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Seismicity Triggering by Stress Transfer of Recent Strong (m>6.0) Earthquakes in Greece

Description: 

We explore a series of recent earthquake sequences in Greece where the seismicity was substantially elevated not only on the fault associated with the main shock but also on the adjacent fault segments. There is accumulated evidence that static Coulomb stress transfer can promote or inhibit subsequent seismicity, the means that the background rate is amplified if the stress change is positive or suppressed if it is negative. When a strong (M>6.0) earthquake occurs to examine the stress imparted to the adjacent fault segments we consider in addition to the background seismicity rate, background and aftershock focal mechanisms, and the main shock finite fault models. Even the most known and extensively investigated faults that might be considered isolated, exhibit geometrical and kinematic complexities, when they are detailed by double–difference relocated seismicity and focal mechanisms. Those complexities are associated with the inherited fault network, fault bends, and breaks, and their obliquity to the dominant stress component or properties of the local seismogenic layer. We used catalogs of precisely relocated aftershocks and examined in several cases whether the static changes caused by the coseismic slip of the main shock promoted failure considering one of the nodal planes of the closest mechanism to each aftershock. We have found that static stress changes are the driving mechanism that triggered the vast majority of the off–fault aftershocks, by unveiling that these stress changes attained positive values at their locations and were efficient to trigger both major and minor adjacent fault segments. Analysis has not evidenced the existence of stress shadows inside areas of negative stress change.

Session: Tectonics and Seismicity of Stable Continental Interiors

Type: Oral

Date: 4/19/2023

Presentation Time: 10:30 AM (local time)

Presenting Author: Eleftheria Papadimitriou

Student Presenter: No

Invited Presentation: 

Authors