Application of SASHA for Mt. Etna case

Task D: Probabilistic Hazard Assessment

Salvatore D'Amico

Istituto Nazionale di Geofisica e VulcanologiaOsservatorio Etneo, Catania (Italy)

UPStrat-MAFA 3rd General Meeting 23-26 July 2013, Selfoss, Iceland

Task D: Probabilistic Hazard Assessment: Application of SASHA for Mt. Etna case

Regional and local seismicity at Mt. Etna

• Mt. Etna area is affected by strong regional earthquakes,

• but also by shallow local earthquakes due to volcano-tectonic faults.

UPStrat-MAFA 3rd General Meeting 23-26 July 2013, Selfoss, Iceland

Task D: Probabilistic Hazard Assessment: Application of SASHA for Mt. Etna case

Features of volcano-tectonic earthquakes Moderate magnitude

ML ≤ 5.0

High values of epicentral intensityI0 ≤ X EMS

Shallow depth sources H < 2 km b.s.l.

Coseismic surface faulting

Strong attenuation of the macroseismic intensity ∆I = 4 in 20 km(~70 km in tectonic areas)

Macroseismic Catalogue of Mt. Etna from 1832 to 2008

Azzaro et al. (2009) http://www.ct.ingv.it/ufs/macro/critical parameter

UPStrat-MAFA 3rd General Meeting 23-26 July 2013, Selfoss, Iceland

Task D: Probabilistic Hazard Assessment: Application of SASHA for Mt. Etna case

1

2

3

X X

XLo

cal

Reg

ion

al

50 yrs exposure time10% probability

The process to compute PSHA by SASHA

Local seismicity

Short exposure times10, 30 years

The “site approach” performs a Poissonian PSHA using the seismic history at a site, i.e. the dataset of macroseismic intensities available for a given locality

UPStrat-MAFA 3rd General Meeting 23-26 July 2013, Selfoss, Iceland

Task D: Probabilistic Hazard Assessment: Application of SASHA for Mt. Etna case

Database and Catalogue

• 4432 macroseismic observations– Statistical estimation on site

• 415 localities (Villages, towns, etc.)

• from 1566 to 2008• Imax IX-X EMS

• 140 earthquakes• from 1000 to 2008• Io EMS (VI - XI-X)• M (3.4 - 4.7)

UPStrat-MAFA 3rd General Meeting 23-26 July 2013, Selfoss, Iceland

Task D: Probabilistic Hazard Assessment: Application of SASHA for Mt. Etna case

Probabilistic Results of Task B

Estimation of probability distributions of

the intensity at a site, given the epicentral

intensity I0 and the site-epicenter

distance, through a binomial-beta model.

I0 = VIIII0 = IX

(Azzaro et al., 2012)

Intensity attenuation at Etna

Point sources

Isotropic model

Linear sources

Anisotropic model15 earthquakesIo > VII

IX 6.1488 0.6076VIII 3.9251 0.5175VII 10.4333 1.1037

IX 1.1844 0.2501VIII 2.1534 0.3654VII 3.0629 0.4248VI 0.9872 0.239

125 earthquakesIo > VI

UPStrat-MAFA 3rd General Meeting 23-26 July 2013, Selfoss, Iceland

Task D: Probabilistic Hazard Assessment: Application of SASHA for Mt. Etna case

1915 Linera Earthquake: Io IX-X – M 4.7

Isotropic Vs Anisotropic model

Isotropic model Anisotropic model

UPStrat-MAFA 3rd General Meeting 23-26 July 2013, Selfoss, Iceland

Task D: Probabilistic Hazard Assessment: Application of SASHA for Mt. Etna case

PSHA Map: attenuated dataIsotropic model Anisotropic model

Exp

osu

re t

ime:

30

yrE

xpo

sure

tim

e: 1

0 yr

Difference: Iso-Ani

10% prob.

UPStrat-MAFA 3rd General Meeting 23-26 July 2013, Selfoss, Iceland

Task D: Probabilistic Hazard Assessment: Application of SASHA for Mt. Etna case

PSHA Map: felt + attenuated dataIsotropic model Anisotropic model

Exp

osu

re t

ime:

30

yrE

xpo

sure

tim

e: 1

0 yr

10% prob.

