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Intermediate-depth Earthquakes Driven by Migrating Strain Localization in the Bucaramanga Earthquake Nest

Description: 

Intermediate-depth earthquakes occur in subduction slabs where extremely high pressures and temperatures make frictional slip unlikely. Understanding the mechanism potentially reveals a mechanical state of the fault zone and the origin of magma in subduction zones. Using a systematic methodology established for shallow earthquakes, we explore for the first time the fine-scale spatiotemporal evolution of intermediate-depth earthquakes within the Bucaramanga earthquake nest to obtain new insight into the physical mechanism from their recurrence intervals and locations. We first construct a high-resolution earthquake catalog through matched-filter detection using the largest 100 earthquakes as template waveforms and continuous waveform data in six years (2016-2021) from 13 stations operated by the Servicio Geológico Colombiano (SGC). Our catalog detects 71,621 events classified into smaller clusters based on the cross-correlation coefficients between the template and continuous waveform. Subsequently, we apply the second round of matched-filter detection for one cluster that records the largest number of detections in the first round. We observe a multi-year evolution of different earthquakes characterized by the number of events in one template family. Relocation of these hypocenters highlights a spatial migration over several kilometers toward the plate interface over several years, highlighting a continuously evolving forcing that drives earthquake activity within the Bucaramanga nest.

Session: Advanced Geophysical Observations, Analytical Methods, and New Insights for Earthquake Swarms - I

Type: Oral

Date: 4/15/2025

Presentation Time: 02:15 PM (local time)

Presenting Author: Ayako

Student Presenter: Yes

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