10:45 AM - 12:15 PM
[SCG45-P25] Broadband source time function estimations of seismic slow earthquakes at the shallow plate boundary in Nankai
Keywords:Slow earthquake, Nankai Trough, Source time function
However, estimated VLFE STFs cannot reproduce tremor envelopes due to a lack of high-frequency components. Then, we added random temporal fluctuations into an obtained smooth VLFE STF. This approach is similar to previous studies for regular earthquakes (e.g., Koyama, 1985; Hisada, 2000). We assumed that fluctuations of source time function can be characterized by a von Kármán autocorrelation function, which is controlled by characteristic time of t0, RMS value of e, and decay rate of k. A decay rate parameter (k) of a von-Kármán autocorrelation function (ACF) can model various decay rates at high-frequency ranges. We tested the case of a von-Kármán ACF with e2/t0 = 0.04 and k = 0.1. High-frequency seismic energies from STFs in this case were several tense times larger than those without temporal fluctuations.
After correcting site amplifications at DONET stations, based on the grid search inversion, we will estimate the optimal parameter set of e2/t0 and k, which can reproduce both VLFE seismograms and tremor envelopes.