a scaling law for slow earthquakes with the availability of the global positioning system and other technical advances a growing number of unusual earthquake phenomena occurring at relatively long periods have been recognized they include deep episodic tremor low frequency earthquakes slow slip events and silent earthquakes based on data chiefly from western japan ide et al report that these slow seismic events follow a unified scaling relationship that clearly differentiates their behaviour from that of regular earthquakes a diverse array of unusual earthquake phenomena occurring at relatively long periods slow events follow a unified scaling relationship that clearly differentiates their behaviour from that of regular earthquakes indicating that they comprise a new earthquake category recently a series of unusual earthquake phenomena have been discovered including deep episodic tremor1 low frequency earthquakes2 very low frequency earthquakes3 slow slip events4 and silent earthquakes5 6 7 8 9 each of these has been demonstrated to arise from shear slip just as do regular earthquakes but with longer characteristic durations and radiating much less seismic energy here we show that these slow events follow a simple unified scaling relationship that clearly differentiates their behaviour from that of regular earthquakes we find that their seismic moment is proportional to the characteristic duration and their moment rate function is constant with a spectral high frequency decay of f 1 this scaling and spectral behaviour demonstrates that they can be thought of as different manifestations of the same phenomena and that they comprise a new earthquake category the observed scale dependence of rupture velocity for these events can be explained by either a constant low stress drop model or a diffusional constant slip model this new scaling law unifies a diverse class of slow seismic events and may lead to a better understanding of the plate subduction process and large earthquake generation

the proportionality between relative plate velocity and seismicity in subduction zones the magnitude and rate of seismicity differ between subduction zones calculations of background seismicity rates based on a global model of subduction zone seismicity reveal a positive correlation between relative plate velocity and background seismicity yet only the seismically quieter zones seem capable of generating magnitude 9 earthquakes

biogeomorphic relationships between slope processes and globular grimmia mosses in haleakala s crater maui hawai i abstract globular mosses were found in haleakala s crater maui at five locations between 2175 and 2725 m the highest altitude site with abundant epilithic mosses growing on alkali olivine basalt outcrops and a large mossball population was studied mossballs form when moss cushions are dislodged from rocks but continue growing unattached to substrate detachment agents include rainsplash desiccation wind frost and disturbance by birds dark rumped petrels that burrow nests under outcrops or by goats when loosened moss polsters are transported down steep 26 34 slopes by different geomorphic processes including frost mainly needle ice activity runoff and wind mossballs contained two species grimmia trichophylla grev and grimmia torquata drumm growing separately or commingled weight size and various shape indices were determined for 260 specimens shape and size were correlated larger mosses become less spheroidal because heavier specimens are less disturbed by needle ice remaining immobile for increasingly longer time periods thus becoming flattened distance of downslope transport from source rockwalls was measured for 330 specimens 83 shifted 100 cm but only 5 had moved 200 839 cm heavier mossballs moved short distances thus 88 of all biomass remained within 200 cm from outcrops substrate soils were compared with those within globoids surface site soils were much coarser than mossball grains twelve substrate samples had on average 21 3 gravel 2 mm 6 1 fines 0 063 mm and 2 1 organic matter in contrast 12 mossballs contained this area is frequently subjected to freezing temperatures while fog interception from incoming tradewinds contributes significant moisture amounts to precipitation ground disturbance by frost activity seemed significant needle ice grows frequently on this slope as evidenced by widespread presence of miniature sorted stripes striated soils fine earth flags below stones gaps around stones and fine soil raised patches observed during multiple visits biogeomorphic interactions between mossballs and substrate at haleakala are briefly discussed from the perspective of self organized criticality and interpreted to represent a self replicating moss dispersal system dependent on slope geomorphic processes

