Just for fun... I
Googled:
From Argonne Nat'l Laboratories:
http://www.newton.dep.anl.gov/askasc...9/env99354.htm
The severity of the earthquake and movement of the fault may
have created a large amount of static electricity, which was
discharged from the ground. This guess is purely speculation
and I hope that a geophysicist can shed more light on this
unusual phenomenon.
David R. Cook
Meteorologist
Climate Research Section
Environmental Science Division
From Southern Illinois University:
http://perspect.siuc.edu/05_fall/earthquakes.html
Scientists in the United States, Europe, and Japan have scrutinized electrical data after the fact and have detected minute increases in electrical activity just before or during big quakes. They've suggested various alternative explanations for these findings, such as earthquake-triggered shifts in the water table or failure of power grids. So Ferré, an assistant professor of geology at SIUC, has gone to the rocks for answers.
The best evidence for earthquake lightning, he says, is locked up in dark veins that are often found cutting through rocks in quake-prone areas. The thin, sheet-like veins resemble a glassy black volcanic rock called tachylite--hence the name "pseudotachylites." Ferré calls them the "black boxes" of earthquakes because, he says, they record information crucial to understanding catastrophic seismic events.
Lots more (see Google link above) but... a place to start,
Fred