Volcanoes: Crucibles of Change

by Richard V. Fisher, Grant Heiken, Jeffrey Hulen

Whenever a volcano threatens to erupt, scientists and adventurers from around the world flock to the site in response to the irresistible allure of one of nature's most dangerous and unpredictable phenomena. In a unique book probing the science and mystery of these fiery features, the authors chronicle not only their geologic behavior but also their profound effect on human life. From Mount Vesuvius to Mount St. Helens, the book covers the surprisingly large variety of volcanoes, the subtle to conspicuous signs preceding their eruptions, and their far-reaching atmospheric consequences. Here scientific facts take on a very human dimension, as the authors draw upon actual encounters with volcanoes, often through firsthand accounts of those who have witnessed eruptions and miraculously survived the aftermath.


The book begins with a description of the lethal May 1980 eruption of Mount St. Helens--complete with an explanation of how safety officials and scientists tried to predict events, and how unsuspecting campers and loggers miles away struggled against terrifying blasts of ash, stone, and heat. The story moves quickly to the ways volcanoes have enhanced our lives, creating mineral-rich land, clean thermal energy, and haunting landscapes that in turn benefit agriculture, recreation, mining, and commerce. Religion and psychology embroider the account, as the authors explore the impact of volcanoes on the human psyche through tales of the capricious volcano gods and attempts to appease them, ranging from simple homage to horrific ritual sacrifice.



Volcanoes concludes by assisting readers in experiencing these geological phenomena for themselves. An unprecedented "tourist guide to volcanoes" outlines over forty sites throughout the world. Not only will travelers find information on where to go and how to get there, they will also learn what precautions to take at each volcano. Tourists, amateur naturalists, and armchair travelers alike will find their scientific curiosity whetted by this informative and entertaining book.

Genres: Science, Geology, Nonfiction

Hardcover

First published May 5, 1997

Reviews

[Tim Martin · Rating 5 out of 5]

_Volcanoes: Crucibles of Change_ by Richard V. Fisher, Grant Heiken, and Jeffrey B. Hulen is a fascinating and very well-written look at volcanoes, including their formation, structure, dangers, benefits, and how they have affected human history. The book is richly illustrated with photographs, maps, and fascinating diagrams explaining volcanic processes.

Part one consisted of four chapters that looked at the geology of volcanoes. Important to understanding volcanoes is knowing where they form; they can appear over subduction zones (where one tectonic plate is pushed under another; the subduction of the Pacific plate under the American plate produces the volcanoes of the Cascade Mountains), extensional boundaries (where plates move apart, mainly between plates on the seafloor), and over hot spots (thermal plumes rising through the mantle than can be well away from either subduction zones or extensional boundaries).

Also important to understanding volcanoes is knowledge of the composition of the magma that forms them. Magma containing less than 55% silica is called basaltic and is very fluid and has low-viscosity. It can easily form large lava flows and gas can rapidly escape from it, forming huge fountains (the authors compared it to the ease with which steam escapes from rapidly boiling water). Rhyolite lava on the other hand is comprised of over 70% silica, is very viscous, and gas does not readily escape from it unless the pressure is big enough (think of how hot oatmeal spatters explosively). Basalt lava generally forms beneath or within oceanic plates, rhyolite lava beneath or within a continental plate, and a third type, andesite lava (between 55% and 70% silica), where the two types of plate overlap.