relations among subduction parameters clues to the dynamics of the subduction process are found in the many measurable parameters of modern subduction zones based on a critical appraisal of the geophysical and geological literature 26 parameters are estimated for each of 39 modern subduction zones to isolate causal relationships among these parameters multivariate analysis is applied to this data set this analysis yields empirical quantitative relations that predict strain regime and strike slip faulting in the overriding plate maximum earthquake magnitude benioff zone length slab dip arc trench gap and maximum trench depth excellent correlation is found between length of the benioff zone and the product of convergence rate and age of the downgoing slab this relationship is consistent with the conductive heating model of molnar et al 1979 if the model is modified in one respect the rate of heating of the slab is not constant it is substantially slower during passage of the slab beneath the accretionary prism and overriding plate the structural style in the overriding plate is determined by its stress state though the stress state of overriding plates cannot be quantified one can classify each individual subduction zone into one of seven semiquantitative strain classes that form a continuum from strongly extensional class 1 back arc spreading to strongly compressional class 7 active folding and thrusting this analysis indicates that strain class is probably determined by a linear combination of convergence rate slab age and shallow slab dip interplate coupling controlled by convergence rate and slab age is an important control on strain regime and the primary control on earthquake magnitude arc parallel strike slip faulting is a common feature of convergent margins forming a forearc sliver between the strike slip fault and trench optimum conditions for the development of forearc slivers are oblique convergence a compressional environment and a continental overriding plate the primary factor controlling presence of strike slip faulting is coupling strongly oblique convergence is not required the rate of strike slip faulting is affected by both convergence obliquity and convergence rate maximum trench depth is a response to flexure of the underthrusting plate the amount of flexural deflection at the trench depends on the vertical component of slab pull force which is very sensitive to slab age and shallow slab dip shallow slab dip conforms to the cross sectional shape of the overriding plate which is controlled by width of the accretionary prism and duration of subduction deep slab dip is affected by the mantle trajectory established at shallow depth but may be modified by mantle flow much of the structural complexity of convergent margins is probably attributable to terrane juxtaposition associated with temporal changes in both forearc strike slip faulting and strain regime empirical equations relating subduction parameters can provide both a focus for future theoretical studies and a conceptual and kinematic link between plate tectonics and the geology of subduction zones

controls of seismogenic zone width and subduction velocity on interplate seismicity insights from analog and numerical models correlations between geodynamic parameters and interplate seismicity characteristics in subduction zones are generally weak due to the short instrumental record and multiparameter influences to investigate the role of subduction velocity vs and the width of the seismogenic zone w on maximum magnitude mmax seismic rate characteristic recurrence rate c and moment release rate mrr we use synthetic data sets from simplified analog and numerical models to gain insight into natural subduction zones seismicity our models suggest that mmax increases with w and is unaffected by vs increases with vs c increases with vs w and mrr increases with vs w in nature only the positive correlation between vs and is significant random sampling of our time series suggest that the positive correlation between vs and can be observed with short observation time windows other correlations including mmax versus w become clear only for time window lengths longer than 1 c

new empirical relationships among magnitude rupture length rupture width rupture area and surface displacement source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude m surface rupture length subsurface rupture length downdip rupture width rupture area and maximum and average displacement per event the resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment moment magnitude subsurface rupture length downdip rupture width and average surface displacement each source parameter is classified as reliable or unreliable based on our evaluation of the accuracy of individual values only the reliable source parameters are used in the final analyses in comparing source parameters we note the following trends 1 generally the length of rupture at the surface is equal to 75 of the subsurface rupture length however the ratio of surface rupture length to subsurface rupture length increases with magnitude 2 the average surface displacement per event is about one half the maximum surface displacement per event and 3 the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement thus for most earthquakes in this data base slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface log linear regressions between earthquake magnitude and surface rupture length subsurface rupture length and rupture area are especially well correlated showing standard deviations of 0 25 to 0 35 magnitude units most relationships are not statistically different at a 95 significance level as a function of the style of faulting thus we consider the regressions for all slip types to be appropriate for most applications regressions between magnitude and displacement magnitude and rupture width and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area the large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults and to estimate the expected surface displacement along a fault for a given size earthquake

