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(June, 26th).

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

科目：地震学ゼミナールIV A, C / Seminar on Seismology IV A, C（修士・博士）
日時：2025年 6月 26日 (木) 13:30~
場所：京都大学 防災研究所 本館E-232D

Date and Time：2025-06-26(Thursday), 13:30~
Place：Uji Campus Main Building E232D

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Speaker（発表者）:　KHAN Jan Sher
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. Unlike traditional step-function-based detections, our adaptation incorporates exponential functions to better reflect the gradual and smooth nature of SSE signals in OBP data.