DESCRIPTION:
Field Observations

Geologic field observations form an important part of any volcano-monitoring program yet are often overlooked in lists of monitoring techniques. Such observations provide the opportunity to integrate many different kinds of data on the spot and to design simple measurements to test key questions resulting from the observations. Field observations go hand in hand with more sophisticated equipment and techniques to form a complete system for monitoring volcanoes. Monitoring programs should explicitly include provisions for geologic field observations and instill in field workers, scientists, and technicians alike, the need to be flexible and clever in designing simple experiments and measurements to test important field observations on the spot. ...

The flexibility provided by field geologic observations cannot be overemphasized. Most electronic sensors are designed to detect and report one parameter, such as tilt, displacement, seismicity, or changes in a particular species of gas. If some unmonitored parameter changes, the sensor either doesn't detect it or may provide spurious information. On-the-spot geologic observation clearly is not restricted to a single parameter, although of course it is restricted to what can be observed with the eyes, ears, and nose. Small changes may go unnoticed by field observers, but large changes may go unnoticed by electronic sensors not monitoring the proper parameter. Only on-the-spot observers can quickly assess the situation and determine which parameters are likely to provide vital information. Measuring an unimportant quantity accurately and continuously using sophisticated equipment can be a waste of time and resources; it is much better to get to the heart of the matter by the simplest means possible.

Another important point is that even the best remote-monitoring techniques require verification by on-site field observations and integration with other data. For example, an electronic tiltmeter may indicate a change, but his change could reflect an electronic problem, an unstable installation, or real deformation of the volcano. Only independent information can determine which interpretation is most likely. ...

... Field observations and related measurements are a vital component of volcano monitoring, just as are electronic sensors, radios, and high-priced surveying equipment. In fact, the two approaches commonly merge. For example, sophisticated (and expensive) EDM's measure to painted wooden boards with plastic reflectors screwed on them ...

... Each geologist or geophysicist who spends much time on a volcano should be trained to observe field conditions, to think about those observations while in the field, and to be flexible and clever in devising simple measurements that can be made quickly and definitively once changes are noted. ...

Keeping accurate notes may be the most important aspect of volcano photography, other than the actual shooting of the photography. Keep notes on cameras, lenses, and filters used, film type, exposure, date and time, weather and lighting conditions, the height of the tripod, the subject being photographed, and the location from where the photography was taken. Keep notes on everything and anything that might be important, for they may prove useful years later.

Return to:
[Volcano and Hydrologic Monitoring Techniques Menu]...