Note on the Magnitude Recurrence Relationships for the Central Highlands, Passamaquoddy Bay, and Moncton Subzones of New Brunswick, Canada

Abstract

The revisions to the list of earthquakes proposed in the previous paper (Burke, 2004, this volume) prompted a study of changes to the magnitude recurrence curves for the Central Highlands, Moncton, and Passamaquoddy subzones. Maximum likelihood estimates of probability were calculated with the magnitude-recurrence curve program of the Geological Survey of Canada (GSC), using the method of Weichert (1980), for three sets of data for each subzone as described below (coordinates and map of the subzones can be seen in Burke, 2004). Magnitude recurrence curves were first calculated for each subzone from the GSC's Seismic Hazard Earthquake Epicentre File (SHEEF) catalog for the New Brunswick region using the GSC's regional completeness dates (Table 1) and are shown in Figures 1A, 2A, and 3A. The catalog used is complete to the end of 2000. The Miramichi aftershock sequence was removed, though the four largest events (“multiple mainshocks”?) were retained. View this table: TABLE 1 Magnitude Completeness Dates A second set of magnitude recurrence curves was then calculated using the revisions and new events proposed by Burke (2004). Lists of earthquakes were taken to be complete for magnitudes greater than 4.0 for the Central Highlands subzone and greater than 3.3 for the Moncton subzone for the period since 1826. The Passamaquoddy Bay subzone was taken as being complete above a magnitude of 3.3 for the period since 1833. The magnitude recurrence curves for these sets of data are shown in Figures 1B, 2B, and 3B. The third set of magnitude recurrence curves was finally calculated using combined data sets with completeness dates as outlined in …