Lava and Lava Flows
- The temperature of basalt lava at Kilauea
reaches 1,160 degrees Celsius
(2,120 degrees Fahrenheit).
-- USGS/VHP Website, 1998
- The tube system (lava tubes) of episode 53 (Pu'u O'o eruption,
Hawaii) carried lava for
10 kilometers (6 miles) from the vent to the sea. So efficient were the tubes
in containing heat that lava cooled only 10 degrees Celsius across that
distance. When it reached the ocean, the lava was still a sizzling 1,140 degrees
Celsius (2,085 degrees Fahrenheit).
-- USGS/HVO Volcano Watch, November 14, 1987
- The temperature of the lava in the tubes is about 1,250 degrees
Celsius (2,200 degrees Fahrenheit).
-- USGS/HVO Volcano Watch, June 4, 1998
- By way of its color, incandescent rock gives a crude
estimate of temperature. For example, orange-to-yellow
colors are emitted when rocks (or melt) are hotter than
about 900 degrees Celsius (1,650 degrees Fahrenheit).
Dark-to-bright cherry red is characteristic
as material cools to 630 degrees Celsius (1,165 degrees
Fahrenheit).
Faint red glow persists down to about 480 degrees Celsius
(895 degrees Fahrenheit).
For comparison, a pizza oven is operated at
temperatures ranging from 260 to 315 degrees Celsius
(500 to 600 degrees Fahrenheit).
-- USGS/HVO Volcano Watch, November 14, 1997
- Lava sampling
can be risky, so why do we bother to do it? Hot lava
samples provide important information about what's
going on in Kilauea's magma chambers. ...
We know from laboratory experiments that the more
magnesium there is in magma, the hotter it is. Chemical
analysis therefore provides the means, not only to
determine the crystallization history of lava, but also to
establish the temperature at which it was erupted. ...
Episode 54 lavas are chemically different from lavas
erupted over the last 12 years. Chemical analyses show
that magma was supplied by two distinct magma bodies
that have resided for years beneath Napau Crater, where
eruptions last occurred in 1983 and in 1968. Lava
nearest Pu'u O'o erupted at 1,125 degrees Celsius to
1,130 degrees Celsius
(2,057 to 2,066 degrees Fahrenheit)
and contains crystals of olivine,
feldspar and pyroxene. Calculations show the source of
this lava was intruded at the beginning of the Pu'u O'o
eruption in January 1983. The lava erupted from the
west wall of Napau tapped a second magma body that
was possibly emplaced in August 1968. This magma,
which had been cooling and crystallizing for a longer
time, erupted with more abundant feldspar and pyroxene
crystals and at lower temperatures of 1,110 to 1,120
degrees Celsius
(2,030 to 2,048 degrees Fahrenheit).
-- USGS/HVO Volcano Watch, March 14, 1997
Pyroclastic Flows, Debris Avalanches, and Lahars
- High-speed avalanches of hot ash, rock fragments, and gas
move down the sides of a volcano during
explosive eruptions or when the steep edge of a dome breaks apart
and collapses. These pyroclastic flows,
which can reach 1,500 degrees Fahrenheit (815 degrees Celsius), and
move at 100-150 miles per hour, are capable of knocking down and
burning everything in their paths.
-- Myers and Brantley, 1995.
- Mount St. Helens, May 18, 1980:
Emplacement temperatures of the debris avalanche ranged from about 70 degrees to 100 degrees C,
and those of the directed blast ranged from about 100 degrees to 300 degrees C
and varied with azimuth from the volcano. Emplacement temperatures of the
pyroclastic-flow deposits ranged from about 300 degrees to 730
degrees Celsius (570 to 1350 degrees Fahrenheit),
near-vent deposits were emplaced at about 750 to 850 degrees C.
-- Banks and Hoblitt, 1981.
- Novarupta (Alaskan Peninsula)
was the source of the world's most voluminous 20th-century
eruption.
The 60-hour eruptive
sequence of 6-8 June 1912 included ...
an 11-cubic kilometer zoned ignimbrite sheet filling the
Valley of Ten Thousand Smokes ...
The "ten thousand smokes" in the ash-flow sheet
mostly died out by 1930, and the few fumaroles
remaining today are odorless wisps that issue from Novarupta and from
intravent fractures nearby. Although orifice temperatures were as high as 645
degrees Celsius (1,193 degrees Fahrenheit)
in 1919, none are hotter than 90 degrees Celsius
(195 degrees Fahrenheit) at present.
-- Hildreth, 1990
Mount St. Helens, 1980 -
Blast Deposits,
Debris Avalanche, Pyroclastic Flows, and Lahars
- Temperatures ranging from about 70 degrees to 277 degrees Celsius
(158 degrees to 531 degrees Fahrenheit)
were measured at 21 localities in deposits of the directed blast (May 18,
1980, at Mount St. Helens).
All but one of these localities were on ponded
deposits in topographic lows.
