Spatiotemporal Characteristics of Tectonic Tremors in the Collisional Orogen of Taiwan

Taiwan offers a distinctive tectonic setting as a collisional orogen, ideal for studying tectonic tremors and the slow deformation process in the mountain-building process. Using continuous seismic data at many stations, which have become available recently, and employing the envelope correlation method, we detected similar to 7,000 tremor events from 2012 to 2022, with waveform characteristics similar to tectonic tremors worldwide. Beyond the previously known tremor zone beneath the southern Central Range, where newly detected tremors align along a low-angle thrust plane, we identified several new tremor "hotspots" spanning 200 km along the mountain belt. These hotspots are situated at the termination of the subducting slabs and around the deep (25-50 km) extension of the Central Range fault, where repeating earthquakes occur at a depth of 10-25 km. Our findings suggest a strong linkage between the tremor generation mechanism and the mountain-building process, potentially influenced by underground fluid and temperature anomalies. Since around 2000, tectonic tremors have been discovered worldwide as geophysical phenomena strongly related to slow deformation and fluid movement inside the Earth. While a small cluster of tremors has been identified in Taiwan, where a rapid mountain-building process occurs, the comprehensive distribution of tremors has remained unknown. Utilizing recently released seismic network records for all of Taiwan, we have clarified a broader pattern of tremor activity, previously unknown, in the region. The tremors are distributed planarly, corresponding to the mountain-building processes and deep underground deformation in Taiwan. Using newly available continuous seismograms, we identified similar to 7,000 tectonic tremors in Taiwan Several tremor hotspots spanning 200 km were newly identified along the mountain belt Tremor distribution suggests planer structures that are contributing to the rapid mountain-building process