VOLCANOS AROUND THE PACIFIC
Elaine Graham Kennedy
Dialogue 10(3):13-16 (1998), "When the Earth's crust
explodes" --- Reproduced here with permission and the accompanying acknowledgments
at the end, after being modified.
Around the rim of the Pacific Ocean
there is a ring of volcanism and earthquake activity that generates
considerable concern for the safety of people and property in that region. Vulcanologists monitor the dormant and active volcanos in an effort to provide an early warning system
for communities that might need to evacuate in the event of an eruption. Modern
technology enables these geologists to monitor numerous factors that have been
identified as indicators of increased activity and probable precursors to
eruptions. These factors may also provide clues to the processes occurring
subsurface that contribute to the eruption events.
It is hoped that an increased understanding of the
subsurface processes will increase the predictive power of the vulcanologists but understanding processes does not answer
the very human question, "Why does this happen?" Other information
sources are needed to help us grapple with that issue. The answer to that
question remains speculative but some basic information about the processes
that produce some of the molten rock within the earth may be helpful. Since
there is a volcanic rim around the Pacific Ocean, this
paper will begin by looking at that region.
The Ring of Fire
Along the margins of the Pacific Ocean,
there are deep trenches. The Pacific Ocean floor sinks
into these trenches and slides below the rocks that form the continental crust.
(See diagram.) This process is referred to as subduction
and volcanologists suggest that this subduction process produces the source material for most of
the volcanism surrounding the Pacific Ocean, hence the
phrase "Ring of Fire." The subducting
oceanic slab carries seawater and some crustal
material with it. The more deeply these materials are subducted the higher the
temperatures and pressures are around the rocks. Eventually the combination of
volatiles or gases produced from the seawater and crustal
material with increasing pressures and temperatures cause melting of the
subducted slab and upper mantle. The melted rock or magma then begins to rise
through the continental crust, generating new, and utilizing old, fractures and
faults and incorporating additional crustal material
as it moves. (Refer to diagram.) When the crustal
rocks melt, some rock types chemically decompose and release gases, e.g. carbon
dioxide and sulfur dioxide. The rising magma may mix with magmas from other
sources, which also contribute volatiles. Gases increase the pressure within
the magma and decrease its density, which aids in the upward movement of the
molten rocks along faults; however, molten rock moving along fractures
does not mean that a volcano is about to erupt. Vulcanologists
look for specific indicators of imminent volcanic activity.
Data is collected on volcanos
worldwide because scientists want to know when the next eruption will occur.
Information that seems most useful includes seismic (earthquake) activity and
types of gases that are being emitted. Common gases released from volcanic
fissures and craters include sulfur dioxide, carbon monoxide, carbon dioxide,
hydrogen sulfide and water vapor. Earthquake activity increases dramatically
just prior to an eruption. Most of the activity is about 4 or less on the
Richter Scale; however, larger-scale earthquakes can
occur with loud noises, liquefaction, and other earthquake related activity. As
pressures build within the magma chamber due to the incorporation of volatiles
from the surrounding crustal rocks, the potential for
Eruption occurs when the pressure in the magma chamber
exceeds the pressure exerted by the weight of the overlying rocks. Loud
explosions and earthquakes often precede and accompany the ejection of lava,
incandescent rocks, gases and ash. Once the eruption occurs, many people are
interested not only in what happened but also ask, "Why did this
Within religious communities, earthquakes and volcanic
eruptions have been of interest since they have been commonly referred to as
"Acts of God." Some think that in the past people attributed
volcanoes and earthquakes to God or evil spirits out of ignorance but the book
of Job makes it clear that both God and Satan act in nature. Now that more is
known about the processes involved in the eruptions, many people no longer
consider such activity as divine or mystical intervention. The Christian
community recognizes the difficulty in knowing how or when God might use
natural processes to His purpose. Thinking that we know how something works
does not mean that God is not involved in the timing of the event or the process.
The concept is a difficult one since we do not know the mind of God. We do not
know if any or all of the events include divine intervention or if most are
simply processes that occur in our world at random. Our lack of knowledge on
this topic should lead us to be cautious with our comments about end of the
world events and judgments.
Volcanism During the Genesis Flood
There is another aspect of volcanism that should be
considered from the Christian perspective. The continental and oceanic rocks
contain an extensive record of volcanism. Seventh-day Adventists believe that
most of this record is part of the Genesis flood. The inclusion of volcanism in
the flood account increases the complexity and devastation of that event.
Aerially extensive basalt flows such as the Siberian Traps, Deccan
Traps in India,
Parana Basalts in Brazil
and the Columbia River Basalts in the northwestern United
States, may have begun during or near the
end of the Genesis flood. In addition, widespread volcanic ash beds are found
interbedded throughout the rock layers of earth=s
crust. During discussions of the biblical flood, Christians comment on the
destructive power of the flood waters but seldom refer to the volcanic and
earthquake related devastation that accompanied that event. As
Christian scientists continue to study the geologic record, their awareness of
the complexity of the Genesis flood increases.
Very little is really known about the subsurface
processes that contribute to volcanism. Most of the theories are developed from
surface measurements. As vulcanologists attempt to
study these processes, they hope to explain why eruptions occur.
Within the Christian community there is an awareness of a
power beyond the physical and chemical processes observed in nature. The
biblical interpretation of volcanoes, earthquakes, floods as judgments causes
Christians to question the randomness of events. Many Christians consider most
natural disasters to be random events, signifying the insecurity of a sinful
world. The biblical perspective ties these events to the end of the world and
their occurrence should strengthen our faith in the second coming of Jesus. A
sudden notable increase in the frequency of natural calamities is predicted for
the period of time just prior to the return of Christ. Although friends and
family may perish during one of these disasters, Christians have faith in the
abiding, undying love of the Father for His children. These processes remind us
of the greatness of God=s
power, and His ability to control the forces of nature.
ACKNOWLEDGMENTS: College and University
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NOTES AND REFERENCES
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W.G.(ed.) 1995. Volcanoes and earthquakes: Geology
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21:18-22; Luke 13:4 & 5 Matthew
13:8; Luke 21:9-11, 25-28