Events that occur infrequently but potentially carry large consequences are classified as a low risk events. An earthquake along the eastern shoreboard of the North American Continent would fall into this classification. "Very high risk" is not a risk classification.

Along convergent plate boundaries, friction from the subducting plate causes earthquakes. These quakes form deep within the Earth and can cause significant damage to the Earth's surface and human developments upon it. An example of a convergent boundary that causes frequent earthquakes is the west coast of the United States. While tornados, tropical storms, and tsunamis created by mass wasting are all natural disasters; they are typically not the result of plate tectonics.

The correct response is lithosphere. The lithosphere is comprised of parts of the crust and upper mantle.

The correct response is seismic waves. Geologists can identify the magnitude of an earthquake using a seismograph that measure seismic wave activity. 

The correct response is dormant. The term dormant volcano refers to any volcano that has never been known to erupt. An active volcano is currently erupting or has been known to erupt in the past. An extinct volcano will never erupt again. 

The correct response is subduction volcano. This type of volcano is formed when plates collide and slide under each other. A rift volcano is formed when plates move away from each other. The other three answer choices describe volcanic activity which was never mentioned in the question.

Both the Hawaiian and the Galapagos islands are formed by 'hot spots' in the Earth's mantle. As the tectonic plate passes over these hot spots, some mantle pushes through to form a volcano beneath the ocean, which gradually builds itself tall enough to become an island. When the plate moves away from the hot spot, the process starts over, and another island forms.

A convergent plate boundary forms when two tectonic plates (large plates that make up the Earth's surface) move towards each other. When they meet, the higher density plate goes underneath (subducting) under the other. This is the type of plate boundary happening along the west coast of the United States. Divergent plate boundaries occur when two tectonic plates move apart. This process, over millions of years, can form ocean basins. As the divergent plate boundaries continue to move apart, new rock is formed between them. This type of plate boundary is taking place in the center of all modern ocean basins. Transform plate boundaries form when two tectonic plates slide against each other. This is occurring in California at the San Andreas Fault. Strike-slip faults are structures that form along transform plate boundaries.