Yellowstone National Park News Release
August 7 , 2003 03-73
TEMPORARY HYDROTHERMAL MONITORING PROGRAM TO BEGIN AT NORRIS GEYSER BASINIn response to notably increased heat and steam emissions in parts of Norris Geyser Basin, the Yellowstone Volcano Observatory will deploy a temporary network of seismographs, Global Positioning System (GPS) receivers, and temperature loggers. The temporal deployment is intended to document chemical and physical signals that accompany this increased activity, to identify the underground locations of hydrothermal steam sources and the relationship of the Norris geyser basin to the background general seismicity, and crustal deformation of the Yellowstone caldera. It may also detect any precursory signals to geyser eruptions and hydrothermal explosions.
The GPS equipment is designed to detect very small movements of the earth, and the seismic array can measure earthquakes associated with flow of thermal water and earthquakes located on buried faults. Seven seismometers that record a wide range of seismic frequencies typical of hydrothermal and volcanic systems, called broadbands, will be placed throughout the Norris Geyser Basin, five of them within and around the hydrothermal disturbed area itself. These "broadband" seismometers are especially sensitive to the long-wavelength ground vibrations that occur as water and gas move through underground cracks as well as deeper volcanic sources.
The seismic array will be complimented by high precision GPS receivers that precisely measure the coordinates of points on the ground from data transmitted by an array of satellites that can be compared with each other to measure the relative ground velocities through time. These data compliment Yellowstone's permanent GPS network.
Movements of the ground associated with underground pulses of water and steam (including geyser eruptions) may be detected by this new technology. Thermometers placed in hot springs and creeks will continuously document the flow of water out of the geyser basin. The scientists hope to link individual pulses of water, changes in their chemistry and temperatures to pressures in the earth. This information may provide information on ground motions and seismic signals that precede them.
The Norris Back Basin has been closed since July 23, 2003, after formation of new mud pots, changes in geyser activity, and significantly increased ground temperatures (up to 200 degrees Fahrenheit) in some areas near the Back Basin trail. Additional observations include vegetation dying due to thermal activity and the changing of several geysers' eruption intervals. The heightened rate of steam discharge has continued to the present time.
The Yellowstone Volcano Observatory (YVO) is a collaborative partnership between the U.S. Geological Survey, the University of Utah and Yellowstone National Park. The Yellowstone seismic and GPS network consists of a modern digitally telemetered network of 22 seismographs and 5 permanent GPS receivers throughout Yellowstone National Park in support of the YVO and a National Science Foundation (NSF) project focused on the Yellowstone hotspot. These networks are operated and recorded by the University of Utah.
The Yellowstone Volcano Observatory is designed to provide geophysical and geochemical monitoring of Yellowstone National Park that enables timely guidance to the NPS and improves scientists understanding of ongoing volcanic, hydrothermal and earthquakes activity. Two NSF-supported University research consortiums and the University of Utah are providing the temporary equipment and technical support (IRIS, Integrated Research Institutes in Seismology and UNAVCO, University NAVSTAR Consortium). Funding is available primarily from the USGS Volcano Hazards Program and Yellowstone National Park.
For more information on YVO, go to
http://volcanoes.usgs.gov/yvoQUESTIONS AND ANSWERS, NORRIS GEYSER BASIN MONITORING NETWORK
August 6, 20031. If the Yellowstone Volcano Observatory is involved, does that mean a volcanic eruption is coming? No. The last time a volcanic eruption occurred at Yellowstone (that is, where molten rock erupted) was 70,000 years ago. There is no reason to expect another volcanic eruption at this time.
2. Why install the monitoring network now? Yellowstone National Park asked YVO to help assess the hazard to the public and NPS property by the increased activity at the Norris Geyser Basin. One potential hazard is hydrothermal (also called phreatic or steam) explosions. This monitoring network will allow scientists to observe precursory activity to hydrothermal explosions, should any occur. In addition, the seismometers and GPS receivers will aid scientists in understanding the behavior of geyser basins, which are among the most seismically active features on earth. Lessons learned today will help ensure public safety tomorrow.
3. What is a hydrothermal explosion? The earth can act like a pressure-cooker with water boiling at higher and higher temperatures as pressure increases beneath the surface. If the pressure is released suddenly, water can boil and expand rapidly, fracturing rocks and throwing them into the air. These hydrothermal explosions occur somewhere in Yellowstone almost every year, though seldom are they witnessed and most are quite small. The resulting craters can be anywhere from a few feet to thousands of feet across. Excelsior Pool in the Midway Geyser Basin was greatly enlarged by hydrothermal explosions in the late 19th Century. The most recent hydrothermal explosion at Norris Basin occurred at Porkchop Geyser in 1989.
4. Has this increased steam emission ever happened before at Norris? Each year, there is a noticeable change in the color and steam discharge of many of Norris' existing geysers and thermal pools. Known as the "annual disturbance", it appears related to increased emission of deep, hot waters. This year, the "annual disturbance" is larger than normal and has resulted in the formation of many new steam vents. The increased steam emission was sufficient to create hazardous conditions for visitors on the Back Basin Trail. Park staff measured ground temperatures of 200 degrees Fahrenheit in the closure area-an unacceptable level for visitor and employee safety.
5. Does YVO expect hydrothermal explosions at Norris? No. However, the possibility remains, and the high ground temperatures and new thermal features in the Back Basin make closure of the area a prudent decision.
6. Where is Norris Geyser Basin? Norris Geyser Basin is located in the northern section of Yellowstone National Park, 22 miles south of Mammoth Hot Springs.
7. When will the temporary closure at Norris be lifted? Park staff will continue to monitor ground temperatures and geyser activity in the Norris area. The temporary closure will be lifted when conditions have returned to acceptable ground temperatures and stable surface conditions have improved.
8. Are other areas in the park being affected by thermal activity? Currently, we have no evidence for increased thermal activity in other areas of the park. We have a large network of seismic instrumentation throughout the park that is monitored on a daily basis.
9. Is YVO related to other U.S. Volcano Observatories? Yes. The USGS operates 5 volcano observatories, including ones in Hawaii, Alaska, the Cascades (Washington) and Eastern California. Unlike some of the other observatories, YVO includes staff and funding from academic and other non-federal sources.
--NPS-
http://www.nps.gov/yell/press/0373.htmVolcano Monitoring at Yellowstone National Park http://volcanoes.usgs.gov/yvo/monitoring.html
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