-- Banks and Hoblitt, 1981
- Emplacement and near-emplacement temperatures ranged from 418
degrees to 297 degrees Celsius (784 degrees to 567 degrees Fahrenheit)
in the pyroclastic-flow deposits of May
18. (Mount St. Helens, May 18, 1980). Temperatures were measured at 13
localities between 1.8 and 9 kilometers (1.2 and 5.5 miles) from the vent.
Attempts to obtain
emplacement temperature nearer to the vent than 1.8 kilometers were frustrated
because deposits were thin and spotty and had cooled appreciably before they
were visited and because conditions were unsafe on the rampart around the vent
until after the June 12, 1980, eruption.
-- Banks and Hoblitt, 1981
- Emplacement temperatures of the debris avalanche ranged from about 70 degrees to 100 degrees C,
and those of the directed blast ranged from about 100 degrees to 300 degrees C
and varied with azimuth from the volcano. Emplacement temperatures of the
pyroclastic-flow deposits ranged from about 300 degrees to 730
degrees Celsius (570 to 1350 degrees Fahrenheit),
near-vent deposits were emplaced at about 750 to 850 degrees C.
-- Banks and Hoblitt, 1981.
- Temperatures in the pyroclastic-flow deposits
(at Mount St. Helens) were
780 degrees Fahrenheit (415 degrees Celsius)
two weeks after the May 18, 1980 eruption.
-- Pringle, 1993.
- Temperatures of 68 to 98 degrees Celsius (154 to 208 degrees
Fahrenheit) were measured at five
localities on the debris avalanche along the North Fork Toutle River and at
one locality north of Spirit Lake between 10 and 12 days after emplacement. At
each locality, four or five measurements were made at depths of 1 to 1.5 meters
(3 to 5 feet).
-- Banks and Hoblitt, 1981
- Destructive mudflows and debris flows began within
minutes of the onset of the May 18, 1980 eruption,
as the hot pyroclastic materials in the debris avalanche,
lateral blast, and ash falls melted snow and glacial
ice on the upper slopes of Mount St. Helens.
On the upper steep slopes of the volcano,
the mudflows traveled as fast as 90 miles an hour; the
velocity then progressively slowed to about 3 miles
an hour as the flows encountered the flatter and
wider parts of the Toutle River drainage. Even after
traveling many tens of miles from the volcano and
mixing with cold waters, the mudflows maintained
temperatures in the range of about 84 to 91 degrees Fahrenheit (30 to 33
degrees Celsius).
-- Tilling, et.al., 1990
Volcanic Gases and Hydrothermal Activity
- A few of the World's passively degassing volcanoes
emit very high-temperature (>600 degrees Celsius (1,100 degrees
Fahrenheit)) gases.
-- USGS/CVO Volcanic Emissions Project, 1996
- Present thermal activity at Mount Hood is in fumarole fields
near Crater Rock, at the apex of a semi-circular zone of fumaroles
and hydrothermally-altered, heated ground. In summer 1987,
maximum ground temperatures were near 85 degrees Celsius (185 degrees
Fahrenheit) and maximum
fumarole temperatures were about 92 degrees Celsius
(198 degrees Fahrenheit), slightly above
the boiling point of water at 3,100 meters (10,170 feet).
-- Swanson, et.al., 1989
Resources:
- Banks and Hoblitt, 1981,
Summary of Temperature Studies of 1980 Deposits:
IN: Lipman and Mullineaux, (eds.), 1981,
The 1980 Eruptions of Mount St. Helens, Washington:
USGS Professional Paper 1250, 844p.
- Hildreth, 1990, IN:
Wood and Kienle, 1990, Volcanoes of North America: United States and Canada:
Cambridge University Press, 354p.
- Myers and Brantley, 1995,
Volcano Hazards Fact Sheet: Hazardous Phenomena at Volcanoes:
USGS Open-File Report 95-231.
- Pringle, 1993,
Roadside Geology of Mount St. Helens National Volcanic Monument
and Vicinity: Washington Department of Natural Resources, Division of Geology
and Earth Resources Information Circular 88.
- Swanson, et.al., 1989,
IGC Field Trip T106: Cenozoic Volcanism in the Cascade Range and
Columbia Plateau, Southern Washington and Northernmost Oregon:
American Geophysical Union Field Trip Guidebook T106, p.8-10, p.17.
- Tilling, Topinka, and Swanson, 1990,
Eruptions of Mount St. Helens: Past, Present, and Future:
USGS Special Interest Publication.
- USGS/Cascades Volcano Observatory's Volcanic Emissions Project, 1996 -
<http://vulcan.wr.usgs.gov/Projects/Emissions/framework.html>
- USGS/Hawaiian Volcano Observatory's Website, 1998 -
<http://hvo.wr.usgs.gov>
- USGS/Volcano Hazards Program's Website, 1998 -
<http://volcanoes.wr.usgs.gov>
|