seismic variability of subduction thrust faults insights from laboratory models 1 laboratory models are realized to investigate the role of interface roughness driving rate and pressure on friction dynamics the setup consists of a gelatin block driven at constant velocity over sand paper the interface roughness is quantified in terms of amplitude and wavelength of protrusions jointly expressed by a reference roughness parameter obtained by their product frictional behavior shows a systematic dependence on system parameters both stick slip and stable sliding occur depending on driving rate and interface roughness stress drop and frequency of slip episodes vary directly and inversely respectively with the reference roughness parameter reflecting the fundamental role for the amplitude of protrusions an increase in pressure tends to favor stick slip static friction is a steeply decreasing function of the reference roughness parameter the velocity strengthening weakening parameter in the state and rate dependent dynamic friction law becomes negative for specific values of the reference roughness parameter which are intermediate with respect to the explored range despite the simplifications of the adopted setup which does not address the problem of off fault fracturing a comparison of the experimental results with the depth distribution of seismic energy release along subduction thrust faults leads to the hypothesis that their behavior is primarily controlled by the depth and time dependent distribution of protrusions a rough subduction fault at shallow depths unable to produce significant seismicity because of low lithostatic pressure evolves into a moderately rough velocity weakening fault at intermediate depths the magnitude of events in this range is calibrated by the interplay between surface roughness and subduction rate at larger depths the roughness further decreases and stable sliding becomes gradually more predominant thus although interplate seismicity is ultimately controlled by tectonic parameters velocity of the plates trench and the thermal regime the direct control is exercised by the resulting frictional properties of the plate interface

global frequency of magnitude 9 earthquakes for decades seismologists have sought causal relationships between maximum earthquake sizes and other properties of subduction zones with the underlying notion that some subduction zones may never produce a magnitude 9 or larger event the 2004 andaman m w 9 2 earthquake called into question such ideas given multicentury return times of the greatest earthquakes ignorance of those return times and our very limited observation span i suggest that we cannot yet make such determinations present evidence cannot rule out that any subduction zone may produce a magnitude 9 or larger earthquake based on theoretical recurrence times i estimate that one to three m9 earthquakes should occur globally per century and the past half century with five m9 events reflects temporal clustering and not the long term average

the seismic cycle at subduction thrusts 1 insights from laboratory models 1 subduction megathrust earthquakes occur at the interface between the subducting and overriding plates these hazardous phenomena are only partially understood because of the absence of direct observations the restriction of the instrumental seismic record to the past century and the limited resolution completeness of historical to geological archives to overcome these restrictions modeling has become a key tool to study megathrust earthquakes we present a novel model to investigate the seismic cycle at subduction thrusts using complementary analog paper 1 and numerical paper 2 approaches here we introduce a simple scaled gelatin on sandpaper setup including realistic tectonic loading spontaneous rupture nucleation and viscoelastic response of the lithosphere particle image velocimetry allows to derive model deformation and earthquake source parameters analog earthquakes are characterized by quasi periodic recurrence consistent with elastic theory the interseismic stage shows rearward motion subsidence in the outer wedge and uplift of the coastal area as a response of locked plate interface at shallow depth the coseismic stage exhibits order of magnitude higher velocities and reversal of the interseismic deformation pattern in the seaward direction subsidence of the coastal area and uplift in the outer wedge like natural earthquakes analog earthquakes generally nucleate in the deeper portion of the rupture area and preferentially propagate upward in a crack like fashion scaled rupture width slip proportionality and seismic moment duration scaling verifies dynamic similarities with earthquakes experimental repeatability is statistically verified comparing analog results with natural observations we conclude that this technique is suitable for investigating the parameter space influencing the subduction interplate seismic cycle

