New methods of volcanic monitoring - infrasound and thermal emission

During the last few years certain new technologies have entered into volcano monitoring. Several of these technologies are being introduced into the systems at Volcán de Colima. An infrared (IR) camera was loaned by the Instituto de Geofísica, UNAM for use at Volcán de Colima during the period September 2004 to January 2006. It was also used at Isla Socorro and El Chichón. Images have been taken of effusive activity at Volcán de Colima and are being used to study the formation of the lava dome and flows during 2004. The camera has also been used to study the eruption column during explosive activity and to observe fluctuations in fumarole temperatures.

The new IR camera arrived during January 2006. It is now being used at least once per week to monitor the fumarole temperatures. Advantage is being taken of the great viewing platform offered by Nevado de Colima. The fumaroles on the north rim can be seen from a point at a similar altitude. We have observed some interesting variations during the 2005-6 period. It is proving to be a very useful tool in the monitoring of activity. In the future the camera may be installed with the data being sense constantly back using a wireless link

Relatively cheap radiometers have been installed at several volcanoes and can allow calculation of the ascent rate of the column and combined with other data, allow the estimation of the source depth of explosive events. Initial results at Colima have proved interesting with the presence, for example, of thermal peaks with no corresponding seismicity.

Infrasound refers to the low frequency acoustic signal that accompanies a volcanic explosion. The signal can be much clearer than the corresponding seismic wave and by considering the two, the source depth of an event can sometimes be determined. Two thermal and two infrasound sensors are being installed during 2006 with telemetry to provide constant monitoring of these characteristics of explosive events.

Dr. Jeff Johnson, University of New Hampshire, USA
Dr. Andy Harris, University of Hawaii
Dr. Servando de la Cruz, Instituto de Geofísica, UNAM, Mexico.
Protección Civil del Estado de Jalisco