A number of published reports claim to have identified magnetic field changes prior to earthquakes. If the magnetic-precursory signals can be shown to be consistent and reproducible, this work would have far-reaching implications for earthquake prediction. The most prominent finding of a magnetic precursor is that measured prior to the 1989 Loma Prieta earthquake in central California by Fraser-Smith et al., 1990, GRL. For my USGS Mendenhall Postdoctoral Fellowship (supervisors Jeffrey Love and Malcolm Johnston), I am conducting a careful and systematic study of these reported precursors. I have re-examined the Loma Prieta precursory data, comparing them against independent data collected at the time of the earthquake from sites in the United State and in Japan. From my analysis, I infer that the key components of the precursory signal identified by Fraser-Smith et al. can very likely be explained by data corruption.

This work has recently been presented at the IUGG Assembly in Perugia, Italy and the AGU Fall Meeting in SF, CA during 2007. We are also preparing manuscripts to submit to refereed journals. A useful by-product of this work is an enhanced fundamental understanding of the other sources of geophysical electromagnetic radiation in the ULF-LF bands, such as magnetospheric, ionospheric, and thunderstorm phenomena.