Volcanoes: Nature’s Awesome Power

1. Volcanoes: Nature’s Awesome Power By Maryann Dobeck

2. Introduction • Centuries ago, native people of Hawaii witnessed volcanic eruptions. • A Hawaiian myth is that a goddess of volcanoes made mountains blow their tops. • Scientists know that forces of nature are the cause of volcanic eruptions.

3. CH.1: The inside story of volcanoes p • Earth is made of four layers, outer layer is the crust. • Geologist’s believe the crust and upper mantle are made of 10 huge plates and 6 smaller plates. • The world’s erupting volcanoes occur along edges or boundaries, of earth’s plates

4. Volcanoes are mountains that are built from eruptions of volcanic materials onto earth’s surface. • When pressure on the magma subsides, the eruption stops. • Three kinds of materials may erupt from a volcano: lava, tephra (rock fragments), and gases.

5. The pressure of the gas in the magma causes the eruption. • A volcano erupts, it can spew out anything from fine particles of dust to huge block of rock as big as a house. • If magma contains a lot of gas, it will burst out violently with rock fragments called pyroclastic materials.

6. Volcanoes on ocean floor/Volcanoes at hot spot • Tectonic plates on the ocean floor are thinner than plates on land. • In 1963, a volcano formed a new island called Surtsey. • The largest volcanoes are above hot spots, areas of superhot rock deep in earth’s.

7. CH.2: Types of volcanoes • Their are three common types of volcanoes: stratovolcano, cinder cone volcano, and shield volcano. • Geologist classify volcanoes based on their size, shape, and formation. • Stratovolcanoes usually have steep sides and a broad base.

8. Cinder cones • As lava explodes from the central vent it breaks into small pieces that fall as cinders around the opening. • Paricutin volcano in Mexico is one the most famous cinder cone volcanoes. • This volcano usually starts out small but they quickly build up into a large volcano.

9. Shield volcanoes • Shield volcanoes are flat and wide. • Most of the Hawaiian Island are shield volcanoes. • Mauna Loa is the worlds largest Volcano.

10. CH.3 • When volcanoes erupt geologists call the most explosive volcanic eruption a Paleean eruption . • Scientists call the least violent kind of eruption a Hawaiian eruption. • Lava streams out of several vents and forms a shield volcano. • 1 of the worlds most DANGEROUS volcano.

11. CH.4: Famous volcanoes & mountains • When mount Vesuvius erupted, ash and lava buried the towns of Pompeii, Herculaneum ,and Stabiae, Krakatoa. • No one lived on Krakatoa, so no one died.

12. Mount ST. Helens • The volcano rumbled with earthquakes.

13. Mount Pinatubo • Mount Pinatubo erupted in a powerful blast 10 times larger than the eruption of MT. St. Helens.