An observational test of the critical earthquake concept

Abstract

Abstract. We test the concept that seismicity prior to a large earthquake can be understood in terms of the statistical physics of a critical phase transition. In this model, the cumulative seismic strain release increases as a power law time to failure before the final event. Furthermore, the region of correlated seismicity predicted by this model is much greater than would be predicted from simple elastodynamic interactions. We present a systematic procedure to test for the accelerating seismicity predicted by the critical point model and to identify the region approaching criticality, based on a comparison between the observed cumulative energy (Benioff strain) release and the power law behavior predicted by theory. This method is used to find the critical region before all earthquakes along the San Andreas system since 1950 with M > 6.5. The statistical significance of our results is assessed by performing the same procedure on a large number of randomly generated synthetic catalogs. The null hypothesis, that the observed acceleration in all these earthquakes could result from spurious patterns generated by our procedure in purely random catalogs, is rejected with 99.5 % confidence. An empirical relation between the logarithm of the critical region radius (R) and the magnitude of the final event (M) is found, such that log R •: 0.5M, suggesting that the largest probable event in a given region scales with the size of the regional fault network.

Spatio-temporal Scanning and Statistical Test of the Accelerating Moment Release (AMR) Model Using Australian Earthquake Data

“…AMR has been tested by substantial researcher (BUFE and VARNES, 1993;BUFE et al, 1994;BOWMAN et al, 1998;JAUME and SYKES, 1999;BREHM andBRAILE, 1998, 1999;ROBINSON, 2000;PAPAZACHOS and PAPAZACHOS, 2000), but mostly in inter-plate areas. One would ask: Can AMR be observed in different tectonic settings?.…”

Parallel 3-D Simulation of a Fault Gouge Using the Lattice Solid Model

“…The gouge particles are non-bonded, and impart forces on neighbouring gouge and roughness particles via the friction interaction described in equations (2). The gouge particles have the same radial size range as the roughness particles.…”

“…The RMS error of the power law time-to-failure fit divided by the RMS error of a linear fit provides a quality-measure for the time-to-failure fits [2]. The lower the quality-measure value, the more superior the power-law fit when compared with the linear fit.…”

Load-Unload Response Ratio (Lurr), Accelerating Moment/Energy Release (Am/Er) and State Vector Saltation As Precursors To Failure of Rock Specimens

“…The former will lead to triggering of earthquakes by tidal stress (GRASSO and SORNETTE, 1998) and consequently anomalously high values of LURR (YIN and YIN, 1991;YIN, 1993;YIN et al, 1994YIN et al, , 1995YIN et al, , 1996YIN et al, , 2000YIN et al, , 2002 are observed prior to large earthquakes. The latter will lead to establishment of long-range correlations in the regional stress field (SYKES and JAUME, 1990;RUNDLE et al, 1999;SAMMIS and SMITH, 1999;PLACE, 2000, 2002;WEATHERLEY, 2002) and accelerating seismic activity of moderate-sized earthquakes (ELLSWORTH et al, 1981;KEILIS-BOROK, 1990;SORNETTE and SAMMI;KNOPOFF et al, 1996 andBOWMAN et al, 1998) and equivalently, the accelerating seismic release prior to large earthquakes follows a power-law time-to-failure relation -AMR/AER (BUFE and VARNES, 1993;BOWMAN et al, 1998;JAUME and SYKES, 1999). Various research groups have tested LURR and AMR/AER using seismological observations.…”

“…The CPH (Critical Point Hypothesis) considers earthquake rupture as a critical point (VERE-JONES, 1977;SORNETTE and SORNETTE, 1990;SORNETTE and SAMMIS, 1995;BOWMAN et al, 1998;RUNDLE et al, 1999;JAUME and SYKES, 1999). According to CPH the crust is not in a continuous state of criticality, but repeatedly approaches to and retreats from a critical state.…”