1. Global Seismograph Network - GSN: [ IU ] DATES OF OPERATION: 01 Dec 1994 to present. SEISMOMETER TYPE & ADC: Geotech KS-36000-I borehole seismometer. ADC is Quanterra QX80. DIGITAL FORMAT: 24 bit integer data words for all broadband, long period, very long period and ultra long period channels. Range: +8,388,607 to -8,388,608 counts EVENT DETECTOR ALGORITHM: None Click on any of the following items for further information.COMMENTS: