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Quantifying Uncertainties for earthquakes’ Magnitude and Depth
Ludmila Provost, Oona Scotti
To cite this version:
Ludmila Provost, Oona Scotti. Quantifying Uncertainties for earthquakes’ Magnitude and Depth. 7th International Colloquium on Historical Earthquakes & Paleoseismology Studies, ICHEPS, Nov 2019, BARCELONE, Spain. 2019. �hal-02635627�
IRSN
INSTITUTDE RADIOPROTECTION ET DE SÛRETÉ NUCLÉAIRE
MEMBEROF
ETSOn Quantifying Uncertainties for earthquakes1
Magnitude and Depth
Ludmila Provost, Oona Scotti
INTRODUCTION
We develop a methodology that quantify uncertainties for earthquakes' (M, H) by giving a space of possible (M,H) solutions based on intensity data uncertainties as well as on IPE epistemic uncertainties: the QUake-MD methodology.
The only data available on historical earthquake are the information provided by historical sources. This information can be translated into intensity through the use of intensity scale.
Magnitude and depth (M, H) can be estimated from macroseismic intensity by using empirical intensity prediction equations (IPE).
However both intensity data and the IPE are marred of uncertainties. Intensity data of one earthquake can be very sparse and their attributed intensity value are often based on one historical source, which can be a secondary source.
Calibration of IPE is a challenging task. Indeed IPEs are sensitive to the choice of calibration earthquake, to the (M, H) instrumental parameter values and associated uncertainties, regional heterogeneities of attenuation, etc.
M, H estimates from macroseismic intensity are thus uncertain. The application of one IPE on macroseismic data gives one couple of (M, H) solution, with eventually an associated uncertainty but is it enough?
Database used for the poster: SisFrance (www.sisfrance.net, consortium BRGM, EDF, IRSN)
3°W 1°W 1°E 3°E 3°W 1°W 1°E 3°E 3°W 1°W 1°E 3°E 3°W 1°W 1°E 3°E
47°N
45°N
43°N
41°N
France
•ÿ o 1
#* çgb°&o SCo0?»
Spain
0 100 200
4 % have more than 50 IDP 20 % of SisFrance database
have only one IDP
In database: before 1976 -> 5708 events after 1976 -> 716 events
i
47°N
45°N
43°N
41°N
Epicenter
I / l-ll II / ll-lll
III / lll-IV IV / IV-V V / V-VI VI / VI-VII VII / VII-VIII VIII / VIII-IX IX / IX-X X / X-XI XI Not-Felt Felt
50 % of SisFrance database have only « Felt » testimonies
T
Need specific treatment
J
QUake-MD : QUantifying Uncertainties for earthquakes' Magnitude and Depth ing s T ^îityvT C uncerta inties
Example of QUake-MD application on one calibration earthquake (Arudy, 1980, instrumental Mw=5.1)
7 - oo OQG
Increasing weiight
»o O O
tn 5
to o o
t O O o
Least square inversion with constraints for depth on data with one IPE
docodoo o
mc
<L)
m oo
4 -
3-
o oa
o CED a*
CSS) ODGOOEDtD OflDfflm
CED
Intensity data weighted by their quality factor
QDO
o IDP
0 RAVG isoseismal
-I—i—i i i | -I—i i i i |
2 5 10 20 50 100 200 Epicentral distance [km]
500
Quality factor Weight
A 4
B 3
C 2
Required
An IPE with the following mathematical formulation:
1 = Cl + C2M + fi log{Dhypo} + Y^hypo
Quality factor associated to each intensity data points
Epicentral intensity I0 with associated uncertainties or I0 min and I0 max
Depth limit Hmin and Hmax for the application of the IPE to estimate (M, H)
6.50
6.25
6.00
5.75
Qj"O
~ 5.50
Di«3
E 5.25
5.00
4.75
4.50
--- i i i i i i i i
---1--- 1
1 1 1 1 1 1 1 1 1 1 i 1 1 1 i
i i i i Intérim’ li of in vers in defjth _______ 1__
1 1 1 1 1
nit [superior limit
on [of inversion
1 in depth 1
2.5 5.0 7.5 10.0 12.5 15.0 17.5 20.0 Depth [km]
I0 + uncertainties filtering
One space of solution for one IPE
N IPEs
Testing Quake-MD on recent earthquakes using internet intensities
Internet intensity (BCSF) from the 06/21/19, 06:50 pm
Latitude: 47.1505°N Longitude: 0.3367°W Date : 21/06/2019 Local time: 09h50
Local magnitude Ml(source Renass): 4.8 Local magnitude Ml(source LDG): 5.2 Magnitude Mw: 3.9 (Satriano)
QUake-MD solutions
5 10 15 20
Profondeur du séisme [km]
Modèle d'atténuation pour la France (ECUM 2019)
Intensité maximale reportee
* m- ■
Intensité moyenne par commune Intensité calculée à l'épicentre Moyenne des distances et intensité
par classe d'intensité (épaisseur de la classe : 1) Modèle d'atténuation
Distance au foyer du séisme [km] 101 1Q2
Distance au foyer dui sais me [km]
+
Distance au foyer du séisme [km]
+
5 5
“ 50■U
Eun
■'li
un -O 45
TJ
_■
J__1
üm
(T3 40
3.5
QUake-MD solutions
Eiarycentre: Mw=4.36, H=14.ü km
□ Pi L.Q km
Percentile ifc: Mw=3.y5, H=B.0km
5 10 15 20
Profondeur du sé sme [km]
25
Need for accurate estimates of instrumental Mw and depth to test Quake-MD
Instrumental magnitude Mw
West France East France
| SE France
8 recent earthquakes with available instrumental Mw compared.
Source of the instrumental Mw:
C. Satriano and B. Delouis
Name of the earthquake
Date Inst. Mw Mmin - Mmax
Quake-MD
H Quake- MD
barycenter
Macrose ismic field quality
Barcelonnette (SE France) 07/04/2014 4.7-4.8 4.2-5.1 9 km A
Barcelonnette (SE France) 06/11/2015 3.9 3.2-4.2 11 km C
La Rochelle (W France) 28/04/2016 3.8-3.9 3.7-4.9 12 km A
Digne-les-Bains (SE France)
10/11/2016 3.5 3-4 9 km C
Saint-Hilaire-de-Voust (W France)
12/02/2018 3.9-4 3.2-4.1 4 km C
Bourg-en-Bresse (E France)
21/11/2018 3.4 3.2-4 12 km B
Montendre (W France) 20/03/2019 3.7 3.6-4.9 9 km B
Layon (W France) 21/06/2019 3.9 3.9-5.1 14 km A
