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Methods for amplitude calibration and orientation discrepancy measurement; comparing co-located sensors of different types in the Southern California Seismic Network

Zefeng Li, Egill Hauksson and Jennifer Andrews
Methods for amplitude calibration and orientation discrepancy measurement; comparing co-located sensors of different types in the Southern California Seismic Network
Bulletin of the Seismological Society of America (June 2019) 109 (4): 1563-1570

Abstract

Modern seismic networks commonly equip a station with multiple sensors, to extend the frequency band and the dynamic range of data recorded at the station. In addition, in our recent study we showed that comparison of data from co-located seismometers and accelerometers is useful for detecting instrument malfunctions and monitoring data quality. In this study, we extend comparison of data from different co-located sensors to two other applications: (1) amplitude calibration for data from vertical short-period sensors with strong-motion sensors as baseline and (2) measurement of orientation discrepancy between strong-motion and broadband sensors. We perform systematic analyses of data recorded by the California Institute of Technology/U.S. Geological Survey Southern California Seismic Network. In the first application, we compare the amplitude of data from vertical short-period sensors to that of data from co-located strong-motion sensors and measure the amplitude calibration factors for 93 short-period sensors. Among them, 49 stations are measured at approximately 1.0, 42 measured at approximately 0.6, as well as two outlying stations: GFF at 0.3 and CHI at 1.3. These values are found to be related to the sensors' sensitivity values. In the second application, we measure orientation discrepancy between 222 co-located broadband and strong-motion sensors. All the vertical orientation differences are found to be within 5 degrees . However, the horizontal orientation differences of 22 stations are greater than 6 degrees , among which four stations have reverse rotation or 180 degrees from the expected orientation. These measurements have been communicated to network operators and fixes are being applied. This study, together with our previously developed data monitoring framework, demonstrates that comparison of different co-located sensors is a simple and effective tool for a broad range of seismic data assessment and instrument calibration.


ISSN: 0037-1106
EISSN: 1943-3573
Coden: BSSAAP
Serial Title: Bulletin of the Seismological Society of America
Serial Volume: 109
Serial Issue: 4
Title: Methods for amplitude calibration and orientation discrepancy measurement; comparing co-located sensors of different types in the Southern California Seismic Network
Affiliation: California Institute of Technology, Division of Geological and Planetary Sciences, Pasadena, CA, United States
Pages: 1563-1570
Published: 20190625
Text Language: English
Publisher: Seismological Society of America, Berkeley, CA, United States
References: 16
Accession Number: 2019-062131
Categories: Seismology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sketch maps
N33°00'00" - N37°00'00", W120°00'00" - W115°00'00"
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2019, American Geosciences Institute. Abstract, Copyright, Seismological Society of America. Reference includes data from GeoScienceWorld, Alexandria, VA, United States
Update Code: 201932
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