Integrating geologic fault data into tsunami hazard studies

Abstract

We present the realization of a fault-source data set designed to become the starting point in regional-scale tsunami hazard studies. Our approach focuses on the parametric fault characterization in terms of geometry, kinematics, and assessment of activity rates, and includes a systematic classification in six justification levels of epistemic uncertainty related with the existence and behaviour of fault sources. We set up a case study in the central Mediterranean Sea, an area at the intersection of the European, African, and Aegean plates, characterized by a complex and debated tectonic structure and where several tsunamis occurred in the past. Using tsunami scenarios of maximum wave height due to crustal earthquakes (<i>M</i>_w=7) and subduction earthquakes (<i>M</i>_w=7 and <i>M</i>_w=8), we illustrate first-order consequences of critical choices in addressing the seismogenic and tsunamigenic potentials of fault sources. Although tsunamis generated by <i>M</i>_w=8 earthquakes predictably affect the entire basin, the impact of tsunamis generated by <i>M</i>_w=7 earthquakes on either crustal or subduction fault sources can still be strong at many locales. Such scenarios show how the relative location/orientation of faults with respect to target coastlines coupled with bathymetric features suggest avoiding the preselection of fault sources without addressing their possible impact onto hazard analysis results

The 2013 European Seismic Hazard Model: key components and results

“…The European Database of Seismogenic Faults (EDSF; Basili et al 2013; Fig. 3), was specifically designed to fulfill the project requirements in terms of exploiting the wealth of Fig.…”

“…The relative weights of these two spatial density functions depend on the earthquake magnitude and are determined by pseudo-prospective forecasting experiments. The model, initially developed for California (Hiemer et al 2013), is applied at the European scale: we generated a crustal model using earthquakes shallower than 40 km depth and active faults of the European Database of Seismogenic Faults (EDSF; Basili et al 2013). We separately modelled seismicity in subduction zones in combination with the models of the Calabrian, Hellenic and Cyprus arcs with their complex 3D geometry.…”

“…In the FSBG-model, activity rates of the mapped fault sources are determined from the available deformation data as inferred from geodetic and geological methods (Basili et al 2008(Basili et al , 2009Haller and Basili 2011;Basili et al 2013). The activity rates in this model are primarily dependent on the slip rate and the maximum magnitude of the fault sources.…”

Probabilistic Tsunami Hazard Analysis: Multiple Sources and Global Applications

“…Zonation is being done by an expert who considers different available tectonic and seismic data sets and, hence, depends on data availability and expert's opinion. Characterization of offshore faults. Compared to onshore faults, offshore faults are generally less well‐known, and different models for the fault maps may exist, or the degree of knowledge of offshore structures may be highly variable (e.g., Basili et al, ). Scaling relations. They are equations that relate different measures associated to earthquake and fault size to each other.…”

Appraising the Early-est earthquake monitoring system for tsunami alerting at the Italian Candidate Tsunami Service Provider

“…For this reason, the Centro Allerta Tsunami (CAT) (Italian for "tsunami alert center"), was established at the INGV headquarter in Rome at the end of 2013. The CAT mission is to implement and maintain a 24/7 service alongside the ordinary seismic surveillance of the national territory, and to work towards a probabilistic seismic hazard assessment (PSHA) for the Italian coasts, that is a tsunami hazard map for seismically induced tsunamis (Basili et al, 2013). CAT-INGV started operations on a 24/7 basis as a CTSP in October 2014.…”