HR: 0830h
AN: T51E-0206    [PDF]
TI: Ultra Sensitive Monitoring of the Geomagnetic Field Combined with Radon Emanation as a Tool for Studying Earthquake Related Phenomena
AU: * Zafrir, H
EM: zafrir@mail.gsi.gov.il
AF: Geological Survey of Israel, 30 Malkhei Israel St., Jerusalem, 95501 Israel
AU: * Zafrir, H
EM: zafrir@mail.gsi.gov.il
AF: SOREQ, NRC, Yavne, 81800 Israel
AU: Ginzburg, B
EM: borginz@soreq.gov.il
AF: SOREQ, NRC, Yavne, 81800 Israel
AU: Hrvoic, I
EM: ivan@gemsys.on.ca
AF: GEM Systems, 52 West Beaver Creek Road West, Suite 14, Richmond Hill, ON L4B 1L9 Canada
AU: Shirman, B
EM: bshirman@netvision.net.il
AF: Survey of Israel, 1 Lincoln St., Tel Aviv, 65220 Israel
AU: Gazit-Yaari, N
EM: naama@mail.gsi.gov.il
AF: Geological Survey of Israel, 30 Malkhei Israel St., Jerusalem, 95501 Israel
AU: Steinitz, G
EM: steinitz@mail.gsi.gov.il
AF: Geological Survey of Israel, 30 Malkhei Israel St., Jerusalem, 95501 Israel
AU: Wilson, M
EM: mike@gemsys.on.ca
AF: GEM Systems, 52 West Beaver Creek Road West, Suite 14, Richmond Hill, ON L4B 1L9 Canada
AB: An ultra sensitive magnetic gradiometric system and a very sensitive, continuous radon monitoring system are located with an existing seismic array, at the Amram Geophysical Observatory near Eilat, Israel. The purpose of setting these independent technologies together was to assess their applicability as a combined tool for studying earthquake related phenomena in the Dead Sea Rift (DSR) - a geodynamically active region (seismogenic). The magnetic system consists of three GEM Systems SuperGrad$^\copyright$ magnetometers, spaced several tens of meters apart, having a sensitivity of 0.05 pT/$\sqrt{Hz}$, bandwidth ranging from DC to 10 Hz and featuring very high long-term stability. Several months of on-site operation shows that the magnetic gradiometric system demonstrates: a) a new capability of ultra-high precise geomagnetic field observations at sub-pT resolution; b) enables the suppression of diurnal variations and pulsations, thus enhancing the resolution of residual shallow crustal contributions; c) the registration bandwidth provides an opportunity to analyze field variation in a wide frequency domain, which was not attainable so far. The initiative of including radon monitoring is based on the combination of: a) large multi-day temporal radon variations are recorded at the Amram site; b) part of the variation is correlated to radon signatures at other locations in the same tectonic segment; c) some of the signals are similar to the multi-day signals, from another part of the DSR, which are significantly related to weak earthquakes in the DSR (Geology, v. 31, 505-508). The operated radon system consists of alpha and gamma ray detectors, integrating at a rate of 15 minutes and having a sensitivity of below 0.1 pCi/l in the geogas. The combined geophysical system is in continuous operation since 2002. It is expected that joint analysis of long-term multi-sensor data series will reveal subtle geophysical signals that precede or follow earthquakes in the region.
UR: http://www.gemsys.ca
DE: 1555 Time variations--diurnal to secular
DE: 1594 Instruments and techniques
DE: 7215 Earthquake parameters
DE: 7223 Seismic hazard assessment and prediction
DE: 8123 Dynamics, seismotectonics
SC: Tectonophysics [T]
MN: 2003 Fall Meeting