Potential geological risks from mud diatremes in the orogen regime of Southwestern Taiwan

In orogenic regions, faults from plate collisions are the main cause of earthquakes. Recent studies have found that underground mudstone structures and intrusions can accompany fault development, causing surface deformation and geological hazards. In southwestern Taiwan, geodetic evidence has detected underground mudstone structures, but their mechanisms of influence remain unclear. This study conducted cores drilling at a hotspot showing positive gravity anomaly. Multi-disciplinary analyses confirmed that sediments came from mudstone at least 3 km in depth. The observed compression validated surface-reaching mudstone intrusions. Electrical resistivity tomography revealed scattered mud intrusions cause localized uplift, potentially damaging structures. This suggests the large mud intrusion/mud diapir extends to shallow depth below the surface, with fractures acting as conduits to the ground (mud diatreme). Mud structures have been found in both collisional and extensional regions, suggesting they influence fault development and surface deformation widely, raising safety concerns in urban due to these geological risks.