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Application of SASHA for the Icelandic case
Vera D’Amico1, Dario Albarello2, Ragnar Sigbjörnsson3, Rajesh Rupakhety3
1 Istituto Nazionale di Geofisica e Vulcanologia, Milano, Italy2 Dip. Scienze Fisiche, della Terra e dell’Ambiente, University of Siena, Italy
3 Earthquake Engineering Research Centre, University of Iceland, Selfoss, Iceland
Input elements used for Iceland
Earthquake catalogue listing magnitude and epicentral intensity
The SHare European Earthquake Catalogue (SHEEC) released by the EU project SHARE
Attenuation model to estimate seismic effects at the site (expressed in terms of probabilities of exceedence of different intensity values) from epicentral information (epicentral intensity and epicentral distance)
The probabilistic attenuation model developed in Task B with the empirical parameters assessed for Iceland
Earthquake catalogue
Earthquakes extracted from
SHare European Earthquake Catalogue
(SHEEC)
released by the EU project SHARE
Earthquake catalogue
To apply the attenuation model of Task B, epicentral intensity I0 is required for each earthquake of the catalogue
A preliminary rough empirical relation was derived from the same events used to calibrate the attenuation model (these are the only events for which an estimate of I0 is available!)
Hazard computation
Hazard has been computed over a regular grid (1680 nodes) covering whole Icelandfor 4 exceedence probabilities for an exposure time of 50 years, equivalent to average return times (ART) of 50, 200, 475, 975 years
For 4 selected localities, further ARTs have been examined and hazard deaggregation performed
ART=50 (p.e. 63% in 50yr) ART=200 (p.e. 22% in 50yr)
ART=475 (p.e. 10% in 50yr) ART=975 (p.e. 5% in 50yr)
Comparison with previous PSHA
ART=475 (p.e. 10% in 50yr) RT=475 (p.e. 10% in 50yr) PGA
Just for qualitative comparison, because of different shaking measure (Intensity vs. PGA), different PSH methodology (SASHA vs. standard Cornell’s approach), different input data (catalogue, attenuation relation,…)