The thickness of the seismogenic zone in the Earth’s crust plays an important role in seismo tectonics, affecting fault system architecture and relative fault activity, earthquake size and distribution within a fault system, and long-term accumulation of tectonic deformation. Within the last two decades, several studies have revealed that aftershocks of large continental earthquakes may occur below the background depth of the seismogenic zone, i.e., below the seismic-aseismic transition zone. This observation may be explained with a strain- and strain-rate induced shift in rheological behavior that follows large mainshocks, transiently changing the deformation style below the seismogenic zone from incipient ductile to seismically brittle failure. As large earthquakes transiently deepen the seismic-aseismic transition zone, it is plausible to assume that larger mainshocks may cause stronger deepening than smaller mainshocks. Corresponding observations however have not yet been reported. Here, we use well-located seismic catalogs from Alaska, California, Japan, and Turkey to analyze if mainshock size positively correlates with the amount of transient deepening of the seismic-aseismic tranition zone. We compare the depths of background seismicity with aftershock depths of 16 continental strike-slip earthquakes (6
|Original language||English (US)|
|Journal||Geophys. Res. Lett.|
|State||Published - Jan 15 2020|
Bibliographical noteKAUST Repository Item: Exported on 2020-04-23
Acknowledged KAUST grant number(s): BAS/1/1339-01-01
Acknowledgements: This research project is supported with funding from King Abdullah University of Science and Technology (KAUST), grant BAS/1/1339-01-01. The Alaska earthquake catalog is provided by the Alaska earthquake center and accessed via NEIC’s comcat catalog web interface https://earthquake.usgs.gov/data/comcat/. The Japan earthquake catalog is provided by Japan Meteorological Agency and the catalog is available at https://www.data.jma.go.jp/svd/eqev/data/bulletin/index_e.html. Seismic catalogs from Turkey have been published by Bohnhoff et al. (2016) and may be found in the supplementary material of this publication. Catalogs from California are hosted at https://scedc.caltech.edu/research-tools/alt324 2011-dd-hauksson-yang-shearer.html (southern California) and at http://www.ncedc.org/ncedc/catalog-search.html (northern California). Kinematic source models were acquired from the SRCMOD database http://equake-rc.info/srcmod/. All web-based data sources (except Japan catalog) were last accessed on August 15th 327 2019. The supplemental online material contains an additional figure, in correspondence to Figure 4, for two different bin-sizes (100-event and 400-event bins respectively).