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Quality analysis of high-frequency air-gun shot seismic recordings in the Juan de Fuca Plate

Sampath Rathnayaka and Haiying Gao
Quality analysis of high-frequency air-gun shot seismic recordings in the Juan de Fuca Plate
Seismological Research Letters (November 2018) 90 (1): 294-304

Abstract

The goal of this study is to extract high-frequency seismic waveforms recorded by both offshore and onshore instrumentations and to quantitatively evaluate the data quality in terms of source-to-receiver distance, source parameters, water depth, and sediment thickness. There were two active-source seismic experiments within the Juan de Fuca plate, MGL1211 and MGL1212, during the first year deployment of the Cascadia Initiative Amphibious Array. In total, we chose 114 ocean-bottom seismometers and 211 inland stations located around the experiment region. The common receiver gathering analysis shows that most offshore stations located in deep-water record clear first P-wave arrivals up to 150 km away from the air-gun shot. The first arrival transits from crustal phase Pg to head wave Pn at a source-to-receiver distance of 25-40 km. For stations located at shallow water, the seismic recordings appear much noisier compared with those of deep-water stations. Only five inland stations record clear air-gun shot signals up to 200 km away from the source. The signal-to-noise ratio of the first P arrivals generally decreases from a few hundred down to a single number with increasing source-to-receiver distance, from deep ( approximately 3000 m) to shallow water ( approximately 100 m), with increasing sediment thickness and decreasing air-gun shot spacing and time interval. On average, the ratio appears 5-10 times lower at inland stations than at offshore stations. The sediment thickness estimated in this study demonstrates significant along-strike variations, which is up to 5 km offshore Oregon and 3.5 km offshore Washington. The coincidence of thick sediments with seismicity suggests the importance of sediments on the coupling of the plate interface.


ISSN: 0895-0695
EISSN: 1938-2057
Serial Title: Seismological Research Letters
Serial Volume: 90
Serial Issue: 1
Title: Quality analysis of high-frequency air-gun shot seismic recordings in the Juan de Fuca Plate
Affiliation: University of Massachusetts at Amherst, Department of Geosciences, Amherst, MA, United States
Pages: 294-304
Published: 20181114
Text Language: English
Publisher: Seismological Society of America, El Cerrito, CA, United States
References: 54
Accession Number: 2019-002329
Categories: SeismologyApplied geophysics
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sketch map
N42°00'00" - N46°19'60", W124°34'60" - W116°34'60"
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: 201903
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