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Seismic Signal Analysis and Temporal Sequencing of Mud Ejections in Dayoukeng, Northern Taiwan

Ya-Chuan Lai 1,2, Min-Hung Shih1,2, Cheng-Horng Lin2,3, and Hsiao-Fen Lee1,2

  • Affiliations: 1National Center for Research on Earthquake Engineering, NARLabs, Taiwan; 2Taiwan Volcano Observatory at Tatun; 3Institute of Earth Sciences, Academia Sinica, Taiwan

  • Presentation type: Poster

  • Presentation time: Thursday 16:30 - 18:30, Room Poster Hall

  • Poster Board Number: 136

  • Programme No: 2.1.46

  • Theme 2 > Session 1

Abstract

Dayoukeng is the most active gas emission and seismically active area within the Tatun Volcano Group, warranting intensive monitoring. Nodal seismometers Zland were deployed to compare seismic signals during anomalous activities. Between late 2021 and early 2022, significant mud-ejected material was observed near the main vent. Geochemical analyses indicated an abnormal increase in cation concentrations in the hot spring at the end of 2021. Real-time webcam data revealed additional steam activity above the main vent, suggesting intensified gas emissions that may have led to a small-scale event. Short-period seismic data from the nearby main vent revealed several stages of signal characteristics, potentially linked to changes in steam activity: 1. Initial Increase: An uptick in microearthquakes at Dayoukeng. 2. Marked Intensification: A substantial rise in signals with complex waveforms comprising seismic and high-frequency acoustic waves lasting several hours. 3. Major Mud-Ejection Phase: Low-frequency microtremors associated with significant mud ejection. 4. Recurrent Composite Signals: Multiple episodes of composite seismic and acoustic wave signals, each persisting for hours. 5. Activity Decline: A sharp decrease in signals, indicating a slowdown in activity. Following the event, recent observations have detected similar mud ejections in Dayoukeng, suggesting state changes that indicate increased regional activity and facilitate the emission of mud. The seismic data from the dense short-period network clearly delineate the temporal sequence of this event, enhancing the understanding and modeling of overall activity in Dayoukeng.