VOLCANOS AROUND THE PACIFIC OCEAN

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.

Introduction

    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.

Diagram of Subduction of Oceanic Plate

Eruption Precursors

    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 increases.

The Eruption

    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 happen?"

Christian Framework

    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.

Conclusions

    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.

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   NOTES AND REFERENCES

  1. Tarbuck, E.J. and Lutgens, F.K. 1987. The earth: an introduction to physical geology: Merrill Publishing Company, Columbus, Ohio, pp. 481-496.  Also, Ruiz, J., Freydier, C., McCandless, T., and Bouse, R. 1997.  Isotopic evidence of evolving crust and mantle contributions for base metal metallogenesis in convergent margins: Geological Society of America, Abstracts with Programs 29:A357.
  2. Hegner, E. and Vennemann, T.W. 1997. Role of fluids in the origin of Tertiary European intra-plate volcanism: evidence from O, H, and Sr isotopes in melilitites: Geology 25:1035-1038. Also, Camp, V.E. and Roobol, M.J. 1991. New geologic maps describing a portion of the Arabian Continental Alkali Basalt Province, Kingdom of Saudi Arabia: Geological Society of America, Abstracts with Programs 23:451.  Hart, G.L., Christiansen, E.H., Best, M.G., and Bowman, J.R. 1997. Oxygen isotope investigation of the Indian Peak Volcanic Field, southern Utah-Nevada: magma source constraints for a late Oligocene caldera system: Geological Society of America, Abstracts with Programs 29:A87.  Nelson, S.A. 1997. Spatial and geochemical characteristics of basaltic to andesitic magmas in the Mexican Volcanic Belt: Geological Society of America, Abstracts with Programs 29:A88.
  3. Duffield, W.A. and Ruiz, J. 1991.  Contaminated caps on large reservoirs of silicic magma: Geological Society of America, Abstracts with Programs 23:397.
  4. Krass, V.C. 1997. Magma mixing as a source for Pinatubo sulfur: Geological Society of America, Abstracts with Programs 29:A164.
  5. Harmon, R.S. and Johnson, K. 1997. H-isotope systematics at Augustine volcano, Alaska: Geological Society of America, Abstracts with Programs 29:A164. Also, Dixon, J. And Clague, D. 1997. Evolving volcanoes and degassing styles in Hawaii: Geological Society of America, Abstracts with Programs 29:A191.
  6. Cordey, W.G.(ed.) 1995. Volcanoes and earthquakes: Geology Today 11:233-237.
  7. Arehart, G.B., Sturchio, N.C., Fischer, T., and Williams, S.N. 1993.  Chemical and isotopic composition of fumaroles, Volcan Galeras, Colombia: Geological Society of America, Abstracts with Programs 25:A326.
  8. Cordey, pp. 236-239.  Also: Smith R.B., Meertens, C.M., Lowry, A.R., Palmer, R., and Ribe, N.M. 1997. The Yellowstone hotspot: evolution and its topographic, deformation and earthquake signatures: Geological Society of America, Abstracts with Programs 29:A166.
  9. Job 1:6-12
  10. Matthew 21:18-22; Luke 13:4 & 5 Matthew
  11. Mark 13:8; Luke 21:9-11, 25-28