Low-frequency earthquakes in the Mexican Sweet Spot

William B. Frank (1) , Nikolaï M. Shapiro (1) , Vladimir Kostoglodov , Allen L. Husker , Michel Campillo (2) , Juan S. Payero , Germán. A. Prieto

1 IPGP - Institut de Physique du Globe de Paris
2 ISTerre - Institut des Sciences de la Terre

We use data from the Meso-America Subduction Experiment to detect and locate low-frequency earthquakes (LFEs) in the Mexican subduction zone. We use visually-identified templates to perform a network waveform correlation search that produced ~17,000 robustly detected LFEs that form 15 distinct families. Stacking an LFE family's corresponding detections results in seismograms with high signal-to-noise ratios and clear P and S wave arrivals; we use these travel times to locate the sources. The resulting locations superpose a previously identified region of permanent non-volcanic tremor (NVT) activity. Husker et al. (2012) called this region a Sweet Spot, suggesting that the local conditions are adequate to continuously generate NVT. The LFE hypocenters have been located at a depth of 40-45 km in an area that is surrounding the upper slab-plate interface. We characterize their focal mechanisms by comparing their stacked seismograms to synthetic seismograms. This analysis reveals a common low-dipping focal mechanism.

Mots clés: low-frequency; earthquakes; tremor; slow-slip; mexico; subduction

Domaines: Planète et Univers [physics]

William B. Frank, Nikolaï M. Shapiro, Vladimir Kostoglodov, Allen L. Husker, Michel Campillo, et al.. Low-frequency earthquakes in the Mexican Sweet Spot. Geophysical Research Letters, 2013, 40, pp.2661-2666. ⟨10.1002/grl.50561⟩. ⟨insu-03581787⟩