quest quun tremblement de terre ? madariag/exposes.html
TRANSCRIPT
![Page 1: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/1.jpg)
Qu’est qu’un tremblement de terre ?
http://www.geologie.ens.fr/~madariag/Exposes.html
![Page 2: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/2.jpg)
Slip is larger near center
![Page 3: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/3.jpg)
Geometry of Landers fault system
Figure shows the fault traces
(Hart et al., 1993)
which ruptured during
the 1992 earthquake,
and those which did not break then
![Page 4: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/4.jpg)
Earthquakes as dynamic shear ruptures
Final slip observed on the fault asdetermined fromGeology,Geodesy andSeismology
Epicenter
Modèle ENS (Peyrat, Aochi, Olsen, Madariaga)
Pre-existing Fault systemin the Mojave desert
![Page 5: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/5.jpg)
Propagacion de la rupture du séisme de Landers
Aochi et al 2002
![Page 6: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/6.jpg)
Variation de contraintes autour de Landers
Le glissement génère Des variations de contraintesQui à leur tour peuvent Des répliques.
En général les répliques seProduisent dans les zones oùLa contrainte augmente.
![Page 7: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/7.jpg)
Observation des oscillations libres sur la terre
![Page 8: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/8.jpg)
![Page 9: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/9.jpg)
Qu’est qu’un tremblement de terre?
![Page 10: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/10.jpg)
Modèle du rebond sismique
Situation quelques jours après un séisme
Situation à mi parcours
Situation quelques jours après le séismesuivant
Déformation présismique
Glissement sismique
![Page 11: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/11.jpg)
DD
Modèle de rupture sismique (dislocation)Modèle de rupture sismique (dislocation)
DAvant le séisme
Pendant et après le séisme
D
Modèle équivalent
Glissement D
M0
![Page 12: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/12.jpg)
![Page 13: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/13.jpg)
Glissement D
Surface de la faille S
Définition de Moment sismique
Mo = D S
Constante élastique
![Page 14: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/14.jpg)
1
3
10
30
100?
Glissement
(m)
31010186
10303.10197
30 10010218
1003003.10229
300?1000?102410
Durée
(s)
Longueur
(km)
Moment
(Nm)
Magnitude
(Mw)
Loi d’échelle des tremblements de terre
![Page 15: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/15.jpg)
Rayonnement et mécanisme au foyer
![Page 16: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/16.jpg)
Ondes sphériques
R
Ondes P
RR
RRt
22
22
2
2
11
R
tfR
tR1
4
1),(
/)(~1
4
1),( Rtief
RR
Solution space temps
Solution space Fourier
propagation
forme d’onde
Divergence géométrique
Front d’ondes
Rai ou rayon
![Page 17: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/17.jpg)
Onde S
Onde P
Onde S
Rayonnement sismique dans un milieux homogène
Mo
Divergence Géométrique
Diagramme de rayonnement
Signal sismique
R
)/(),(1
4
1),( 03
RtMR
tRu S SR
)/(),(1
4
1),( 03
RtMR
tRu P PR
![Page 18: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/18.jpg)
Rayonnement des ondes S :
SV SH
Rayonnement des ondes P :
Diagramme de rayonnement
![Page 19: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/19.jpg)
M0 (t)
temps
M0
Rayonnement sismique
Moment sismique final
temps
M0 (t)
M0
°
Signal sismique idéalisé
Durée ~
)()( /200 tHe
tMtM t
Peak~Mo/
)()/1(1)( /00 tHetMtM t
![Page 20: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/20.jpg)
M0 (t)
temps
M0
Rayonnement sismique
Moment sismique final
temps
M0 (t)
M0
°
Signal sismique idéalisé
Durée ~
)()( /200 tHe
tMtM t
Peak~Mo/
)()/1(1)( /00 tHetMtM t
![Page 21: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/21.jpg)
Fonctions source des plus gros séismes récents
![Page 22: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/22.jpg)
Mo
Corner frequency
Asymptote à haute fréquence
Numérique
Le spectre de Brune (1970)
Brune spectrum
220
20
00 )(ff
fMfM
f-2
![Page 23: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/23.jpg)
Spectrum of Tarapaca earthquakedi
spla
cem
ent
spec
tral
am
plitu
de
-2 slope
20s
0.2
![Page 24: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/24.jpg)
Spectral stack of small earthquakes in Tocopilla Following Prieto et al. , 2004
From these spectra we can compute 3 quantities Mo, Er and fc
Main event
![Page 25: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/25.jpg)
Modèles de source sismique finie
Loi d’échelle
Modèle de faille circulaire
![Page 26: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/26.jpg)
Aki earthquake scaling law 1967
Size
There is a single scale:
Earthquake size L
![Page 27: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/27.jpg)
Summary of Observed Radiated Energy vs Moment
Then since Mo ~ L3 , U ~ L3 and E
s ~ L3
so that Gc ~ L (Aki, 1979)!
Thus Es ~ 10-5 M
o ~ UDD
![Page 28: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/28.jpg)
L L0L
L2
L
L-1
L3
L2
Fundamentals of earthquake scaling
Surface
Signal
Spectrum
f
t
![Page 29: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/29.jpg)
1
3
10
30
100?
