A SEARCH FOR ELF VLF ACTIVITY ASSOCIATED WITH EARTHQUAKES USING ISIS SATELLITE DATA/

For more than 10 years, researchers using satellite observations have reported anomalous phenomena associated with seismic activity. Increas es in ELF/VLF filter amplitudes have been associated with preshock and postshock events near satellites in a number of studies. However, an examination of the wideband ELF/VLF data from the low-altitude ISIS sa tellites shows no significant changes in electromagnetic (EM) activity associated with earthquakes. In the analysis of wideband data from 16 4 satellite passes above 39 earthquakes, no unique or familiar (previo usly observed) ''seismo-active emission'' can be linked to the occurre nce of a nearby earthquake. The electromagnetic activity levels in ELF /VLF spectra observed by the ISIS 2 satellite before and after 37 shoc ks is examined and compared with a set of selected control orbits. Com parisons are made of EM activity changes between earthquake passes and control passes over the epicenter location. No increase in the activi ty for earthquake passes is found. These results do not change when va rious constraints are placed on the data in an attempt to test for dep endencies on different criteria. No precursory, coseismic, or postseis mic effects are found. No significant evidence is found for difference s between the data sets which would suggest any ''seismo-active'' acti vity.