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A teleseismic analysis of the New Brunswick earthquake of January 9, 1982

January 1, 1983

The analysis of the New Brunswick earthquake of January 9, 1982, has important implications for the evaluation of seismic hazards in eastern North America. Although moderate in size (mb 5.7), it was well-recorded teleseismically. Source characteristics of this earthquake have been determined from analysis of data that were digitally recorded by the Global Digital Seismograph Network. From broadband displacement and velocity records of P waves, we have obtained a dynamic description of the rupture process as well as conventional static properties of the source. The depth of the hypocenter is estimated to be 9 km from depth phases. The focal mechanism determined from the broadband data corresponds to predominantly thrust faulting. From the variation in the waveforms the direction of slip is inferred to be updip on a west dipping NNE striking fault plane. The steep dip of the inferred fault plane suggests that the earthquake occurred on a preexisting fault that was at one time a normal fault. From an inversion of bodywave pulse durations, the estimated rupture length is 5.5 km. Average properties of the rupture process were examined by a moment tensor analysis of long-period P and SH body waves. The long-period moment of this earthquake was 5.3 × 1024 dyne cm. The static and dynamic stress drops are 41 and 65 bars, respectively, similar to those of many earthquakes with similar moment in regions that are more seismically active. The joint epicenter determination algorithm was used to locate, relative to the mainshock, the three teleseismically recorded aftershocks that occurred through March 31, 1982. The relocated hypocenters of the aftershocks are significantly different from each other and from that of the mainshock; they provide additional support for the source dimensions inferred from the waveform analysis.

Publication Year 1983
Title A teleseismic analysis of the New Brunswick earthquake of January 9, 1982
DOI 10.1029/JB088iB03p02199
Authors G. L. Choy, J. Boatwright, J. W. Dewey, S.A. Sipkin
Publication Type Article
Publication Subtype Journal Article
Series Title Journal of Geophysical Research Solid Earth
Index ID 70011602
Record Source USGS Publications Warehouse