Regional Spectral Analysis of Three Moderate Earthquakes in Northeastern North America

Boatwright, John; Seekins, Linda C.

doi:10.1785/0120100225

Cited by 54 publications

(52 citation statements)

References 24 publications

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“…The Q model used in the plot, as determined by the average event-based attenuation in the frequency range from 0.32 to 16 Hz, at distances from 150-500 km (as described in Atkinson and Boore, 2014), is given by Q 416f 0:43 . This event-based Q model is within the range of typical regional Q models, such as those of Atkinson (2004) and Boatwright and Seekins (2011). In particular, it is very similar to the average Q relationship for southern Ontario and western Quebec, Q ∼ 500f 0:5 , as reported by Mereu et al (2013).…”

Section: Attenuation and Source Characteristicssupporting

confidence: 72%

Characteristics of the 17 May 2013 M 4.5 Ladysmith, Quebec, Earthquake

Atkinson

Assatourians

Lamontagne

2014

Seismological Research Letters

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The 17 May 2013 M 4.5 Ladysmith, Quebec, earthquake produced a rich instrumental and felt ground-motion database. We use instrument-corrected response spectra and Fourier amplitude data from 189 stations, at distances from 10 to 700 km, to examine the attenuation and source characteristics of this event. An interesting observation is that amplitudes were elevated throughout southern Ontario, probably due to site effects, possibly coupled with source radiation effects. Using attenuation-corrected observations, in combination with the known seismic moment to constrain the absolute amplitude level at the source, we obtain an apparent source spectrum for the Ladysmith earthquake. The Ladysmith source spectrum is well described by a Brune model spectrum for an event of M 4.5 with a stress drop of ∼500 bars. Overall, the source and attenuation characteristics of the Ladysmith event were typical for regional events. The earthquake occurred within the boundaries of the Ottawa-Bonnechere graben, which suggests a reactivation of one of its faults, though it is unclear which fault was involved. The focal mechanism does not match the orientation of the most conspicuous lineaments of the area. The earthquake may have reactivated a northwest-southeast brittle fault of local extent or a ductile thrust fault of the Grenville Geological Province.

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Section: Attenuation and Source Characteristicssupporting

confidence: 72%

Characteristics of the 17 May 2013 M 4.5 Ladysmith, Quebec, Earthquake

Atkinson

Assatourians

Lamontagne

2014

Seismological Research Letters

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“…Given that there are no data within 10 km, this result may seem paradoxical, but it is easily explained. The two attenuation models only differ inside of 10 km (with geometrical spreading of 1/R 1.3 and 1/R Boore et al (2010), minus stations S05 and S14; add NCEER = add site class A NCEER data from Boatwright and Seekins (2011); xBS11= remove Bea10' data classified as site class other than A by BS11; BS11 params = the inversion for ∆σ used BS11 parameters for source velocity, radiation pattern, and site class A amplifications. σ RSDL = the standard deviation of the residuals between observed and simulated logPSA (base 10 logarithms).…”

Section: Discussionmentioning

confidence: 99%

Updated Determination of Stress Parameters for Nine Well-Recorded Earthquakes in Eastern North America

Boore

2012

Seismological Research Letters

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Stress parameters (∆σ) are determined for nine relatively wellrecorded earthquakes in eastern North America for ten attenuation models. This is an update of a previous study by Boore et al. (2010). New to this paper are observations from the 2010 Val des Bois earthquake, additional observations for the 1988 Saguenay and 2005 Riviere du Loup earthquakes, and consideration of six attenuation models in addition to the four used in the previous study. As in that study, it is clear that ∆σ depends strongly on the rate of geometrical spreading (as well as other model parameters). The observations necessary to determine conclusively which attenuation model best fits the data are still lacking. At this time, a simple 1/R model seems to give as good an overall fit to the data as more complex models.

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“…When the hypocentral distance becomes large, the surface waves become more dominant, and geometrical spreading is ideally 1= R p . Though this crossover distance (the point at which the geometrical spreading deviates from 1=R) is suggested to be about 50 km for crustal earthquakes (Boatwright and Seekins, 2011), we consider 1=R as the geometrical spreading out to 150 km, the full range of our data. Because tectonic tremor occurs deeper than crustal earthquakes, the crossover distance should be larger.…”

Section: Method: Simultaneous Estimation For Attenuation Parameter Anmentioning

confidence: 99%

Seismic-Wave Attenuation Determined from Tectonic Tremor in Multiple Subduction Zones

Yabe¹,

Baltay²,

Ide³

et al. 2014

Bulletin of the Seismological Society of America

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Tectonic tremor provides a new source of observations that can be used to constrain the seismic attenuation parameter for ground-motion prediction and hazard mapping. Traditionally, recorded earthquakes of magnitude ∼3-8 are used to develop ground-motion prediction equations; however, typical earthquake records may be sparse in areas of high hazard. In this study, we constrain the distance decay of seismic waves using measurements of the amplitude decay of tectonic tremor, which is plentiful in some regions. Tectonic tremor occurs in the frequency band of interest for ground-motion prediction (i.e., ∼2-8 Hz) and is located on the subducting plate interface, at the lower boundary of where future large earthquakes are expected. We empirically fit the distance decay of peak ground velocity from tremor to determine the attenuation parameter in four subduction zones: Nankai, Japan; Cascadia, United States-Canada; Jalisco, Mexico; and southern Chile. With the large amount of data available from tremor, we show that in the upper plate, the lower crust is less attenuating than the upper crust. We apply the same analysis to intraslab events in Nankai and show the possibility that waves traveling from deeper intraslab events experience more attenuation than those from the shallower tremor due to ray paths that pass through the subducting and highly attenuating oceanic crust. This suggests that high pore-fluid pressure is present in the tremor source region. These differences imply that the attenuation parameter determined from intraslab earthquakes may underestimate ground motion for future large earthquakes on the plate interface.

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Regional Spectral Analysis of Three Moderate Earthquakes in Northeastern North America

Cited by 54 publications

References 24 publications

Characteristics of the 17 May 2013 M 4.5 Ladysmith, Quebec, Earthquake

Characteristics of the 17 May 2013 M 4.5 Ladysmith, Quebec, Earthquake

Updated Determination of Stress Parameters for Nine Well-Recorded Earthquakes in Eastern North America

Seismic-Wave Attenuation Determined from Tectonic Tremor in Multiple Subduction Zones

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