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WITHDRAWN Seismic Patterns of the Luzon Arc South of Taiwan

Description: 

WITHDRAWN Arc–continent collision is an important tectonic process along convergent margins, yet how crustal deformation and seismogenic structures evolve from intra-oceanic subduction through an incipient transition to mature collision remains incompletely resolved. We use the Luzon Arc south of Taiwan as a natural along-strike that spans (from south to north) an active subduction domain, a transition zone, and the northern arc–continent collision zone. We analyze continuous waveforms from seven onshore stations and nineteen ocean-bottom seismometers (OBS) deployed for three years (2007–2009), totaling 36,180 waveforms. We apply machine-learning phase detection followed by stacking–migration event localization, using the regional 1D velocity model of Huang et al. (2014). It yields 4,855 well-located events—more than the 381 events reported for the offshore and period in the standard local catalog—substantially improving offshore-to-onshore seismicity continuity. Then, we integrate the very preliminary relocated seismicity with bathymetry, Bouguer gravity, and magnetic anomaly maps to relate earthquake distributions to along-arc structural segmentation. In the southern subduction domain, seismicity tracks a N–S-trending arc expressed by NE–SW en échelon bathymetric lineaments. North of 20.71°N, this pattern terminates within the transition zone, where the arc narrows and shifts to an overall NW–SE trend; seismicity there is comparatively sparse during the deployment, consistent with spatially localized and possible rapidly varying slab-related processes. In the collision domain, where the arc impinges on the Eurasian continental shelf, we identify a NW–SE-trending crustal-scale structure extending at least ~100 km from the transition into the collision zone, coincident with gravity and magnetic anomalies, and with seismicity suggestive of conjugate faulting. Our preliminary results demonstrate that integrating OBS observations with modern detection and location methods can help to resolve along-strike changes in seismogenic architecture of the arc across the subduction-to-collision transition south of Taiwan.

Session: Linking Subduction Zone Processes and Cascading Hazards in Alaska, Cascadia, Chile and Beyond [Poster]

Type: Poster

Date: 4/16/2026

Presentation Time: 08:00 AM (local time)

Presenting Author: Samsul H. Wiyono

Student Presenter: Yes

Invited Presentation: 

Poster Number: 138

Authors