Results from IMS Seismic Array in Niger

The International Monitoring System (IMS) of the Preparatory Commission of the Comprehensive Nuclear Test-Ban Treaty Organization (CTBTO) has built a sixteen element broadband seismic array in southwestern Niger near the town of Torodi. This is the first array to be built in West Africa. The array has a diameter of 6 km (three rings with a central element), contains twelve vertical and four 3-component broadband sensors, all with identical instrument responses (Guralp CMG-3TB broadband sensors, flat to velocity from 100 seconds to 40 Hz). Many elements have seismic noise characteristics at or below Peterson’s Low Noise Model at greater than 0.5 Hz. All of the sensors are emplaced in 50 m boreholes in crystalline rock.