Review:

# Role of Real-Time GNSS in Near-Field Tsunami Forecasting

## Yusaku Ohta^{*,†}, Takuya Inoue^{**}, Shunichi Koshimura^{**}, Satoshi Kawamoto^{***}, and Ryota Hino^{*}

^{*}Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University

6-6 Aramaki-Aza-Aoba, Aoba-ku, Sendai 980-8578, Japan

^{†}Corresponding author

^{**}International Research Institute of Disaster Science, Tohoku University, Sendai, Japan

^{***}Geospatial Information Authority of Japan, Tsukuba, Japan

This short paper reviews the role of real-time global navigation satellite system (GNSS) in near-field tsunami forecasting. Recent efforts highlight that coseismic fault model estimation based on real-time GNSS has contributed substantially to our understanding of large magnitude earthquakes and their fault expansions. We briefly introduce the history of use of real-time GNSS processing in the rapid estimation of the coseismic finite fault model. Additionally, we discuss our recent trials on the estimation of quasi real-time tsunami inundation based on real-time GNSS data. Obtained results clearly suggest the effectiveness of real-time GNSS for tsunami inundation estimation as the GNSS can capture fault expansion and its slip amount in a relatively accurate manner within a short time period. We also discuss the future prospects of using real-time GNSS data for tsunami warning including effective combination of different methods for more reliable forecasting.

*J. Disaster Res.*, Vol.13, No.3, pp. 453-459, 2018.

