Coseismic gravity and displacement changes of Japan Tohoku earthquake … · 2017. 2. 15. · Coseismic gravity and displacement changes of Japan Tohoku earthquake (Mw 9.0) Xinlin
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g e o d e s y a nd g e o d yn am i c s 2 0 1 6 , v o l 7 n o 2 , 9 5e1 0 0
a Institute of Seismology, China Earthquake Administration, Wuhan 430071, Chinab Earthquake Research Institute, The University of Tokyo, Tokyo 1130032, Japanc State Key Laboratory of Geodesy and Earth's Dynamics, Institute of Geodesy & Geophysics, Chinese Academy of
Sciences, Wuhan 430077, China
a r t i c l e i n f o
Article history:
Received 1 September 2015
Accepted 26 November 2015
Available online 25 March 2016
Keywords:
Tohoku earthquake (Mw 9.0)
Co-seismic gravity change
Co-seismic displacement change
Coseismic geoid change
Dislocation theory
Global Positioning System
Absolute gravity measurement
Relative gravity measurement
* Corresponding author. Institute of SeismolE-mail address: [email protected]
hosting by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access
article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
How to cite this article: Zhang X, et al., Coseismic gravity and displacement changes of Japan Tohoku earthquake (Mw 9.0),Geodesy and Geodynamics (2016), 7, 95e100, http://dx.doi.org/10.1016/j.geog.2015.10.002.
ogy, China Earthquake Administration, Wuhan 430071, China.(X. Zhang).
ute of Seismology, China Earthquake Administration.
ier on behalf of KeAi
ina Earthquake Administration, etc. Production and hosting by Elsevier B.V. on behalf of KeAi
ss article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
March 11, 2011. The observed data shows the basic gravity
change contour in Fig. 1. In addition, a theoretical co-seismic
gravity changes were calculated based on a dislocation theory
with a self-gravitating and layered spherical earth model in
Fig. 1 and for 29 reference sites in Fig. 2. The observed gravity
and displacement changes agree well with the calculated
results which also confirm that the theory correctly estimates
co-seismic gravity and displacement changes.
And the modeled coseismic geoid change with the
maximum value is 50 mm locating east of the epicenter and
the geoid is changed in several thousand kilometers area from
focal region and decreased with the distance.
Furthermore, the observed gravity changes are not coin-
cided the theoretical results completelywhich imply thatmore
realistic earth model and reliable fault model are necessary.
Finally, the observed gravity changes in some region are
negative where an obvious subsidence is detected by GPS,
which can not be explained simply by vertical displacement of
the crust. This indicates that the mass redistribution in the
underground affects the gravity changewhich can be regarded
as dilatation of rocks occurred above the down-dip end of the
fault. This result supports the conclusion ofHan et al. [4]which
showed that GRACE satellites detected a crustal dilatation due
to the 2004 Sumatra earthquake by the terrestrial observation
with a higher spatial and temporal resolution.
Acknowledgments
We greatly appreciate the helpful suggestions from editors
and anonymous reviewers. This study is supported by the
Research Fund Program of Institute of Seismology, Chinese
Earthquake Administration (IS201226045), the Open Research
Fund Program of the State Key Laboratory of Geodesy and
Earth's Dynamics (SKLGED2013-3-7-E), and the National Nat-
ural Science Foundation of China (41404065).
r e f e r e n c e s
[1] Barnes DF. Gravity changes during the Alaska earthquake. JGeophys Res 1966;71:451e6.
[2] Tanaka Y, Okubo S. First detection of absolute gravitychanges caused by earthquake. Geophys Res Lett2001;28(15):2979e81.
[3] Imanishi Y, Sato T, Higashi T, Sun W, Okubo S. A network ofsuperconducting gravimeters detects submicrogal coseismicgravity changes. Science 2004;306:476e8.
[4] Han SC, Shum CK, Bevis M, Ji C, Kuo C. Crustal dilatationobserved by GRACE after the 2004 Sumatra-Andamanearthquake. Science 2006;313:658e62.
[5] Heki K, Matsuo K. Co-seismic gravity changes of the 2010earthquake in central Chile from satellite gravimetry.Geophys Res Lett 2010;37:L24306.
[6] Okubo S. Potential and gravity changes raised by pointdislocations. Geophys J Int 1991;105:573e86.
[7] Okubo S. Gravity and potential changes due to shear andtensile faults in a half-space. J Geophys Res1992;97:7137e44.
[8] Sun W, Okubo S. Surface potential and gravity changes dueto internal dislocations in spherical Earth-1. Theory for apoint dislocation. Geophys J Int 1993;114:569e92.
[9] Sun W, Okubo S, Fu G, Araya A. General formulations ofglobal and co-seismic deformations caused by an arbitrarydislocation in a spherically symmetric earth model-applicable to deformed earth surface and space-fixed point.Geophys J Int 2009;177:5817e33.
[10] Tanaka Y, Okuno J, Okubo S. A new method for thecomputation of global viscoelastic post-seismic deformationin a realistic earth model (I) e vertical displacement andgravity variation. Geophys J Int 2006;164:273e89.
[11] Han SC, Sauber J, Luthcke S. Regional gravity decrease afterthe 2010 Maule (Chile) earthquake indicates large-scale massredistribution. Geophys Res Lett 2010;37:L23307.
Xinlin Zhang, assistant researcher, Insti-tute of Seismology, Chinese EarthquakeAdministration. His interests includedislocation theory and gravity observationdata interpretation and application.