Clustering features of seismicity in Italy during 2005 to 2016

Jiancang Zhuang, Yicun Guo, Maura Murru, Giuseppe Falcone, & Elisa Tinti

Submitted August 14, 2017, SCEC Contribution #7667, 2017 SCEC Annual Meeting Poster #009

Compiled by Istituto Nazional Geofisca e Vulcanologia, Italy, the ISIDE catalog includes high quality records of the occurrence times, locations, magnitude and other information of earthquakes that occurred in the Italy region since 2005-4-16. To study the characteristics of seismicity in Italy, we make use of the original form and two extended versions of the space-time ETAS model, the hypocentral 3D ETAS model and the finite-source ETAS model. Our results show:
(a) The rupture geometries of large earthquakes, including the 2009-4-6 M6.3 L'Aquila, the 2012-5-20 M6.1 Emilia, the 2016-0-24 M6.0 Amatrice, the 2016-10-30 M6.2 Norcia earthquakes, control the spatial locations of their direct aftershocks. These direct aftershock aftershock mainly concentrate near, some parts close to the parts on the rupture plane with large slips but seldom overlap with them, indicating that aftershocks are the continuation of the rupture process of the mainshocks.
(b) When the focal depth is considered in seismicity modeling, improved probability forecasting of seismicity and hazard assessment can be obtained.
(c) The background seismicity rate is not stationary in all the areas, but shows several phases tuned by the major events.
(d) Adopting isotropic spatial response causes underestimate of the triggering effect of the mainshock, and such biases can be corrected by incorporating the rupture geometry of major events into the model formulation.
(e) Comparing to the original point-source model, there are more direct aftershock from the mainshock estimated with the new model the earthquake data;
(f) Comparison between the reconstruct of offspring productivity function of each patch on the earthquake fault plan and the fault slip distribution shows that direct offspring of an earthquake mainly distribute around the place where large slips have occurred.

Key Words
ETAS, rupture geometry, aftershock productivity, Norcha earthquake

Zhuang, J., Guo, Y., Murru, M., Falcone, G., & Tinti, E. (2017, 08). Clustering features of seismicity in Italy during 2005 to 2016. Poster Presentation at 2017 SCEC Annual Meeting.

Related Projects & Working Groups
Collaboratory for the Study of Earthquake Predictability (CSEP)