global correlations between maximum magnitudes of subduction zone interface thrust earthquakes and physical parameters of subduction zones abstract the maximum earthquake magnitude recorded for subduction zone plate boundaries varies considerably on earth with some subduction zone segments producing giant subduction zone thrust earthquakes e g chile alaska sumatra andaman japan and others producing relatively small earthquakes e g mariana scotia here we show how such variability might depend on various subduction zone parameters we present 24 physical parameters that characterize these subduction zones in terms of their geometry kinematics geology and dynamics we have investigated correlations between these parameters and the maximum recorded moment magnitude m w for subduction zone segments in the period 1900 june 2012 the investigations were done for one dataset using a geological subduction zone segmentation 44 segments and for two datasets rupture zone dataset and epicenter dataset using a 200 km segmentation 241 segments all linear correlations for the rupture zone dataset and the epicenter dataset r 0 00 0 30 and for the geological dataset r 0 02 0 51 are negligible low indicating that even for the highest correlation the best fit regression line can only explain 26 of the variance a comparative investigation of the observed ranges of the physical parameters for subduction segments with m w 8 5 and the observed ranges for all subduction segments gives more useful insight into the spatial distribution of giant subduction thrust earthquakes for segments with m w 8 5 distinct narrow ranges are observed for several parameters most notably the trench normal overriding plate deformation rate v opd i e the relative velocity between forearc and stable far field backarc trench normal absolute trench rollback velocity v t subduction partitioning ratio v sp v s the fraction of the subduction velocity that is accommodated by subducting plate motion subduction thrust dip angle st subduction thrust curvature c st and trench curvature angle t the results indicate that m w 8 5 subduction earthquakes occur for rapidly shortening to slowly extending overriding plates 3 0 v opd 2 3 cm yr slow trench velocities 2 9 v t 2 8 cm yr moderate to high subduction partitioning ratios v sp v s 0 3 1 4 low subduction thrust dip angles st 30 low subduction thrust curvature c st 2 0 10 13 m 2 and low trench curvature angles 6 3 t 9 8 epicenters of giant earthquakes with m w 8 5 only occur at trench segments bordering overriding plates that experience shortening or are neutral v opd 0 suggesting that such earthquakes initiate at mechanically highly coupled segments of the subduction zone interface that have a relatively high normal stress deviatoric compression on the interface i e a normal stress asperity notably for the three largest recorded earthquakes chile 1960 alaska 1964 sumatra andaman 2004 the earthquake rupture propagated from a zone of compressive deviatoric normal stress on the subduction zone interface to a region of lower normal stress neutral or deviatoric tension stress asperities should be seen separately from frictional asperities that result from a variation in friction coefficient along the subduction zone interface we have developed a global map in which individual subduction zone segments have been ranked in terms of their predicted capability of generating a giant subduction zone earthquake m w 8 5 using the six most indicative subduction zone parameters v opd v t v sp v s st c st and t we identify a number of subduction zones and segments that rank highly which implies a capability to generate m w 8 5 earthquakes these include sunda north sulawesi hikurangi nankai northern ryukyu kamchatka kuril japan aleutians alaska cascadia mexico central america south america lesser antilles western hellenic and makran several subduction segments have a low score most notably scotia new hebrides and mariana

scaling relations of earthquake source parameter estimates with special focus on subduction environment abstract earthquake rupture length and width estimates are in demand in many seismological applications earthquake magnitude estimates are often available whereas the geometrical extensions of the rupture fault mostly are lacking therefore scaling relations are needed to derive length and width from magnitude most frequently used are the relationships of wells and coppersmith 1994 derived on the basis of a large dataset including all slip types with the exception of thrust faulting events in subduction environments however there are many applications dealing with earthquakes in subduction zones because of their high seismic and tsunamigenic potential there are no well established scaling relations for moment magnitude and length width for subduction events within this study we compiled a large database of source parameter estimates of 283 earthquakes all focal mechanisms are represented but special focus is set on large subduction zone events in particular scaling relations were fitted with linear least square as well as orthogonal regression and analyzed regarding the difference between continental and subduction zone oceanic relationships additionally the effect of technical progress in earthquake parameter estimation on scaling relations was tested as well as the influence of different fault mechanisms for a given moment magnitude we found shorter but wider rupture areas of thrust events compared to wells and coppersmith 1994 the thrust event relationships for pure continental and pure subduction zone rupture areas were found to be almost identical the scaling relations differ significantly for slip types the exclusion of events prior to 1964 when the worldwide standard seismic network was established resulted in a remarkable effect on strike slip scaling relations the data do not show any saturation of rupture width of strike slip earthquakes generally rupture area seems to scale with mean slip independent of magnitude the aspect ratio l w however depends on moment and differs for each slip type

