Mauna Loa: A Decade Volcano
by J.P. Lockwood and J.M.
Rhodes.
The reference for this publication is Periodico di Mineralogia
(Rome), 44, 45-47, 1995.
The paper was presented as part of the Decade Volcano Symposium
at the IAVCEI
Conference, Volcanoes in Town, September,
1995, Rome.
Introduction
Mauna Loa is a giant, active basaltic shield volcano which rises
over 4 km above sea level, another 5 km above the north-central
Pacific seafloor, and another 8 km above the isostatically
depressed seafloor of the Pacific Plate, for a total volcanic
height of 17 km. It is the most voluminous volcano on Earth
(>75,000 km³ ), with a subareal surface area of over
5,000 km² (half the Island of Hawaii). Mauna Loa is
one of the Earth's most active volcanoes, having erupted more
than 30 times since its first documented historical eruption in
1843. Mauna Loa has been selected as one of 15 "Decade Volcanoes"
by the International Association of Volcanology and Chemistry of
the Earth's Interior (IAVCEI). This status provides opportunities
for increased multidisciplinary and multinational efforts to
understand volcanic processes and better monitor this great
volcano, with the purpose of mitigating volcanic hazards at this
and at similar volcanoes around the world.
Problems and Opportunities at Mauna Loa
The principal hazards posed by Mauna Loa eruptions are its
frequent, high-volume lava flows (a Holocene coverage rate of
about 40% per thousand years), the long lengths of these flows (5
have reached the sea since 1868), and lava fluidity (which
results in high flow velocities -- especially on steep slopes).
These flows pose serious risks to people living on lower slopes
and to their properties. The recent recognition of the extent of
major prehistoric submarine and subareal landslides from the
south and west flanks of Mauna Loa is another long-term hazard
here and at many other oceanic volcanoes. While the population at
risk from Mauna Loa eruptions is small (about 75,000), the growth
of Hawaii's tourist industry has produced large developments
along the coast (more than $2 billion has been invested in new
construction since the last eruption in 1984). The indiference of
modern populations and governmental agencies to volcanic hazards
also greatly increases risk. Whereas the Polynesian discoverers
of Hawaii developed a respect for the destructive potential of
Mauna Loa and learned to coexist with volcanic activity over
millenia, recent immigrants tend to deny the potential for
disaster, and regard eruptive activity as potentially
"entertaining."
The principal importance of Mauna Loa to the Decade Volcano
program derives not from the magnitude of the associated risk,
however, but rather is related to its value as a "laboratory" for
refinement of volcano monitoring and risk mitigation techniques.
The excellent exposures and accessibility of the volcano make
past and future lava flows ideal for detailed studies and
observation. Mauna Loa has the best documented prehistoric
eruptive chronology of any volcano on Earth, so that models of
volcano genesis can be tested against the actual record of
eruptive activity. The accumulated record of instrumental
monitoring carried on by the Hawaiian Volcano Observatory over
the past half century is a valuable resource, and its present
instrumental network makes it one of the best monitored of all
Decade Volcanoes (along with Etna and Sakurajima). Although much
has been learned about Mauna Loa's seismicity and on-going
deformation, the questions before us are much more numerous than
the answers behind us. The deployment and testing of new
monitoring equipment and techniques here can build on our past
and present knowledge to better develop new methodologies for use
at other Decade Volcanoes.
Progress Toward Decade Volcano Goals
A well-attended symposium at the Fall, 1993 meeting of the
American Geophysical Union involved the presentation of nearly 40
papers about Mauna Loa (AGU, 1993). An informal meeting after the
symposium led to the identification of about 50 scientists with
an interest in Mauna Loa research. Since that meeting, most
effort has focused on the production of a monograph about Mauna
Loa, to be published by the AGU this Fall. The monograph,
entitled Mauna Loa - a Decade Volcano will include
about 20 papers, covering a wide spectrum of present-day Mauna
Loa knowledge, in the fields of petrology, geochemistry, submarine
geology, seismicity, deformation, gravity, remote sensing,
historical and prehistoric chronology, long-term volcano
evolution, ecology, and hazards analysis.
