← Back to Sessions

Characteristics of Intermediate and Deep-focus Earthquakes Along the Tonga Subduction Zone Revealed by Cross-correlation Earthquake Relocation

Description: 

The mechanisms underlying the genesis of intermediate and deep-focus earthquakes remain a topic of debate, with dehydration embrittlement, thermal runaway, and phase transformational faulting proposed as leading hypotheses. The Tonga Wadati-Benioff Zone, which is characterized by (1) seismicity gaps, (2) a transition between single and double seismic zones, and (3) dense deep earthquake clusters, provides a unique setting for examining these hypotheses. We explore the variations in seismicity along the Tonga subduction zone using high-precision earthquake relocations, incorporating waveform cross-correlation differential times. We take advantage of a regional machine learning catalog including ocean bottom seismometers in the study region from 2009 to 2010 and a temporary land-based network from 1993 to 1995. We relocated over 10,000 earthquakes that reveal linear trends missing from the original catalog. We provide a more detailed examination of the high intermediate-depth seismicity belt, which, as identified by Wei et al. (2017), becomes shallower with increasing slab temperature. Double seismic zones, where present, converge at varying depth (250 – 350 km) whereas seismicity branches into multiple segments at depths greater than 400 km. The spatial correlation of these intricate seismicity patterns along the Tonga seismic zone with seismic velocity structure, temperature, slab age, b-value, convergence rate, and local stress regimes can advance our understanding of the processes governing intermediate and deep-focus earthquakes.

Session: Unusual Earthquakes and Their Implications - I

Type: Oral

Date: 4/16/2025

Presentation Time: 02:15 PM (local time)

Presenting Author: Farzaneh

Student Presenter: No

Invited Presentation: 

Poster Number:

Authors