Dead Sea Fault area microearthquake observations from 4 borehole stations
Abstract
Seismological measurements conducted in deep boreholes can provide information not available in measurements taken on the surface. We demonstrate this with 4 borehole stations along the Dead Sea Fault. One is a seismometer in the Masada Deep borehole (MDBI), an abandoned oil well, at a depth of 1,256 m (1,516 bsl). This installation has been in operation since end of 2012. Recently another borehole station (YEL3; an abandoned water well) was installed in the Dead Sea basin, about 8 km south of MDBI. Both stations are located near the Western Boundary Fault of the Dead Sea basin. Another two borehole stations, about 160 km north of the Dead Sea basin, were installed on adjacent sides of the Sea of Galilee, near this basin's boundary faults.
In this talk we present observations of Dead Sea Fault microearthquakes at each station. Only a few of these events were recorded by the Israel Seismic Network (ISN). The seismic background noise reduction of these stations has obvious advantages in detection and identification of earthquakes and explosions. For example, the stations detect about 30% more quarry explosions as compared to observations of the ISN. As a result, we also show that borehole seismograms are broader-band than the on-surface observations of nearby comparable seismometers. Many of the earthquakes, sometimes in clusters, occurred directly underneath MDBI, at depths of 10-25 km. These events have unique waveforms, not previously seen in Dead Sea Fault earthquake signals. Using cross-correlation technique we have found several new locations of seismic activity, either underneath the station or along the Dead Sea Fault. To better understand these new locations and waveforms, we are seeking to add further downhole sites, including the testing of new borehole instruments and data analysis methods.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.S11D0386H
- Keywords:
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- 7209 Earthquake dynamics;
- SEISMOLOGYDE: 7212 Earthquake ground motions and engineering seismology;
- SEISMOLOGYDE: 7215 Earthquake source observations;
- SEISMOLOGYDE: 7223 Earthquake interaction;
- forecasting;
- and prediction;
- SEISMOLOGY