Figure 5. Map of the world showing active plate boundaries (blue lines), recorded seismic activity (yellow dots), and active volcanoes (red triangles). Note the general lack of strong seismic
volcanic and seismic activity in the northern Atlantic Ocean. The mid-Atlantic ridge is a passive boundary, a spreading center, which is spreading at a rate of about 25 mm/yr. The only active
subduction zones are at the Puerto Rico Trench (Caribbean Plate and North American Plate), and at the South Sandwich Islands (image adapted from San Diego State University and NASA).
Last updated on October 6, 2005