Difference: Iso-Ani

UPStrat-MAFA 3rd General Meeting 23-26 July 2013, Selfoss, Iceland

Task D: Probabilistic Hazard Assessment: Application of SASHA for Mt. Etna case

0

Fiandaca

Moscarello

Pernicana

S. Tecla

Tremestieri

0.0 0.5 1.0 1.5 2.0 2.5

4.5

4

3.5

Hazard deaggregation: Zafferana (Iexp: VIII) 37.6920 15.1040 7 ZAFFERANA_ETNEA

3002 1832 11 24 37.6160 15.0260 3.70 7.00 11. 0.01

3004 1850 1 1 37.6170 14.9230 3.90 7.50 18. 0.01

3005 1855 1 26 37.7240 15.1470 3.90 7.50 5. 0.12

3015 1865 7 19 37.7020 15.1530 4.50 9.00 4. 0.54

3056 1875 1 7 37.6260 15.1360 3.70 7.00 8. 0.02

3100 1881 2 12 37.7100 15.1680 3.70 7.00 6. 0.04

3146 1883 3 22 37.6530 15.0650 4.10 8.00 6. 0.50

3151 1883 3 22 37.6020 15.0030 3.70 7.00 13. 0.01

3171 1883 3 26 37.6120 15.0280 3.50 6.50 11. 0.01

3204 1883 4 28 37.6130 15.0280 3.50 6.50 11. 0.01

3225 1883 6 24 37.7050 15.1210 3.70 7.00 2. 0.50

3270 1885 9 25 37.6140 15.0270 3.70 7.00 11. 0.01

3273 1885 10 2 37.6140 15.0260 3.50 6.50 11. 0.01

3614 1901 5 11 37.6170 15.0290 3.70 7.00 11. 0.01

3770 1908 5 9 37.6690 15.1650 3.50 6.50 6. 0.02

3951 1914 5 8 37.6590 15.1490 4.70 9.50 5. 0.50

4010 1918 11 24 37.6860 15.1400 3.50 6.50 3. 0.04

4062 1920 9 26 37.7130 15.1610 3.90 7.50 6. 0.08

4244 1935 6 30 37.6550 15.1570 3.50 6.50 6. 0.02

4254 1942 11 15 37.6140 15.0290 3.50 6.50 11. 0.01

4261 1950 4 8 37.7070 15.1640 3.90 7.50 6. 0.08

4286 1952 3 19 37.6600 15.1470 3.90 7.50 5. 0.50

4408 1971 4 21 37.7140 15.1480 4.10 8.00 5. 0.21

4500 1984 10 19 37.6940 15.1030 3.70 7.00 0. 1.00

4768 2002 10 29 37.8070 15.0720 3.50 6.50 13. 0.01

4769 2002 10 29 37.6490 15.1720 3.50 6.50 8. 0.01

6003 1633 2 22 37.6140 15.0260 3.90 7.50 11. 0.03

6010 1634 12 21 37.6140 15.0810 3.70 7.00 9. 0.02

6019 1669 3 10 37.6150 15.0140 3.70 7.00 12. 0.01

6020 1669 3 10 37.6140 15.0260 3.90 7.50 11. 0.03

6023 1669 3 11 37.6150 15.0140 3.70 7.00 12. 0.01

6080 1805 7 11 37.7180 15.1500 4.30 8.50 5. 0.25

0

Tremestieri

Moscarello

Moscarello

Fiandaca

S. Leonardello

Tremestieri

Tremestieri

Tremestieri

Tremestieri

Tremestieri

Moscarello

S. Tecla

S. Leonardello

Moscarello

Tremestieri

S. Leonardello

S. Tecla

Moscarello

S. Tecla

Pernicana

S. Tecla

Exposure time 30 yrs - 10% prob.

3.5 4.0 4.5

Magnitude

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1

FaultsID YE MO DA LAT LON M Io DIST PROB

UPStrat-MAFA 3rd General Meeting 23-26 July 2013, Selfoss, Iceland

Task D: Probabilistic Hazard Assessment: Application of SASHA for Mt. Etna case

3.5 4.0 4.5

Magnitude

0

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tan

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(k

m)

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1

Acireale (Iexp VI)

Hazard deaggregation

3.5 4.0 4.5

Magnitude

0

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tan

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(k

m)

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Zafferana (Iexp VIII)

3.5 4.0 4.5

Magnitude

0

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tan

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(k

m)

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Nicolosi (Iexp VII)

0

Fiandaca

Moscarello

Pernicana

S. Tecla

Tremestieri

0.0 0.5 1.0 1.5 2.0 2.5

4.5

4

3.5

0

Fiandaca

Moscarello

Pernicana

S. Tecla

Tremestieri

0.0 1.0 2.0 3.0 4.0 5.0 6.0

4.5

4

3.5

0

Fiandaca

Moscarello

Pernicana

S. Tecla

Tremestieri

0.0 0.2 0.4 0.6 0.8 1.0

4

3.5

Exposure time 30 yrs - 10% prob.

UPStrat-MAFA 3rd General Meeting 23-26 July 2013, Selfoss, Iceland

Task D: Probabilistic Hazard Assessment: Application of SASHA for Mt. Etna case

Giardini-Naxos

Acireale

Adrano

Bronte

Catania

Giarre

Linguaglossa

Nicolosi

Randazzo

Tremestieri Etneo

Zafferana Etnea

• Variability of hazard at local scale along the volcano edifice

• High values (XIII - IX) of IEXP

• Main contribute to hazard by STF and MF

• Useful tool for establishing a priority of intervention for retrofit actions of urban areas.

• Identification of earthquakes to be used for scenario in Task F

Conclusions

Giardini-Naxos

Acireale

Adrano

Bronte

Catania

Giarre

Linguaglossa

Nicolosi

Randazzo

Tremestieri Etneo

Zafferana Etnea

Exp. time 30 yrs10% prob.

Exp. time 10 yrs10% prob.

MF

STF

UPStrat-MAFA 3rd General Meeting 23-26 July 2013, Selfoss, Iceland

Task D: Probabilistic Hazard Assessment: Application of SASHA for Mt. Etna case

Open questions and Suggestions

• Dependency of hazard from uncertainties in epicentral intensity

• Extensive use of the anisotropic model for all earthquakes with known seismogenic fault– Use of a "standard" size for linear

source for each Epicentral intensity class

Giardini-Naxos

Acireale

Adrano

Bronte

Catania

Giarre

Linguaglossa

Nicolosi

Randazzo

Tremestieri Etneo

Zafferana Etnea

Giardini-Naxos

Acireale

Adrano

Bronte

Catania

Giarre

Linguaglossa

Nicolosi

Randazzo

Tremestieri Etneo

Zafferana Etnea

Exp. time 30 yrs10% prob.

Exp. time 10 yrs10% prob.