Empirical Green's function study of the January 17, 1994 Northridge, California earthquake

Abstract

The January 17, 1994 Northridge main‐shock was analyzed using an empirical Green's function approach to estimate the spatial and temporal distribution of fault slip. Far‐field source time functions obtained from seismograms recorded by the Berkeley Digital Seismic Network (BDSN) and TERRAscope stations reveal the distributed nature of the source and the presence of a second large subevent. The location of the fault beneath the San Fernando valley as well as the updip directivity of the rupture contributed to the locally heavy damage due to this earthquake.

Fluid‐faulting interactions: Fracture‐mesh and fault‐valve behavior in the February 2014 Mammoth Mountain, California, earthquake swarm

“…In order to investigate the rupture of the swarm's largest event and its influence on the aftershock sequence, we performed a finite-source inversion for this M 3.1 event using an empirical Green's function deconvolution approach [e.g., Mori and Hartzell, 1990;Dreger, 1994]. We first determined the moment rate function (MRF) by…”

“…Eight broadband seismic stations give MRFs with good signal-to-noise ratio; these are then backprojected onto the fault plane to estimate the fault slip. A detailed description of the finite-source inversion can be found in Dreger [1994] and Taira …”

Can slip heterogeneity be linked to earthquake recurrence?

“…As shown in Figure 1c, To study how the change in source properties ties to recurrence behavior, empirical Green's function (eGf) deconvolution is conducted to extract the relative source time function (RSTF) for a target event. The obtained RSTF is later introduced in kinematic source inversion modeling of slip distribution in an asperity [e.g., Mori and Hartzell, 1990;Mori, 1993;Dreger, 1994;Hough and Dreger, 1995;Dreger et al, 2007]. A detailed description of methodology can be found in Hough and Dreger [1995] and is also described in the supporting information.…”

Rupture process for micro-earthquakes inferred from borehole seismic recordings

“…The finite-source rupture inversion used in this paper is the same as those used in Dreger (1994) and Dreger (1997) where a complete description of the methodology can be found. We here briefly summarize the inversion…”

“…Following Dreger (1994), we invert the MRFs to obtain the spatial distribution of fault slip. We assume that the source nucleates at a single point on the fault surface and that slip is propagates over the fault plane with a constant rupture velocity.…”