Linear Relationship Between Aftershock Productivity and Seismic Coupling in the Northern Chile Subduction Zone

0517239 - GFÚ 2020 RIV US eng J - Journal Article
Hainzl, S. - Sippl, Christian - Schurr, B.
Linear Relationship Between Aftershock Productivity and Seismic Coupling in the Northern Chile Subduction Zone.
Journal of Geophysical Research-Solid Earth. Roč. 124, č. 8 (2019), s. 8726-8738. ISSN 2169-9313. E-ISSN 2169-9356
Institutional support: RVO:67985530
Keywords : seismic coupling * aftershocks * earthquake triggering
OECD category: Volcanology
Impact factor: 3.639, year: 2019
Method of publishing: Open access
https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2019JB017764

The aftershock productivity is known to strongly vary for different mainshocks of the same magnitude, which cannot be simply explained by random fluctuations. In addition to variable source mechanisms, different rheological properties might be responsible for the observed variations. Here we show, for the subduction zone of northern Chile, that the aftershock productivity is linearly related to the degree of mechanical coupling along the subduction interface. Using the earthquake catalog of Sippl et al. (2018, ), which consists of more than 100,000 events between 2007 and 2014, and three different coupling maps inferred from interseismic geodetic deformation data, we show that the observed aftershock numbers are significantly lower than expected from the Bath's law. Furthermore, the productivity decays systematically with depth in the uppermost 80 km, while the b value increases. We show that this lack of aftershocks and the observed depth dependence can be simply explained by a linear relationship between the productivity and the coupling coefficient, leading to Bath law only in the case of full coupling. Our results indicate that coupling maps might be useful to forecast aftershock productivity and vice versa.
Permanent Link: http://hdl.handle.net/11104/0302539