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Spatial variations of rock damage production by earthquakes in southern California

Yehuda Ben-Zion, & Ilya Zaliapin

Published August 10, 2018, SCEC Contribution #8379, 2018 SCEC Annual Meeting Poster #066

We perform a comparative spatial analysis of earthquake production of rupture area and volume in southern California using observed seismicity and basic scaling relations from earthquake phenomenology and fracture mechanics. The analysis employs the catalog of Hauksson et al. (2012; extended to later years) for the period 1981-2017. We use only background events in the magnitude range [2-4] from a declustered version of the catalog to get temporally stable results representing typical activity during an inter-seismic period on all faults. The derived estimates can help separating rock damage and composition in models of seismic velocities and attenuation coefficients for the region. The analysis also highlights seismic zones that are active persistently beyond fluctuations associated with the large events. The results exhibit the following features. Regions of relative high inter-seismic damage production include the SJF, South Central Transverse Range (SCTR) especially near fault junctions (CP, SGP), Eastern CA Shear Zone (ECSZ) and Brawly seismic zone (BSZ) - Salton Sea area. The zones with high damage production are not necessarily associated with large earthquakes; there are M5 events outside these zones and very active damage areas with no large events in the last 30 years. The Imperial fault, BSZ, so. SAF and ECSZ form a quasi-linear zone with ongoing damage production. The regions around the 1992 Joshua Tree and Landers earthquakes are active before 1990 and outline the ruptures of the future events. The seismically active crust becomes shallower to the NE from the peninsular ranges to the Mojave, north of the SCTR, and to the SE along the SJF and Elsinore fault, in agreement with Moho depth variations. The seismicity and damage zone are generally patchy, but more pronounced and continuous along-strike of main faults below 7.5 km than in the shallower crust.

Key Words
seismic rock damage, inter-seismic period, declustered catalog

Ben-Zion, Y., & Zaliapin, I. (2018, 08). Spatial variations of rock damage production by earthquakes in southern California. Poster Presentation at 2018 SCEC Annual Meeting.

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