Yellowstone Caldera Chronicles is a weekly column written by scientists and collaborators of the Yellowstone Volcano Observatory. This week’s contribution is from Shaul Hurwitz, research hydrologist with the U.S. Geological Survey.
Volcanoes have sparked the imagination of many ancient civilizations, giving rise to abundant myths and legends. The ancient Greeks and the Romans explained volcanoes as sites of gods. In fact, the word “volcano” is derived from Vulcan who was the ancient Roman god of fire (Hephaestus was the Greek equivalent). Early theories of volcanic eruptions invoked fire and combustion because of a lack of understanding of the physics and chemistry of magma. Some volcanic rocks were thought to have formed from water until enough observations could prove otherwise. But these developments took time.
Knowledge of past volcanic eruptions is often limited because of a lack of records from witnesses. For example, our knowledge of the powerful and lethal Minoan eruption, which occurred around 1600 BCE on the island of Santorini in Greece, was mostly obtained by geological and archeological research done more than 3500 years later. More recently, the 1815 Tambora eruption in Indonesia—one of the most powerful eruptions of the past millennia—has few eyewitness accounts, and most knowledge of the eruption and the subsequent year without a summer is from modern scientific analysis.
Some eruptions, however, were very well documented by contemporary witnesses and helped to dispel ideas that volcanism is related to fire or that volcanic rocks are left behind by water. For example, Pliny the Younger carefully observed and described the 79 CE eruption of Mount Vesuvius, which destroyed the Roman cities of Pompeii and Herculaneum and had lasting effects on Roman society. In Iceland, detailed documentation by the priest Jón Steingrímsson described the impacts of the 1783-1784 Laki eruption that led to the death of over 50% of Iceland’s livestock population and much of the island’s human population. It is by combining both eyewitness observations and scientific analysis of undescribed events that modern volcanology was born.
Much of the foundation for a modern and rigorous scientific discipline was established In the late 19th and early 20th centuries by scientists such as Giuseppe Mercalli, who defined eruption types as Strombolian and Vulcanian using observations at the Italian volcanoes Vesuvius, Stromboli, and Vulcano. Similarly, Alfred Lacroix studied the 1902 and subsequent eruptions of Montagne Pelée on the island of Martinique in the eastern Caribbean Sea and coined the French term “nuée ardente” (glowing cloud) for deadly pyroclastic flows that devastated the city of Saint-Pierre. In 1841, founding of the Vesuvius Observatory in Italy—the first volcano observatory in the world—provided the infrastructure needed for dedicated research.
In the first half of the 20th century, scientists that include (among many others) Thomas Jaggar (founder of the Hawaiian Volcano Observatory in 1912), Howel Williams (who developed the principles of volcanic caldera formation), Norman Bowen (a leading expert on igneous rocks), Kiyoo Mogi (a pioneer in models of magma induced deformation), Gladys West who pioneered GPS technology, Sigurdur Thorarinsson (developer of tephra studies), and USGS scientists Florence Bascom (who contributed to a type of identification for volcanoes through geologic mapping), Robert L. Smith (an expert on ash flow tuffs), and Wes Hildreth (who generated exhaustive geologic maps and descriptions of volcanic histories) led to a significantly better understanding of volcanic processes through detailed investigations of volcanoes around the world, laboratory experiments, mapping, and chemical and mineralogical characterization of rocks. Much of the expanding knowledge on volcanism was incorporated into the theory of plate tectonics, mostly in the 1960s.
Some of the most recent advances in volcanology have been through analytical and experimental developments in chemistry and physics. For example, mass spectrometers provide the means to date past volcanic eruptions and determine their chemical compositions. Digital seismometers provide information needed to track magma transport in the subsurface. Space-based measurements provide information on uplift and subsidence of the ground surface. The composition of volcanic gases and their emission rate, which provide information on magma at depth, are mostly measured remotely and autonomously. The volume and growth rate of active lava flows and domes can be measured with oblique photogrammetry using drones (UAS). Satellites orbiting in space provide diverse types of information, including thermal anomalies. Combining the many types of measurements with mapping of erupted volcanic rocks allows for a multidisciplinary effort that can provide information on the timing, locations, and sizes of past eruptions, which in turn aids efforts to issue forecasts and assess hazards.
The USGS Volcano Hazards Program (VHP) was established in the early 1980s to address the national need for volcano information following the 1980 eruption of Mount St. Helens. In 2001, the Yellowstone Volcano Observatory (YVO) was the fourth of the five USGS volcano observatories to be established. Since then, monitoring of volcanic and hydrothermal activity has substantially evolved with the incorporation of new technologies. The YVO monitoring plan and the VHP recommended capabilities and instrumentation for volcano monitoring in the United States are intended to address the USGS mission “to enhance public safety and minimize social and economic disruption from eruptions by delivering effective forecasts, warnings, and information on volcano hazards based on a scientific understanding of volcanic processes.”
Nearly all countries with active volcanoes currently have institutes dedicated to monitoring volcanic activity. The advent of modern communication methods, and especially the internet in the 1990s, has allowed observatories worldwide to share information, learn from each other, and provide global alerts. With support from the USGS, the Global Volcanism Program (GVP), which is part of the Smithsonian Institution, documents and disseminates information about global volcanic activity, and it is a great place to learn more about eruptions past and present around the world.
It has taken volcanology several millennia to transform from myths and legends to a modern and interdisciplinary science that utilizes emerging technologies and effective communications. The advancing technology that forms the basis of modern volcanology makes people around the world better informed and protected from volcanic hazards.
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