5. Global Seismograph Network - GSN: IRIS -1 System

DATES OF OPERATION:  	29 Aug 1989 to 26 Nov 1990.

SEISMOMETER TYPE
Geotech model 36000-i borehole seismomter.  The Geotech Model GS-13 is used for the 
very-short period data (EHZ, EHN, EHE)..

DIGITAL FORMAT:
24 bit integer data words for all broad-band (20 sps), long period (1 sps), very  
long period (0.1 sps) and ultra long period (0.01 sps) channels.  Range: 
+8,388,607 to -8,388,608 counts.  16 bit integer data words for very short period
(100 sps), mass position, and all environmental channels.  Range: +32767 to -32768.

EVENT DETECTOR ALGORITHIM:  
The event detector used for the EH_ components is described in Murdock (1991).

COMPONENTS, SAMPLING RATES AND SENSITIVITIES:
All of the broadband components are identical to those listed for the IRIS-2
system.  Exceptions are the very short period components which were installed 
on 12 January 1990.  These very short period seismometers were located in the 
vault described in station ALQ.  Please note that the coordinates and elevation 
are slightly different from those described in station ALQ.  These coordinates
can be found in this Station Book for station ALQ.

Click on any of the following items for further information.

CHECK NOTES

• Channel Data
• Amplitude Response to Ground Velocity
• Seismic Noise Study graph information

• Seismic Noise Level - Annual
• Seismic Noise Level - Seasonal/Diurnal

COMMENTS:
The transfer functions for the IRIS-1 seismometer are identical to those for the 
IRIS-2 system with the exception of the very short period components.  The filter
system for these components is different with the IRIS-1 system, and, therefore, 
the transfer functions are slightly different.