Volcanoes: Nature’s Awesome Power By Maryann Dobeck

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.

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

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.

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.

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.

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.

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.

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

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.

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.

Mount ST. Helens The volcano rumbled with earthquakes.

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