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Relocation of the 1982 Miramichi, New Brunswick, Canada, aftershock sequence
  • Shutian Ma,
  • Dariush Motazedian
Shutian Ma
Carleton University

Corresponding Author:[email protected]

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Dariush Motazedian
Carleton University
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Abstract

On 9 January 1982, in the Miramichi region of New Brunswick, Canada, an earthquake with body-wave magnitude (mb) 5.7 occurred. Itwas followed by extensive aftershocks and felt throughout eastern Canada and northeastern USA. Digital seismic stations were not yet commonby 1982. Fortunately, three stations (KLN, EBN and GGN) produced excellent waveform records for the larger aftershocksallowingthese aftershocks to be relocated. For each aftershock,its focal depth was first determinedusing thedepth phase sPg; then, with depth fixed, the epicenter was determinedusing a set of arrival times recorded for the Pg-, Sg-, and Pn-phases at the three stations.Sixty-eight aftershocks were relocated; mostof them occurred in a 5×5 km areaand with depthsof2 to 6 km. The epicentres formed two linear trends in theNE-SW direction. The trends were close to the northeast strike of the focal mechanism of the mainshock and consistent with the topographic trend near the source region. A gap betweenthe trends separated the epicenters into two groups. One group representstherupture area caused by themainshock, and the other groupmight represent the rupture area caused by the mb 5.4principal aftershock.