Co-seismic and near-seismic ULF electromagnetic events as observed in Karimshino station at Kamchatka
Abstract
Using magnetic field and electric field ULF (0.003 3 Hz) variations observed in Karimshino complex geophysical station at Kamchatka during last 2 years together with seismometer recordings the co-seismic (±1minute around arrival time of seismic shock) and near-seismic (±3 hours) electromagnetic events have been analyzed. Unlike artificial shaking effect the co-seismic electromagnetic pulses begin several seconds before the seismic pulses and continue about 30-40 seconds after them. Comparisons of wavelet electric and magnetic spectra are chosen for identification of the real events. Explanation by MHD mechanisms and results of computations are presented. Near-seismic ULF magnetic noise intensification about 0,5-2 hours ahead of the strong earthquakes is also considered. Unfortunately it is difficult to distinguish it from the magnetospheric magnetic pulsations. Nevertheless the possibility of its generation by electrokinetic mechanisms during accelerated preseismic water movement with velocity up to 0.1 m/s as well as MHD mechanisms caused by rock fractures near focal zone are also discussed.
- Publication:
-
EGS - AGU - EUG Joint Assembly
- Pub Date:
- April 2003
- Bibcode:
- 2003EAEJA.....2717S