Lithospheric Attenuation of the Mackenzie Mountains, Northern Canadian Cordillera from Local and Regional Seismic Phases

Session: Seismicity and Tectonics of Stable Continental Interiors [Poster]
Type: Poster
Date: 4/30/2020
Time: 08:00 AM
Room: Ballroom
Description: 

We carry out tomographic and regionally-averaged inversions for Lg, Pg, Pn and Sn phase attenuation (1/Q) in the Mackenzie Mountains of the northern Canadian Cordillera to evaluate source spectra and site amplification from earthquakes of M_L >= 3 from twenty years of the Canadian National Earthquake Database. The northern Canadian Cordillera is host to some of the largest continental earthquakes in Canada and the highest seismicity rates. Seismic attenuation is used as a parameter in ground motions models (GMMs) for seismic hazard assessment, and since it varies regionally, care must be taken in assigning these parameters in GMMs. Data from broadband seismic stations from the Canadian National Seismic Network as well as regional networks and stations from the Mackenzie Mountains Earthscope Project are used to maximize raypath density of the amplitude dataset. Both time domain displacement amplitudes and rms pseudo displacement amplitudes are employed in the inversions. In the tomographic inversion, observed amplitudes are corrected for geometrical spreading and solve for lateral attenuation, along with source (seismic moment) and site terms. Teleseismic body wave tomography of the region suggests the presence of a buried craton with high upper mantle velocities. We compare the Q inversions from regional Pn and Sn phases with teleseismic results to assess the correlation between attenuation and velocity anomalies.

Presenting Author: Claire Perry

Authors