While the attention of most North Americans has been focused on Hurricane Irma, about to unleash her fury on Florida, a strong earthquake struck off the Pacific Coast of southern Mexico yesterday. The magnitude 8.2 quake occurred along a subduction zone, where the Cocos Plate (a remnant of the massive Farallon Plate) is dipping beneath the North American Plate; unfortunately, at least 58 persons were killed by the earthquake.
In such subduction zones, the edge of the over-riding plate is pulled down by friction with the subducting plate. Eventually, this edge rebounds upward, displacing a massive amount of seawater and often triggering a tsunami. Fortunately, in this case, the latter did not develop.
As the North and South American Plates continue to drift westward in concert with the opening of the Atlantic Ocean, subduction of the Farallon remnants (the Juan de Fuca, Cocos and Nazca Plates, north to south) will continue, igniting volcanic ranges (the Cascades, Mexican volcanoes, Central American volcanoes and the Andes) as they melt and triggering earthquakes offshore that spread across the mainland.
In such subduction zones, the edge of the over-riding plate is pulled down by friction with the subducting plate. Eventually, this edge rebounds upward, displacing a massive amount of seawater and often triggering a tsunami. Fortunately, in this case, the latter did not develop.
As the North and South American Plates continue to drift westward in concert with the opening of the Atlantic Ocean, subduction of the Farallon remnants (the Juan de Fuca, Cocos and Nazca Plates, north to south) will continue, igniting volcanic ranges (the Cascades, Mexican volcanoes, Central American volcanoes and the Andes) as they melt and triggering earthquakes offshore that spread across the mainland.
