A study of the historical seismicity of New Brunswick has been made by scanning weekly local newspapers from the early 1800's to 1961 for references to possible earthquakes. Lateral searches of other contemporary newspapers and diaries were also made for the dates of newly found events and for earthquakes listed previously in the Canadian Earthquake Epicentre File (CEEF).
Three regions of enhanced activity were identified: the Central Highlands (Miramichi) subzone, the Passamaquoddy Bay subzone, and the Moncton subzone. From the scanning process, eleven previously unlisted earthquakes were found in the Central Highlands region and parameters of nine events listed in the CEEF were found in need of revision. An additional eleven previously unlisted earthquakes were found in the Passamaquoddy Bay region by the scanning process and parameters of 26 CEEF-listed events needed revision. The Moncton region shows the least activity, with six additional unlisted earthquakes being found by the scanning process and parameters of two events listed in the CEEF needing revision. The study showed that some earthquakes listed in the CEEF had been mislocated and that other events listed as earthquakes were actually explosions or meteorological effects, such as cryoseisms or thunderstorms.
Data from an instrumentally recorded earthquake in 1999 in the Passamaquoddy Bay region showed that the magnitude based on the area where the earthquake was felt exceeded the instrumentally determined magnitude by 0.9. Caution should therefore be exercised in applying felt area-magnitude relationships to small earthquakes.