1. Ocean/Ocean: where tectonic boundary is in oceanic material. One plate will SUBDUCT or sink back into the asthenosphere.
Features: deep ocean trench, volcanic island arc
Geologic effects: deep focus earthquakes, subduction of one plate and explosive volcanism
Example: Philippines
2. Ocean/Continent: where tectonic boundary is between oceanic and continental material. Characterized by subduction of the OCEAN plate.
Features: deep ocean trench adjacent to shoreline, volcanic mountain range inland from the coast
Geologic effects: deep focus earthquakes, subduction of the ocean plate, explosive volcanism
Example: Andes Mountains, Cascade Range
3. Continent/Continent: where tectonic boundary is in continental material.
Features: large mountains
Geologic effects: extensive earthquake activity, NO subduction, NO volcanism, highly deformed, folded and metamorphosed rock units
Example: Himalayas
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