Beamforming technique for investigation of lateral variability at geotechnical sites

A beamformer in seismology is a signal receptor with a series of geophones, in which a beam of elastic waves is formed like a light beam by adjusting signal delays at individual geophones. Recently, beamforming has extended its applications to surface-wave measurement. In surface-wave measurement, b...

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Main Authors: Norfarah Nadia Ismail, Sung-Ho Joh, Raja Hassanul Musa Raja Ahmad
Format: Article
Language:English
Published: Universiti Kebangsaan Malaysia 2012
Online Access:http://journalarticle.ukm.my/5681/
http://journalarticle.ukm.my/5681/1/17%2520Norfarah.pdf
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author Norfarah Nadia Ismail,
Sung-Ho Joh,
Raja Hassanul Musa Raja Ahmad,
author_facet Norfarah Nadia Ismail,
Sung-Ho Joh,
Raja Hassanul Musa Raja Ahmad,
author_sort Norfarah Nadia Ismail,
building UKM Institutional Repository
collection Online Access
description A beamformer in seismology is a signal receptor with a series of geophones, in which a beam of elastic waves is formed like a light beam by adjusting signal delays at individual geophones. Recently, beamforming has extended its applications to surface-wave measurement. In surface-wave measurement, beamforming provides unique advantages over other surface-wave methods, such as full automation in data analysis as well as directional signal reception to minimize scattered noise and multiple reflections in signals. However, certain defects depreciate the value of beamforming in terms of its practicality and feasibility. These include the requirement of having many receivers and the loss of small wavelength data due to spatial aliasing. It leads to insensitivity in identification of lateral variability, which creates the problem of having to smooth out geologic features and complexities like folding, faults and fractures. In this paper, advances in the refinement of beamforming were described on two counts: improvement of sensitivity in identification of lateral variability and recovery of aliased wave numbers, which enables evaluation of shallow material. On the passage to refinement, synthetic waveforms for typical layering systems were generated to figure out characteristics of beamformer velocities in comparison with SASW velocities and theoretical normal-mode velocities.
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spelling oai:generic.eprints.org:56812016-12-14T06:39:10Z http://journalarticle.ukm.my/5681/ Beamforming technique for investigation of lateral variability at geotechnical sites Norfarah Nadia Ismail, Sung-Ho Joh, Raja Hassanul Musa Raja Ahmad, A beamformer in seismology is a signal receptor with a series of geophones, in which a beam of elastic waves is formed like a light beam by adjusting signal delays at individual geophones. Recently, beamforming has extended its applications to surface-wave measurement. In surface-wave measurement, beamforming provides unique advantages over other surface-wave methods, such as full automation in data analysis as well as directional signal reception to minimize scattered noise and multiple reflections in signals. However, certain defects depreciate the value of beamforming in terms of its practicality and feasibility. These include the requirement of having many receivers and the loss of small wavelength data due to spatial aliasing. It leads to insensitivity in identification of lateral variability, which creates the problem of having to smooth out geologic features and complexities like folding, faults and fractures. In this paper, advances in the refinement of beamforming were described on two counts: improvement of sensitivity in identification of lateral variability and recovery of aliased wave numbers, which enables evaluation of shallow material. On the passage to refinement, synthetic waveforms for typical layering systems were generated to figure out characteristics of beamformer velocities in comparison with SASW velocities and theoretical normal-mode velocities. Universiti Kebangsaan Malaysia 2012-12 Article PeerReviewed application/pdf en http://journalarticle.ukm.my/5681/1/17%2520Norfarah.pdf Norfarah Nadia Ismail, and Sung-Ho Joh, and Raja Hassanul Musa Raja Ahmad, (2012) Beamforming technique for investigation of lateral variability at geotechnical sites. Sains Malaysiana, 41 (12). pp. 1621-1627. ISSN 0126-6039 http://www.ukm.my/jsm/
spellingShingle Norfarah Nadia Ismail,
Sung-Ho Joh,
Raja Hassanul Musa Raja Ahmad,
Beamforming technique for investigation of lateral variability at geotechnical sites
title Beamforming technique for investigation of lateral variability at geotechnical sites
title_full Beamforming technique for investigation of lateral variability at geotechnical sites
title_fullStr Beamforming technique for investigation of lateral variability at geotechnical sites
title_full_unstemmed Beamforming technique for investigation of lateral variability at geotechnical sites
title_short Beamforming technique for investigation of lateral variability at geotechnical sites
title_sort beamforming technique for investigation of lateral variability at geotechnical sites
url http://journalarticle.ukm.my/5681/
http://journalarticle.ukm.my/5681/
http://journalarticle.ukm.my/5681/1/17%2520Norfarah.pdf