Shallow tremor list observed by Distributed acoustic sensing (DAS) and DAS data off Cape Muroto, southwest Japan

Distributed Acoustic Sensing (DAS) data (hdf5 data) with the Muroto Cable, southwest Japan, when shallow tremors are observed (period: January 30–February 8, 2022).

I added a list of shallow tremors observed by DAS and shallow very low frequency earthquakes (VLFEs) corresponding to these tremors in the newest version.

The DAS measurement is conducted by AP Sensing with a sensing length of 55 km along the Muroto Cable. Gauge length is 40.8 m. The waveforms were stacked in successive 10 channels to downsample to 51-m channel spacing and decimated to 100 Hz sampling.

The tremor analysis with this DAS data is presented in AGU Fall Meeting 2022 (https://agu.confex.com/agu/fm22/meetingapp.cgi/Paper/1101461) and written in a submitted paper.

The filename of hdf5 DAS data show the start time (year-month-day_hour.minute.second) in UT. The data length of each file is one minute. The values of matrices in hdf5 files are converted to differential phase by multiplying pi/32768. After integrating the differential phases, phases can be converted to strain based on equation (10) of SEAFOM (2018) (https://seafom.com/?mdocs-file=1270). The optical wavelength of DAS system is 1550 nm, the effective index of refraction in sensing fiber is 1.4682, the photo-elastic scaling factor is 0.78.

Data Set S1: Tremor list observed by DAS located from DAS and DONET data

Data Set S2: Tremor list located from only DONET data

Data Set S3: VLFE list which temporally correspond to tremors observed by DAS

channelinfo.txt: DAS channel position information that are used for locating tremors. The channel position was determined by using the air gun signals.

DONET broadband seismograms data can be downloaded from the website of National Research Institute for Earth Science and Disaster Resilience Hi-net (https://hinetwww11.bosai.go.jp/auth/download/cont/?LANG=en).