Long-Range Dependence in Low-Frequency Earthquakes Catalogs?

Date: 4/24/2019

Time: 06:00 PM

Room: Grand Ballroom

Long-range dependence is a phenomenon that may arise in the statistical analysis of time series data. It relates to the slow rate of decay of the statistical dependence between two points with increasing time interval between the points. Evidence of long-range dependence has been found in regional and global earthquake catalogs, and in catalogs of mining-induced seismicity. Low-frequency earthquakes (LFEs) are small magnitude earthquakes, with typical magnitude less than 2, and reduced amplitudes at frequencies greater than 10 Hz relative to ordinary small earthquakes. Their occurrence is often associated with tectonic tremor and slow slip events along the plate boundary in subduction zones and occasionally transform fault zones. They are usually grouped into families of events, with all the earthquakes of a given family originating from the same small patch on the plate interface, and recurring more or less episodically in a bursty manner. In this study, we analyze catalogs of LFEs from the Olympic Peninsula, Northern California, Mexico, and the San Andreas Fault. For each family of LFEs, we translate the catalog into a continuous time series defined by number of events per minute. The sample interval is 1 minute. Then, we compute the value of the fractional parameter d, which represents how fast the variance in the number of LFEs increases with the length of the time window considered. For most families of the catalogs studied, we find that 0 < d < 0.5, which is characteristic of long-range dependence in the time series. The only exception is the San Andreas Fault catalog, where the LFE families show a wider range of behaviors, and where only some of the families exhibit evidence for long-range dependence. Long-range dependence may be explained by interactions among several asperities associated with the same LFE family. The statistical characterization of LFE occurrence could provide important constraints on future mechanical models of slow earthquake phenomena.

Presenting Author: Ariane Ducellier

Authors