Geoscience Reference
In-Depth Information
How much current can be delivered per unit rock volume? In the case of gabbro
the rock volume between the pistons in about 10 cm
3
. We measure typically 300 pA.
If the rock volume were 1 km
3
, the outfl ow current would be on the order of 30,000
A. By stressing the rock tiles faster, the steady-state outfl ow currents were found to
increase to 50,000 A, plus an initial spike that can rise to 100,000 A/km
3
.
In an electrochemical battery the current fl owing through the outer circuit is car-
ried by electrons, while the current through the electrolyte is carried by cations. In the
case of the rocks, the current fl owing through the outer circuit is carried by electrons,
while the current running through the rock, the internal current, is carried by defect
electrons or holes, also known as “positive holes” or pholes for short at briefl y outlined
above.
KEYWORDS
•
Earthquake lights
•
Low frequency electromagnetic
•
Pre-earthquake phenomena
•
Seismological models
ACKNOWLEDGMENTS
This work has been supported in part by the NASA Ames Research Center Director's
Discretionary Fund and by a GEST Fellowship from the NASA Goddard Space Flight
Center, Planetary Geodynamics Laboratory. I thank my students and my coworkers A.
Takeuchi (supported by a JSPS fellowship) and Dr. Bobby WS Lau (supported through
a grant from NGA).
