Seismo-electromagnetics are various electro-magnetic phenomena believed to be generated by tectonic forces acting on the Earth's crust, and possibly associated with seismic activity such as earthquakes and volcanoes.
[citation needed] The VAN method – named after P. Varotsos, K. Alexopoulos and K. Nomicos, authors of the 1981 papers describing it[1][2] – measures low frequency electric signals, termed "seismic electric signals" (SES), by which Varotsos and several colleagues claimed to have successfully predicted earthquakes in Greece.
[23] They have deployed a network of sensor stations that detect the electromagnetic pulses the team believes precede major earthquakes.
[31] Additional magnetometers were subsequently deployed across northern and southern California, but after ten years, and several large earthquakes, similar signals have not been observed.
More recent studies have cast doubt on the connection, attributing the Corralitos signals to either unrelated magnetic disturbance[32] or, even more simply, to sensor-system malfunction.
[34] Two recent studies by Konstantinos Eftaxias and his colleagues examined ULF magnetic fields preceding major earthquakes.
[36][37][better source needed] Professor Kosuke Heki of Hokkaido University in Japan said that he discovered by accident that GPS signals changed about 40 minutes before the 2011 Tohoku-Oki earthquake.
He suggested that the GPS signals were detecting variations in the levels of the TEC (total electron content) of the ionosphere in the hour preceding an earthquake.
[38][39] The "Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions" satellite, constructed by CNES, has made observations which show strong correlations between certain types of low frequency electromagnetic activity and the most seismically active zones on the Earth, and have shown a sharp signal in the ionospheric electron density and temperature near southern Japan seven days before a 7.1 magnitude earthquake occurred there (on August 29 and September 5, 2004, respectively).
More in general, it has been proposed for defining the near-Earth electromagnetic, plasma, and particle environment, and for studying perturbations and instabilities in the ionosphere-magnetosphere transition region.
[41] The Deformation, Ecosystem Structure and Dynamics of Ice (DESDynI) radar satellite, which was canceled in the White House's 2012 budget proposal, would have the capacity to identify elastic strain in tectonic plates, combining L-band interferometric synthetic aperture radar and a multi-beam infrared lidar to detect strains in the Earth's surface that could lead to serious earthquakes.
[42][43] Russia and the United Kingdom agreed to jointly deploy two satellites in 2015 that will measure electromagnetic signals that are released from the earth's crust prior to earthquakes.