Space–time behaviour of magnetic anomalies induced by tsunami waves in open ocean

Abstract

The magnetic anomaly induced by an inhomogeneous velocity field under tsunami waves in open ocean is investigated. With asymptotical analysis, an explicit series solution of the kinematic dynamo problem is established for weak dispersive water waves. The magnetic field induced by typical tsunami models, including single wave and -wave, can be directly obtained using the proposed series solution. The characteristics of the magnetic field induced by two realistic tsunami events are investigated. By analysis, the magnetic magnitude induced by a 1 m high tsunami is estimated as of the order of 10 nT at the sea surface, which depends on the wave parameters as well as the Earth's magnetic field. The space and time behaviour of the magnetic field shows fair similarity with the field data at Easter Island during the 2010 Chile tsunami.