what type of geological activity is common close to oceanic trenches where subduction is taking place?
Explosive volcanoes are found there too. Both types of subduction zones are associated with large earthquakes that originate at a depth of as much as 700 km (435 miles). The deep earthquakes below subduction zones occur in a plane that dips 30Â° or more under the overriding plate. Typical trench depths are 8 to 10 km (5 to 6 miles). The longest trench is the Peru-Chile Trench, which extends some 5,900 km (about 3,700 miles) along the west coast of South America.