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Potency-magnitude Scaling Relations for Southern California Earthquakes with 1.0 < ML < 7.0

Yehuda Ben-Zion, & Lupei Zhu

Published March 2002, SCEC Contribution #627

Linear and quadratic scaling relations between potency P0 and local magnitude ML for southern California earthquakes are derived using observed data of small events (1.0 < ML < 3.5) recorded in the Cajon Pass borehole and moderate events (3.5 < ML < 6.0) recorded by the broad-band TERRAscope/TriNet network. The derived relations are extended to ML = 7.0 and compared with observed potency–magnitude values of four earthquakes in the extended range. The results indicate that a linear scaling relation can describe accurately data extending only over 2–3 orders of magnitudes. The best-fitting slope of a linear log P0 vs ML scaling for the small Cajon Pass events is about 1.0, while the slope for the 3.5 < ML < 6.0 events is about 1.34. A quadratic relation can fit the data well over the entire 1.0 < ML < 7.0 magnitude range. The results may be explained in terms of a continuous transition from a limiting scaling P0 ~ (rupture area) for highly disordered small events, to a limiting scaling P0 ~ (rupture area times slip) for crack-like large events. Such a transition is expected to characterize evolving seismicity on heterogeneous faults, where small events propagate in (and are arrested by) a rough fluctuating stress field, while large events propagate across a relatively smooth correlated field.

Ben-Zion, Y., & Zhu, L. (2002). Potency-magnitude Scaling Relations for Southern California Earthquakes with 1.0 < ML < 7.0. Geophysical Journal International, 148(3), F1-F5. doi: 10.1046/j.1365-246X.2002.01637.x.