Seismic monitoring and high-frequency noise using arrays in the Arabian Peninsula
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S. I. GSF 2018
Seismic monitoring and high-frequency noise using arrays in the Arabian Peninsula Moira L. Pyle 1 & Rengin Gök 1 & Abdullah Al-Amri 2 & Issa El-Hussain 3 & Yasir Al-Rawahi 3 Received: 27 April 2020 / Accepted: 10 September 2020 # Saudi Society for Geosciences 2020
Abstract Seismic arrays provide useful tools for regional seismic monitoring. Two small-aperture, regionally-oriented arrays, QWAR and HQAR, were deployed in Saudi Arabia and Oman in 2012 and 2016. We utilize a time-domain beampacking method, similar to frequency-wavenumber analysis, to examine the performance of the arrays in terms of slowness and azimuthal bias and event detection capabilities. Additionally, we investigate persistent ambient noise sources recorded by the arrays. We find that the arrays provide slowness vectors with biases comparable with similar-sized arrays of the International Monitoring System in other locations around the world. At QWAR, regional events of magnitude 3.0 and above are detected a majority of the time, and as magnitudes increase to 4.0 and above, the detection rate is greater than 82%. Strong noise generation, primarily with slownesses characteristic of Lg waves, is found in the directions of the northern Arabian/Persian Gulf and southern Red Sea and may be a factor in event detection capabilities. Keywords Array analysis . Seismic noise . Beamforming . Event detection
Introduction The Middle East is a complicated tectonic region with large amounts of active seismicity. Seismic monitoring and improved methods for detecting and locating earthquakes are key to a better understanding of local seismic hazard. While many seismic networks are already in place in the region and its surrounding, the addition of small-aperture seismic arrays can provide additional tools for the monitoring process. Arrays provide information on the direction of incoming energy in the form of an apparent velocity and backazimuth direction that allows for distinctions between different seismic phases with different ray parameters as well as backPrepared for submission to Arabian Journal of Geosciences, LLNLJRNL-808484 This article is part of the Topical Collection on Seismic and Earthquake Engineering Studies in the Arabian Plate and the Surrounding Region * Moira L. Pyle [email protected] 1
Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
2
King Saud University, Riyadh, Saudi Arabia
3
Sultan Qaboos University, Muscat, Oman
projection to source regions. Additionally, arrays can provide similar information about ambient seismic noise, which can aid in a better understanding of detection limitations. As part of capacity building and joint research efforts of the Seismic Cooperation Program at Lawrence Livermore National Laboratory, two arrays were collaboratively installed in Saudi Arabia in 2012 and Oman in 2015 (Fig. 1). The arrays, located on the relatively stable Arabian Peninsula, are surrounded by divergent, transform, and convergent plate boundaries, placing them in a prime location to aid in regional even
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