הרצאת מועמד למשרת חוקר במכון הגיאולוגי Foreshocks, aftershocks and what’s ever is in between them: The interaction between mainshock rupture, seismicity and the crustal stress

Large earthquakes result from cycles of strain accumulation and release. The mechanism diversity and spatial distribution of moderate size earthquakes at the periphery of the mainshock is influenced by the interaction of the mainshock rupture perturbation superimposed on the crustal stress state. Understanding the seismicity patterns of foreshocks and aftershocks can give us useful information about the source properties of the mainshock and the amount of the volumetric elastic strain drop around the plate boundary. This study demonstrates three examples of interactions between mainshocks and periphery seismicity on subduction zone plate boundary megathrusts:

1. Variations in aftershocks productivity are attributed to two distinctive trends: a regional trend with island arcs in the western Pacific being more productive than continental arcs in the eastern Pacific, and a trend of lower productivity for higher stress drop mainshocks when examined as a function of MW.

2. Systematic examination of smaller earthquakes before and after the large earthquakes shows that regions that slip significantly in the mainshock have few overlapping aftershocks, indicating that the shear stress in those regions has significantly lowered below the failure stress.

3. Mainshocks that rupture across the shallow megathrust to near the trench have greater intraplate aftershock faulting diversity than events with rupture confined to deeper portions of the megathrust.


תאריך 28/06/2017 09:00 10:15
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