Canadian Seismological Stations

Abstract

ALL seismological stations in Canada now come within the jurisdiction of one department, with the Dominion Observatory at Ottawa as the Central Station (Earthquake Notes, 12, Nos. 1 and 2, Sept. 1940). There are seven stations besides Ottawa, and several improvements have recently been made. The Victoria station is now in the Dominion Astrophysical Observatory, where a vertical Wiechert seismograph and improved Milne-Shaw instruments are in operation. At Saskatoon two horizontal Mainka seismographs are in operation, whilst at Toronto the two Milne-Shaw seismographs have been improved by mirror replacements. The Kirkland Lake station commenced operation in December 1939 with a standard geophone and special recorder made by the Heiland Research Corporation. The Shawinigan Falls station employs a Wood-Anderson seismograph, whilst the Seven Falls station has Wood-Anderson and Milne-Shaw seismographs. The Halifax station has been entirely re-equipped. The Mainka instruments have been discarded and the station has now photographic recording Bosch seismographs formerly at Ottawa. Ottawa discarded the Wiechert vertical seismograph and installed Benioff short- and long-period vertical seismometers in addition to the two Milne-Shaw instruments. The Canadian Broadcasting Corporation now transmits the Dominion Observatory noon time signals over the entire Canadian network, so that accurate timing is possible at all the seismograph stations. Seismograms from all the Canadian stations are now sent to Ottawa for analysis and interpretation, and the results published in the Monthly Bulletin issued by the Dominion Observatory.