Source: Lisa Christiansen, Caltech Tectonics Observatory (2008) view source. Wide bands of scattered earthquakes mark continent-continent convergent margins (e.g., between the Indian and Eurasian plates), or continental rift zones (e.g., in eastern Africa). Wider bands with earthquakes at a range of depths are subduction zones. Narrow bands with shallow earthquakes (marked in red) indicate transform boundaries or mid-ocean ridge divergent boundaries. Bands of earthquakes mark tectonic plates. Figure 12.16 Earthquakes greater than magnitude 5, from 2000 to 2008. Wide swaths of scattered earthquakes may also correspond to continental rift zones, such as in eastern Africa. Wide swaths of scattered earthquakes may correspond to continent-continent collision zones, such as between the Eurasian plate and the African, Arabian, and Indian plates to the south. Bands of earthquakes are wider along subduction zones because they take place throughout the subducting slab that extends beneath the opposing plate. Subduction zones have earthquakes at a range of depths, including some more than 700 km deep. Mid-ocean ridges and transform margins have shallow earthquakes (usually less than 30 km deep), in narrow bands close to plate margins. The depths of earthquakes, and the width of the band, depend on the type of plate boundary. Bands of earthquakes trace out plate boundaries (coloured dots, Figure 12.16).
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