Geological Society of America

T33 The Multidisciplinary Approach of the Seismotectonics as a Key Tool to Expand Horizons on Faulting Process Understanding and to Address Effective Seismic Hazard Assessment II

Monday, 26 October 2020
5:30 PM - 8:00 PM
Meeting Rooms

LINKING FIELD DATA, STRESS MODELLING AND COSMOGENIC ANALYSES TO UNDERSTAND FAULT INTERACTION AND HISTORICAL EARTHQUAKES IN THE ITALIAN APENNINES

Paper number: T33-2
Program: Technical Sessions
Time: 5:35 PM – 5:50 PM

Authors

Zoe Mildon Presenting Author
University of Plymouth, Plymouth
Gerald P. Roberts
UCL/Birkbeck, University of London, London
Joanna Faure-Walker
University College London, London, N/A
Shinji Toda
Tohoku University, Sendai
Francesco Iezzi
UCL/Birkbeck, University of London, London
Claudia Sgambato
University College London, London, N/A
Joakim Beck
King Abdullah University of Science and Technology, Thuwal
Ioannis Papanikolaou
Agricultural University of Athens, Athens
Alessandro Michetti
Università degli Studi dell’Insubria, Como

Abstract

Combining observations from different data sets is an important approach to understand fundamental earthquake processes and the associated seismic hazard. In the central and southern Apennines, the normal faults are well-exposed at the surface as carbonate bedrock scarps that have been formed since the demise of the Last Glacial Maximum (15 ± 3 kyrs). Because of the excellent exposure, we have a wealth of data, including the geometry of faults, the throw since the LGM, a detailed record of historical earthquakes, and the slip history over the last 15 ± 3 kyrs from cosmogenic dating. These data sets allow us to explore fault interaction, the historical earthquake sequence and effect of fault geometry on earthquakes.

Using these data sets gives us a range of novel insights into how these faults interact together and what the past occurrence of earthquakes can tell us about future earthquakes (or not!). Studying the cumulative stress changes associated with historical earthquakes can tell us that the way faults interact and behave is dependent on the geometry of the fault array and that considering the cumulative stress is more insightful that considering single coseismic stress changes. Indeed, the pattern of cumulative stress may have controlled the magnitude and order of the 2016 earthquake sequence (3 M>5.9 earthquakes from August – October 2016). Looking over longer time periods, we hypothesise that earthquake clustering may also be controlled by changes in stress induced by slip on neighbouring faults. The geometry of the faults is highly variable, with changes in strike, dip and slip vector recorded along fault systems. These variations can tell us about rupture segmentation and may explain the scatter in Dmax/fault length scaling relationships. Ultimately, the question becomes what do our findings mean for seismic hazard assessment and how might they be utilised?

Geological Society of America Abstracts with Programs. Vol. 52, No. 6

doi: 10.1130/abs/2020AM-356119

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