The rotation sensor at Pinon Flat Observatory

Optical sensor technology has recently led to the development of rotation sensor with high enough resolution for broadband seismology. The GEOsensor is a seismic measurement platform, comprising a large ring laser, a standard seismometer, and auxiliary devices like a GPS referenced time base, a temperature, and a pressure sensor, etc. Following completion of the system at the Geodetic Observatory Wettzell (Germany), such a sensor system was installed at the geophysical observatory located in Piñon Flats, CA (USA). The ring laser, installed in Winter 2005, measures the vertical component of the rotation vector (i.e. rotation, twist, or spin around a vertical axis). At present key issues are stabilizing the continuous observations and investigating the external influences (e.g., temperature changes) on the observations. We will present technical details of the installation and instrument properties and show observations from local, regional, and global events.