Velocity analysis of 1982 Miramichi earthquake data

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University of New Brunswick


Seismological recordings of aftershocks from the January 9th, 1982 Miramichi earthquake sequence were analyzed to develop a velocity model from arrival time picks of P- and S- phases. The best located large aftershock of the sequence occurring at 13:34(UT) on January 17, 1982 was well recorded by a total of 38 local and regional stations throughout Eastern Canada and Northern New England. A three-layered earth with homogeneity of velocity and geology within the layers was modelled by approximating travel time curves on time .vs. distance plots by straight lines. A revised velocity mode I obtained by dropping anomalous points from the data set produce velocities consistent with previous estimates. These data points were assigned travel time corrections to account for differences in geology near the station. A 17.3 km. thickness was assigned to the granite of the North Pole Stream Pluton, the location of the earthquake epicenter. Records of a Heath Steele Mine blast which occurred on January 21,1982 were analized to estimate an origin time for the blast and the velocity within the meta sediments surrounding the pluton.