There has not been a major earthquake in what is known as the Cascadia subduction zone since about 9 p.m. on Jan. 26, 1700, long before Europeans first landed on Vancouver Island. One is the oral histories and archeological remains of the various First Nations whose villages were swamped by a tsunami. But every year or so, there is a roughly month-long “slow slip,” when the North American plate lurches southwesterly over the Juan de Fuca plate. It is usually accompanied by bursts of tremors, but the physics of “slow slip” is not well understood. They found the Juan de Fuca plate is moving under the North American plate at around four centimetres a year as the North American plate slips over it.

Source: National Post January 02, 2019 15:00 UTC