relation between subduction megathrust earthquakes trench sediment thickness and upper plate strain 1 giant earthquake moment magnitude mw 8 5 forecasts for subduction zones have been empirically related to both tectonic stresses and geometrical irregularities along the subduction interface both of these controls have been suggested as able to tune the ability of rupture to propagate laterally and in turn exert an important control on giant earthquake generation here we test these hypotheses and their combined influence by compiling a dataset of trench fill thickness a proxy for smoothing of subducting plate relief by sediment input into the subduction channel and upper plate strain a proxy for the tectonic stresses applied to the subduction interface for 44 segments of the global subduction network we statistically compare relationships between upper plate strain trench sediment thickness and maximal earthquake magnitude we find that the combination of both large trench fill 1 km and neutral upper plate strain explains spatial patterns of giant earthquake occurrence to a statistically significant degree in fact the concert of these two factors is more highly correlated with giant earthquake occurrence than either factor on its own less frequent giant earthquakes of lower magnitude are also possible at subduction zones with thinner trench fill and compressive upper plate strain extensional upper plate strain and trench fill 0 5 km appear to be unfavorable conditions as giant earthquakes have not been observed in these geodynamical environments during the last 111 years

the seismic cycle at subduction thrusts 2 dynamic implications of geodynamic simulations validated with laboratory models 1 the physics governing the seismic cycle at seismically active subduction zones remains poorly understood due to restricted direct observations in time and space to investigate subduction zone dynamics and associated interplate seismicity we validate a continuum visco elasto plastic numerical model with a new laboratory approach paper 1 the analogous laboratory setup includes a visco elastic gelatin wedge underthrusted by a rigid plate with defined velocity weakening and strengthening regions our geodynamic simulation approach includes velocity weakening friction to spontaneously generate a series of fast frictional instabilities that correspond to analog earthquakes a match between numerical and laboratory source parameters is obtained when velocity strengthening is applied in the aseismic regions to stabilize the rupture spontaneous evolution of absolute stresses leads to nucleation by coalescence of neighboring patches mainly occurring at evolving asperities near the seismogenic zone limits consequently a crack or occasionally even pulse like rupture propagates toward the opposite side of the seismogenic zone by increasing stresses ahead of its rupture front until it arrests on a barrier the resulting surface displacements qualitatively agree with geodetic observations and show landward and from near the downdip limit upward interseismic motions these are rebound and reversed coseismically this slip increases adjacent stresses which are relaxed postseismically by afterslip and thereby produce persistent seaward motions the wide range of observed physical phenomena including back propagation and repeated slip and the agreement with laboratory results demonstrate that visco elasto plastic geodynamic models with rate dependent friction form a new tool that can greatly contribute to our understanding of the seismic cycle at subduction zones

stable creeping fault segments can become destructive as a result of dynamic weakening faults in earth s crust accommodate slow relative motion between tectonic plates through either similarly slow slip or fast seismic wave producing rupture events perceived as earthquakes these types of behaviour are often assumed to be separated in space and to occur on two different types of fault segment one with stable rate strengthening friction and the other with rate weakening friction that leads to stick slip the 2011 tohoku oki earthquake with moment magnitude m w 9 0 challenged such assumptions by accumulating its largest seismic slip in the area that had been assumed to be creeping here we propose a model in which stable rate strengthening behaviour at low slip rates is combined with coseismic weakening due to rapid shear heating of pore fluids allowing unstable slip to occur in segments that can creep between events the model parameters are based on laboratory measurements on samples from the fault of the m w 7 6 1999 chi chi earthquake the long term slip behaviour of the model which we examine using a unique numerical approach that includes all wave effects reproduces and explains a number of both long term and coseismic observations some of them seemingly contradictory about the faults at which the tohoku oki and chi chi earthquakes occurred including there being more high frequency radiation from areas of lower slip the largest seismic slip in the tohoku oki earthquake having occurred in a potentially creeping segment the overall pattern of previous events in the area and the complexity of the tohoku oki rupture the implication that earthquake rupture may break through large portions of creeping segments which are at present considered to be barriers requires a re evaluation of seismic hazard in many areas

