Answer to Question 1
Answer: During an oceanic-continental convergence event, the subducting ocean slab scraps along the landward side of the trench piling up sediment from the land and scraping off sediment from the ocean floor. Small amounts of ocean crust, sedimentary rocks, and metamorphic rocks may also be included in the wedge.
Answer to Question 2
Answer: Earthquakes that occur east of the Rocky Mountains are less frequent but often more damaging because the underlying bedrock in the central and eastern United States is older and more rigid; therefore, seismic waves can travel greater distances with less loss of strength (attenuation) than on the west coast.
