How much of the Earth is volcanic?

More than 80 percent of the Earth's surface -- above and below sea level -- is of volcanic origin. Gaseous emissions from volcanic vents over hundreds of millions of years formed the Earth's earliest oceans and atmosphere, which supplied the ingredients vital to evolve and sustain life. Over geologic eons, countless volcanic eruptions have produced mountains, plateaus, and plains, which subsequently eroded and weathered into majestic landscapes and formed fertile soils.

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Will extinct volcanoes on the East Coast of the U.S. erupt again?

No. Through plate tectonics, the eastern U.S. has been isolated from the global tectonic features (tectonic plate boundaries and hot spots in the mantle), that cause volcanic activity. So new volcanic activity is not possible now or in the near future. If you wait around several hundred million years, maybe... Remnants of past volcanism are found...

Which volcanoes in the conterminous United States have erupted since the Nation was founded?

Excluding steam eruptions, these volcanoes have shown activity: Mount St. Helens, Washington - Eruptions and/or lava dome growth occurred in the late 1700s, 1800-1857, 1980-1986, and 2004-2007. Lassen Peak, California - A series of steam blasts began on May 30, 1914. An eruption occurred 12 months later on May 21, 1915. Minor activity continued...

Where does the United States rank in the number of volcanoes?

The United States ranks third, behind Indonesia and Japan, in the number of historically active volcanoes (that is, those for which we have written accounts of eruptions). In addition, about 10 percent of the more than 1,500 volcanoes that have erupted in the past 10,000 years are located in the United States. Most of these volcanoes are found in...

What kind of school training do you need to become a volcanologist?

There are many paths to becoming a volcanologist. Most include a college or graduate school education in a scientific or technical field, but the range of specialties is very large. Training in geology, geophysics, geochemistry, biology, biochemistry, mathematics, statistics, engineering, atmospheric science, remote sensing, and related fields can...

What are some benefits of volcanic eruptions?

Over geologic time, volcanic eruptions and related processes have directly and indirectly benefited mankind. Volcanic materials ultimately break down and weather to form some of the most fertile soils on Earth, cultivation of which has produced abundant food and fostered civilizations. The internal heat associated with young volcanic systems has...

What are some examples of supervolcanoes?

Volcanoes that have produced exceedingly voluminous pyroclastic eruptions and formed large calderas in the past 2 million years include Yellowstone, Long Valley in eastern California, Toba in Indonesia, and Taupo in New Zealand. Other 'supervolcanoes' would likely include the large caldera volcanoes of Japan, Indonesia, Alaska (e.g. Aniakchak,...

Do volcanoes affect weather?

Yes, volcanoes can affect weather and the Earth's climate . Following the 1991 eruption of Mount Pinatubo in the Philippines, cooler than normal temperatures were recorded worldwide and brilliant sunsets and sunrises were attributed to this eruption that sent fine ash and gases high into the stratosphere, forming a large volcanic cloud that...

How many active volcanoes are there on Earth?

There are about 1,500 potentially active volcanoes worldwide, aside from the continuous belts of volcanoes on the ocean floor at spreading centers like the Mid-Atlantic Ridge . About 500 of those 1,500 volcanoes have erupted in historical time. Many of those are located along the Pacific Rim in what is known as the " Ring of Fire ." In the United...

Do volcanoes affect weather?

Yes, volcanoes can affect weather and the Earth's climate . Following the 1991 eruption of Mount Pinatubo in the Philippines, cooler than normal temperatures were recorded worldwide and brilliant sunsets and sunrises were attributed to this eruption that sent fine ash and gases high into the stratosphere, forming a large volcanic cloud that...
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vertical columns of volcanic rock at Devils Postpile National Monument
July 11, 2016

Vertical columns of volcanic rock at Devils Postpile National Monument

Vertical columns of basaltic volcanic rock at Devils Postpile National Monument are formed when a think lava flows slowly cools. The vertical columns are a reflection of stress and shrinkage of the rock as it cools.

Image: Footprints in Ash from 1790 Kilauea Volcano Eruption
March 14, 2016

Footprints in Ash from 1790 Kilauea Volcano Eruption

Footprints made in muddy ash during Kilauea's 1790 eruption are reminders that people experienced the largest explosive eruption in Hawai‘i in 1,000 years. More than 80, and possibly several hundred, people were killed by the eruption soon after the footprints were made.

A typical portion of the pāhoehoe flow margin near the flow front, ...
October 26, 2014

A typical portion of the pāhoehoe flow margin near flow front, just...

A typical portion of the pāhoehoe flow margin near the flow front, just downslope of Cemetery Rd./AP‘A‘ā St. The horizontal incandescent cracks seen in the center and right portions of the photo indicate that the flow was inflating. pāhoehoe inflation is driven by continued supply of lava beneath the surface crust, which slowly raises the surface.

Image: Volcanic Deposits at Okmok
August 6, 2010

Volcanic Deposits at Okmok

Some of the thick volcanic deposits at Okmok that are being studied to reconstruct the sequence of events during the 2008 eruption.  Photo taken on August 6, 2010 by Dr. Ort.

Image: Trees Buried in Volcanic Sediment,  Sandy River 1
January 15, 2009

Trees Buried in Volcanic Sediment, Sandy River 1

Trunks of forest trees, initially growing on a terrace above the Sandy River (Oregon) at Oxbow Regional Park, were buried by rapid deposition of sediment following a dome-building eruption at Mount Hood in 1781. Erosion during a flood about a week before the photo was taken exposed this "ghost forest".  

In the photo is Dan Daly, a naturalist interpreter with Metro

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Image: Stories of Lava Flows and Volcanic Landscapes from Ka‘u to North Kona Featured in Public Talk
August 19, 2006

Stories of Lava Flows and Volcanic Landscapes from Ka'u to North Kona Featured in Public Talk

Two prominent, historic lava flows are visible in this aerial photo of West Hawai‘i. Kīholo Bay is flanked by the 1859 Mauna Loa flow (left) and a Hualālai flow that  erupted around 1800 or earlier (right). These lava flows and other volcanic landscapes along Highways 11 and 190 will be the focus of a Volcano Awareness Month talk in Kona on Jan. 22

Image: Aerial View of Mauna Loa Volcano, Hawaii
January 9, 1985

Aerial View of Mauna Loa Volcano, Hawaii

USGS Hawaiian Volcano Observatory scientists monitor Mauna Loa, the largest active volcano on Earth. In this 1985 aerial photo, Mauna Loa looms above Kīlauea Volcano’s summit caldera (left center) and nearly obscures Hualālai in the far distance (upper right).

Attribution: Natural Hazards
Alaska geology map revealed

Alaska geology revealed (GIP-168)

This map shows the generalized geology of Alaska, which helps us to understand where potential mineral deposits and energy resources might be found, define ecosystems, and ultimately, teach us about the earth history of the State.