5.4 Aftershock Causes Partial Building Collapse in Klamath Falls

A damaging aftershock of the September earthquakes near Klamath Falls, Ore., struck Saturday afternoon, causing the partial collapse of a small shopping center and cracking walls anew in the courthouse in the southern Oregon city, authorities reported.

The U.S. Geological Survey and the UC Berkeley Seismographic Laboratory said the 2:15 p.m. temblor registered a moderately strong magnitude 5.4 and was centered 15 miles northwest of Klamath Falls in the same vicinity as two magnitude 5.9 quakes that struck on Sept. 20.

No casualties were reported this time. The September jolts killed two people and damaged more than 100 buildings.

But radio station reports from the area told of considerable breakage and a frightened populace in the city of 18,500 residents.

The roof of a structure known as the Arcade Hotel Building, with a restaurant, a comic book shop and a bookstore, gave way, showering debris into the street.

Sam Hamilton, director of the Klamath County emergency communications center, told the Associated Press that windows shattered and bricks fell out of several other buildings, including the City Hall and the county library, where a roof collapsed.

The earthquake also was felt in Medford and Eugene, although no damage was reported in either city.

Douglas Dreger, a UC Berkeley research seismologist, said the 5.4 aftershock was followed three minutes later by another that registered a magnitude 4.1. More than 40 milder jolts occurred later in the afternoon. Noting that there have been numerous aftershocks in the area since September, Dreger said more probably can be expected.

The seismic activity is centered near Klamath Lake at the western edge of the Great Basin, which stretches east from California through Nevada into Utah, Dreger said.

Although such major Cascade volcanoes as Mt. Shasta and Mt. McLoughlin are nearby, Dreger said the present quake sequence is not volcanic in origin and represents “normal faulting in an area where the Earth’s crust is pulling apart.” Slowly, the distance between the Wasatch Front near Salt Lake City and the Cascades and Sierra Nevada is increasing.

Oregon is not generally as seismically active as California. But the quakes of the last three months near Klamath Falls have been the strongest in the area since record-keeping began in 1860.

John Nabelek, an Oregon State University geophysicist, said, “There are lots of fresh-looking faults in the Klamath Falls vicinity where earthquakes can occur.” A fresh-looking fault, however, can be hundreds of years old.