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Tool to calculate the theoretical tidal response

Tidal stress can influence seismicity at various scales, from low-frequency tremors to great earthquakes.

Please see our paper [Hirose et al. 2019, JGR] for the details.

2020/06/29: We released the Fortran program "TidalStrain.2" that calculates the theoretical tidal response of the solid earth on an arbitrary fault plane at an arbitrary depth from the earth’s surface to the core-mantle boundary (~2891 km). Please feel free to download.

Please see here about bugs of the old version "TidalStrain" which we released on 27 August 2019.

2020/09/18: We also released the Fortran program "loadgreenf4" for in-situ calibration of borehole type strainmeter based on tidal response, and it is enclosed in "TidalStrain.2".

*Acknowledgments: Our program "TidalStrain.2" uses a most part of subroutines in "GOTIC2 (version 2004.10.15) [Matsumoto et al., 2001; Matsumoto, 2004]" to calculate ocean tide loading effects. The programs "static", "loadgreenf3_mod", and "loadgreenf4" use a part of the calculation logic of "DISPER80" [Saito, 1988]. We greatly thank for them.

Note that "source_mod2020/*_mod2020.f" indicate subroutines that are different from original subroutines in "GOTIC2".

Matsumoto, K., T. Sato, T. Takanezawa, and M. Ooe, 2001, GOTIC2: A program for computation of oceanic tidal loading effect, J. Geod. Soc. Japan, 47, 243-248.
Matsumoto, K., 2004, https://www.miz.nao.ac.jp/staffs/nao99/, we browsed it on June 3, 2020.
Saito, M., 1988, DISPER80: A subroutine package for the calculation of seismic normal-mode solutions, Seismol. Algorithms, pp. 293-319.

Theoretical tidal response

Fig.1. An example of the theoretical tidal response.

(green) volumetric strain, (red) shear stress, (blue) normal stress during 1 day before and after 3 May 2006 at 15:27 UTC (Mw 8.0).

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