Geology topics

Research about Klamath Falls

Source-linked reports with geographic coverage including Klamath Falls.

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USGS1993

The Klamath Falls, Oregon, earthquakes on September 20, 1993

The strongest earthquake to strike Oregon in more than 50 yrs struck the southern part of the State on September 20, 1993. These shocks, a magnitude 5.9 earthquake at 8:28pm and a magnitude 6.0 earthquake at 10:45pm, were the opening salvo in a swarm of earthquakes that continued for more than three months. During this period, several thousand aftershocks, many strong enough to be felt, were recorded by seismographs. The mainshocks caused light moderate damage at Klamath Falls, a town of about 18,000 residents located only about 20 km east of the epicentral area. Damage included toppled chimneys, cracked masonry, and fallen parapets. Power outages occurred after the strongest shocks. In addition, strong shaking broke water mains, and landslides temporarily blocked highways. the earthquakes also caused two fatalities. A rockfall crushed an automobile, killing a motorist, and an elderly lady had a heart attack. the low population density in the epicentral area- less than five people per sq km- kept the toatl dollar loss to about 7.5 million dollars.

Oregon↗

USGS1993

Damages from the 20 September earthquakes near Klamath Falls, Oregon

The Klamath Falls earthquakes of 8:28PM PDT (magnitude 5.9) and 10:45 PM PDT (magnitude 6.0) on September 20, 1993, were felt over an area of about 130,000 sq km in southwestern Oregon and northern California. Losses due to property damage are preliminary estimated to be about 7.5 million. A motorist died when the car he was driving was crushed by a boulder in an earthquake-induced rockfall, and an elderly woman died of a heart attack that was apparently triggered by one of the earthquakes. Most of the damage resulting from the earthquakes was reported from Klamath Falls, approximately 20 km from the source region of earthquakes. As has commonly been the case with earthquakes in other parts of the United States, the degree of damage was highly uneven in Klamath Falls. Most of the town escaped with little damage to buildings or building contents. Losses were concentrated in the downtown area, but even there most of the buildings were not damaged. The unevenness of damage in earthquakes results primarily from large differences in the seismic resistance of individual buildings and differences in the seismic response due to different soil conditions and geology beneath buildings.

Oregon↗

USGS1993

Precisely locating the Klamath Falls, Oregon, earthquakes

The Klamath Falls earthquakes on September 20, 1993, were the largest earthquakes centered in Oregon in more than 50 yrs. Only the magnitude 5.75 Milton-Freewater earthquake in 1936, which was centered near the Oregon-Washington border and felt in an area of about 190,000 sq km, compares in size with the recent Klamath Falls earthquakes. Although the 1993 earthquakes surprised many local residents, geologists have long recognized that strong earthquakes may occur along potentially active faults that pass through the Klamath Falls area. These faults are geologically related to similar faults in Oregon, Idaho, and Nevada that occasionally spawn strong earthquakes. In this article we present preliminary results of a close-in, instrumental study of the Klamath Falls earthquake sequence, carried as a cooperative effort by scientists from the U.S Geological Survey (USGS) and universities in Washington, Orgeon, and California. In addition to obtaining much mroe accurate earthquake locations, this study has improved our understanding of the relationship between seismicity and mapped faults in the region.

Oregon↗

USGS1993

Historic and prehistoric earthquakes near Klamath Falls, Oregon

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.

Oregon↗