Abstract
We analyze the seismicity rate immediately after the 2004 Mw6.0 Parkfield, California, earthquake from near‐source seismograms. By scrutinizing high‐frequency signals, we can distinguish mainshock coda from early aftershocks occurring as soon as 30 s after the mainshock. We find, as expected, that a significant fraction of aftershocks in the first few hours after the main shock are missing in the Northern California Seismic Network catalog. We observe a steady rate of aftershocks in the first 130 s, followed by a power‐law decay of aftershock activity. Thus, there appears to be a distinct early stage of aftershock activity that does not fit the Omori's law with a constant p value, a phenomenon that we refer to as Early Aftershock Deficiency (EAD). Our observation suggests that mainshock rupture and aftershocks are distinct processes, not described by a single Omori's law. Several physical models of aftershocks can explain the EAD.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.