March 5 Geo class

Introduction to Volcanism at Subduction Zones

Overview of Subduction Zone Volcanism
- Focus on oceanic plates interacting with oceanic plates.
- Importance of understanding melting temperatures in the context of volcanism.

Mechanism of Partial Melting
- Subducting oceanic plate releases fluids into the asthenosphere, decreasing melting temperatures.
- This leads to partial melting of the asthenosphere and subsequent rise of magma through oceanic crust.
Characteristics of Eruptions
- Eruptions are typically explosive.
- Stratovolcanoes are commonly formed at these divergent boundaries.
Evidence of Stratovolcano Characteristics in Images
- Analysis of pyroclastic flows rather than lava flows.
- Pyroclastic flows indicate explosive eruptions due to higher silica content.

Montserrat and Soufrière Hills Volcano
- Historical eruptions and impacts on the city of Plymouth.
- Evacuations and significant devastation caused by pyroclastic flows in 1995 and subsequent years.
Mount Pelee, Martinique
- Catastrophic eruption in 1902 resulted in high fatalities.
- Discussion of rapid pyroclastic flow covering the village of Saint Pierre and the survival of one individual due to imprisonment.
Sumatra and Tsunami Context
- Reconnection to past topics discussing the 2004 tsunami resulting from significant earthquake activity.
- Importance of tectonic activities in creating both earthquakes and volcanic eruptions.

Mount St. Helens, USA
- Background and details of the 1980 eruption.
- Significant land deformation and lateral blasts associated with the eruption.
- Seismic activity as a precursor to eruptions and the monitoring of volcanic activity.
Mount Vesuvius, Italy
- History of eruptions including the famed destruction of Pompeii in 79 AD.
- Impacts of persistent volcanic activity on populated areas and current threat levels due to prolonged dormancy.

General Overview of Hot Spots
- Definition and characteristics of hot spots, distinguishing them from plate boundary volcanism.
- Role of mantle plumes and decompression melting in magma generation.
Volcanism in Oceanic Environments
- Basaltic magma quality leading to shield volcano formations.
- Case study examples with Hawaiian Islands showcasing the development of a chain of volcanoes due to plate movement over a stationary plume.

Yellowstone Supervolcano
- Historical eruptions, outline of caldera formation, and implications of future activity.
- Distinction between basaltic magma from the mantle and its interaction with volcanic rocks to produce rhyolitic magma and explosive eruptions.
- Highlight the immense size of the geothermal system and the potential danger of future eruptions.

Significance of Geological Activity Monitoring
- Importance of understanding eruptions to anticipate potential hazards.
- Community preparedness and monitoring best practices for volcanic activity prediction.
Discussion of past eruptions and their geological implications, emphasizing the fertilizer role of understanding geysers as indicators of volcanic activity.