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Regional spectral analysis of moderate earthquakes in northeastern North America—Final Report to the Nuclear Regulatory Commission, Project V6240, Task 3

Open-File Report 2018-1073
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https://doi.org/10.3133/ofr20181073

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Abstract

We analyze the Fourier spectra of S+Lg+surface wave groups from the horizontal and vertical components of broadband and accelerogram recordings of 120 small and moderate (2< Mw <6) earthquakes recorded by Canadian and American stations sited on rock at distances from 3 to 600 kilometers. There are seven Mw 4.0–4.5, six Mw 4.5–5.0, and three Mw ≥5 earthquakes in this event set. We test the regional spectral analysis by comparing the moment magnitudes with the moment magnitudes from the earthquake moment tensors determined by Bob Herrmann (St. Louis University) for 27 events, obtaining dMw=0.004±0.074. We determine the Lg attenuation in seven regions within northeastern North America: Charlevoix, lower St. Lawrence, Maine, Northern New York, lower Great Lakes, Ontario, and Nunavut. These attenuation estimates yield an average attenuation Q= (368±13)f (0.54±0.02) for the Appalachian region, a stronger attenuation Q= (317±16)f (0.54±0.03) for the Appalachian lowlands, and a weaker attenuation Q=(455±20)f (0.51±0.02) for Ontario and western Quebec. For events in Nunavut and northernmost Quebec, we estimate a similar attenuation for r <450 km, but a weaker attenuation Q= (773±70)f (0.27±0.06) for Lg propagation for 450< r <1700 kilometers. This far-regional attenuation allows us to analyze recordings of the 1989 Ungava and Payne Bay earthquakes obtained in Ontario and southern Quebec. We use these regional attenuations to determine the corner frequencies, stress drops, and radiated energies of the 120 earthquakes.

Suggested Citation

Boatwright, J., 2018, Regional spectral analysis of moderate earthquakes in northeastern North America—Final report to the Nuclear Regulatory Commission, project V6240, task 3: U.S. Geological Survey Open-File Report 2018–1073, 39 p., https://doi.org/10.3133/ofr20181073.

ISSN: 2331-1258 (online)

Study Area

Table of Contents

  • Preface
  • Abstract
  • Introduction
  • Regional Spectral Analysis (RSA)
  • Comparing RSA Moments to Estimates from Moment Tensor Analyses
  • S+Lg Attenuation in Northeastern North America
  • Earthquake Stress Drops in Northeastern North America
  • References Cited
Publication type Report
Publication Subtype USGS Numbered Series
Title Regional spectral analysis of moderate earthquakes in northeastern North America—Final Report to the Nuclear Regulatory Commission, Project V6240, Task 3
Series title Open-File Report
Series number 2018-1073
DOI 10.3133/ofr20181073
Year Published 2018
Language English
Publisher U.S. Geological Survey
Publisher location Reston, VA
Contributing office(s) Earthquake Science Center
Description Report: vi, 39 p.
Country United States
Online Only (Y/N) Y
Google Analytic Metrics Metrics page
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