Frank Perkins | Thursday, February 06, 2014
“Related expedition in Costa Rica”
My experience with this project actually dates to 1989 when a very similar project, under the same Principal Investigator was conducted in Costa Rica. It remains one of most memorial expeditions.
The broad objective of our research was prediction of eruptions. To do this, we made precise terrain elevation measurements around the crater, coupled with sensitive gravitational measurements.
The gravity meters were very precise, and they were challenging and fun to operate. They are easily capable of measuring the difference in gravity between the floor and a table top. They use a manually adjusted spring-balanced mass, with the balance read using an optical eyepiece. The instrument needs to be precisely leveled to operate, and, as might be imagined, is very sensitive to the slightest movement. Further, to avoid errors from backlash in the mechanism, the balance needs to be approached from the same direction each time, so an overshoot requires backing off and re-approaching the balance. At each location, two volunteers would take a gravity reading, and they needed to closely agree.
This was all accomplished while crouching on the ground over the big gray box, sometimes with jets of steam shooting out nearby. As we crouched over it, we looked like worshipers to some strange deity. The balancing operation required a degree of skill, and the competitive challenge of getting it right so the reading would agree with your companion's reading made for fun. Tedious fun, but fun!