The enigma of the Arthur's Pass, New Zealand, earthquake: 2. The aftershock distribution and its relation to regional and induced stress fields

Abstract

Abstract. The aftershock distribution of the 1994 Arthur's Pass earthquake, Mw6.7, is unusual for a reverse faulting event in that it extends 12 km NNW and 30 km SSE of the actual fault plane, which strikes NE-SW. We have used several methods to infer the regional stress field in the region, including geodetic results, earthquake mechanisms, and inversion of P wave polarity data for the stress tensor orientation. The inversion method is new and does not require the focal mechanisms of the events used. It also incorporates the Coulomb failure criterion. All results point to a stress field favoring strike-slip faulting, not thrusting, with near-horizontal cvl and cv3 principal axes striking at 298 ø and 28 ø . Using dislocation theory, we calculate the stress induced

Microearthquake Study of the Salton Sea Geothermal Field, California: Evidence of Stress Triggering - Masters Thesis

“…This value is similar to that used by Robinson and McGinty (2000). Many studies of Coulomb failure in southern California such as King et.…”

“…This method searches over stress tensor orientations and finds the stress tensor orientation which best matches the observations in the data set. Robinson and McGinty (2000) determined that this method is less dependent on station distribution than focal mechanism methods and can often find principal stress axis when no single well constrained focal mechanism could be obtained. The inversion uses a bootstrap method that samples with replacement to obtain the best stress tensor within a given confidence interval.…”

“…Inversion to obtain stress tensor from microearthquake first motion data was done following the method described by Robinson and McGinty (2000). This method applies the Coulomb failure criteria of Okada (1992) to the observations of first motion.…”

Tectonics of the Taranaki region, New Zealand: Earthquake focal mechanisms and stress axes

“…We estimate the σ 1 and σ 3 axes by inversion of focal mechanisms using the program FMSI (Gephart & Forsyth 1984;Gephart 1990) and by inversion of first motions using the program GETSTRESS (Robinson & McGinty 2000). We use two methods to ensure that our results do not depend on the inversion algorithm.…”

Relating Crustal Structure and Stress Indicators in the Azores Islands

“…Although the 3D revised hypocenters solutions are more accurate, the error involved in the measurement of the splitting directions allows using the simpler 1D approach: the already referred sampling rate of 62.5 Hz, for the data stored for the majority of the digital temporary stations, coupled with the difficulties in the north alignment of the seismic sensors in basaltic oceanic islands, outmanoeuvre the accuracy of using 3D locations instead of 1D. On the other hand, most of the programs available for crustal stress modelling are 1D based (Robinson & McGinty, 2000). The detection and quantification of such anisotropy was possible only in some of the digital stations located on the islands of Faial and Pico (cf.…”