[ghsc-seminars] Friday @ 11 am, GHSC Brown Bag: Francesco Visini, Istituto Nazionale di Geofisica e Vulcanologia, =?UTF-8?B?TOKAmUFxdWlsYQ==?=, Italy

[Oliver Boyd]

LONG-TERM RATE OF EARTHQUAKE RUPTURES IN COMPLEX FAULT SYSTEMS

 

Francesco VISINI1, 

In collaboration with: 

Alessandro VALENTINI2, 

Thomas CHARTIER3,4, 

Oona SCOTTI4, 

Bruno PACE2

 

1Istituto Nazionale di Geofisica e Vulcanologia, L’Aquila, Italy

2Università degli Studi di Chieti-Pescara Disputer Department, Chieti, Italy

3Ecole Normale Supérieure de Paris, Geosciences Department, Paris, France

4Institut de Radioprotection et Sûretét Nucléaire, Paris, France

 

Use of faults in seismic hazard models allows capturing the recurrence of large-magnitude events and therefore improve the reliability of probabilistic seismic hazard assessment (PSHA). In the past decades, fault segmentation provided an important framework for quantifying fault-based PSHA. However, in the last years, complex coseismic ruptures (e.g. 2010 M 7.1 Canterbury, 2012 Mw 8.6 Sumatra, 2016 Mw 7.8 Kaikōura, 2016 Mw 6.5 central Italy) imposed to pay particular attention to the treatment of all possible combinations of rupture scenarios for PSHA. Here we present two methodologies to model rate of ruptures along fault systems, one based on a floating rupture approach (FRESH) and another one based on assumed rupture scenarios (SUNFISH). They represent alternatives to SHERIFS, an approach recently proposed to go one step beyond the strictly-segmented one commonly used in Europe. Differences in the three approaches are related to the way slip rate, rupture geometries and MFD are modelled. To quantify differences between the three methodologies, we compared PSHA results based on geometries and slip rates of a fault system located in NE Italy, assuming a specified maximum magnitude and the same seismic moment rate target. Finally, we shown that the three methodologies are able to solve for the long-term rate of ruptures with resulting PSHA that reflect the fault system geometry and slip rates, without any assumption on segment boundaries. Using fault-based approaches in PSHA requires collecting as much local geological information as possible. Now that multi-fault rupture approaches are available, simplistic, uniform slip rate approaches along complex fault systems should be avoided to the benefit of local data collection, which should be strongly encouraged (fault slip rates should be locally evaluated, fault geometries should be studied).

 

Friday, June 19th, 2018, 11 am (Mountain Time)
USGS, 1711 Illinois Street, Golden, CO
5th Floor Conference Room (535)

*Note: Please arrive ~5 minutes early and bring photo ID for airport-style security measures now in place at the USGS building.

Thank you,
GHSC Seminar Committee 

Mirus, Ben - bbmirus at usgs.gov
Josh Rigler - erigler at usgs.gov
Oliver Boyd - olboyd at usgs.gov

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