The use of waveform cross correlation to recover the aftershock sequence of the August 14, 2016 earthquake within Sakhalin Island

TL;DR

This paper demonstrates that waveform cross correlation significantly improves detection, localization, and completeness of aftershock sequences following the 2016 Sakhalin earthquake, especially for smaller events.

Contribution

It introduces a waveform cross correlation method for enhanced aftershock detection and location, surpassing routine seismological processing in accuracy and event count.

Findings

Increased number of detected aftershocks with multiple station associations

Lowered magnitude threshold for catalog completeness

More precise epicenter locations within the fault zone

Abstract

The method of waveforms cross correlation (WCC) is used to detect signals from aftershocks of the August 14, 2016 earthquake within Sakhalin Island, which had local magnitude ML = 6.1. Arrivals of regular P- and S-waves detected by the WCC method with various master events at 6 regional stations are associated into a set of seismic events called the cross correlation standard event list (XSEL). We compare the XSEL with the bulletin for the same aftershock sequence compiled in routine seismological processing. The principal advantage of the XSEL is expressed in the increasing number of found seismic events with three or more associated stations, a slight decrease in the magnitude threshold of catalogue completeness, and more accurate location of the epicentres for even the smallest aftershocks. The improved aftershock locations tend to cluster in a narrow zone corresponding to the western board of the Central Sakhalin fault, which defines the boundary between the Okhotsk and the Eurasian (Amur) slabs.