How many and what size of earthquakes occur near Portland?
In this century there have been three significant earthquakes near Portland: in 1877 (M 5.3), 1962 (M 5.5), and 1993 (M 5.5). Additionally, Portland has been damaged by earthquakes that occurred in the Puget Sound region, such as the 1949 magnitude 7.1 event near Olympia, WA, and the 1965 magnitude 6.5 event located between Seattle and Tacoma. • Q: Could a big earthquake in California, Alaska, or Japan cause earthquakes in Washington or Oregon? A: Historical data and theory suggests that earthquakes only provoke other shocks within a limited area around the fault rupture. Distant earthquakes have no direct effect on Washington and Oregon. Earthquakes in California, Alaska and Japan are caused by the interaction of different plates than the earthquakes in the Pacific Northwest. However, the 1992 Landers earthquake in southern California caused an increase in tiny earthquakes in geothermal areas as far away as The Geysers in northern California. • Q: Could bridges collapse due to seismic
