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

SASHA code

Step 1

Step 2

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!)

Earthquake catalogue

I0 derived from Mw

(time period:1706-2008)

Attenuation model

by courtesy of Varini et al., 2013

by courtesy of Varini et al., 2013

Attenuation model

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)

Hazard curves

ART=475 (p.e. 10% in 50yr)Hazard curves

Iref

Hazard deaggregation

ART=475 (p.e. 10% in 50yr)

Distance (km)

Magnitude

Iref=8

Distance (km)

Magnitude

Hazard deaggregation

ART=475 (p.e. 10% in 50yr)

Iref=8

ART=475 (p.e. 10% in 50yr)

Hazard deaggregation

Distance (km)

Magnitude

Iref=8

Distance (km)

Magnitude

ART=475 (p.e. 10% in 50yr)

Hazard deaggregation

Iref=7

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,…)