Alberta has always been a seismically quiet part of North America. There is no evidence that the province has ever experienced a significantly destructive earthquake, and there is no reason to believe that one is imminent. There have been fewer than 15 catalogued events greater than magnitude 3.5 since 1985.* Alberta does experience very small earthquakes. These earthquakes are usually less than 3 local magnitude (ML). Although it is unusual to feel a an earthquake smaller than 2.5 ML, it is important to monitor them.
Since seismic monitoring began in earnest in the mid-1960s, data collected have shown a recent increase in small- to microearthquake activity. From 1985 to 2010, Earthquakes Canada recorded 471 earthquakes in Alberta. The vast majority of these were natural earthquakes that occurred in a southeast trend along the Rocky Mountain Foothills. However, clusters of activity have also been observed in regions associated with gas production.
Scientists believe that it is important to understand Alberta’s seismicity patterns as well as the causes of the increased numbers of small and micro-earthquakes. Some of these earthquakes may have been triggered or induced by oil and gas production.
AGS is playing a leading role in monitoring Alberta seismicity through the Alberta Earthquake Studies Project (AESP).
* “Magnitude” is a concept describing the size of an earthquake. There are different ways of measuring magnitude, which are described in greater detail in the “Earthquake Magnitudes” section.