Seismometer Installation - 2

Installing the threaded mating flange
A threaded mating flange is installed on the threaded casing. This particular flange was a prototype. Current versions are simpler.

Mating the casing to the well head enclosures was done at Lajitas with a custom threaded flange.

Sealer added ready for enclosure.
A padlock and chain hang on the left side of the casing. This was used to secure the cover while the cement was curing. This particular site was close to a well traveled highway.

Mounting the enclosure

The enclosure is mounted to the well with 8 large bolts. One or more bolts may be electrically connected to the casing to secure a good electrical ground. Once the box is installed, it forms a convenient structure for mounting a small winch used to lower the seismometer.

Gauging the hole

A dummy seismometer is lowered into the hole to gauge the depth. During installation the seismometer will be lowered by electric winch within a foot of the bottom and then by hand for the final distance. Lowering by winch avoids banging the seismometer against the side of the hole, while the final hand work allows much gentler placement on the bottom of the hole.

Lowering the seismometer
The case to the right contains the seismometer locking kit

The seismometer is attached to the cable and ready to be lowered into the hole. To lock the mass during this operation, a DC current is applied to the main coil to force it against the stops. A volt-meter and amp-meter monitor this operation and insure the coil remains locked during the operation.

Checking the level
The biggest problem is usually getting enough light down at the bottom of the hole to read the level. A strong spotlight is useful here.

By examining the level on the top of the instrument through a small telescope, it is possible to determine if the instrument is level. On occassion it is necessary to rotate the seismometer slightly to avoid irregularities on the floor.

At this point the seismometer is in the hole and the site is ready for the final electronics installation and configuration.