REFERENCE: The Blue Planet An Introduction to Earth System Science. Brian J. Skinner and Barbara W. Murck (2011) Third Edition. John Wiley and Sons

Transcription

1 REFERENCE: The Blue Planet An Introduction to Earth System Science. Brian J. Skinner and Barbara W. Murck (2011) Third Edition. John Wiley and Sons Inc.

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3 PLATE BOUNDARIES OCEAN FLOOR SEISMIC ACTIVITY WORLD'S VOLCANOES

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6 VOLCANO: Is a vent from which magma, solid rock debris, and gases are erupted. MAGMA: Is the mixture of molten rock, suspended minerals grains, and dissolved gases that forms in the crust or mantle when temperatures are sufficiently high. LAVA: Is the magma that reaches the Earth's surface.

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8 1. It has a range of compositions, but Silica (SiO 2 ) is always predominant. 2. It has the properties of a liquid (ability to flow). 3. It is characterized by high temperatures.

9 The average compositions of the solid part of the three principal kinds of magma. In addition to the solid materials, the magmas also contain dissolved gases. Basaltic magma has a low content of dissolved gas; andesitic and rhyolitic magmas tend to be very gassy.

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12 Diagram illustrating the locations of the major kinds of volcanoes in a plate-tectonic setting.

13 The Ring of Fire around the Pacific Ocean basin is formed by andesitic volcanoes. The Ring of Fire is coincident with subduction zones where lithosphere capped with oceanic crust is being subducted into the asthenosphere. Volcanoes in the Pacific Ocean, such as Mauna Loa, erupt basaltic magma but not andesitic magma.

14 Long-lived hot spots (magma sources) deep in the mantle can be used to determine the absolute motions of plates. Because the hot spots lie far below the lithosphere and do not move laterally, each is marked by a chain of volcanoes on the surface of the lithosphere. The youngest volcano in a chain lies directly above the hot spot.

15 Hawaiian Hot Spot

16 Bora Bora was formed around four million years ago after volcanoes erupted from the sea bed. As the volcano sank back into the Pacific Ocean, a ring of coral reefs, or atolls, formed to mark the ancient coastline. The infamous Bora Bora lagoon also formed between the reef and the island around this time. The volcanic core that still remains on the main island of Bora Bora is actually sinking at a rate of one centimeter per century. It will take about 25 million years for Bora Bora s main island to sink completely into the ocean, leaving just a coral atoll.

17 A lethal cloud of CO2 bubbled up from the bottom of Lake Nyos after the stratification of the lake water was disturbed. The gas, which is invisible and heavier than air, flowed over the natural dam surrounding the lake and down the adjacent valley.

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24 The ash plume of southwestern Iceland's Eyjafjallajokull volcano streams southwards over the Northern Atlantic Ocean in a satellite photograph made April 17, The erupting volcano in Iceland sent new tremors on April 19, but the ash plume which has caused air traffic chaos across Europe has dropped to a height of about 2 km (1.2 mi), the Meteorological Office said. (REUTERS/NERC Satellite Receiving Station, Dundee University, Scotland)

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26 Mount Merapi, in Java (Indonesia)

27 Cleveland Volcano at Aleutian Arc, Alaska ISS- Digital Camera

28 INFRARED IMAGES This is a satellite image showing the area around Mount Vesuvius and the bay of Naples, Italy. Vesuvius, an active volcano, is the circular structure, center right. Recent lava flows show up bright red in this image, which recorded infrared radiation (heat). Older lavas and volcanic ash show up as yellows and oranges. The dark blue and purple region at the head of the bay is the city of Naples. Left of Naples, near the center of the image, is a cluster of small volcanoes called the flegreian fields. Changes in the temperature of the ground surface can be monitored by comparing successive satellite images, because infrared imagery is sensitive to the temperature of ground materials.

29 Advanced Very High Resolution Radiometer (AVHRR) Band Wavelength (mm)

30 GPS

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32 Horizontal displacement of GPS benchmarks on Mauna Loa and Kilauea volcanoes, Hawaii Map showing direction and amount of horizontal displacement (blue vectors) of GPS stations on Mauna Loa and Kilauea volcanoes relative to a permanent GPS station located on Mauna Kea (north of Mauna Loa) between June 2000 and July 2001.

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34 TOMS Measurements of Volcanic Emissions Sulfur Dioxide (SO2) Ash and Aerosols These false-color images are from the June 16, 1991 eruption of Mt. Pinatubo, Philippines. The gas and ash clouds were tracked by TOMS for several weeks as they encircled the Earth. These satellite observations demonstrate the enormous amounts of gas and ash emitted, as well as details such as differences in peak concentrations and geographic extent. TOMS also detects many smaller volcanic clouds

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38 SOUFRIERE HILLS MONTSERRAT -Began erupting on July 18, Dome collapse on June 25, An ash cloud erupted from the Volcano on October 27, 1999

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42 Watch the YouTube video called How Volcanoes Form