Postseismic gravity changes after the 2011 Tohoku earthquake observed by superconducting gravimeters at Mizusawa, Japan

Earth, Planets and Space

Full Paper

Ryuichi Nishiyama¹  Yuichi Imanishi¹  Koji Matsuo²  Takahito Kazama³  Yoshiaki Tamura⁴ 

[1] Earthquake Research Institute, The University of Tokyo, 1-1-1, Yayoi, Bunkyo, 113-0032, Tokyo, Japan;Geospatial Information Authority of Japan, 1 Kitasato, 305-0811, Tsukuba, Ibaraki, Japan;Graduate School of Science, Kyoto University, Oiwake, Kitashirakawa, Sakyo, 606-8502, Kyoto, Japan;Mizusawa VLBI Observatory, National Astronomical Observatory of Japan, 2-12 Hoshigaoka, Mizusawa, 023-0861, Oshu, Iwate, Japan;

关键词: 2011 Tohoku earthquake;    Superconducting gravimeter;    Postseismic gravity changes;    Satellite gravity measurements;   

DOI  :  10.1186/s40623-023-01901-9

 received in 2023-03-27, accepted in 2023-09-10,  发布年份 2023

来源: Springer

【 摘 要 】

Postseismic gravity changes after the 2011 Tohoku earthquake (Mw9.0) were investigated using the data from superconducting gravimeters (SGs) at Mizusawa, Japan. The data in the period from 2014 to 2021 were used in the analysis. The SG data were first corrected for instrumental drift using the results of absolute gravity measurements. Then, correction for the hydrological effect was applied based on physical modeling of soil moisture. Finally, the effect of vertical displacement of the station (free-air effect) was corrected using GNSS data. After these corrections, residual gravity indicated a long-term increase, with its rate gradually decreasing with time. This fact suggests that viscoelastic relaxation after the earthquake played an important role in producing the long-term gravity changes. Fitting a decaying exponential function of time to the residual series yielded 89.4 ± 4.4 µGal (1 µGal = 10–8 ms–2) as the total gravity change and 635 ± 17 days as the characteristic time scale. In addition to the ground-based observations, the data from satellite gravity missions GRACE/GRACE-FO were analyzed to retrieve gravity changes at Mizusawa. Similar analysis of the satellite-based data yielded 15.2 ± 1.6 µGal as the total gravity change and 3444 ± 599 days as the characteristic time scale. The difference in the estimates of the total gravity change, of a factor of about 6, from the ground-based and the satellite-based observations may be attributed to the limited spatial resolution in the latter method. The difference in the estimates of the time scale, of a factor of about 1/5, may originate from the difference in the depth where the two kinds of gravimetry are mainly sensitive. Referring to recent theoretical studies on postseismic deformations after the 2011 Tohoku earthquake, our results can be interpreted consistently by assuming the existence of a layer of viscoelastic materials with viscosity 2×1018Pa s\documentclass[12pt]{minimal}\usepackage{amsmath}\usepackage{wasysym}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{amsbsy}\usepackage{mathrsfs}\usepackage{upgreek}\setlength{\oddsidemargin}{-69pt}\begin{document}$$2\times {10}^{18} \text{Pa s}$$\end{document} underneath the Tohoku area of Japan.Graphical Abstract

【 授权许可】

CC BY   
© The Society of Geomagnetism and Earth, Planetary and Space Sciences / The Seismological Society of Japan / The Volcanological Society of Japan / The Geodetic Society of Japan / The Japanese Society for Planetary Sciences 2023

【 图 表 】

Fig. 3

Fig. 7

Fig. 3

Fig. 1

Fig. 1

Fig. 4

Fig. 4

Fig. 1

Fig. 1

12936_2023_4724_Article_IEq33.gif

12888_2023_5172_Article_IEq2.gif

Fig. 1

13063_2023_7612_Figx_HTML.png

Fig. 1

Fig. 1

13690_2023_1170_Article_IEq80.gif

Fig. 3

Fig. 1

12938_2023_1153_Article_IEq25.gif

41408_2023_902_Tab1_HTML.png

Fig. 2

12888_2023_5172_Article_IEq1.gif

13690_2023_1170_Article_IEq212.gif

13690_2023_1170_Article_IEq211.gif

13690_2023_1170_Article_IEq210.gif

13690_2023_1170_Article_IEq209.gif

13690_2023_1170_Article_IEq208.gif

13690_2023_1170_Article_IEq207.gif

12888_2023_5142_Article_IEq15.gif

12888_2023_5142_Article_IEq14.gif

12888_2023_5142_Article_IEq13.gif

12888_2023_5142_Article_IEq12.gif

12888_2023_5142_Article_IEq20.gif

12888_2023_5142_Article_IEq11.gif

12888_2023_5142_Article_IEq19.gif

12888_2023_5142_Article_IEq10.gif

12888_2023_5142_Article_IEq9.gif

12888_2023_5142_Article_IEq8.gif

12888_2023_5142_Article_IEq7.gif

12888_2023_5142_Article_IEq6.gif

12888_2023_5142_Article_IEq5.gif

12888_2023_5142_Article_IEq4.gif

12888_2023_5142_Article_IEq3.gif

13690_2023_1170_Article_IEq188.gif

13690_2023_1170_Article_IEq75.gif

13690_2023_1170_Article_IEq187.gif

13690_2023_1170_Article_IEq74.gif

Fig. 5

Fig. 2

13690_2023_1170_Article_IEq183.gif

40798_2023_628_Figh_HTML.png

40798_2023_628_Figg_HTML.png

Fig. 4

Fig. 2

Fig. 2

Fig. 1

13690_2023_1170_Article_IEq172.gif

Fig. 1

Fig. 5

Fig. 2

Fig. 4

Fig. 1

Fig. 6

Fig. 1

42004_2023_990_Article_IEq88.gif

13690_2023_1170_Article_IEq60.gif

13690_2023_1170_Article_IEq58.gif

Fig. 4

Fig. 5

Fig. 2

Fig. 2

Fig. 2

Fig. 4

Fig. 4

Fig. 4

42004_2023_990_Article_IEq32.gif

13690_2023_1170_Article_IEq30.gif

12936_2023_4724_Article_IEq82.gif

13690_2023_1170_Article_IEq23.gif

13690_2023_1170_Article_IEq22.gif

Fig. 3

13690_2023_1170_Article_IEq21.gif

Fig. 1

12888_2023_5172_Article_IEq48.gif

12888_2023_5172_Article_IEq46.gif

41408_2023_919_Article_IEq15.gif

41408_2023_919_Article_IEq13.gif

41408_2023_919_Article_IEq12.gif

41408_2023_919_Article_IEq11.gif

Fig. 1

12888_2023_5172_Article_IEq31.gif

Fig. 5

12888_2023_5172_Article_IEq22.gif

Fig. 6

Fig. 5

42004_2023_995_Article_IEq11.gif

Fig. 3

Fig. 4

Fig. 1

Fig. 2

12888_2023_5142_Article_IEq26.gif

40795_2023_760_Article_IEq26.gif

13690_2023_1170_Article_IEq198.gif

Fig. 5

Fig. 2

Fig. 1

12951_2023_2095_Article_IEq4.gif

13690_2023_1170_Article_IEq165.gif

13690_2023_1170_Article_IEq162.gif

13690_2023_1170_Article_IEq53.gif