Earthquake Monitoring at Mount Adams
The Pacific Northwest Seismic Network (PNSN) and CVO monitor seismicity at Mount Adams via a single nearby station (ASR, located about 10 km (6 mi) from the summit) and the broader regional PNSN network. Since station ASR was installed in 1982, only nine earthquakes have been located by the PNSN within 10 km of the summit (most recently a M 1.2 in April of 2006), including just five within 5 km. With just one nearby station, it is likely that very small (M < 1.0) earthquakes are not routinely detected and located at Mount Adams. Despite the small network and likelihood that small earthquakes have been missed, Mount Adams is still considered one of the most seismically quiet volcanoes in the Washington and Oregon Cascades.
At the first sign of unusual earthquake activity, scientists will deploy additional instruments on and around Mount Adams to monitor earthquakes, deformation, and other symptoms of volcanic unrest. The monitoring information will be used to assess the state of unrest and to issue appropriate advisories and warnings to emergency-response officials and the public.