PSN-L Email List Message

Subject: KS36k is a triaxial seismometer
From: sean@...........
Date: Mon, 30 Apr 2001 02:03:59 -0500 (CDT)

Following up on the info Dennis has provided
Re. the KS36k triaxial seismometer.

The fundamental design was first described by Melton in 1960, and a 
patent was granted in 1965 on the "Angular Composite Seismometer"

The original prototype design was described in the BSSA in June 1970:

"The Symmetrical Triaxial Seismometer - Its Design for
Application to Long-Period Seismometry", by Ben S. Melton and
B. M. Kirkpatrick; BSSA, Vol 60, No3, Pgs 717-739, June 1970.

(B.M.Kirkpatrick was a project engineer at Teledyne Geotech)
The research was supported by the Air Force AFTAC, ARPA, and
the VELA uniform programs (of the cold war).

The borehole prototypes were 10" in diameter and 99" long, and weighed
420 pounds. A single axis module weighed 107 pounds.

The basic configuration is that of three identical sensors mounted
as in a corner-cube, with the sensitive axis of each inclined inward 
53 degrees from the vertical. This is currently used in the STS-2 
sensor and the Trillium. The outputs of all three sensors, usually 
labeled U,V,W, are summed into orthogonal outputs X,Y,Z by resistors.
In the STS-2, these resistors are of course identical for the 
vertical output (25k of of U, 26k of V, and 26k of W). For the 
Y output, The U channel is the fundamental (0k), summed with
23k of V and 23k of W. The X channel is 19k of U, 38k of V, and
38k of W.

So it is important to note that a single sensor of the KS36k will not
work as a stand alone seismometer. All three must be used and summed 
as above.  One could remove them from the long borehole casing and 
operate them in a circle on a pier at 120 deg relative rotation, or 
put them in a relative fat tank (like the STS-2) on a single base for 
pier or shallow posthole installation. Or the Ks36k could be kept 
intact and put into a relative deep hole (gt. 10 meters) to provide 
the thermal equilibrium that the sensors require.


Public Seismic Network Mailing List (PSN-L)

[ Top ] [ Back ] [ Home Page ]

Larry Cochrane <cochrane@..............>