Due to the remote location of the mainshock and a series of strong aftershocks, damage to structures was limited to a few cabins close to the areas of the highest intensity.

The results of a separate study indicated that it may have been a larger event, placing the shock in the North Cascades, just south of the Canada–United States border at Ross Lake.

Although activity in the Pacific Northwest (especially west of the Cascades in Washington) has occasionally been located near the subduction zone, earthquakes there (1949 Olympia, 1965 Puget Sound, 2001 Nisqually) have mostly been intraslab events.

[4][5] As there were only six seismometers operating in Washington state and western British Columbia even as late as 1969, there are insufficient instrumental records for older events in the region.

Malone and Bor ran three simulations, with a projected M7.4 event occurring at a depth of 37 miles (60 km), but took into consideration the differences in attenuation both east and west of the Cascades.

Trenching studies revealed a northwest-dipping thrust fault measuring at least 75 km (47 mi) long which last moved between 1856 and 1873 during a single earthquake.

[1] A relationship exists between the depth of the mainshock and the occurrence of aftershocks, and several Pacific Northwest earthquakes illustrate this link, like the February 1981 M5.5 Elk Lake event in southwest Washington that was followed by more than 1,000 in the first two years.

[6] Aftershocks did follow the 1872 event, and during the initial 24 hours they were strong enough to be felt over a broad area, from Idaho and into southern British Columbia.