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Contact: Barbara McGehan
NOAA Instrument Survives Volcano; Provides Wealth of Information
According to government and university scientists, a device placed by the National Oceanic and Atmospheric Administration's Pacific Marine Environmental Laboratory has provided an eyewitness account of what happens when an underwater volcano erupts. The device survived after being engulfed by a lava flow during an active eruption in 1998.
The site of the 1998 eruption was Axial volcano, along the Juan de Fuca Ridge seafloor, located about 300 miles off of Cannon Beach, Ore. This volcano has been the focus of a long-term NOAA research effort called the Vents Program, that seeks to understand the mechanisms by which the earth's interior exchanges heat and chemicals with the earth's surface through seafloor spreading centers.
In an article in the August 16 issue of Nature, Christopher G. Fox and Robert W. Embley from the Commerce Department's NOAA facility in Newport, Ore., and William W. Chadwick, Jr. of Oregon State University's Cooperative Institute for Marine Resources Studies, describe in detail the results obtained from this serendipitous occurrence.
"We began monitoring Axial in 1987, using simple bottom pressure recorders to measure the long-term vertical movements of the seafloor associated with magma transport within the volcano," reports Fox. "We never expected to get this close a look at the eruptive process."
The seafloor instrument, a Volcanic System Monitor, had been installed on the summit of Axial in October 1997 to continue the decade-long research effort begun by scientists in 1987. The precise location of the VSM was based on geological and geophysical measurements and was thought to overlie the magma center. Following the eruption, NOAA vessels visited the site and attempted to recover the instrument. Although the VSM responded, it would not release to the surface. Later investigations using a Remotely Operated Vehicle showed the instrument to be trapped in the lava flow. A plan was formulated to recover the instrument in 1999.
Surprisingly, the instrument was recovered with very little damage. According to Chadwick, "the maximum temperature recorded inside the instrument during the eruption was only 7.5 degrees Celsius. This was remarkably low considering that the instrument was sitting atop basaltic lava that had probably erupted at around 1,190 degrees Celsius." Scientists believe this was due to the thermal insulation provided by the surface crust that forms and thickens when submarine lava flows come into contact with frigid sea water.
"Much of the data were intact, in particular the pressure and temperature data," said Fox.
The data give a detailed view of the dynamics of a deep ocean volcanic eruption. In addition to the information on the flow itself, the long-term pressure record, in conjunction with other instruments deployed around the volcano by NOAA's Vents Program, provided a picture of what happened to the magma in the subsurface, making the 1998 Axial event the first deep submarine eruption ever recorded.
According to Fox, little is known about deep-sea eruptions because only in the last decade have we been able to detect them, and none has ever been witnessed. "The data we report here, recorded by the VSM instrument caught in the 1998 lava flow at Axial volcano, were obtained by fortuitous circumstance. The instrument was simply in the right place at the right time, with the right sensors - and - happened to survive the eruption," said Fox.
"It is doubtful that we will ever be clever enough to intentionally place an instrument in an active submarine lava flow, so this serendipitous recording becomes a benchmark in our understanding of submarine volcanism," Fox concludes.
The Commerce Department's National Oceanic and Atmospheric Administration is dedicated to enhancing economic security and national safety through the prediction and research of weather and climate-related events and providing environmental stewardship of our nation's coastal and marine resources. To learn more about NOAA, please visit http://www.noaa.gov.
For more information about the Pacific Marine Environmental Laboratory and the Vents Program, visit: http://www.pmel.noaa.gov/vents.