Earthquake Risk:Most earthquakes occur near the boundaries of tectonic plates. The transform plate boundary in California and the convergent plate boundaries in Oregon, Washington, and Alaska have the highest earthquake risks in the United States. However, not all earthquakes occur near the plate boundary. Some of the largest earthquakes in the United States have occurred far from the plate. boundaries. Because earthquakes threaten people's lives, seismologists study the likelihood of an earthquake occurring in a given area. Probability is one of several factors that contribute to earthquake risk assessment. Seismologists also study past seismic activity, the geology around a fault, population density, and building design in an area to assess risk. Engineers use these risk assessments to design earthquake-proof structures that are able to withstand the shaking during an earthquake.