Earthquakes

Actually that link is quite relevant. That earthquake page is one the main webpages that we use for tracking down sources of problems in the IFO (like losing lock). As it happens I just spent a week down at LIGO Livingston observatory as a Scimon so tracking earthquakes was one of my jobs. There are a lot of earthquakes in Alaska that have an effect on the IFOs but if there is a earthquake bigger that 5.0 it will likely have an effect no matter where it is. There are several seismometers at the LIGO sites that make it very easy to know when an earthquake is affecting the data.

Earthquakes will cause the sensitivity of the IFOs to go down and sometimes even break lock, but the IFOs are built so the earthquakes and other sources of noise have as little impact on the data as possible. They are very poor earthquake detectors.