[S-GD01] Geodetic Advances in Crustal Dynamics and Environmental Change for Taiwan and Neighboring Regions

[SGD01-P05] Assessment of Geological Disaster Characteristics in the Ciaotou Science Park, Taiwan Using InSAR and Geodetic Data

*Kuo-En Ching¹, Ming Yang¹, Chih-Heng Lu¹, Wu-Lung Chang², Shih-Han Hsiao¹, Chien-Liang Chen³ (1.National Cheng Kung University, 2.National Central University, 3.Geological Survey and Mining Management Agency, MOEA)

Keywords:Mobile shale, Creeping fault, Earthquake potential

The case of the Chungliao Tunnel section of National Freeway No. 3 suggests that identifying geological disaster types, intensities, and affected areas before major projects helps in selecting the most suitable construction methods during planning. The Ciaotou Science Park is currently in its early planning stage. According to the geological investigation, the Chegualin fault, which caused damage to the Chungliao Tunnel, may extend westward through the park. However, the current understanding of the fault activity, seismic potential, and impact is not clear. Additionally, the Gunshuiping mud volcano, possibly related to mobile shale, exists within the park, but the exact location and deformation impact of this mobile shale remain uncertain. This study collected Sentinel-1 satellite images from the 2016 Meilun Earthquake, GNSS station data, and leveling data to analyze crustal deformation in the Ciaotou Science Park. Using InSAR, 79 ascending and 59 descending Sentinel-1 images from 2016 to 2018 were analyzed with multi-temporal InSAR to derive the velocity field. GNSS and leveling data from Company T and CGS from 2016 to 2021 were also used for coordinate time-series analysis to obtain horizontal and vertical velocity fields. The velocity field inversion method integrated all data, providing a high-precision, high-resolution three-dimensional velocity field. The study found that the region moves southwestward at a rate of 43-58 mm/yr, with a boundary defined by the Chegualin fault. The southern side of the fault exhibits higher velocity components by about 10 mm/yr compared to the northern side. The vertical velocity is between -5 to 5 mm/yr, showing an uplift in the east and subsidence in the west, with a slight uplift to the south. The Chegualin fault is identified as a high-angle right-lateral fault with a slip rate of 8-10 mm/yr and exhibits creeping fault characteristics. It may extend southwestward, connecting with the Youchang fault. The uplift on the southern side of the fault is presumed to be related to mud intrusion activity. Fluid and methane in the mobile shale reduce the seismic potential of the fault, while fractures from the fault provide pathways for the development of the Gunshuiping mud volcano. Given the rapid erosion and high resilience of materials in southwestern Taiwan, evidence of fault activity is not preserved. High-density InSAR and geodetic data analysis are essential to clarify the geological hazards in the Ciaotou Science Park.