Magnetic signals from natural hazards
Earth's salty oceans are electrically conductive fluid passing through Earth's variable main magnetic field-- so they induce electric currents and magnetic fields of their own. Marine magnetic fields depend on the given ocean flow's transport and electrical conductivity. All forms of ocean flow induce magnetic fields-- including the flow caused by tsunamis. Tsunamis can be created by submarine earthquakes, landslides, or volcanic eruptions. The magnetic fields induced by tsunamis can be used to better understand the geophysical processes creating tsunamis, as well as to improve our tsunami hazard warning systems.
Earthquake-induced tsunamis
T. Minami, N. R. Schnepf, & H. Toh (2021). Tsunami-generated magnetic fields have primary and secondary arrivals like seismic waves. Scientific Reports, 11, doi.org/10.1038/s41598-021-81820-5.
N. R. Schnepf, M. C. Nair, C. An, H. Sugioka & H. Toh (2016). Time-frequency characteristics of tsunami magnetic signals from four Pacific Ocean events. Global Tsunami Science: Past and Future, Volume I (pp. 3935-3953). Birkhäuser, Cham. doi.org/10.1007/978-3-319-55480-8_14.
Eruption-induced hazards / tsunamis
N. R. Schnepf, T. Minami, H. Toh, & M. Nair (2022). Magnetic Signatures of the January 15 2022 Hunga Tonga–Hunga Ha`apai Volcanic Eruption. Geophysical Research Letters, doi: 10.1029/2022GL098454.