Fig. 5From: Tsunami-induced magnetic fields detected at Chichijima Island before the arrival of the 2011 Tohoku earthquake tsunamiGeneration of induction of electric current by a tsunami according to the Biot-Savart law. a Relationship of geomagnetism, tsunami flow, and induced electric current, where F z is the Z component of Earth’s magnetism, J is electric current density, and V x is flow velocity. b The Biot-Savart law shows the relation between J and the induced magnetic field dB z, expressed as \( {B}_Z=\frac{\mu }{4\pi}\frac{Jdl \sin \theta }{R^2} \), where μ is the magnetic permeability (see Appendix 3), R is the distance between electric current and observation point, dl is the micro distance, and θ is the angle between dl and R Back to article page