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SuperGrad -
Frequently Asked Questions: The System
Increasingly, researchers are looking in to the applications of
magnetics alone or in combination with seismic or radon measurements for
earthquake research. GEM's new SuperGrad technology is the highest
sensitivity gradiometer ever developed for these types of applications.
Below is
a set of commonly asked system-related questions about SuperGrad.
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What is the SuperGradiometer?
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What is the range of influence of SuperGrad?
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What is the role of SuperGrad in earthquake research applications?
* What are its limitations?
What is the SuperGradiometer?
The GEM Systems
GSMP-20GS3 is the highest sensitivity total magnetic field measuring
device ever developed. The GSMP-20GS has a 0.05 pT root-mean-square (rms)
sensitivity at a sampling rate of 20 Hz (averaged over a 1 second
interval) – making it well over an order-of-magnitude more sensitive
than any other gradiometer in existence.
The GSMP-20GS3 was
developed in response to the United State Geological Survey’s (USGS)
requirement for an ultra-high sensitivity magnetic gradiometer. Key
technologies include the implementation of optically pumped Potassium
methods combined with large sensors for ultra-high sensitivities,
suitable for resolving very subtle anomalies.
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What is the range of influence of SuperGrad?
Depending on the
strength of total field anomaly generated by a subsurface object or
source, the range of influence of SuperGrad is estimated to lie between
10’s to several 100’s of kilometers of the surface. This range makes it
ideal for investigation of earthquake sources which
generally lie well within these extents.
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What is the role of SuperGrad in
earthquake research?
According to
earthquake researchers,
“There is convincing evidence that changes in ground resistivity and low
frequency (dc to 10Hz) electric and magnetic fields precede
earthquakes.”
The SuperGrad’s role
is to look at low frequency magnetic phenomena with a greater
sensitivity than ever before possible. This is the objective of current
research in Israel which is progressing with the establishment of a
second observatory station, in the central sector of the Dead Sea Rift,
to complement the existing station established in 2001.
Specifically, the
SuperGrad is targeted to sense extremely minute variations in
gradiometric fields that may be associated with the precursor movement
and/or strain loading prior to an upcoming earthquake event.
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What are its limitations?
The main limitation
of SuperGrad reflects the key strength of the method (i.e. sensitivity). The
system is very sensitive and must be totally immobilized in order to
maintain precise measurement. This can be mitigated through careful
design and thermal shielding of the instrument sensors in a wind-proof
enclosure.
During an earthquake,
the sensors will necessarily move as the ground encounters
strong motion. Therefore, readings will be disrupted during the
earthquake and may be shifted after the event.
However, as the
purpose of the system is to detect precursor events, this sensitivity is
not a significant issue; the system is able to detect the events for
which it is designed provided installation guidelines are followed.
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For
more information
For more information
on Potassium technologies, please
refer to the
technical papers on this site.
Specifications on the SuperGrad are provided in the
GSMP-20S3 brochure.
In addition, you may want to
refer to:*
SuperGrad - FAQ: Basic
*
SuperGrad - FAQ: The System
*
SuperGrad / Radon - FAQ: ISGR
* SuperGrad - FAQ: SuperGrad in Action
If you would like
information specific to your work, please visit our
Quotations
area and submit a Request for Quotation. We would be delighted to
provide you with a no-obligation quote suited to your exact needs.
GEM Advanced Magnetometers.
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