Analyzing Seismic Signals of the 2021 Dayoukeng Mud Ejection in Northern Taiwan

The research findings indicate that the Dayoukeng area is the most active region in the Tatun Volcano Group, Taiwan. In early 2022, mud ejecta was discovered near the main fumarole, indicating heightened activity. Comparative geochemical analysis revealed an abnormal increase in the cation concentration of hot spring at the end of 2021. Real-time webcam further identified additional steam activity above the main vent between Dec 12, 2021 and Jan 2, 2022. It is speculated that during this period, Dayoukeng may have experienced intensified steaming. A nearby network with dense seismic Zland nodes offers a unique opportunity to detect the signals during this anomalous activity in Dayoukeng. By scrutinizing and comparing the characteristics of these signals, we try to decipher the temporal variations of the sequence.

The data from nearby stations indicate a gradual increase in Dayoukeng’s activity starting from Dec 8, 2021. Initially, there is a gradual increase in signals, predominantly microearthquake within Dayoukeng. Subsequently, a notable increase in signals, characterized by a combination of seismic and acoustic signals, is observed. On Dec 12, microtremors possibly associated with mud ejections are detected. Following this, there is a repetitive occurrence of the previous seismo-acoustic observations, each enduring for several hours, persisting until a few days later. Such seismic data of dense short-period seismic network provides a chronological sequence of the Dayoukeng event, thereby facilitating the subsequent model for the entire event.