Faults are rarely completely smooth, with topographic undulations coming from the distribution of asperities along fault surface. Understanding effects surface topography on strength and earthquake source properties has been limited due to a lack in situ observations field. Here we use simulated cycles metre-scale laboratory faults show degree heterogeneity, especially macroscopic peak represented by shear force required commence failure. Our results demonstrate that less heterogeneous is...

A system for automated moment tensor determination by inverting on-line broadband seismic waveforms operated the FREESIA project has been developed. When an Email notice of earthquake occurrence arrives from Japan Meteorological Agency (JMA), this automatically retrieves dataset waveform inversion, examines quality data, and determines filtering coefficients as well data windows. This inversion uses long period waves (from 20 seconds to 50 seconds) so that procedure is insensitive onset wave...

We propose a new source-time function, to be used in kinematic modeling of ground-motion time histories, which is consistent with dynamic propagation earthquake ruptures and makes feasible the interpretation slip models. This function derived from first proposed by Yoffe (1951), yields traction evolution showing slip-weakening behavior. In order remove its singularity, we apply convolution triangular obtain regularized called function. parameterization this slip-velocity through final slip,...

High‐velocity friction experiments on a fault gouge collected from the Nojima activated during 1995 Kobe earthquake showed that coefficient decreased 0.63 to 0.18 over slip weakening distance, D c , at high rates of ∼ 1 m/s. The dramatic drop in more than 0.3 is consistent with for estimated seismological observations. Experimentally determined becomes 5 m higher normal stress 1.85 MPa, close order magnitude seismologically 0.5 m. difference not significant because fracture energy consumed...

Abstract We propose a new boundary integral equation method (BIEM) to model the spontaneous propagation of rupture on planar fault embedded in homogeneous elastic medium. The BIEM formulation is very compact and fast computation, so that we are able study effect different slip- rate-dependent friction laws dynamic shear propagation. simulated by sudden break asperity under two laws, rate and/or slip weakening. examined both long circular asperities. corresponds 2D anti-plane or in-plane...

We have simulated the rupture process of 1992 Landers, California, earthquake using a realistic nonplanar fault geometry, including bends and branches, through three‐dimensional boundary integral equation method. Considering an external loading system due to local tectonics as well structure, we could reproduce characteristic features this such spontaneous transfer between faults, pattern slip distribution, propagation front without assuming any laterally heterogeneous distribution...

Abstract The rupture process of the 1983 Japan Sea earthquake (MJMA = 7.7) is determined by applying waveform inversion displacement-type, strong motion records based on Bayesian method. synthesis seismic motions from main shock made using two aftershocks 7.1 and MJMA 6.1) as empirical Green's functions. fault consists subfaults. aftershock (M occurring south used for southern subfault function 7.1) north northern subfault. In this synthesis, it not necessary to calculate propagation path...

We conduct meter-scale rock friction experiments to study strain rate effect on fault slip and rupture evolution. Two samples made of Indian metagabbro, with a nominal contact dimension 1.5 m long 0.1 wide, are juxtaposed loaded in direct shear configuration simulate the motion. A series experimental tests, under constant loading rates ranging from 0.01 mm/s 1 fixed normal stress 6.7 MPa, performed conditions changing rates. Load cells displacement transducers utilized examine macroscopic...

Abstract In southwest Japan, great earthquakes have occurred on the plate interface along Nankai trough with a recurrence time of approximately 100 years. Most previous studies estimated slip deficits seismogenic zone from interseismic Global Navigation Satellite System (GNSS) velocity data assuming slip‐response functions for an elastic medium. The observed surface velocities, however, include effects viscoelastic relaxation in asthenosphere caused by motion associated seismic cycles. If...

The preparation process of natural earthquakes is still difficult to quantify and remains a subject debate even with modern observational techniques. Here, we show that foreshock activity can shed light on understanding the earthquake based results meter-scale rock friction experiments. Experiments were conducted under two different fault surface conditions before each run: less heterogeneous without pre-existing gouge more gouge. fewer foreshocks occurred along driven by preslip; in...

Abstract In this study we use the precursory acoustic emission (AE) activity during nucleation of stick‐slip instability as a proxy to investigate foreshock occurrence prior natural earthquakes. We report on three experiments performed cylindrical samples Indian metagabbro under upper crustal stress conditions (30–60 MPa). AEs were continuously recorded by eight calibrated sensors experiments. Seismological parameters (moment magnitude, corner frequency and stress‐drop) detected (−8.8 ≤ M w...

We have investigated how the automated moment tensor determination (AMTD) system using FREESIA/KIBAN broadband network is likely to behave during a future large earthquake. Because we do not enough experience with (M > 8) nearby earthquake, computed synthetic waveforms for such an event by assuming geometrical configuration of anticipated Tokai earthquake and several fault rupture scenarios. Using this data set, examined behavior AMTD learn prepare event. For our assume its focal mechanism,...

Abstract The 2016 M 7.8 Kaikōura (New Zealand) earthquake struck the east coast of northern South Island, resulting in strong ground shaking and large surface fault slip. Since was well recorded by a local strong‐motion seismic network, near‐fault data may provide direct measurements dynamic parameters associated with fault‐weakening process. Here we estimate proxy for slip‐weakening distance , defined as double fault‐parallel displacement at time peak velocity, from accelerograms station....

We investigate the faulting process of aftershock region 2000 western Tottori earthquake ( M w 6.6) by combining hypocenters and moment tensor solutions. Aftershock locations were precisely determined double difference method using P - S -phase arrival data Japan Meteorological Agency unified catalog. By relocated solutions aftershocks broadband waveform inversion FREESIA (F-net), we successfully resolved very detailed fault structures activated mainshock. The estimated model resolves 15...

[1] We investigated dynamic rupture scenarios of anticipated megathrust earthquakes on the Nankai-Tonankai subduction zone, southwest Japan. To improve scenario reliability, model parameters should be constrained by available data, or derived from their analysis. employed three-dimensional plate interface geometry and slip-deficit rate interface. Accumulated was used to obtain stress drop distribution earthquakes. The estimated is consistent with seismogenic asperity locations known analysis...

We investigate the effect of fault surface roughness on rupture preparation characteristics using meter-scale metagabbro specimens. repeatedly conducted experiments with same pair rock specimens to make rough. obtained three experimental results under conditions (6.7 MPa normal stress and 0.01 mm/s loading rate) but at different (smooth, moderately roughened, heavily roughened). During each experiment, we observed many stick-slip events preceded by precursory slow slip. investigated when...