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Near‐continuous tremor and low‐frequency earthquake activities in the Alaska‐Aleutian subduction zone revealed by a mini seismic array
Author(s) -
Li Bo,
Ghosh Abhijit
Publication year - 2017
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2016gl072088
Subject(s) - subduction , geology , episodic tremor and slip , seismology , slipping , seismic array , tectonics , fault (geology) , plate tectonics , mechanical engineering , engineering
Tectonic tremor and low‐frequency earthquakes (LFEs) are relatively poorly studied in the Alaska‐Aleutian subduction zone due to the limited data availability, difficult logistics, and rugged terrain. Using 2 months of continuous data recorded by a mini seismic array in the Akutan Island, we detect near‐continuous tremor activity with an average of 1.3 h of tectonic tremor per day using a beam backprojection method. Tremor sources are clustered in two patches with an ~25 km gap in between them. In addition, we visually identify three low‐frequency earthquakes, and using them as templates, we detect ~1300 additional LFEs applying a matched‐filter method. Tremor and LFE activities agree well in space and time, and LFEs show a much smaller recurrence interval during tremor than during non‐tremor time periods. Tremor sources propagate both along the strike and dip directions of the subduction fault with velocities ranging between 13 and 110 km/h. Prolific patchy tremor and LFE activities suggest lateral heterogeneity in the locked to freely slipping transition zone, indicating that slow earthquakes may play an important role in the earthquake cycles in this subduction zone.