ABSTRACT

I present a set of routines in MATLAB for estimating the second‐degree moments of an earthquake’s rupture from far‐field body waves. The second moments describe the length, width, duration, and directivity of a rupture. The second‐moments approach is particularly useful when a seismic dataset is dense enough to resolve the primary finite‐source properties but the geodetic data needed for a well‐resolved finite‐fault inversion are not available. In particular for Mw 3–6 earthquakes, this approach can be a useful way to estimate rupture area without the assumptions of typical corner‐frequency approaches. The provided software utilizes empirical Green’s function deconvolution to isolate the apparent source time function (ASTF) for each station and phase. The spatial variations in the duration of the ASTF are quantified and inverted for the second moments. The inverse problem is solved using MATLAB’s convex optimization routines for systems of linear matrix inequalities. An error analysis using the jackknife and bootstrap methods is included. An example Mw 4.7 earthquake from the San Jacinto fault is used to demonstrate the method.

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