Lecture-17 - Lecture 17 Eruptions and Lava Flows Tuesday,...

Info iconThis preview shows pages 1–7. Sign up to view the full content.

View Full Document Right Arrow Icon
1 Lecture 17 – Eruptions and Lava Flows T u e sday, November 4 th , 200 8 Types of Eruptions Eruption types are based on the eruption characteristics of a well-known volcano. There are five such types:- ± Hawaiian ± Surtseyan ± Strombolian ± Vulcanian ± Plinian (Krakatoan) (Note - your text includes a type called Vesuvian, this is really only a variation of Plinian)
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
2 The most useful classification of eruption types is based on:- ± How big the eruption is ± How explosive or violent it is Examples of Hawaiian eruptions Fire-fountaining (or curtains of fire), Kilauea, 1971 Molten magma is ejected from cracks to produce fire fountains that jet the lava 30 -50 feet into the air. Molten magma hitting the ground flows away as lava flows, whereas cooled magma produces cinders (spatter) near the vents.
Background image of page 2
3 Kilauea Iki, 1959 1500 ft high Puu Oo, 1984 1300 ft high Magma also jets from single vents, sometimes producing fire-fountains over 1000 ft high. Again, it may flow away as lava or build cinder (spatter) cones. On Kilauea volcano are many pits or craters. Frequently, lava cascades into these pits to produce molten lava lakes.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
4 Examples of Strombolian eruptions The island of Stromboli Stromboli erupting at night (note trajectory of volcanic bombs). A strombolian eruption on Mount Etna, Sicily. Examples of Surtseyan eruptions Basaltic magma reacts violently with sea water to produce steam. This in turn fragments the magma to produce fine ash which is building a cone. Eventually this cone will grow into an island.
Background image of page 4
5 Once the island is formed, and the volcanic conduit is isolated from the sea water, then the eruption becomes much less explosive, resembling Hawaiian style of eruptions. Examples of Vulcanian eruptions Vulcanian eruptions during the early days of volcanic activity at Mount St. Helens, 1980. Vulcanian eruptions do not include juvenile material. They are steam-blasts, in which pre-existing rock is fragmented by steam explosions. The steam results from magma heating up ground water.
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
6 Examples of Plinian eruptions
Background image of page 6
Image of page 7
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 08/09/2009 for the course GEOSCIENCE GEO-105 taught by Professor Rhodes during the Fall '08 term at UMass (Amherst).

Page1 / 19

Lecture-17 - Lecture 17 Eruptions and Lava Flows Tuesday,...

This preview shows document pages 1 - 7. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online