were evaluated at many other villages of the island the offshore nne ssw oriented strike slip right lateral fault was activated by the main shock this fault is the northern termination of the cephalonia transform fault the most characteristic macroseismic effects were extensive typical ground failures like rock falls soil liquefactions subsidence densification ground cracks and landslides these macroseismic effects are remarkably similar to those reported from some historical lefkada shocks e g 1704 1914 ms 6 3 and 1948 ms 6 5 sand boils and ground fissures with ejection of mud were observed at the seaside of the town of lefkada and in the villages of nydri and vassiliki in situ soil profiles are obtained based mainly on borings after the earthquake boreholes records with spt values standard penetration test are obtained and the simplified procedure originally developed by seed and idriss was employed to evaluate the liquefaction resistance of soils the results indicated that the silty sandy layer which lies beneath the artificial fill in the coastal zone in lefkada town had liquefied during the 14 august earthquake an attempt was also made to establish a preliminary microzonation map for lefkada town using the data from liquefaction potential index analyses our map was validated by the occurrence of liquefaction phenomena inside the town

the origin of lunar crater rays abstract lunar rays are filamentous high albedo deposits occurring radial or subradial to impact craters the nature and origin of lunar rays have long been the subjects of major controversies we have determined the origin of selected lunar ray segments utilizing earth based spectral and radar data as well as feo tio 2 and optical maturity maps produced from clementine uvvis images these include rays associated with tycho olbers a lichtenberg and the messier crater complex it was found that lunar rays are bright because of compositional contrast with the surrounding terrain the presence of immature material or some combination of the two mature compositional rays such as those exhibited by lichtenberg crater are due entirely to the contrast in albedo between ray material containing highlands rich primary ejecta and the adjacent dark mare surfaces immaturity rays are bright due to the presence of fresh high albedo material this fresh debris was produced by one or more of the following 1 the emplacement of immature primary ejecta 2 the deposition of immature local material from secondary craters 3 the action of debris surges downrange of secondary clusters and 4 the presence of immature interior walls of secondary impact craters both composition and state of maturity play a role in producing a third combination class of lunar rays the working distinction between the eratosthenian and copernican systems is that copernican craters still have visible rays whereas eratosthenian aged craters do not compositional rays can persist far longer than 1 1 ga the currently accepted age of the copernican eratosthenian boundary hence the mere presence of rays is not a reliable indication of crater age the optical maturity parameter should be used to define the copernican eratosthenian boundary the time required for an immature surface to reach the optical maturity index saturation point could be defined as the copernican period

seismic driving of sand beach ridge formation in northern honshu japan abstract the coastal sendai plain consists of an extensive sand beach ridge system that was inundated by the 2011 tohoku oki tsunami the spatial and temporal extent of these beach ridges appears to match well with the record of past earthquakes and tsunamis in the region and it is proposed that they could have formed as a result of a process called seismic driving this process recognises the widespread and catastrophic disruption of the environment caused by a large earthquake a series of immediate and delayed after effects created by a cascade of geomorphological processes linking the earthquake with beach ridge formation is examined for the sendai plain the significance of the role played by volcanic eruptions smaller earthquakes and climate related high intensity and duration rainfall activity is also highlighted at a region wide scale the beach ridge systems of ishinomaki akita aomori and tanabu are also considered alongside those of the sendai plain throughout northern honshu there appears to be synchronous beach ridge formation albeit based upon a moderately poor chronological resolution further data indicate that there may also be contemporaneous evidence on hokkaido to the north more detailed research is now needed in order to secure a higher resolution dataset of the spatial and temporal extent of beach ridges throughout the region in order to determine whether they preserve a record of the magnitude and frequency of earthquakes and potentially tsunamis related to activity on both the japan and kuril trenches if strong seismic driving linkages can be proven it offers the intriguing possibility of being able to develop a far more comprehensive record of past earthquakes and tsunamis local regional and distant than currently exists records could be based on both tsunami deposits in the low lying swales and the spatial and temporal extent of the intervening beach ridges