gravitational seismology retrieving centroid moment tensor solution of the 2011 tohoku earthquake 1 mass rearrangement within the crust and lithospheric mantle and ocean water redistribution caused by great earthquakes are made visible by their coseismic gravity signature nowadays detectable by the gravity recovery and climate experiment grace space mission here we present a novel procedure for estimating the principal seismic source parameters hypocenter and moment tensor that relies solely on space gravity data from grace applied for the first time to the 2011 tohoku earthquake it yields a seismic source model that is consistent with a thrust earthquake and geological information of the subduction zone it closely resembles the global centroid moment tensor project solution based on the teleseismic wave inversion although the moment magnitude is higher 9 13 0 11 compared to 9 08 and the hypocenter is further offshore by about 40 km within the oceanic plate this procedure will become an important tool in seismology as it complements centroid moment tensor analysis by exploiting the new gravity data from grace

rupture and variable coupling behavior of the mentawai segment of the sunda megathrust during the supercycle culmination of 1797 to 1833 we refer to periods of subduction strain accumulation beneath the mentawai islands sumatra as supercycles because each culminates in a series of partial ruptures of the megathrust in its final decades the finale of the previous supercycle comprised two giant earthquakes in 1797 and 1833 and whatever happened in between this behavior between two great ruptures has implications for how the megathrust will behave between its more recent partial failure during the m w 8 4 earthquake of 2007 and subsequent large ruptures we synthesize previously published coral microatoll records and a large new coral data set to constrain not only these two giant ruptures but also the intervening interseismic megathrust behavior we present detailed maps of coseismic uplift during the two earthquakes and of interseismic deformation during the periods 1755 1833 and 1950 2000 as well as models of the corresponding slip and coupling on the underlying megathrust the large magnitudes we derive m w 8 6 8 8 for 1797 and m w 8 8 8 9 for 1833 confirm that the 2007 earthquakes released only a fraction of the moment released during the previous rupture sequence whereas megathrust behavior leading up to the 1797 and 2007 earthquakes was similar and comparatively simple behavior between 1797 and 1833 was markedly different and more complex several patches of the megathrust became weakly coupled following the 1797 earthquake we conclude that while major earthquakes generally do not involve rupture of the entire mentawai segment they may significantly change the state of coupling on the megathrust for decades to follow influencing the progression of subsequent ruptures

the seismic cycle at subduction thrusts insights from seismo thermo mechanical models 1 the underestimation of the size of recent megathrust earthquakes illustrates our limited understanding of their spatiotemporal occurrence and governing physics to unravel their relation to associated subduction dynamics and long term deformation we developed a 2 d continuum viscoelastoplastic model that uses an eulerian lagrangian finite difference framework with similar on and off fault physics we extend the validation of this numerical tool to a realistic subduction zone setting that resembles southern chile the resulting quasi periodic pattern of quasi characteristic m8 m9 megathrust events compares quantitatively with observed recurrence and earthquake source parameters albeit at very slow coseismic speeds without any data fitting surface displacements agree with gps data recorded before and during the 2010 m8 8 maule earthquake including the presence of a second order flexural bulge these surface displacements show cycle to cycle variations of slip deficits which overall accommodate 5 of permanent internal shortening we find that thermally and stress driven creep governs a spontaneous conditionally stable downdip transition zone between temperatures of 350 c and 450 c ruptures initiate above it and below the forearc moho propagate within it interspersed by small intermittent events and arrest below it as ductile shearing relaxes stresses ruptures typically propagate upward along lithological boundaries and widen as pressures drop the main thrust is constrained to be weak due to fluid induced weakening required to sustain regular subduction and to generate events with natural characteristics fluid pressures of 75 99 of solid pressures the agreement with a range of seismological geodetic and geological observations demonstrates the validity and strength of this physically consistent seismo thermo mechanical approach

