Other Notable Supervolcanoes
While Yellowstone and Toba receive much of the scientific and public attention given to supervolcanoes, several other systems around the world have produced massive eruptions and continue to pose potential hazards. Understanding these diverse systems provides insights into the range of supervolcanic behavior and helps scientists better assess global volcanic risks.
Long Valley Caldera, California
Long Valley Caldera, located in eastern California, formed during the massive Bishop Tuff eruption approximately 760,000 years ago. This eruption ejected about 650 cubic kilometers of material and created a caldera roughly 20 by 30 kilometers in size. The eruption deposits extend across much of the western United States, demonstrating the far-reaching impacts of the event.
The Long Valley system has remained active since the caldera-forming eruption, with numerous smaller eruptions occurring over the past several hundred thousand years. The most recent volcanic activity included eruptions from the Mono-Inyo chain about 600 years ago and ongoing hydrothermal activity throughout the caldera.
Long Valley has shown signs of unrest since the late 1970s, including earthquake swarms, ground uplift, and increased carbon dioxide emissions. The unrest prompted the U.S. Geological Survey to issue a volcanic hazard notice in 1982, though no eruption has occurred. The system continues to be closely monitored as one of the potentially active supervolcanoes in the United States.
The proximity of Long Valley to populated areas of California, including the Los Angeles metropolitan region, makes it a significant volcanic hazard despite the low probability of a major eruption. Even smaller eruptions could cause significant disruption to transportation, utilities, and agriculture in the region.
Campi Flegrei, Italy
The Campi Flegrei (Phlegraean Fields) volcanic system near Naples, Italy, represents one of the most potentially dangerous supervolcanoes due to its location in a densely populated region. The system has produced two major eruptions: the Campanian Ignimbrite eruption about 40,000 years ago and the Neapolitan Yellow Tuff eruption about 15,000 years ago.
The Campanian Ignimbrite eruption was one of the largest volcanic events to occur in Europe during the late Pleistocene, ejecting an estimated 300 cubic kilometers of material and creating a caldera that underlies much of the modern Naples metropolitan area. Deposits from this eruption have been found across the Mediterranean region.
Campi Flegrei has shown periodic signs of unrest throughout recorded history, including significant ground uplift episodes in the 1970s and 1980s that raised parts of the town of Pozzuoli by several meters. More recent unrest since 2005 has included continued ground uplift, increased seismicity, and changes in gas emissions.
The location of Campi Flegrei in one of Europe's most densely populated regions makes it a significant hazard even for relatively small eruptions. The Naples metropolitan area is home to over 3 million people, many of whom live directly above or adjacent to the volcanic system.
Taupo Volcanic Zone, New Zealand
New Zealand's Taupo Volcanic Zone hosts multiple supervolcanic systems in a compact area, making it one of the most volcanically active regions in the world. The zone includes several calderas that have produced massive eruptions within the past 30,000 years, including systems at Taupo, Okataina, and other centers.
The Oruanui eruption from Lake Taupo about 26,500 years ago was one of the largest eruptions of the past 100,000 years, ejecting approximately 1,170 cubic kilometers of material. This eruption created much of the modern Lake Taupo and deposited volcanic material across much of New Zealand's North Island.
More recently, the 1800-year-old Taupo eruption was smaller than the Oruanui event but still significant enough to be classified as a VEI 7 eruption. This eruption occurred in recorded Maori oral history and caused significant environmental impacts across New Zealand.
The Taupo Volcanic Zone continues to show high levels of activity, with frequent earthquakes, active geothermal systems, and occasional small eruptions from various centers. The region is closely monitored by GeoNet, New Zealand's geological hazard monitoring system.
Valles Caldera, New Mexico
The Valles Caldera in northern New Mexico formed during two major eruptions: the Otowi eruption 1.61 million years ago and the Tshirege eruption 1.25 million years ago. The more recent eruption ejected about 600 cubic kilometers of material and created the current 20-kilometer-diameter caldera.
Following the caldera-forming eruptions, the Valles system produced numerous smaller eruptions, including lava domes and flows that continued until about 40,000 years ago. The system also hosts significant geothermal resources that have been explored for energy development.
Current activity at Valles Caldera is limited to geothermal features and occasional small earthquake swarms. The system is considered to be in a quiet phase, though it remains classified as potentially active due to its relatively recent volcanic history.
The Valles Caldera is significant for scientific research as it provides insights into the long-term evolution of supervolcanic systems and the transition from active to extinct volcanism. The caldera has been preserved as a national monument, providing opportunities for both scientific research and public education about supervolcanoes.