Detecting low-frequency earthquakes within non-volcanic tremor in southern Taiwan triggered by the 2005 Mw8.6 Nias earthquake

We use a matched filter technique to detect 41 low-frequency earthquakes (LFEs) within 700-s of triggered tremor signals in the Southern Central Range in Taiwan during the surface waves of the 2005 Mw8.6 Nias earthquake off the coast of northern Sumatra. The depth distributions of LFEs after double-difference relocations concentrate at the depth range of 12-38 km below the background seismicity and above the Moho depth inferred from receiver function studies. The locations of LFEs are close to the downward extension of the steep-dipping Chaochou-Lishan fault with only modestly high Vp/Vs ratios (1.75-1.85). Our observation indicates that at least portions of triggered tremor consists of many LFEs, similar to ambient tremor observed at other major plate boundary faults. Citation: Tang, C.-C., Z. Peng, K. Chao, C.-H. Chen, and C.-H. Lin (2010), Detecting low-frequency earthquakes within non-volcanic tremor in southern Taiwan triggered by the 2005 Mw8.6 Nias earthquake, Geophys. Res. Lett., 37, L16307, doi:10.1029/2010GL043918.