Earthquakes have rocked the Klamath Falls in the past will continue to do so in the future. Scientists estimate the likelihood of future damaging earthquakes in an area by examining the area's past record of earthquakes and by evaluating the area's earthquake potential in relationship to its geologic setting. To supplement the historic catalog, which often covers only a short time span, they also attempt to identify prehistoric earthquakes preserved in the rocks and sediments of the area. The conclusion drawn from such studies in the Klamath Falls area is that earthquakes in the 4-6 magnitude range, which are capable of light to moderate damage, occur on the order of one or more every few decades. Even a major earthquake in the 7+ magnitude range cannot be ruled out at some future time. However, the area's historic record, which goes back only about 100 yrs, is too short to estimate the frequency of such large shocks. This article is a brief summary of the geologic setting and the historic and prehistoric record of earthquakes in Klamath Falls and the surrounding area.