Future Plans
The principal need for future progress of the Muana Loa Decade
Volcano Project is to establish better communications between
(a) those directly involved in present or proposed Mauna Loa
research, and (b) between Mauna Loa researchers and researchs at
other Decade Volcanoes, so that the knowledge gained at Mauna
Loa can be readily shared with others around the world, and so
that we can learn of complementary efforts. Toward this end,
those directly involved in Mauna Loa research need to better
organize themselves, and modern electronic communication
channels need to be developed. A Worldwide Web home page will be
established this summer at the University of Hawaii for posting
information about Mauna Loa Decade Volcano studies. The Internet
address:
http://www.soest.hawaii.edu/mauna_loa/
The webmaster for tis page is Prof. Gerard Fryer (address:
gerard@soest.hawaii.edu) -- contributions to
this page are welcome!
As to specific avenues for future research, the following are
considered important:
Volcanic processes
What additional studies of past eruptions could lead to a better
understanding of eruptive style? What new technology should be
employed to better understand the next Muana Loa
eruption? Can specific individuals and equipment be identified
(and funded) to be placed on "ready alert" to travel to Hawaii
as soon as the next eruption appears imminent?
Geochemical and petrological processes
Much work has been done to characterize the compositional
variability of Mauna Loa eruptive products. Are new or untried
techniques appropriate to resolve unsolved (or unasked) questions
about the genesis, storage, transport and eruption of Muana Loa
magma or on the scale and dynamics of the Hawaiian plume?
Geophysical processes
What tools are needed to better assess the present internal
structure of Mauna Loa and the dynamics of deformation,
seismicity, thermal and electrical changes as magma intrudes and
migrates within the Mauna Loa edifice? Could techniques be
developed or applied to Mauna Loa to assess the susceptibility to
giant landslides?
Remote sensing
Mauna Loa is one of the best-exposed and most accessible
volcanoes on Earth for remote-sensing from airborne and orbiting
platforms. New satellite systems with powerful tools for volcano
analysis will be launched during the coming decade. What new
information can be obtained about Mauna Loa from above, and how
can this information best be integrated with expanded efforts at
"ground-truth"? The remote-sensed data to be collected from Mauna
Loa not only holds great promise for our understanding of this
volcano, but will form the interpretational basis for studies of
numerous volcanoes elsewhere on Earth and far beyond.
Biological significance
Mauna Loa has become the focus of major biological
investigations, which involve understanding of rates and
processes of forest growth, especially in the high-rainfall
forests of the volcano's lower flanks. The ages and morphologies
of underlying lava substrates are critical factors in the
development of tropical rainforsets on young volcanoes, and the
rates of volcano activity thus have major impact on forest
dynamics. Studies of forest development rates can also provide
information on the age of the underlying lava flows, and may thus
allow low-cost, low-precision "dating" of lava flows at other
volcanoes where laboratory dating of flows is not an option.
Atmospheric research
The Mauna Loa Observatory (MLO), an atnmospheric research
facility of the National Atmospheric and Oceanic Administration,
is located on Mauna Loa's north flank. Careful records of
atmospheric composition for over 35 years have revealed a great
deal about changing global atmospheric compositions, but have
also obtained unique data about the local injection of CO2 and
SO2 from Mauna Loa sources. Cooperative studeis between volcanic
gas chemists and researchers at MLO during the Decade to come
could yield new findings for both groups.
Lava dispersion
Development of appropriate contingency plans for engineering
countermeasures to mitigate the impact of advancing lava flows.
Monitoring and public information
Incerased monitoring capability and beter understanding of the
processes which lead to eruptions will enable scientists to give
earlier warnings of imminent eruptive activity to threatened
populations and to better advise local government agencies about
land-use planning issues.
Decade Volcano Demonstration Projects are important components of
the International Decade of Natural Disaster Reduction (Barberi
and oithers, 1990). An essential Program is the need to develop
and disseminate accumulating knowldege and new monitoring
techniques which can be exported to other areas where populations
are threatened by hazardous volcanoes. This ultimately is the
most important purpose of Decade research ar Mauna Loa.
References
American Geophsyical Unon (1993), Fall Meeting Abstracts,
EOS, Trans. Am. Geophys. Union, 74, n. 43,
742 pp.
Barberi, F.R., et al., Reducing volcanic disasters in the 1990's
(1990), Volcanological Soc. Japan Bull., 35,
80.
