Earthquake
Hazards. Israeli Scientists are Taking
the Long-term View to Monitoring and Prediction
Scientists
from the Soreq Nuclear Research Center, Geological Survey of
Israel and Survey of Israel, and GEM professionals are collaborating
on a long-term research project into earthquake hazards. The
study is based on examination of results from GEM's ultra-high
sensitivity
SuperGrad
system and radon monitoring systems.
Discrimination
of Sources
During
the last few decades, many investigations have looked into the
relation between seismic activity and anomalous behavior of
the geomagnetic field. However, seismically related changes
in the behavior of the Earth's magnetic field are very often
overlapped by diurnal variations of ionosphere and magnetosphere
origin and sometimes by artificial field disturbances (from
densely populated regions).
Scientists
are looking into the solution of the origin discrimination problem
by taking into account the difference in distance between observation
point and field sources. This difference brings the opportunity
for distinction of the source location on the base of field
spatial structure analysis.

With
the development of GEM's new super-sensitive optically pumped
Potassium gradiometer (shown above), there is now an opportunity
for short-base gradiometer measurements with sub-pT resolution.
The application of such a technique is intended to significantly
suppress the external variations and thus give good grounds
to filter out magnetic field changes that are not related to
earthquake phenomena.
Integration
of Radon Measurements
Since
1990, various studies have been performed to evaluate radon
anomalies along the western shore of the Dead Sea. The results
obtained show that correlation of Rn events with earthquakes
in the nearby sectors of the Rift exceeds significantly the
value expected for randomness. Moreover, the correlation improves
for earthquake magnitudes > 2 and > 3 in the nearby sectors
of the Rift. The establishment of this link between Rn events
and earthquakes in a specific region is a contribution to the
notion of using Rn monitoring as an earthquake precursor.
The
scientists expect results of joint monitoring of geochemical
(Rn) and geomagnetic parameters in the test site, analyzed together
with the regional seismic data will enable them to obtain higher
correlations between earthquakes and precursor phenomena.
Long-term
Monitoring
To
this end, they are carrying out long-term simultaneous measurements
of Earth's magnetic field gradient (difference) and Rn emanation
in the Northwestern part of the Dead Sea Rift transform. This
is the first time that combined radon and geomagnetic measurements
have been conducted.
The
ultimate goal is to integrate Rn stations and super-sensitive
magnetic gradiometers into a multi-channel system for geophysical
monitoring of active faults -- an extremely attractive complementary
approach to the problem of earthquake prediction.
For
more information, interested readers may also want to refer
to the following
link.
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