Compare And Contrast Mauna Loa's Eruption Styles

Compare and contrast the eruption styles of the Mauna Loa Volcano in Hawaii and Mount Pinatubo in Philippines

Watch the video titled “Meet the Volcanoes” (2 min 57 s). Be prepared to discuss. Video Source: NOVA. (2013, January 3). Meet the Volcanoes [Video file]. Retrieved from (Links to an external site.) .

Compare and contrast the eruption styles of the Mauna Loa Volcano in Hawaii and Mount Pinatubo in Philippines. Include a review of the plate tectonic setting, as well as the role of magma composition and viscosity at each location in shaping the morphology of the volcano and eruption style.

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The comparison of the eruption styles of Mauna Loa in Hawaii and Mount Pinatubo in the Philippines necessitates an understanding of their distinct geological environments, magma characteristics, and the resultant volcanic behaviors. These two volcanoes exemplify contrasting eruption styles that are primarily driven by their unique plate tectonic settings and magma compositions, which influence their morphology and eruptive mechanisms.

Mauna Loa, situated on the Big Island of Hawaii, is a classic shield volcano characterized by broad, gentle slopes and relatively effusive eruptions. Its tectonic setting is located over the Hawaii hotspot, a plume of hot mantle material that creates volcanic activity independent of tectonic plate boundaries. This hotspot-driven volcanism results in the gradual accumulation of large volumes of basaltic magma, which is low in silica content. The low silica content yields low viscosity magma that allows gases to escape easily, leading to sustained, gentle eruptions. These eruptions primarily produce flowing lava that slowly spreads over the landscape, contributing to the volcano’s massive size and shield-like shape.

In contrast, Mount Pinatubo in the Philippines is located at the convergent margin of the Philippine Sea Plate and the Eurasian Plate. This subduction zone setting results in the melting of oceanic crust, generating magma with a higher silica content. The magma at Pinatubo is more viscous, rich in silica, and contains a higher volatile content (particularly water vapor and carbon dioxide). This composition leads to explosive eruption styles characterized by the buildup of pressure within the volcano’s conduit, culminating in violent eruptions capable of ejecting ash, pyroclastic flows, and volcanic gases over large areas. The highly viscous magma at Pinatubo results in the steep, stratovolcano morphology, with explosive eruptions that can significantly alter the landscape in a short period.

The differences in magma viscosity directly influence the morphology and eruption style of these volcanoes. Mauna Loa’s low-viscosity basaltic lava flows smoothly and steadily, constructing a large shield volcano with gentle slopes. Conversely, Pinatubo’s high-viscosity magmas tend to plug the volcanic conduit, building up pressure until explosive eruption occurs, creating a stratovolcano with a more conical and steep profile. The contrasting plate tectonic settings therefore play a pivotal role in determining the physical characteristics and eruptive behavior of each volcano, illustrating how tectonic forces shape volcanic activity globally.

In summary, Mauna Loa and Mount Pinatubo exemplify different volcanic eruption styles driven by their tectonic environments and magma compositions. Mauna Loa’s hotspot setting and basaltic, low-viscosity magmas promote gentle, effusive eruptions that produce broad shield shapes. Conversely, the subduction zone environment at Pinatubo produces felsic, high-viscosity magmas that lead to explosive eruptions and steep stratovolcano morphology. Understanding these differences enhances our comprehension of volcanic processes and the influence of tectonic settings on volcanic behavior.

References

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  • Hawaiian Volcano Observatory. (2018). Mauna Loa—Volcano Information. United States Geological Survey. https://volcanoes.usgs.gov/volcanoes/mauna_loa/
  • Philippine Institute of Volcanology and Seismology (PHIVOLCS). (1992). Mount Pinatubo—Eruption Overview. https://www.phivolcs.dost.gov.ph/index.php/volcano-hazard-forecasts/volcano-hazard-watch/4070-mount-pinatubo
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  • U.S. Geological Survey. (2020). Volcano Hazards Program—Mount Pinatubo. https://volcanoes.usgs.gov/volcanoes/pinatubo/
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