The following sections briefly review property damage in Washington. Selected catalogs that contain chronological lists of earthquake locations, magnitudes, and damage for Washington earthquakes are listed following the references for this report. See also a compilation of out-of-print reports by Thorsen (1986) and Gonen and Hawkins (1974). Table 2 and Figure 13 give information about specific earthquakes causing damage in Washington. Reports of damage caused by earthquakes in Washington and northern Oregon provide examples of the location and kinds of damage to be expected in future earthquakes.

The earthquake of December 14, 1872, ranks as Washington's most widely felt earthquake. However, its occurrence in a relatively remote and sparsely populated part of the state during a period early in Washington's history limits the information available about damage near the epicenter. Severe damage to a log cabin was noted near Lake Chelan; ground sinking and upheaval were also observed nearby. Numerous landslides occurred near the lake and along the Columbia River. There were also reports of persons thrown to the ground near the mouth of the Wenatchee River.

The northeastern Oregon Milton-Freewater earthquake of July 15, 1936, is the most destructive earthquake of the eastern Washington-Oregon border region since the late 1800s (Shannon and Wilson, Inc., 1975). Its intensity was greatest (VII) at Freewater, State Line, and Umapine in Oregon. Moderate damage occurred in Athena and Milton. Windows broke, walls cracked, a few chimneys collapsed, a two-story concrete house near Umapine lost part of the top of its second story, and some standing railroad cars near Milton were derailed (Brown, 1937). Two schools in Umapine were damaged. Water issued from cracks as much as 60 meters long. Numerous aftershocks were reported until November 1936 (Coffman and others, 1982). This earthquake was also felt widely in parts of Idaho.

Damage from the November 12, 1939, Olympia earthquake was most severe in Centralia, Elma, and Olympia, where chimneys were broken, plaster cracked, and various objects overturned (Coombs and Barksdale, 1942). Swaying power lines caused short circuits that produced power failures in Olympia and Centralia. In Tacoma, a 200-pound terra cotta cornice that was attached to two buildings fell after being loosened by the differential movement between the buildings (Coombs and Barksdale, 1942).

The earthquake of April 29, 1945, occurred near North Bend, Washington, along the westem edge of the Cascades. The most severe damage reported included a broken water main and damaged chimneys in North Bend. Bricks were dislodged in a dozen or more homes in the Cle Elum area, and a Roslyn boy was struck on the head by a falling brick. At the Mount Si Ranger Station, near North Bend, "the earth buckled and heaved, and tons of rock and earth cascaded down the 4,000-foot cliffs of Mount Si" (Bodle and Murphy, 1947). The 1945 earthquake was thought to have occurred on a fault trending north from Mount Si to the Tolt River area (Bradford and Waters, 1934). However, recent mapping of the area indicates that the supposed fault trace along the west side of Mount Si is created by the differential resistance to weathering between the rocks forming Mount Si and those to the west (Tabor and others, 1982).

The magnitude of the 1946 Puget Sound earthquake was nearly as large as that of the Seattle-Tacoma earthquake of 1965. In Seattle, the most severe damage caused by this earthquake was to industrial buildings built on filled ground in the Duwamish River valley and on the former tide-flat area at the south end of Elliott Bay. There was also heavy damage to waterfront structures built on pilings in Seattle (Barksdale and Coombs, 1946). In Olympia, fire trucks were moved to the street because of fear that the building would collapse; the firehouse doors were nearly jammed because of distortion suffered during the earthquake. Although damage in Tacoma was less spectacular than in Seattle or Olympia, six fires there were started when chimneys cracked during ground shaking.

The best documented large earthquakes in Washington are the deep Puget Sound earthquakes of April 13, 1949, between Tacoma and Olympia, and April 29, 1965, between Seattle and Tacoma (Edwards, 1951). The damage patterns in both of these earthquakes were similar, although the 1949 earthquake was more destructive ($150 million damage versus $50 million damage, in 1984 dollars). Some of the damage sustained in 1965 was to buildings previously weakened by the 1949 earthquake.

In both the 1949 and 1965 earthquakes there was substantial damage to older masonry buildings with inferior mortar (Gonen and Hawkins, 1974) and to buildings with inadequate anchorage of framing to floor and roof joists (Seattle Fire Department, unpub. report, 1965; MacPherson, 1965). Differential ground settlement caused significant damage to both new and old buildings. Most damage in Seattle during the 1949 and 1965 earthquakes was concentrated in areas of filled ground, especially in the Pioneer Square area, where there are many older masonry buildings, and along the waterfront ( Figure 39). In 1965 nearly every waterfront facility in Seattle was damaged. In Tacoma, damage occurred mainly to cornices and chimneys of older structures built on soft ground in lowland areas and on firmer gravel in highland areas. In Olympia, damage was primarily confined to the old part of the city and to areas of the port built on artificial fill. In 1949 a portion of Olympia's industrial area, built on fill extending into Puget Sound, settled 5 inches. Forty percent of business buildings and houses were damaged in Centralia in 1949. In Chehalis, four schools, the City Hall, the library, and the court house were damaged considerably, although all were built on solid ground.

Washington schools sustained a disproportionately high level of damage during the 1949 and 1965 earthquakes (Gonen and Hawkins, 1974). In 1949 and 1965, Seattle schools built prior to 1950 suffered extensive structural and non-structural damage. Thirty Washington schools, normally serving 10,000 students, were damaged in 1949. (See for example, Figure 40.) Ten of these schools were condemned and permanently closed (Gonen and Hawkins, 1974). Three Seattle schools were torn down, and one was rebuilt (Martens, 1984). Following the 1965 earthquake, eight Seattle schools normally serving 8,800 students were closed until inspections could be carried out to determine their safety (Martens, 1984). In 1949, a large brick gable over the entry of Lafayette Elementary School in West Seattle collapsed directly onto an area normally used for assembly of pupils at the time of day the earthquake occurred (U.S. Geological Survey, 1975) ( Figure 41).

Similarly, the Washington State Training School for Boys, in Chehalis, sustained severe damage when a gable collapsed daring the 1949 Olympia earthquake ( Figure 42). Fatalities and injuries to school children would have been much higher had many Puget Sound schools not been vacant because of spring vacation.

Wood frame residences were usually undamaged except for failures of brick fireplaces and chimneys extending above the roof. Experience in California and elsewhere shows that fireplaces and chimneys are one of the principal hazards to frame residences subjected to strong ground motion. Edwards (1951) estimated that more than 10,000 chimneys in northwestern Washington required repair after the 1949 earthquake. Seventy-five percent of the chimneys in Chehalis had to be replaced. Damage to split-level homes was greater than in other frame residences because the two sections of such homes vibrated at different frequencies, concentrating stress along the junction between the sections. Some split-level houses collapsed completely (Gonen and Hawkins, 1974).

Structural damage in multistory buildings was generally limited in both the 1949 and 1965 earthquakes. However, damage to the State Capitol in Olympia and other older structures in the capitol complex was severe due to the lack of lateral bracing and the collapse of brick and stone facing ( Figure 43). After the 1965 earthquake, the Capitol was temporarily closed, and government activities were moved to nearby motels.

Fortunately, fire was not a major problem in either the 1949 or 1965 earthquake even though numerous water mains broke. In the 1949 earthquake, 24 breaks were reported in water mains in Olympia, resulting in a temporary closing of the business district. In Tacoma, water mains broke because of landslides and settling of tide flats. A 60-inch main broke at the Seattle city reservoir. Centralia's gravity-feed water system was badly damaged. In 1965, three water mains (two 20-inch and one 12-inch) failed in Seattle, and two of three 48-inch water supply lines broke in Everett where the trestle carrying them crosses an area of poor soil. Pressure surges in pipes were reported in Tacoma but did not cause pipe failures.

In 1949, power failures occurred in Seattle when swinging transmission lines touched, causing circuit breakers to trip. In Tacoma, the transformer banks at the Bonneville Power Plant substation needed to be realigned. In Chehalis, electric power service was disrupted for about 2 hours. In 1965, two Bonneville Power Administration transmission towers toppled near Everett. These towers carried 230,000-volt electrical power from Chief Joseph Dam to the Snohomish substation.

In 1949, the Seattle gas distribution system broke at nearly 100 points, primarily because gas mains separated from connecting pipes where the pipes were buried in filled ground. Although a major break occurred in Olympia's gas mains, there was no crippling interruption of service.

After the 1949 earthquake, damaged lift bridges in Seattle and Tacoma would not open and close. Only minor damage occurred to the State highway system, and that was due mainly to ground settlement and a few small slides onto roadways and railway tracks. Landslides also occurred in 1965.