The USGS is currently using GPS to measure the changes in a volcano prior to or during an eruption. GPS can measure horizontal changes between different GPS receivers down to a couple of millimeters and vertical changes of about 10 millimeters (1 cm). By visiting the same locations every few months, volcanologists can determine where and how much the volcano is changing shape.
The positions of a volcano's benchmarks are measured on a regular basis depending on the activity of the volcano. Increasingly, continuous GPS measurements are being made at active US volcanoes in order to detect magma rising toward a volcano's surface and improve our warning capabilities. The direction in which benchmarks move and the rates of movement often enable us to estimate the source of the deformation.
This photo shows a GPS receiver on the south flank of Kilauea. Note the benchmark below the receiver. Photo by Steve Mattox, March 1992.
At the Hawaii Volcano Observatory (HVO), near real-time deformation monitoring of Kilauea and Mauna Loa is done with a network of sixteen continuous GPS stations. Continuous Global Positioning Survey (GPS) data is sampled every 30 seconds and a one day average is taken and downloaded. This network is a cooperative effort between HVO, Stanford University, and the University of Hawaii. This data allows tracking of mid- to long-term changes in the magma system.
The following is a link to the HVO page.
http://hvo.wr.usgs.gov/observatory/work.html
Another Volcano where GPS is used to monitor changes is Mt St Helens in Washington. Back in 1980 when Mt St Helens first erupted, one scientist was killed from the blast gathering data. GPS technology didn’t exist as it does today. Today, fixed GPS monitors can measure a volcano’s growth and movement in real time. Scientists no longer have to risk their lives and put themselves in close proximity to the active volcano to gather data. Since GPS has become accurate within millimeters, I think it is a great tool to help monitor for possible eruptions so lives can be saved.
Scientists have been recently monitoring this volcano since earthquakes started back in September 2004.
U.S. Geological Survey scientist Dan Dzurisin at a Global Positioning System (GPS) station on the east flank of Mount St. Helens (station Southeast Ridge). Mount Adams volcano is visible in the distance. More than a dozen GPS stations have been installed on or around Mount St. Helens to measure any deformation of the ground surface that might accompany an intense swarm of earthquakes that began on September 23. USGS photograph taken on 29 September 2004 by Mike Poland.
The reason I selected this topic was because I am intrigued with volcanoes. I have been to Volcano’s National Park in Hawaii and hiked some of the trails around the Kilauea Caldera. I remember when Mt St Helens erupted in May of 1980 and have hiked its crater. You can still see the damage from the eruption. Parts of Spirit Lake still have trees and logs floating in it. I was there hiking the crater a few weeks before they shut it down in 2004 due to earthquakes and volcanic activity. The crater had started to swell slightly.
Just for fun:
Here is a link to the Mt St Helens Volcano Cam which is mounted at the Johnson Ridge Observatory which sits on a bluff just 5-1/2 miles from the crater at an elevation of 4,314 feet and offers grand views of Mount St. Helens and much of the 1980 blast zone.
http://www.gonorthwest.com/washington/cascades/mt_st_helens/St-Helens-Cam.htm
