Yesterday's magnitude 7.4 earthquake in western Colombia developed where the Malpelo Microplate is subducting beneath the South American Plate. This small tectonic plate, thought to have formed during the Miocene Period (about 15 MYA), is wedged between the Cocos Plate, to its west, and the Nazca Plate, to its south.
The latter two plates are remnants of the massive Farallon Plate; remnants of that oceanic plate are subducting beneath the Pacific Northwest, Mexico and South America, producing volcanic ranges along the western coast of the Americas. The subduction of the Farallon Plate began as the Atlantic Ocean opened, some 160 million years ago, and continues today.
In addition to the earthquakes that occur in these subduction zones, tsunamis may develop if the leading edge of the Continental Plate rebounds upward. See: Tsunamis and Subduction Zones