[SCG48-P38] Possible tectonic tremor activities near the VLFE epicenters in the Sanriku-Oki region in 2011
Keywords:tectonic tremor, Sanriku–oki
We detected four sequences of continuous rises of amplitudes on the OBS records. Each of the sequence has a duration of ~ half a day. The sequences were composed of numerous wave trains with good correlations in their growths and decays in observed amplitudes among the stations, but no distinct P- or S-wave onsets were identified for individual wave trains. Interestingly, the spatial variation of the wave trains amplitudes is similar to those of the previously identified VLFEs. These observations suggest that the sequences were composed of small seismic events closely located each other and to the known VLFEs. It is also notable that some of the VLFE-like events discovered by the OBS data were contained in the sequences. We regard the discovered sequence as a kind of tectonic tremor activity and will inspect their characteristics, such as frequency content and its variability, to clarify their nature and discuss their relevance to slow slip events along the shallow subduction interface, which might promote the activities.