Earthquakes of magnitude 2-2.8 are nothing by San Francisco standards, but when Mount St. Helens starts feeling 10 of them in a 24-hour period, we here at SFist know that's not where we want to be. Mount St. Helens, the most active volcano in North America, last erupted in 1980, and has been closely scrutinized ever since.
The USGS has issued a Notice of Volcanic Unrest, leading the US Forest Service to close many of the hiking trails on the mountain to the public, though visitors centers are remaining open.
Unfortunately, experts are still unsure about what might be causing the earthquakes, but the last time there were this many quakes in such a short time period was when the lava dome that currently caps the volcano was formed.
Thankfully, SFist visited Mount St. Helens last week, missing all the excitement by 7 days.