shocks in a box an analogue model of subduction earthquake cycles with application to seismotectonic forearc evolution 1 we introduce and test an experimental approach to simulate elastoplastic megathrust earthquake cycles using an analogue model and apply it to study the seismotectonic evolution of subduction zones the quasi two dimensional analogue model features rate and state dependent elastic frictional plastic and viscoelastic material properties and is scaled for gravity inertia elasticity friction and viscosity the experiments are monitored with a high resolution strain analysis tool based on digital image correlation particle imaging velocimetry piv providing deformation time series comparable to seismologic geodetic and geologic observations in order to separate elastic and nonelastic effects inherent the experimental deformation patterns we integrate elastic dislocation modeling edm into a hybrid approach we use the analogue earthquake slip and interseismic locking distribution as edm dislocation input and forward model the coseismic and interseismic elastic response the residual which remains when the edm prediction is subtracted from the experimental deformation pattern highlights the accumulation of permanent deformation in the model the setup generates analogue earthquake sequences with realistic source mechanisms and elastic forearc response and recurrence patterns and reproduces principal earthquake scaling relations by applying the model to an accretionary type plate margin we demonstrate how strain localization at the rupture peripheries may lead to a seismotectonically segmented forearc including a tectonically stable shelf and coastal high 20 plate convergence accommodated by internal shortening overlying the area of large megathrust earthquake slip fifty to 75 of plate convergence is accommodated by internal shortening in the slope region where earthquake slip tapers out toward the trench the inner forearc region remains undeformed and represents a basin

modeling the seismic cycle in subduction zones the role and spatiotemporal occurrence of off megathrust earthquakes shallow off megathrust subduction events are important in terms of hazard assessment and coseismic energy budget their role and spatiotemporal occurrence however remain poorly understood we simulate their spontaneous activation and propagation using a newly developed 2 d physically consistent continuum viscoelastoplastic seismo thermo mechanical modeling approach the characteristics of simulated normal events within the outer rise and splay and normal antithetic events within the wedge resemble seismic and seismological observations in terms of location geometry and timing their occurrence agrees reasonably well with both long term analytical predictions based on dynamic coulomb wedge theory and short term quasi static stress changes resulting from the typically triggering megathrust event the impact of off megathrust faulting on the megathrust cycle is distinct as more both shallower and slower megathrust events arise due to occasional off megathrust triggering and increased updip locking this also enhances tsunami hazards which are amplified due to the steeply dipping fault planes of especially outer rise events

earthquake supercycle in subduction zones controlled by the width of the seismogenic zone some subduction zones experience earthquake supercycles numerical simulations show that successive megathrust earthquakes may load neighbouring parts of the fault causing it to eventually fail in a giant earthquake that completes a supercycle

physical characteristics of subduction interface type seismogenic zones revisited 1 based on global earthquake catalogs the hypocenters nodal planes and seismic moments of worldwide subduction plate interface earthquakes were extracted for the period between 1900 and 2007 assuming that the seismogenic zone coincides with the distribution of 5 5 m 7 earthquakes the subduction interface seismogenic zones were mapped for 80 of the trench systems and characterized with geometrical and mechanical parameters using this database correlations were isolated between significant parameters to identify cause effect relationships empirical laws obtained in previous studies were revisited in light of this more complete accurate and uniform description of the subduction interface seismogenic zone the seismogenic zone was usually found to end in a fore arc mantle rather than at a moho depth the subduction velocity was the first order controlling parameter for variations in the physical characteristics of plate interfaces determining both the geometry and mechanical behavior as such the fast subduction zones and cold slabs were associated with large and steep plate interfaces which in turn had large seismic rates the subduction velocity could not account for the potential earthquake magnitude diversity that was observed along the trenches events with mw 8 5 preferentially occurred in the vicinity of slab edges where the upper plate was continental and the back arc strain was neutral this observation was interpreted in terms of compressive normal stresses along the plate interface large lateral ruptures should be promoted in neutral subduction zones due to moderate compressive stresses along the plate interface that allow the rupture to propagate laterally

an integrated perspective of the continuum between earthquakes and slow slip phenomena slow slip a mechanism by which faults can relieve stress was thought to be distinct from earthquakes however a global review of slow slip phenomena suggests that instead there is a continuum between the two types of event