I have had a number of inquiries to the Center in the last several days, asking about reports of rumblings at Mount St Helens. A little research shows that there have indeed been a number of earthquakes in the vicinity of Mount St Helens, since the start of 2018. Those earthquakes – one of which reached magnitude 3.9 – are focused on the Bean Creek valley – a tributary of Smith Creek, which, in turn, flows south to join Muddy River, and hence drains into the Lewis River basin. To view a larger version of the map, please click on the small map.
There have, of course, been rumblings before, in recent years. There were a number of tremors in 2016. Magnitude 3.9 is fairly substantial. It is possible for an earthquake that size to cause a little damage, and it could certainly be felt. However, Bean Creek happens to be in a remote area of the Gifford National Forest.
The Pacific Northwest Seismic Network report that this cluster of tremors is due to local fault lines in and around Bean Creek, and is not associated with magma under Mount St Helens. It follows that these events are not likely to be linked to a possible forthcoming eruption of the volcano.
Nevertheless, it must always be remembered that Mount St Helens is the most active volcano in the contiguous 48 states. There is always a danger of further eruptions. An eruption on the scale of that of 2004 is not unlikely, though we probably do not expect something as violent as the 1980 eruption.