今週のうなぎセミナーについてお知らせいたします。

Here is information of the Unagi-seminar(December, 18th).

************** Seminar on Seismology IV B, D /地震学ゼミナールIV B, D (Unagi Seminar) **************

科目：地震学ゼミナールIV B, D / Seminar on Seismology IV B, D（修士・博士）
日時：2025年 12月 18日 (木) 13:30~
場所：京都大学 防災研究所 本館E-232D

Date and Time：2025-12-18(Thursday), 13:30~
Place：Uji Campus Main Building E232D

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Speaker 1（発表者）:　Jan Sher Khan
Title（題目）:
Greedy Automatic Signal Decomposition (GrAtSiD) for Ocean Bottom Pressure Data at the Hikurangi subduction zone New Zealand

Abstract（要旨）:
Slow Slip Events (SSEs) represent a critical class of transient tectonic phenomena that occur along subduction zones-such as the Hikurangi margin in New Zealand, without generating strong seismic shaking. Detecting these events using Ocean Bottom Pressure (OBP) data remains challenging due to the different oceanographic and instrumental noise.
In this study, we first applied the Baytap08 tidal analysis software to isolate and remove predictable tidal components from raw OBP time series. The resulting non-tidal residuals will be then analyzed using a modified version of the Greedy Automatic Signal Decomposition (GrAtSiD) algorithm, originally developed for GNSS data.
This method decomposes the residual pressure signal into a combination of secular, seasonal, and transient components using a greedy basis selection approach with L2-regularized inversion.

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Speaker 2（発表者）:　Tomomitsu Hamano（濱野　智光）
Title（題目）:
Reflected Waves Following S-waves Observed by DAS Seismic Observation in Oku-Noto

Abstract（要旨）:
Distributed Acoustic Sensing (DAS) measurements were conducted in 2023 and 2025 to observe earthquakes in Oku-Noto. Among those data, we found that direct S-waves from some events were followed by S-waves that may be reflected in the lower crust. In this study, we estimate the distribution of the reflection points by applying the method of Matsumoto and Hasegawa (1996).