DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions) was a French micro-satellite operated by CNES devoted to the investigation of the ionospheric disturbances due to seismic and volcanic activity.
It was launched on June 29, 2004, on a quasi Sun-synchronous circular orbit with an inclination of about 98.23° and an altitude of about 710 km.
The satellite performs 14 orbits per day and measures continuously between -65° and +65° of invariant latitude.
[1] DEMETER observed an increase in ultra low frequency radio waves in the month before the 2010 Haiti earthquake.
[2] During the 2010 eruption of Mount Merapi, DEMETER noted anomalies in the ionosphere.