- [1] T. Ozaki, “Outline of the 2011 off the Pacific coast of Tohoku Earthquake (M
_{w}9.0) – Tsunami warnings/advisories and observations –,” Earth Planets Space, Vol.63, pp. 827-830, doi: 10.5047/eps.2011.06.029, 2011. - [2] T. Kato, Y. Terada, et al., “Real-time observation of tsunami by RTK-GPS,” Earth Planets Space, Vol.52, pp. 841-845, doi: 10.1186/BF03352292, 2000.
- [3] K. M. Larson, P. Bodin, et al., “Using 1-Hz GPS data to measure deformations caused by the Denali fault earthquake,” Science, Vol.300, pp. 1421-1424, doi:10.1126/science.1084531, 2003.
- [4] K. M. Larson, “GPS seismology,” J. of Geod., Vol.83, Issue 3-4, pp. 227-233, doi:10.1007/s00190-008-0233-x, 2009.
- [5] Y. Ohta, I. Meilano, et al., “Large surface wave of the 2004 Sumatra-Andaman earthquake captured by the very long baseline kinematic analysis of 1-Hz GPS data,” Earth Planets Space, Vol.58, No.2, pp. 153-157, doi: 10.1186/BF03353372, 2006.
- [6] S. Miyazaki, K. M. Larson, et al., “Modeling the rupture process of the 2003 September 25 Tokachi-Oki (Hokkaido) earthquake using 1-Hz GPS data,” Geophys. Res. Lett., Vol.31, L21603, doi:10.1029/2004GL021457, 2004.
- [7] G. Blewitt, C. Kreemer, et al., “Rapid determination of earthquake magnitude using GPS for tsunami warning systems,” Geophys. Res. Lett., Vol.33, L11309, doi:10.1029/2006GL026145, 2006.
- [8] G. Blewitt, W. C. Hammond, et al., “GPS for real-time earthquake source determination and tsunami warning systems,” J. of Geod., Vol.83, pp. 335-343, doi:10.1007/s00190-008-0262-5, 2009.
- [9] S. V. Sobolev, A. Y. Babeyko, et al., “Tsunami early warning using GPS-Shield arrays,” J. of Geophys. Res., Vol.112, Issue B8, pp. 1-18, doi:10.1029/2006JB004640, 2007.
- [10] D. Melgar, Y. Bock, et al., “Real-time centroid moment tensor determination for large earthquakes from local and regional displacement records,” Geophys. J. Int., Vol.188, Issue 2, pp. 703-718, doi: 10.1111/j.1365-246X.2011.05297.x, 2012.
- [11] D. Melgar, B. W. Crowell, et al., “Rapid modeling of the 2011 M
_{w}9.0 Tohoku-oki earthquake with seismogeodesy,” Geophys. Res. Lett., Vol.40, pp. 2963-2968, doi:10.1002/grl.50590, 2013. - [12] D. Melga and Y. Bock, “Near-field tsunami models with rapid earthquake source inversions from land- and ocean-based observations: The potential for forecast and warning,” J. of Geophys. Res.: Solid Earth, Vol.118, Issue 11, pp. 5939-5955, doi: 10.1002/2013JB010506, 2013.
- [13] D. Melgar, J. Geng, et al., “Seismogeodesy of the 2014 M
_{w}6.1 Napa earthquake, California: rapid response and modeling of fast rupture on a dipping strike-slip fault,” J. of Geophys. Res.: Solid Earth, Vol.120, pp. 5013-5033, doi:10.1002/2015JB011921, 2015. - [14] D. Melgar, R. M. Allen, et al., “Local tsunami warnings: Perspectives from recent large events,” Geophys. Res. Lett., Vol.43, pp. 1109-1117, doi:10.1002/2015GL067100, 2016.
- [15] Y. Ohta, T. Kobayashi, et al., “Quasi real-time fault model estimation for near-field tsunami forecasting based on RTK-GPS analysis: Application to the 2011 Tohoku-Oki earthquake (Mw 9.0),” J. of Geophys. Res., Vol.117, Issue B2, B02311, doi: 10.1029/2011JB008750, 2012.
- [16] Y. Ohta, T. Kobayashi, et al., “Rapid coseismic fault determination of consecutive large interplate earthquakes: The 2011 Tohoku-Oki sequence,” Int. Association of Geod. Symposia 2015, Springer, doi:10.1007/1345_2015_109, 2015.
- [17] B. W. Crowell, Y. Bock, et al., “Real-time inversion of GPS data for finite fault modeling and rapid hazard assessment,” Geophys. Res. Lett., Vol.39, No.9, pp. 1-6, doi:10.1029/2012GL051318, 2012.
- [18] H. Tsushima and Y. Ohta, “Review on Near-Field Tsunami Forecasting from Offshore Tsunami Data and Onshore GNSS Data for Tsunami Early Warning,” J. Disaster Res., Vol.9, No.3, pp. 339-357, doi: 10.20965/jdr.2014.p0339, 2014.
- [19] S. Kawamoto, Y. Ohta, et al., “REGARD: A new GNSS-based real-time finite fault modeling system for GEONET,” J. of Geophys Res.: Solid Earth, Vol.122, pp. 1324-1349, doi:10.1002/2016JB013485, 2017.
- [20] S. Kawamoto, Y. Hiyama, et al., “First Result from the GEONET Real-time Analysis System (REGARD): the Case of the 2016 Kumamoto Earthquakes,” Earth, Planets Space, Vol.68, No.190, doi:10.1186/s40623-016-0564-4, 2016.
- [21] D. L. Wells and K. J. Coppersmith, “New Empirical Relationships among Magnitude, Rupture Length, Rupture Width, Rupture Area, and Surface Displacement,” Bull. of Seismol. Soc. of America, Vol.84, No.4, pp. 974-1002, 1994.
- [22] I. Abe and F. Imamura, “Study on the evaluation of tsunami inundation in real time with database and its accuracy (in Japanese with English abstract),” J. of Japan Society of Civil Engineers, Series B2 (Coastal Engineering), Vol.66, pp. 261-265, doi:10.2208/kaigan.66.261, 2010.
- [23] V. V. Titov, “Tsunami forecasting in The Sea,” Vol.15: Tsunamis, chap. 12, edited by E. N. Bernard and A. R. Robinson, pp. 371-400, Harvard Univ. Press, Cambridge, Mass, 2009.
- [24] A. R. Gusman, Y. Tanioka, et al., “A methodology for near-field tsunami inundation forecasting: Application to the 2011 Tohoku tsunami,” J. of Geophys. Res.: Solid Earth, pp. 1-21, doi:10.1002/2014JB010958, 2014.
- [25] B. J. Meade, “Algorithms for the calculation of exact displacements, strains, and stresses for triangular dislocation elements in a uniform elastic half space,” Comput. and Geosci., Vol.33, Issue 8, pp. 1064-1075, doi: 10.1016/j.cageo.2006.12.003, 2007.
- [26] T. Inoue, Y. Ohta, et al., “A study on methods for applying fault models rapidly estimated using real-time GNSS to tsunami simulation,” J. of Japan Society of Civil Engineers, Series B, Vol.72, No.2, pp. 355-360, 2016.
- [27] S. Koshimura, T. Oie, et al., “Developing fragility functions for tsunami damage estimation using numerical model and post-tsunami data from Banda Aceh, Indonesia,” Coastal Engineering J., Vol.51, No.3, pp. 243-273, 2009.
- [28] S. Kawamoto, K. Miyagawa, et al., “Development and assessment of real-time fault model estimation routines in the GEONET real-time processing system,” Int. Association of Geod. Symposia, doi:10.1007/1345_2015_49, 2015.
- [29] The 2011 Tohoku Earthquake Tsunami Joint Survey Group, “Nationwide Field Survey of the 2011 Off the Pacific Coast of Tohoku Earthquake Tsunami,” J. of Japan Society of Civil Engineers, Series B, Vol.67, No.1 pp. 63-66, 2011.
- [30] T. Iinuma, M. Ohzono, et al., “Coseismic slip distribution of the 2011 off the Pacific coast of Tohoku Earthquake (M 9.0) estimated based on GPS data – Was the asperity in Miyagi-oki ruptured?,” Earth, Planets and Space, Vol.63, No.7, pp. 643-648, doi:10.5047/eps.2011.06.013, 2011.
- [31] T. Iinuma, R. Hino, et al., “Coseismic slip distribution of the 2011 off the Pacific Coast of Tohoku Earthquake (M 9.0) refined by means of seafloor geodetic data,” J. of Geophys. Res., Vol.117, B07409, doi:10.1029/2012JB009186, 2012.
- [32] H. Tsushima, R. Hino, et al., “tFISH/RAPiD: Rapid improvement of near-field tsunami forecasting based on offshore tsunami data by incorporating onshore GNSS data,” Geophys. Res. Lett., 41, pp. 3390-3397, doi:10.1002/2014GL059863, 2014.
- [33] T. Nagai, “Development and improvement of the Japanese coastal wave observation network (NOWPHAS),” J. of Japan Society of Civil Engineers, No.609 (VI-41), pp. 1-14, 1998 (in Japanese).
- [34] Y. Kaneda, “Real time monitoring systems and advanced simulation researches for Earthquakes/ Tsunami disaster mitigation,” AGU Fall Meeting 2013, San Francisco, NH34A-04, 2013.
- [35] N. Takahashi, Y. Ishihara, et al., “New buoy observation system for tsunami and crustal deformation,” Marine Geophys. Res., Vol.35, Issue 3, pp. 243-253, doi:10.1007/s11001-014-9235-7, 2014.
- [36] M. Imano, M. Kido, et al., “Improvement in the Accuracy of Real-Time GPS/Acoustic Measurements Using a Multi-Purpose Moored Buoy System by Removal of Acoustic Multipath,” Int. Association of Geod. Symposia, doi: 10.1007/1345_2015_192, 2015.