Earthquake Summary Poster
Poster of the Heilongjiang, China Earthquake of 28 June 2002 - Magnitude 7.3
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DISCUSSION
This deep earthquake occurred within the subducted Pacific plate, about 1300 km (about 800 miles) west of the JapanTrench, where the oceanic Pacific plate begins its descent into the mantle. As the plate subducts beneath Asia at a rate of about 9 cm (about 3 inches) per year, it generates earthquakes. The positions of these earthquakes form features known as Wadati-Benioff zones that image the tectonic plate's decent into the mantle. This earthquake occurred near the base of its particularly long and straight Wadati-Benioff zone that is well imaged in the accompanying cross-section. Since 1972, this segment of the subducted Pacific plate has produced 11 earthquakes with focal-depths between 400 km and 600 km, and with magnitudes of 6 or greater. Worldwide, the deepest reliably located earthquakes occurred about 680 km beneath the Earth's surface. |