Seismology, Tsunami, Volcanology
The Earth system is a dynamically coupled system composed of the ionosphere, atmosphere, ocean, and solid earth (mantle and core) bound by the elastic, gravitational, Coriolis, and electro-magnetic forces. We study various geophysical phenomena such as Earth/crustal deformation, gravity change, ionospheric disturbance, seismic waves, atmospheric waves (acoustic and gravity ones), tsunamis, ocean tides to understand the mechanisms of multi-sphere interactions, including not limited to, during earthquakes and volcanic eruptions. Based upon physical first principles and deep geophysical insight we aim at discovering and comprehensively understanding new geophysical phenomena.
We discovered the mechanisms for example
(1) Atmospheric pressure change associated with a M8 class earthquake in Japan and modeling the relationship between the ground motion and atmospheric pressure change.
(2) Acoustic resonant oscillations between the atmosphere and the solid Earth during major volcanic eruptions.
(3) Traveltime delay and initial phase reversal of trans-oceanic tsunamis.
Our new research targets are
(1) Tsunamis without tsunami sources: Retrieval of tsunamis by the interferometry of deep ocean pressure records.
(2) Atmospheric waves and ionospheric disturbance excited by earthquakes and volcanic eruptions.
and many more studies on multi-sphere interactions.
1. Watada, S.(2023), Progress and Application of the Synthesis of Trans-oceanic Tsunamis, Prog. Earth Planet. Sci., 10, 26, doi:10.1186/s40645-023-00555-1
2. Watada, S., Imanishi, Y., and Tanaka, K. (2023), Detection of air temperature and wind changes synchronized with the Lamb wave from the 2022 Tonga volcanic eruption, Geophys. Res. Lett., 50, e2022GL100884, doi:10.1029/2022GL100884.
3. Watada, S., S. Kusumoto, and K. Satake (2014), Traveltime delay and initial phase reversal of distant tsunamis coupled with the self-gravitating elastic Earth, J. Geophys. Res. Solid Earth, 119(5), 4287–4310, doi:10.1002/2013JB010841.