Abstract

I compare intensity data from 17 predigital intraslab earthquakes in south‐central Alaska and digitized waveforms for nine of these events to similar data for the 24 January 2016 Iniskin and 30 November 2018 Anchorage intraslab events. Both the 2016 and 2018 events were associated with amplification of strong ground motion at distances of over 100 km from their epicenters, likely due to the velocity structure associated with flat slab subduction in the region as well as the thick sedimentary sequence found within the Cook Inlet basin. Six of the predigital events also appear to have similar amplification of strong ground motion. Waveform comparisons suggest the 4 May 1934 Prince William Sound and 3 October 1954 Kenai Peninsula events had similar focal mechanisms and depths to the 30 November 2018 Anchorage event. Earthquakes occurring in regions where the P‐wave velocity of the slab exceeds 7.5  km/s tend to be associated with higher strong ground motions.

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