Towards automated estimates of directivity and related source properties of small to moderate earthquakes in Southern California with second seismic moments

Haoran Meng, Yehuda Ben-Zion, & Jeff J. McGuire

Published August 15, 2016, SCEC Contribution #6836, 2016 SCEC Annual Meeting Poster #229

We develop a method for automated estimation of directivity, rupture area, duration, and centroid velocity of earthquakes in Southern California with second seismic moments. A 1D ray tracing and an automated picking algorithm are combined to give initial S phase picks. These are refined for time domain deconvolution using a grid search within a short time window around the automated S picks. Source time functions of target events are derived using deconvolution with stacked Empirical Green’s Function (EGFs) selected by spatial and magnitude criteria as well as performances in the deconvolution. The use of stacked EGFs helps to reduce non-generic source effects such as directivity in individual EGFs. The method is suitable for analysis of large seismic dataset and so far works for target events with magnitudes as small as 3.5. Applications to several small to moderate earthquakes in southern California indicates that most have significant directivity. In particular, the recent June 2016 Mw 5.2 Borrego Springs earthquake is found to have strong directivity to the northwest.

Key Words
Second moment, directivity, automated estimation, stacked EGFs

Citation
Meng, H., Ben-Zion, Y., & McGuire, J. J. (2016, 08). Towards automated estimates of directivity and related source properties of small to moderate earthquakes in Southern California with second seismic moments. Poster Presentation at 2016 SCEC Annual Meeting.

Related Projects & Working Groups
Seismology