Seismicity - Taimi Mulder and Garry Rogers

123°45' 40' 35' 30' 25' 20' 15' 10' 05' 123°00' 55' 50' 45' 40' 35' 30' 25' 20' 15' 122°10'
Earthquake Seismicity Map
Arc Explorer
Themes visible in the above map: SEISMICITY: ALL, LATITUDE/LONGITUDE, COASTLINE and LAND. Several fields of data are available for this earthquake suite. Click here for the list of data fields available for query.
Arc Explorer
Themes visible in the above map: SEISMICITY: 5 KM to 0 KM, LATITUDE/LONGITUDE, COASTLINE and LAND. Several fields of data are available for this earthquake suite. Click here for the list of data fields available for query.

Arc Explorer
Themes visible in the above map: SEISMICITY: 10 KM to 5 KM, LATITUDE/LONGITUDE, COASTLINE and LAND. Several fields of data are available for this earthquake suite. They are as follows:

FIELD DATA TYPE
DEPTH_KM Earthquake depth in kilometres
LAT Earthquake latitude
LONG Earthquake longitude
HOUR Time of earthquake in the 24 hour clock (ie. 11:21 p.m. = 2321)
MAG Magnitude of the earthquake
YYYY/MM/DD Date of the earthquake in year/month/day format.

Seismicity Map

Click here for a figure displaying the depth distribution for these earthquakes.

Click here for a figure displaying the magnitude distribution of these earthquakes.

The above mapsheets show the locations of all earthquakes that have occurred in the eastern Juan de Fuca Strait between January 1981 and December 1999. They are all of magnitude <= 4.0. Before 1981 the seismic network was too sparse to provide adequate depth control over this region. Earthquakes in southwestern British Columbia and the Pacific Northwest occur in three main source zones; along the subduction margin at the contact between the Juan de Fuca and North American plates, within the subducting Juan de Fuca plate, and within the North American crust. It is events from this latter source zone which are presented in the maps above. In many respects, it is these crustal events that may pose the most significant hazard because they can occur anywhere within the crust, local to major population centres, and at shallow depths.

For comparison purposes, in this atlas, the earthquakes have been divided into a shallow suite (0-5 km and 5-10 km) and the entire suite which encompasses both North America and Juan de Fuca plate events, the deepest event being within the Juan de Fuca plate at a depth of 64 km. In general, the events near the surface have poor depth control with errors ranging up to 10 km. Errors generally decrease with depth; events around 20 km depth typically have errors on the order of 1-3 km. The locations shown here are "raw" locations from the Geological Survey of Canada earthquake catalogue, each event being located with a set of stations from the US and Canada which are at uncontrolled azimuths and distances from the epicentre. No effort has been made to optimize the locations of these earthquakes with respect to one another and any interpretations made from this data set must take this into account.

North America plate earthquakes are distributed through the crust with the largest concentration around 20 km and a maximum depth of approximately 30 km. The deep events are found below 30 km depth and occur within the Juan de Fuca plate, forming an approximately 10 km thick zone of events dipping to the east.

Reference citation:
Mulder, T., and Rogers, G., 2000. Recorded seismicity of the eastern Juan de Fuca Strait, in: Mosher, D.C. and Johnson, S.Y. (Eds.), Rathwell, G.J., Kung, R.B., and Rhea, S.B. (Compilers), Neotectonics of the eastern Juan de Fuca Strait; a digital geological and geophysical atlas. Geological Survey of Canada Open File Report 3931

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123°45' 40' 35' 30' 25' 20' 15' 10' 05' 123°00' 55' 50' 45' 40' 35' 30' 25' 20' 15' 122°10'
48°30'
25'
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48°00'
123°45' 40' 35' 30' 25' 20' 15' 10' 05' 123°00' 55' 50' 45' 40' 35' 30' 25' 20' 15' 122°10'
48°30'
25'
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15'
10'
05'
48°00'