The 2008 eruption of the unmonitored Kasatochi volcano, Alaska, distributed volcanic gases over most of the continental United States within a week ( Figure 1.1).įinally, volcanoes are important economically. Many volcanoes in the United States have the potential for much larger eruptions, such as the 1912 eruption of Katmai, Alaska, the largest volcanic eruption of the 20th century ( Hildreth and Fierstein, 2012). The 2014 steam explosion at Mount Ontake, Japan, killed 57 people without any magma reaching the surface. Even modest eruptions, such as the 2010 Eyjafjallajökull eruption in Iceland, have multibillion-dollar global impacts through disruption of air traffic. Globally, volcanic eruptions caused about 80,000 deaths during the 20th century ( Sigurdsson et al., 2015). Eruptions can change weather patterns, disrupt climate, and cause widespread human suffering and, in the past, mass extinctions. Volcanoes have enormous destructive power. Our understanding of how volcanoes work and their consequences is also shared with the millions of people who visit U.S. Understanding how volcanoes form, how they erupt, and their consequences requires an understanding of the processes that cause rocks to melt and change composition, how magma is stored in the crust and then rises to the surface, and the interaction of magma with its surroundings.
Yet, despite the great variability in the ways volcanoes erupt, eruptions are all governed by a common set of physical and chemical processes. Eruptions are influenced by the tectonic setting, the properties of Earth’s crust, and the history of the volcano. Volcano landforms and eruptive behavior are diverse, reflecting the large number and complexity of interacting processes that govern the generation, storage, ascent, and eruption of magmas.
More than a dozen are usually erupting at any time somewhere on Earth, and close to 100 erupt in any year ( Loughlin et al., 2015).
Most of Earth’s atmosphere, water, and crust were delivered by volcanoes, and volcanoes continue to recycle earth materials. Volcanoes are a key part of the Earth system.
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