The absence of major earthquakes within the past century, however, doesn’t mean that there’s no potential for them to occur. Accurate seismic data are relatively short in earth science terms, with instrumental records dating back only as far as the early twentieth century: written evidence suggests that the largest event on this section of the fault occurred in 1700 – this huge quake is thought to have had a magnitude of M9.0 – as large as the 2011 Japanese earthquake.
The occurrence of significant tremors along this zone is well established and seismologists believe that Oregon tremors have a pattern of long recurrence intervals. A recent study of historic earthquakes (based upon sediment data) by scientists at Oregon University suggests that a major earthquake along the Cascadia subduction zone, between Vancouver Island and California’s Cape Mendocino, is by no means unexpected.
Future Quakes in the Pacific Northwest
Although the January 30 tremor was relatively small, it illustrates the complex situation of the Earth’s crust off the western United States and Canada as the Farallon plate subducts and breaks into smaller plates with fracture zones between them – leaving the west coast still at risk of a major seismic event.
Goldfinger, C. et al. Turbidite Event History—Methods and Implications for Holocene Paleoseismicity of the Cascadia Subduction Zone. USGS Professional Paper 1661-F. Accessed January 30, 2013.
Natural Resources Canada. The M9 Cascadia Megathrust Earthquake of January 26, 1700. Accessed January 30, 2013.
USGS. M5.3 – 263km WNW of Bandon, Oregon. Accessed January 30, 2013.
Vancouver Sun. Magnitude 5.3 quake strikes off Oregon coast; no tsunami danger, no damage. Accessed January 30, 2013.
Yeats, R. Active Faults of the World. (2012). Cambridge University Press 2012
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