Glissement
(m)
31010186
10303.10197
30 10010218
1003003.10229
300?1000?102410
Durée
(s)
Longueur
(km)
Moment
(Nm)
Magnitude
(Mw)
Loi d’échelle des tremblements de terre
![Page 30: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/30.jpg)
Le séisme du Sendaï -Tohoku OkiOff-Pacific coast of Tohoku earthquake
![Page 31: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/31.jpg)
The 2011 Tohoku-oki earthquake
![Page 32: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/32.jpg)
La sismicité est aléatoire et imprévisible
![Page 33: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/33.jpg)
Modèle de rebond élastique en zone de subduction
Avant le séisme
Au cours du séisme
![Page 34: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/34.jpg)
Modèle de rebond élastique en zone de subduction
Situation initiale
Situation intermédiaire
Le séisme
Zone sismogène Zone de glissement
bourrelet
Rotation de la zone de glissement
![Page 35: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/35.jpg)
Seismic gaps in Japan
Quelques fois ça marche pas du tout
![Page 36: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/36.jpg)
Sismicité historique du Tohoku (Abe, Kanamori, Brady, etc)
Pourquoi on n’a pas envisagé le séisme de Tohuku ?
![Page 37: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/37.jpg)
![Page 38: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/38.jpg)
Principales répliques
![Page 39: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/39.jpg)
![Page 40: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/40.jpg)
Déformation du Japon avant le séisme de Tohoku
![Page 41: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/41.jpg)
Couplage au Japon: deux points de vue
![Page 42: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/42.jpg)
Tohoku 2011
Low and high frequency sources
![Page 43: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/43.jpg)
monte
Déformation cosismique
![Page 44: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/44.jpg)
Envisat interferometry
50 cm band
![Page 45: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/45.jpg)
Déplacement du Japon provoqué par le séisme de Tohoku
from Aria/JPL/Caltech, contours en mètres
![Page 46: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/46.jpg)
Tohoku earthquake: Inversion des données géodésiques
![Page 47: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/47.jpg)
Enregistrements GPS continus (1 Hz)
![Page 48: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/48.jpg)
Inversion of motograms of the 2011 Tohoku earthquake
Reduced set of stations
![Page 49: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/49.jpg)
![Page 50: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/50.jpg)
![Page 51: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/51.jpg)
![Page 52: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/52.jpg)
Section sismique le long de la côte
![Page 53: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/53.jpg)
![Page 54: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/54.jpg)
Rupture process in Japan
![Page 55: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/55.jpg)
Observed vs synthetic seismograms
![Page 56: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/56.jpg)
Modèle dérivé du champ proche
NIED
Modèle dérivé de la géodésie spatiale
GSI
![Page 57: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/57.jpg)
Distribution de glissement du séisme
Kikuchi et al , EPSL,Oct. 2011
![Page 58: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/58.jpg)
Comparaison glissement présismique et co-sismique
Kikuchi et al, 2011Hashimoto et al, Nature Geosciences, 2009
![Page 59: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/59.jpg)
Le séisme a été aussi destructeur que le tsunami
Accélération maximale
3g
Below are the earthquakes which had tsunami magnitude of above Mt=9.0:1837 Valdivia, Chile 9.31841 Kamchatka 9.01868 Arica, Chile 9.01877 Iquique, Chile 9.01946 Aleutians 9.31952 Kamchatka 9.01957 Aleutians 9.01960 Chile 9.41964 Alaska 9.12004 Sumatra, Indonesia 9.0
![Page 60: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/60.jpg)
![Page 61: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/61.jpg)
Faux !
tsunami (a wave in a port)
Vrai!
![Page 62: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/62.jpg)
Les plus gros tsunamis historiques
1837 Valdivia, Chile 9.31841 Kamchatka 9.01868 Arica, Chile 9.01877 Iquique, Chile 9.01946 Aleutians 9.31952 Kamchatka 9.01957 Aleutians 9.01960 Chile 9.41964 Alaska 9.12004 Sumatra, Indonesia 9.02011 Tohoku, Japon 9.0
![Page 63: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/63.jpg)
What is a tsunami ?
),(),(1
2
2
2
2
2txu
xtxu
tc zz
tsunami speed ghc
h
uz
typically
h= 3000 m g =10m/s2 c = 175 m/s ou 700 km/hh= 1000 m c = 100 m/s or 360 km/h
A shallow water wave
![Page 64: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/64.jpg)
Generation of large tsunamis in subduction zones
sismogenic zone
Transition zone
8 cm/year
Uplift produces tsunami
![Page 65: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/65.jpg)
Tsunami produit par le séisme de Tohuku du 11/03/2011
![Page 66: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/66.jpg)
![Page 67: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/67.jpg)
Amplification près de la côte
En fait le processus est nonlinéaire.
![Page 68: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/68.jpg)
Tsunami runup and elevation
Tsunami height or elevation
![Page 69: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/69.jpg)
Inundation de l’aéroport de Sendai
![Page 70: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/70.jpg)
Modern Geography
Inundation mapsFrom satellites
![Page 71: Quest quun tremblement de terre ? madariag/Exposes.html](https://reader038.vdocuments.us/reader038/viewer/2022110117/551d9da0497959293b8ce4f7/html5/thumbnails/71.jpg)
A l’origine du tsunami
Soulèvement du fond marin
GSI
Hauteur d’eau par Fujii-Satake
ISEE –ERI Tsukuba-Tokyo