Volcanoes may take a variety of forms. Composite volcanoes or stratovolcanoes, such as Mount St. Helens and Mount Fuji, are graceful, solitary, often quite high and covered in snow or ice and are comprised of innumerable layers of rubble and debris from previous eruptions. Lava domes are protrusions of lava on the outside slope of many composite volcanoes or within their craters, built by the slow extrusion of viscous silica-rich magma. Calderas (from Spanish for "cauldron") are very large craters formed when the ground surface collapsed as the result of the extrusion of very large amounts of ash, pumice, and rock and can be quite large. Cinder cones or scoria cones are relatively small volcanoes, high mounds with small craters at the top, comprised of basaltic fragments called cinders or scoria, rocks that contain an abundance of bubble-like chambers. They often occur in clusters and on the slopes of other types of volcanoes. Maars are small volcanoes with wide craters that formed from the sudden explosion that occurred when rising magma came into contact with groundwater or surface water. Shield volcanoes are broad and have low slopes and are constructed of solidified basaltic lava that was originally in a highly fluid state. Littoral cones are formed when lava flows into water, explodes, and forms a pile of debris into a volcano-like shape; not actually volcanoes, they have no underground source.

Eruption types can vary as well. Gas eruptions can be quite silent but lethal, such as the Lake Nyos eruption of deadly carbon dioxide on August 21, 1986 in Cameroon, which killed 1,700 people. Hawaiian eruptions include gusher-like lava flows and lava rivers and produce congealed globs of lava that fly through the air (called lapilli if 2 to 64 millimeters, bombs if larger). Strombolian eruptions produce high-arching, incandescent "rooster-tails" and ejecta that can form cinder cones. Plinian eruptions produce ash columns as high as 50 kilometers into the sky, which thanks to high winds can spread ash hundreds or thousands of square kilometers (the name derives from Pliny the Elder, the Roman nobleman who died in the A.D. 79 eruption of Vesuvius).

Volcanoes as noted form underwater and in fact most may be located deep in the sea; one estimate put the number at one million volcanoes with 75,000 rising to over 1 kilometer from the seafloor. Explosive eruptions rarely occur, as 1 kilometer or more below the surface of the sea water pressure is generally greater than any explosive pressure. Some volcanic systems produce black smokers, hydrothermal systems that release black, turbulent clouds of suspended metal-sulfide materials, often creating oases of life in the deep sea.

Part two looked at the many hazards of volcanoes. Pyroclastic flows (or volcanic hurricanes) are searing, kiln-hot winds that move faster than ordinary hurricanes and can kill people and animals due to high heat, ash particles that can clog throats and lungs, and by hurtling tons of cobble and boulder sized particles. A pyroclastic surge is a diffuse, gas-rich pyroclastic flow that can move farther and over ridges and water. Debris avalanches can also be a danger, especially if they enter water and produce tsunamis. Volcanic flows or lahars (from an Indonesian word) are masses of mud, sand, gravel, and boulders mixed with water and having the consistency of freshly made cement. Lahars often dam rives and can produce derivative floods for years to come. Also posing a danger are lava flows and ash clouds (the latter can bring down jet aircraft).

Part three looked at the many benefits of volcanoes. In addition to producing every atmospheric gas aside from oxygen, volcanoes have given us therapeutic hot springs, clean and safe geothermal energy, igneous rock that can be cut into blocks and used as building stones, fine-grained ash that can be used as a polishing compound (like in toothpaste), concrete (the Romans mined ash they called pozzuolana and made concrete from it to produce their roads, viaducts, and monumental buildings), pumice (long used as an exfoliant scrub and as an abrasive cleaner), obsidian (once highly valued for arrowheads and knives), bentonite (a clay made from volcanic ash, used in everything from the drilling industry to ceramics to adhesives to kitty litter), gemstones (diamonds were brought from deep within the Earth's surface by volcanoes), rich agricultural soil, and the preservation of fascinating fossils and artifacts (such as at Pompeii).

[Linda Gaines · Rating 4 out of 5]

This book is a bit like a textbook, but it is interesting nonetheless. It introduces some basic concepts and makes it easy to understand them. It covers many different examples and at times reads like short stories.

[Robert · Rating 4 out of 5]

I read this book about 10 years ago. It taught me everything I wanted to know about Volcanoes.

[Alyssa · Rating 5 out of 5]

Great book I have read it a few times now and I really like it.