earthquake induced landslides in central america central america is a region of high seismic activity and the impact of destructive earthquakes is often aggravated by the triggering of landslides data are presented for earthquake triggered landslides in the region and their characteristics are compared with global relationships between the area of landsliding and earthquake magnitude we find that the areas affected by landslides are similar to other parts of the world but in certain parts of central america the numbers of slides are disproportionate for the size of the earthquakes we also find that there are important differences between the characteristics of landslides in different parts of the central american isthmus soil falls and slides in steep slopes in volcanic soils predominate in guatemala and el salvador whereas extensive translational slides in lateritic soils on large slopes are the principal hazard in costa rica and panama methods for assessing landslide hazards considering both rainfall and earthquakes as triggering mechanisms developed in costa rica appear not to be suitable for direct application in the northern countries of the isthmus for which modified approaches are required

the 25 november 1988 saguenay quebec earthquake source parameters and the attenuation of strong ground motion the saguenay earthquake of 25 november 1988 occurred close to the southern margin of the saguenay graben in southern quebec it was caused by almost purely dip slip faulting centered at a depth of 26 km with a p axis oriented northeast southwest this faulting mechanism is similar to those of the larger historical earthquakes in eastern north america but the focal depth is substantially greater than all but one of these events the seismic moment estimated from regional pni waves and teleseismic long period body waves is 5 10 24 dyne cm corresponding to a moment magnitude of 5 8 the source duration of the earthquake is estimated to be 1 8 sec corresponding to a stress drop of 160 bars which is not significantly higher than the average stress drop of 120 bars estimated from previous large earthquakes in eastern north america in order to simultaneously match the recorded ground motion amplitudes of strong motion acceleration strong motion velocity and teleseismic short period and long period body waves it is necessary to use a source function having a complex shape that implies the presence of asperities and larger local stress drops the large set of strong motion recordings of the saguenay earthquake has been used to validate a procedure for estimating strong ground motion attenuation based on a simple wave propagation model the most important feature of the recorded strong motions is that their peak amplitudes do not decay significantly with distance inside 120 km but then decay abruptly beyond 120 km profiles of recorded accelerograms with absolute times indicate that at distances beyond 64 km the peak ground motions are due to strong postcritical reflections from velocity gradients in the lower crust the principal shear wave arrivals and the variation of their peak amplitudes with distance were reproduced in synthetic seismograms generated using a regional crustal structure model the critical distances for the postcritical reflections were short because of the deep focal depth of the event causing the elevation of ground motion amplitudes out to 120 km similar studies of earthquakes in other regions of eastern north america indicate that the strength of the postcritical reflections and the distance ranges over which they are dominant are controlled by the focal depth and crustal structure regional variations in crustal structure thus give rise to predictable regional variations in strong ground motion attenuation

triggers for the formation of porphyry ore deposits in magmatic arcs porphyry ore deposits supply much of the copper molybdenum gold and silver used by humans a review of the main processes that trigger porphyry ore formation suggests that sulphide saturation of the magmas that supply the metals could be the overriding mechanism that helps control the temporal and spatial distribution of the ore deposits

evidence for nonlinear diffusive sediment transport on hillslopes and implications for landscape morphology steep soil mantled hillslopes evolve through the downslope movement of soil driven largely by slope dependent transport processes most landscape evolution models represent hillslope transport by linear diffusion in which rates of sediment transport are proportional to slope such that equilibrium hillslopes should have constant curvature between divides and channels on many soil mantled hillslopes however curvature appears to vary systematically such that slopes are typically convex near the divide and become increasingly planar downslope this suggests that linear diffusion is not an adequate model to describe the entire morphology of soil mantled hillslopes here we show that the interaction between local disturbances such as rainsplash and biogenic activity and frictional and gravitational forces results in a diffusive transport law that depends nonlinearly on hillslope gradient our proposed transport law 1 approximates linear diffusion at low gradients and 2 indicates that sediment flux increases rapidly as gradient approaches a critical value we calibrated and tested this transport law using high resolution topographic data from the oregon coast range these data obtained by airborne laser altimetry allow us to characterize hillslope morphology at 2 m scale at five small basins in our study area hillslope curvature approaches zero with increasing gradient consistent with our proposed nonlinear diffusive transport law hillslope gradients tend to cluster near values for which sediment flux increases rapidly with slope such that large changes in erosion rate will correspond to small changes in gradient therefore average hillslope gradient is unlikely to be a reliable indicator of rates of tectonic forcing or baselevel lowering where hillslope erosion is dominated by nonlinear diffusion rates of tectonic forcing will be more reliably reflected in hillslope curvature near the divide rather than average hillslope gradient