Wow, an earthquake in Germany! Whoda thunk they'd allow such a thing!
It was only an M4.2, but it's in the Rhine Valley Graben, which is very interesting, if you are at all interested in Europe. :) This is a failed rift and is probably identical to others in North America, such as New Madrid, Ottawa, etc. It can spit out a large earthquake every 300 years or so, but I think this is a fragmented mechanism, and not capable of really large earthquakes. I'm sure the water-based fault mechanisms are active here, but do they have the seismic monitoring required? Just don't build standard N-S American condos here, people!