Series of earthquakes under Mount St. Helens, Washington
A series of small to moderate earthquakes shook Mount St. Helens volcano in Washington over the past couple of days. The largest was M3.9 at a depth of 10.2 km (6.2 miles) on January 3, 2018, followed by M2.7, M2.0 and M1.9. The quakes are believed to be tectonic in…