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Published on: August 17, 2016
Remote triggering of deep earthquakes in the 2002 Tonga sequences
Rigobert Tibi1, Douglas A Wiens, Hiroshi Inoue
1Department of Earth and Planetary Sciences, Washington University, St. Louis, Missouri 63130, USA. tibi@seismo.wustl.edu
Nature
|August 22, 2003
Summary
Deep earthquakes can be triggered by both static and dynamic stress changes, similar to shallow earthquakes. This study provides the first evidence of this phenomenon in deep earthquakes, expanding our understanding of earthquake triggering mechanisms.
Area of Science:
- Seismology
- Earthquake Science
- Geophysics
Background:
- Earthquake triggering is well-documented for shallow crustal earthquakes.
- Mechanisms include static stress changes (nearby) and dynamic stresses (nearby and remote).
- Triggering of deep earthquakes remains largely undocumented.
Purpose of the Study:
- To analyze the 19 August 2002 Tonga deep earthquake sequence.
- To provide evidence for static and dynamic triggering in deep earthquakes.
- To investigate earthquake nucleation in aseismic regions.
Main Methods:
- Detailed analysis of seismic data from the Tonga earthquake sequence.
- Modeling of static stress changes from the mainshock.
- Comparison of triggered event locations and origin times with seismic wave arrivals.
Main Results:
- A magnitude 7.7 earthquake was triggered 7 minutes after a 7.6 magnitude mainshock at a depth of 598 km.
- Nearby aftershocks were located in areas of enhanced static stress.
- The second mainshock and other triggered events occurred at remote distances, suggesting dynamic triggering.
- Triggered events occurred in previously aseismic regions, not correlating with seismic wave arrival times.
Conclusions:
- Deep earthquakes can be triggered by both static and dynamic stress changes.
- Dynamic triggering may play a significant role in deep earthquake sequences.
- Triggered deep earthquakes may occur in regions near criticality, requiring external influences for nucleation.
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