MOUNT ADAMS, Wash. — Six earthquakes were recorded at Mount Adams in September, the most since monitoring began in 1982, according to the U.S. Geological Survey's Cascades Volcano Observatory.
The agency and the Pacific Northwest Seismic Network recorded six earthquakes at its seismic station located about 7 miles southwest of the volcano's summit, as well as other stations further from the volcano. Those earthquakes ranged from magnitude 0.9 to 2.0.
According to USGS, earthquakes at Mount Adams typically happen once every two to three years.
No earthquakes were felt on the surface, the agency said, and there have been other smaller earthquakes that have not been located. Satellite imagery has also not shown any ground deformation at Mount Adams.
"Currently, there is no indication that the level of earthquake activity is cause for concern, and the alert level and color code for Mount Adams remain at GREEN/NORMAL," USGS reassured.
Experts will continue to monitor earthquake activity.
Mount Adams' seismic network is sparse, as it only has one station near the volcano, but the Cascades Volcano Observatory and Pacific Northwest Seismic Network plan to add more temporary stations in the area, which will detect smaller earthquakes, as well as stronger data estimates of their size, location and depth. Those stations will be south and southwest of the volcano.
The second-tallest volcano in Washington is ranked as a "high threat" volcano by USGS. If it erupts, residents will encounter lahars, or muddy flows of rock, ash and ice that surge downstream, causing landslides, the agency said.
The south-central Washington volcano is about 50 miles west-southwest of Yakima, and 30 miles north of the White Salmon-Hood River area of Washington and Oregon. Mount Adams is part of the Mount Adams-King Mountain volcanic field, which contains more than 120 smaller volcanoes in parts of Skamania, Lewis, Klickitat and Yakima counties, as well as the western part of the Yakama Nation.