Subsurface fault geometries in inland Hokkaido from geometric clustering of dense hypocenter distributions
Abstract
Abstract The oblique subduction of the Pacific plate beneath Hokkaido, northernmost Japan, drives the collision between the Kuril forearc and the NE Japan arc. This collision has generated some deep and damaging inland crustal earthquakes. However, most of the seismic activity occurs at blind faults with unknown geometries. To understand the orientations and extent of these faults and their implications on the seismotectonics of inland Hokkaido, we analyzed dense crustal seismicity in inland Hokkaido to determine hidden planar fault geometries. First, we applied a deep-learning model to pick seismic P and S phases. The detected phases were associated using PyOcto and located using NonLinLoc tools. The hypocenter locations within the inland crust were relocated using tomoDD and a three-dimensional seismic velocity model. Finally, we reconstructed intricate fault geometries based on hierarchical clustering of the dense hypocenter distributions and their normal vectors. A total of 184 rectangular fault segments were successfully reconstructed in the whole inland Hokkaido region, with dominant depths in the upper crust between 6 km and 12 km. Deep faults below 20 km were found exclusively within the Hidaka collision zone in southern Hokkaido. Our results reveal that the inland Hokkaido region is dominated by high-angle faults with dip angles larger than 60°. In central Hokkaido from north to south, the faults form north-south lineaments consistent with gravity anomalies and…
Read the paper
Related studies
- Current state and future directions for deep learning based automatic seismic fault interpretation: A systematic review
- Physics of Partially Saturated Porous Media: Residual Saturation and Seismic-Wave Propagation
- Modern Imaging Using Seismic Reflection Data
- Effects of marine seismic surveys on free-ranging fauna: a systematic literature review
- A review of the recent seismic activity in the southern part of egypt (upper egypt)
- A review of research on mechanism of seismic attenuation and energy compensation
Go deeper in Evidence Hub
Evidence Hub adds a study data sheet (design, sample size, evidence level, key numbers), an AI summary and a chat grounded in the paper's text.