EIL - STATION INSTRUMENTATION 

2. High-Gain Long-Period Seismograph System-HGLP:  [HG]

Dates of Operation:   29 Jun 1972 to 02 Jan 1979.	

SEISMOMETER TYPE:
Teledyne-Geotech long-period 3 component system, Model S-11 vertical and two 
Model S-12 horizontals.  Seismometers are located in sealed metal tanks filled 
with argon gas.

DIGITAL FORMAT:
16 bit integer data words for all components.  Range: +32767 to - 32768 counts.

EVENT DETECTOR ALGORITHM:  None.

Click on any of the following items for further information
COMMENTS: The HGLP Seismograph Network was the first global network of digitally recording seismograph stations. Installations began in August, 1972, and the last system was closed in 1979. The initial hardware included long-period phototube amplifiers (PTA) which had inherent drift problems which in turn affected the calibration. The PTAs were replaced with Ithaco amplifiers in early 1975 which resulted in a standard response curve for the HGLP Network. All of the data was recorded on 7 track magnetic tape. In 1985 all of the HGLP data was rerecorded on 9 track magnetic tape in SRO format. This data is now available in the SEED format, however, it should be noted that the calibration for much of the data is suspect. The Ithaco amplifiers were installed at EIL on 17 Mar 1975. Due to electric power interuptions and other problems at the station, there are frequent gaps in the data.