PSU Magazine Winter 1993

Matthew Mabey, geologist and civil engineer, is opening the public's eyes to the reality of a great shake in our lifetime. By Brian White Assistant Professor Matthew Mabey f you live in western Oregon, you're likely to experience or be near a significant, damage– causing earthquake in your lifetime. Predicting earthquakes has always been something of a shaky business, but a mounting body of scientific findings-and the simple computing of odds-indicates that the Pacific Northwest is ripe for a major quake in the not- a-distant future. Matthew Mabey has no intention of alarming Northwest residents, but he's on a public information mission of sorts. Mabey, as istant professor of civil eng ineering and geology at PSU, gives one or two public talks each month, calmly exp laining the region's propen– sity for earthquakes. He spoke in November on the sub– ject during the Portland State Univer– sity Alumni Association's annua l weekend seminar program. Mabey knows he's facing a fairly skeptical audience. After all, cities such as Portland and Eugene haven't endured the widespread damage and suffering that quake have caused in San Francisco, Los Angele , and other Californian urban centers. In other words, out of sight, out of mind. "Most pe pie here just don't have the direct experience of frequently occurring earthquake that residents of California have. It take a long time to raise public awarenes ,"says Mabey, who in add ition to his PSU work serves as an earthquake engineer for the state Department of Geology and Mineral Industries in Portland. The Northwest is no stranger to earthquakes. In 1949, a quake register– ing 7.1 on the Richter scale rattled Puget Sound residents, caus ing sig– nificant structural damage and some deaths in the Seattle area. In Portland, numerous chimneys toppled as a result of the quake. But that was more than 40 years ago. Another Puget Sound-based quake, in 1965, reached 6.5 in intensity but had minor impact on Oregon' popula– tion centers. Portland's largest recorded quake, carrying a 5. 7 Richter reading, took place in 1877. According to scienti ts' calculations, the Portland area can expect to see a quake of 6.0 strength (enough to cause significant damage) about once every 100 years. That means the area is due. California gets most of the lower 48's earthquakes. All of those are of the crustal variety, caused by pressure in the land plates that makeup the earth's surface. These quake are noted by PSU7