Seismometer Installation

Adjusting the free period and leveling the seismometer
Installation of the seismometer begins with adjusting the free period and mass position. Here the free period is being checked with a spectrum analyzer and is typically set to 0.1%. The feet on the bottom of the seismometer are adjusted for a level surface.

The installation of the seismometer begins with final adjustment of the instrument for free period and a level surface. It is assumed, because of the way the borehole-vault floor was poured, that the floor surface will be level. Final adjustment of the instrument free period is needed to adjust for any changes that may have occured during shipping or transport and to verify that all instruments are set exactly the same.

Because the sites at Lajitas are far from commercial power, it is convenient to setup the seismometer prior to moving all the equipment to the element location.

Cleaning out the hole
This hole, used later for the KS36000 broadband instrument, had flakes of cement on the bottom floor of the vault. Somehow, during casing cemeting, some cement had gotten on the inside of the casing and later flaked off. It was cleaned out with large wads of sticky tape on the end of a pole

In some cases, the hole has accumulated small amounts of water or flakes of rust, or even small pubbles. The bottom on the hole is checked with a small telescope and any problems removed.

Removing excess water with a sponge tool

Once the borehole vault is clean, the rest of the seismometer installation may begin.