Earthquakes near Tonga trench

Location of the 2009 epicenter and that of a similar earthquake in 1917 (white circles) in relation to the bend in the Tonga trench (yellow line). Large open arrow shows direction and speed (237 mm/yr) of relative convergence between the Pacific plate and the overriding plate. Islands labeled “Samoa” include Samoa and American Samoa. Dots are epicenters of previous earthquakes; larger dots indicate earthquakes of greater magnitude. Red triangles, volcanoes. For more information, see “This Dynamic Planet: World Map of Volcanoes, Earthquakes, Impact Craters, and Plate Tectonics,” USGS Geologic Investigations Map I-2800.