Geologists have mapped the recent earthquakes in California and Mexico and have found a pattern called the Mogi doughnut. The concept of mapping, originally from Japan, shows that earthquakes occur in a circular pattern over decades – building up to one very large quake in the middle of the doughnut hole. Geologists believe that the recent quakes in California and Mexico, combined with seismic events including the 1989 and 1994 quakes, could be the precursors to a far larger rupture. Experts have been predicting for years that it will happen – we just don’t know when.
The idea behind the doughnut is simple. Earthquakes in California are caused by tectonic movements in which the Pacific plate slides northwest relative to the North American plate. As the plates move, stress builds along both sides of the Earth’s crust. The stress casuses smaller faults at first, as they need less pressure to break and thus produces small earthquakes. As the stress moves to bigger faults that need more pressure to erupt, larger and larger earthquakes will happen until the “Big One” happens.
Whether the doughnut concept is true or not, the reality is that westcoast is shaking more than in recent years.