Application of Simulated Data: The Mt Etna Case

Langer, Tusa, Scarfì, Azarro, Varini*, Zonno…INGV – Oss. Etneo, Catania, Italy

CNR-IMATI – Milano, Italy

Tectonic & Geological Features

Siniscalco et al., 2012

Deformation Field

Regional Displacement field, see D’Agostino & Selvaggi, 2004

Horizontal Displacement (p. a., in mm) see Gugielmino et al., 2011

Seismicity Patterns Etna(2009-2012)

© INGV – staff analysts Oss. Etneo, Catania)-

Typical Waveforms of Shallow (SEE) and Deeper Etna Events

(DEE)

-2.0E+06

-1.5E+06

-1.0E+06

-5.0E+05

0.0E+00

5.0E+05

1.0E+06

1.5E+06

2.0E+06

0 5 10 15 20 25

Time (s)

Vel

oci

ty (

cts)

-3.0E+06

-2.0E+06

-1.0E+06

0.0E+00

1.0E+06

2.0E+06

3.0E+06

0 5 10 15 20 25

Time (s)

Vel

oci

ty (

cts)

-3.0E+06

-2.0E+06

-1.0E+06

0.0E+00

1.0E+06

2.0E+06

3.0E+06

0 5 10 15 20 25

Time (s)

Vel

oci

ty (

cts)

-1.5E+06

-1.0E+06

-5.0E+05

0.0E+00

5.0E+05

1.0E+06

1.5E+06

0 5 10 15 20 25

Time (s)

Vel

oci

ty (

cts)

-2.0E+06

-1.5E+06

-1.0E+06

-5.0E+05

0.0E+00

5.0E+05

1.0E+06

1.5E+06

2.0E+06

0 5 10 15 20 25

Time (s)

Vel

oci

ty (

cts)

-2.5E+06

-2.0E+06

-1.5E+06

-1.0E+06

-5.0E+05

0.0E+00

5.0E+05

1.0E+06

1.5E+06

2.0E+06

2.5E+06

0 5 10 15 20 25

Time (s)

Vel

oci

ty (

cts)

E

N

Z

Supferf. Etnean Event (M=3.8, d=5km, z= 1 km) Deeper Etnean Event (M=3.6, d=5km, z= 6 km)

The basement of Mt Etna

Resistivity profile after Siniscalco et al., 2012. Intermediate resisitivy (several to ca. 60 Ohm.m are indentified as sedimentary substratum, mainly tertiary and quaternary clays)

Data Set from Relevant Areas

Empirical GMPEs

Group Y a b c LogY

SEE*

PGA (cm s-2) -0.805 0.817 -1.989 0.372

PGV (cm s-1) -2.898 1.060 -1.829 0.365

PGD (cm) -4.580 1.279 -1.668 0.382

DEE**PGA (cm s-2) -0.298 0.845 -2.002 0.372

PGV (cm s-1) -2.071 0.883 -1.813 0.328

PGD (cm) -3.474 0.862 -1.523 0.345

EEE***PGA (cm s-2) -0.293 0.809 -1.835 0.410

PGV (cm s-1) -2.322 0.946 -1.704 0.347

PGD (cm) -4.061 1.003 -1.402 0.369

Empirical Ground Motion Prediction(3<M<4.8)

Shallow (z=1km), M=4.3 Deep(z=25),M=4.4

The Problem of Direct Extrapolation of empirical GMPEs

-1

0

1

2

3

4

0.5 1 1.5 2

Log Dist [km]

Lo

g P

GA

[g

al]

Etna DEE M=4 Etna DEE M=6 Sabette & Pugliese '87 M=4 Sabetta & Pugliese '87 M=6

A Way Out: Complex Extented Source Model (EXSIM)

-4-3.5

-3-2.5

-2-1.5

-1-0.5

0

0.51

0 0.5 1 1.5 2 2.5

Log Dist Hypo (km)

Lo

g A

max

(g

al)

First attempts…Empirical Results for M=3.3

Synthetic Results (EXSIMI) for Standard Input Parameters (M=3.3,

z=1 km, L=W=500m, stress =5 bar, Q=30*f0.7)

Trial Input Parameters (Etna)Q0 (f < 1Hz) QN βS (sup/deep) βM (sup/deep) R-1 R0 R-0.5

90 90*f0.7 1.8/3.0 km/s 2.4-3.0/3-3.5 km/s 0-35 35-70 >70 km

βS= velocity at sourc, βM = velocity of propagation medium (geom. spreading)

Mw (5/50 bar) 3.3/4.0 4.3/5.0 5.3/6.0 --/7.0Length (km) 0.88 2.8 8.8 28.0Width (km) 0.44 1.4 4.4 14.0

Etna 1914 Etna 9.10.2002Mw 5 4.8

Stress 20 bar 20 barLength (km) 8.0 5.6Width (km) 2.5 1.4

General scaling laws

Case studies (superficial)

SEE, M=3.3.fmax =5

DEE, M=4

Exsim Synthetic (Hardrock) vs. Empiric

Site Thickness S-Velocity Density QSite C 5 m 100 m/s 1700 kg/m3 10

5 m 400 m/s 1700 kg/m3 20Site B 20 m 400 m/s 1700 kg/m3 15

Volc. Rock 100 m 2000 m/s 2000 kg/m3 30

Layer Thickness S-velocity Density Q

Shale 100 m 600 m/s 1800 kg/m3 20

Cons. Shale 500 m 1500 m/s 2100 kg/m3 70

Cons. Shale 300 m 1700 m/s 2200 kg/m3 100

Limestone 5000 m 2600 m/s 2500 kg/m3 150

Basement 3500 m/s 2800 kg/m3

Generalized Velocity Models

Case Mt Etna, 1914. M=5, I =IX

I (Observed)

I (from Housner Intensity: I = 1.41 ln (Ih)

+7.98

Exsim, Site C

Exsim, Site B

Exsim, Hardrock

Case Mt Etna 1914 (M ca. 5, I = IX)

I (Observed)

Case Etna, 1914, (ctd)

Log PGA (gal), syn Log PGV (cm/s), syn.

Etna 29.10.2002 Etna 29.10.2002 (EXSIM)Io VIII 8

PGA 18 km 15 gal 8…15 galPGV 4.5 cm/s 0.6..1.1 cm/s

From Milana et al., 2008

Exsim simulation for M=6 DEE event: Catania /Acireale 1818

-1

-0.5

0

0.5

1

1.5

2

2.5

3

0.5 1 1.5 2

Log Dist Campbell [km]

Lo

g P

GA

[g

al]

M=4

M=5

M=6

M=7

-1

-0.5

0

0.5

1

1.5

2

2.5

3

0.5 1 1.5 2

Log Dist JB [km]

Lo

g P

GA

[g

al ]

M=4

M=5

M=6

M=7

“Extrapolation” via synthetic simulation

-1

0

1

2

3

4

0.5 1 1.5 2

Lo

g P

GA

[g

al]

Log Dist [km]

Etna DEE M=4

Etna DEE M=6

Sabette & Pugliese '87 M=4

Sabetta & Pugliese '87 M=6

Conclusion

• Distinction of two dynamic regimes• Different GMPE for shallow and deeper events• Empirical GMPEs should not extrapolated to

larger events• Small events may be used for calibrating input

pameters in synthetic modelling• Discrepances between empirical GMPEs for

large and small earthquakes can be explained by using extended sources.