Poster Session:

THE 01 JANUARY 2000 KIPAWA EARTHQUAKE (MN=5.2)

ADAMS, J., BENT, A., DRYSDALE, J. A., HALCHUK, S., LAMONTAGNE, M., MA, S., WETMILLER, R. J., WOODGOLD, C., (alphabetical order), National Earthquake Hazards Program, Geological Survey of Canada (GSC), 7 Observatory Cres., Ottawa K1A 0Y3, Canada; and DASTOUS, J.-B., Hydro-Quebec / IREQ, 1800 blvd Lionel Boulet, Varennes, Quebec, J3X 1S1.

The Kipawa earthquake (mN=5.2 OTT; mb=4.5 pIDC) occurred 01 January 2000 at 11:22:57 UT (6:22 EST). The epicentre (46.88N 78.92W) was under Lac Kipawa about 10 km north of the town of Temiscaming, Quebec. The earthquake was felt to distances exceeding 500 km. The "Felt Earthquake" form on the GSC Web pages has received more than 550 submissions from 170+ communities. A program was developed to to aid analysts in quickly scanning the felt information. The shaking was very strong for residents within 50 km of the epicentre (intensity MM VI), and minor damage (fallen light objects, one broken ventilation pipe, and cracks in plaster) was reported. The seismograph EEO (Eldee, Ontario, 29 km) recorded a 0.023g vertical acceleration and a digital strong motion unit operated by Hydro-Quebec at 68 km distance recorded about 0.014g horizontal acceleration. A total of 17 aftershocks were recorded, ranging from ML -1.1 to mN 2.2. To supplement station EEO two portable recorders and a digital strong motion instrument were installed on 02 January 2000 at approximately 9 to 22 km epicentral distance. Preliminary analysis for the mainshock, from P-nodal and surface wave modelling, indicates thrust faulting on E-W or SE-NW trending planes and a depth, verified by depth phase beamforming, of 13-16 km. The epicentre is within 15 km of that of the magnitude 6.2, 1935 Timiskaming earthquake, and lies in a cluster of 76 located earthquakes since 1935. The area averages one M>3 earthquake every second year. There is an indication of a NW-SE elongation (parallel to the major faults of the Ottawa valley) and focal mechanisms consistently show a NE-dipping NW-trending plane, which would be consistent with a fault outcropping under the Ottawa River and Lake Timiskaming.

For more info on this earthquake: www.seismo.nrcan.gc.ca