Burst, background, and triggered low-frequency earthquakes and non-volcanic tremors

Since the first observations of slow-slip events (SSEs), non-volcanic tremor (NVT), and low-frequency earthquakes (LFEs), strong links have been identified between the three slow earthquake phenomena, such as increased NVT and LFE activity during large SSEs and the burst-like, or episodic, behavior of both NVT and LFEs. We focus here on the latter observation, exploring this distinct characteristic of LFEs and NVT. Analysis of the LFE and NVT catalogs from Guerrero, Mexico and Parkfield, California reveals a steady background event rate underlying a non-periodic burst-like behavior. We develop a simple algorithm to generate a catalog of bursts for both LFEs and NVTs, separating the events that occur within bursts from the background rate. We observe that just as LFEs and NVTs occur on two different time scales (from seconds to minutes or hours), their bursts occur on similarly different time scales (from minutes or hours to days). Using these decomposed background and burst event rates, we then attempt to model different potential triggering mechanisms such as slow-slip events with a brittle ductile friction model (Daub et al. [2011]) that could potentially reproduce the observed behavior.