I believe they are referring to continuous earthquake activity....or a “swarm” of earthquakes, if you will.
I figured that was what it was, but I wanted to make sure you weren't talking about bees. ;)
Yes a swarm is a series of small earthquakes that means lava is moving underground. In this case it seems to be moving closer to the surface. From 10 to 7 miles depth. I’ll be back tomorrow with some data from the Pinatubo eruption, the book “Volcano Cowboys” has a lot of detail. Also look for increased activity at times of the full and the new moon. We have just had a full moon.