[S-CG64_30PM1] Slow earthquakes

[SCG64-14] Improvement of tectonic tremor detecting and locating methods: Case study in Shikoku and Kanto

*Kevin CHAO¹, Kazushige OBARA¹ (1.ERI, the University of Tokyo)

Keywords:ambient tremor, Shikoku, Kanto, tremor auto-detection technique

Obtaining accurate tremor sources in time and space is important because it provides essential information that reveals the mechanism of tremor activity. Recent findings of triggered tectonic tremor in recently discovered regions in Hokkaido (Obara, GRL, 2012), Kyushu, and Kanto (Chao and Obara, AGU Meeting, 2012) provide an ideal dataset with which we can test the clock-advanced model, which predicts the occurrence of triggered tremor in regions where ambient tremor occurs. In this study, we improve upon two existing tremor detecting and locating methods: 1) the WECC (Waveform Envelope Correlation and Clustering) auto-detecting algorithm (Wech and Creager, GRL, 2008), which auto-detects tremor episodes, and 2) the improved conventional envelope cross-correlation technique (Obara, Science, 2002; Chao et al., BSSA, 2013), which accurately pinpoints the locations of short duration tremor sources in space. Using WECC, we detected tremor episodes in western Shikoku and compared the results with existing NIED tremor catalogs (Maeda and Obara, JGR 2009; Obara et al., GRL, 2010). Our preliminary results indicate that during testing period (i.e., tremor episodes between 2012/05/25 and 2012/06/02), the WECC was able to successfully auto-detect the same ambient tremor episodes listed in the NIED tremor catalogs. The tremor detections by WECC show similar tremor migrations pattern as the features from the NIED tremor catalog. In addition, the WECC is able to capture more small tremor episodes that are not included in the NIED catalog. Our next step will be to apply the WECC to the entire dataset to determine whether it can successfully detect all tremor episodes while minimizing noise. Using the modified envelope cross-correlation technique, we plan to conduct a 3D grid search to locate accurate triggered tremor sources in Kanto following several teleseismic earthquakes. This modified technique has been used to locate micro-earthquakes (M