Tracking the spatio-temporal evolution of foreshocks preceding the Mw 6.3 2009 L'Aquila Earthquake

Abstract

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A long-lived swarm on the Central Bransfield Basin, Antarctica

“…We then performed the detection of new events with template matching (Gibbons and Ringdal, 2006) and a single station approach (Poli, 2017). Because the use of a single station can reduce the detection sensitivity and increase the presence of unwanted signals, we combined visual inspection and detection with fake templates (e.g., waveforms flipped in time, Cabrera et al, 2020), to define an optimal detection threshold (3-components average correlation coefficient greater than 0.5). This template matching detection, allowed the identification of 36241 earthquakes, ~300 times more than the initial catalogue (Fig.…”

“…Then we estimated the magnitude of each newly detected event by computing the mean S-wave amplitude ratio between the template events and the detections over the three components. Using the template event's catalogue magnitude as a reference, the detection magnitude can then be determined assuming that a ratio of 10 corresponds to a variation of one-unit magnitude (e.g., Cabrera et al, 2020).…”