An earthquake‐like magnitude‐frequency distribution of slow slip in northern Cascadia

摘要: [1] Major episodic tremor and slip (ETS) events with Mw 6.4 to 6.7 repeat every 15 ± 2 months within the Cascadia subduction zone under Olympic Peninsula. Although these major ETS are observed release strain, smaller “tremor swarms” without detectable geodetic deformation more frequent. An automatic search from 2006–2009 reveals 20,000 five-minute windows containing which cluster in space time into 96 swarms. The 93 inter-ETS swarms account for 45% of total duration detection during last three cycles. number swarms, N, exceeding τ follow a power-law distribution N ∝ τ−0.66. If is proportional moment release, inferred follows standard Gutenberg-Richter logarithmic frequency-magnitude relation, lying on same trend. This relationship implies that 1) fundamentally similar events, just frequent; 2) despite fundamental differences moment-duration scaling, slow magnitude-frequency as normal earthquakes b-value 1.