Oh com'on Mr. USGS! Admit you don't have a speck of monitoring there! Your whole life is dedicated to surfing the big ones in Callie!
So when these poor people have the same booming as in New Brunswick, you don't know your seismic from a hole in the wall!
Anyway, poor people, these things happen, and are called micro-swarms. They can happen very close to the surface in hard rock, and explode like a tea party marine! They have never really developed into anything, and should soon go away. I'll bet if you scratched the surface there, you would find some very high stresses right at the surface. Great place for nuclear waste!