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I work to understand the subsurface deformation under combined effects from internal tectonic forces and external environmental perturbations (rainfall, snow, sea-level changes, temperature, etc).
Low-frequency earthquakes
Low-frequency earthquakes
LFEs in Nankai, Japan
LFEs in Nankai, Japan
An example of spatial distribution of regular earthquakes (upper one) and Low frequency Earthquakes (lower one) in the Nankai region, Japan.
Seasonal subsurface deformation
Seasonal subsurface deformation
Continuous seismic 𝛿𝑣/𝑣 throughout Japan
Continuous seismic 𝛿𝑣/𝑣 throughout Japan
(2015-2017)
(2015-2017)
During my PhD at ISTerre (Grenoble, France), I work with Michel Campillo, Florent Brenguier, and Robert van der Hilst. The research topic was to follow the changes in the physical properties of the crust beneath Japan using ambient seismic noise-based monitoring technology.
Wang, Q.-Y., Brenguier, F., Campillo, M., Lecointre, A., Takeda, T., & Aoki, Y. (2017). Seasonal crustal seismic velocity changes throughout Japan. Journal of Geophysical Research: Solid Earth, 122, 7987– 8002. https://doi.org/10.1002/2017JB014307
This figure above gives un example of how the precipitation affects seismic velocity changes in Kyushu both spatially and temporally.
Earthquake-related crustal deformation
Earthquake-related crustal deformation
2011 Mw 9.0 Tohoku-Oki earthquake, Japan
2011 Mw 9.0 Tohoku-Oki earthquake, Japan
(2017 -2018)
(2017 -2018)
The measured seismic velocity changes are subject to not only to external forcing changes such as the hydrological effects (Wang at al., 2017, JGR) and internal forcing produced by such as different earthquakes (Wang at al., 2019, JGR).
I study also changes of the crustal state before and after the 2011 Mw 9.0 Tohoku-Oki earthquake. For the first time, we find both dynamic and static strain related seismic velocity reduction concentrated at different depths.
Spatial distribution of seismic velocity drops at different period bands in Honshu, Japan.
Wang, Q.-Y., Campillo, M., Brenguier, F., Lecointre, A., Takeda, T., & Hashima, A. (2019). Evidence of changes of seismic properties in the entire crust beneath Japan after the Mw 9.0, 2011 Tohoku-oki earthquake. Journal of Geophysical Research: Solid Earth, 124, 8924– 8941. https://doi.org/10.1029/2019JB01780
Seismic and Geodetic observations
(2017-2018)
Seismic and Geodetic observations
(2017-2018)
There are good correlation among the time series of seismic 𝛿v/v, GPS vertical displacement, and GRACE measured gravity field.
The left figure shows a comparison between seismic 𝛿v/v and the GRACE-measured Equivalent water height (cm) from different sites in Japan.
Wang Q.-Y. Monitoring of the mechanical properties of the crust beneath Japan from continuous data of the Hi-net network. Applied geology. Université Grenoble Alpes, 2018. English. ⟨NNT : 2018GREAU047⟩. ⟨tel-02143062⟩
Evidence of fluid migration revealed by seismic interferometry
(2019 - 2020)
Evidence of fluid migration revealed by seismic interferometry
(2019 - 2020)
The right figure shows a simultaneous increase in the number of LFEs and decrease in seismic wave velocity along the central volcanic chain in Japan. Both are supposed to related to the fluid migration after the big 2011 Tohoku-Oki earthquake.
Wang, Q. Y., Campillo, M., Brenguier, F., Lecointre, A., Takeda, T., & Yoshida, K. (2021). Seismic evidence of fluid migration in northeastern Japan after the 2011 Tohoku-oki earthquake. Earth and Planetary Sciences Letters, 563, 116894. https://doi.org/10.1016/j.epsl.2021.116894
Uniformed Coda sensitivity kernels
(2019 - now)
Uniformed Coda sensitivity kernels
(2019 - now)
After receiving my PhD from ISTerre, France, I worked at ISTerre as a postdoc researcher in 2019 and junior researcher in 2020 on the inversion of seismic monitoring results and interpreting the 4-D tomography beneath the eastern Japan.
With all the collaborators: Takashi Hirose, Ludovic Margerin, Hisashi Nakahara, Takeshi Nishimura, Eric Larose, and Michel Campillo, we have first applied the Mont-Carlo based 2-D kernels in studying both seismic scattering and velocity related to the 2011 Tohoku-Oki earthquake, Japan.
A paper titled "Time lapse imaging of seismic scattering property and velocity in northeast part of Japan between 2008 and 2012" is about to submit.
The right two figures show a travel-time sensitivity kernel from Mont-Carlo simulation between two stations. The upper one is implemented with mean free path of 100 km and the lower one is with 200km.
Non-uniformed Coda sensitivity kernels
(2021 - now)
Non-uniformed Coda sensitivity kernels
(2021 - now)
Some exciting theoretical tests are on-going.
van Dinther, C., Wang, Q., Margerin, L., and Campillo, M.: The impact of laterally varying scattering properties on subsurface monitoring using coda wave sensitivity kernels: Application to fault zone and volcanic areas, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-11414, https://doi.org/10.5194/egusphere-egu22-11414, 2022.
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