What is the difference between "magma" and "lava"?

Scientists use the term magma for molten rock that is underground and lava for molten rock that breaks through the Earth's surface. 

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How big is the magma chamber under Yellowstone?

Yellowstone is underlain by two magma bodies . The shallower one is composed of rhyolite (a high-silica rock type) and stretches from 5 km to about 17 km (3 to 10 mi) beneath the surface and is about 90 km (55 mi) long and about 40 km (25 mi) wide. The chamber is mostly solid, with only about 5-15% melt. The deeper reservoir is composed of basalt...

How hot is a Hawaiian volcano?

Very hot!! Here are some temperatures recorded at different times and locations: The eruption temperature of Kīlauea lava is about 1,170 degrees Celsius (2,140 degrees Fahrenheit). The temperature of the lava in the tubes is about 1,250 degrees Celsius (2,200 degrees Fahrenheit). The tube system of episode 53 (Pu'u O'o eruption) carried lava for...

Lava sampling: Why do we do it?

Hot lava samples provide important information about what's going on in a volcano's magma chambers. We know from laboratory experiments that the more magnesium there is in magma, the hotter it is. Chemical analysis, therefore, provides the means not only to determine the crystallization history of lava but also to establish the temperature at...

Why is it important to monitor volcanoes?

The United States and its territories contain 169 geologically active volcanoes, of which 54 volcanoes are a high threat or very high threat to public safety. Many of these volcanoes have erupted in the recent past and will erupt again in the foreseeable future. As populations increase, areas near volcanoes are being developed and aviation routes...

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...

How Do Volcanoes Erupt?

Deep within the Earth it is so hot that some rocks slowly melt and become a thick flowing substance called magma. Since it is lighter than the solid rock around it, magma rises and collects in magma chambers. Eventually, some of the magma pushes through vents and fissures to the Earth's surface. Magma that has erupted is called lava. Some volcanic...

How many active volcanoes are there on Earth?

There are about 1,350 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 1,350 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...

Can an eruption at one volcano trigger an eruption at another volcano?

There is no definitive evidence that an eruption at one volcano can trigger an eruption at a volcano that’s hundreds of kilometers/miles away or on a different continent. There are a few historic examples of simultaneous eruptions from volcanoes (or volcanic vents ) located within about 10 kilometers (6 miles) of each other, but it's difficult to...
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Date published: July 31, 2017

Subsurface Magma Triggers Earth’s Most Severe Extinction

Subsurface magma intrusions (sills), rather than surface lava flows, may have triggered the Earth’s most catastrophic extinction event approximately 252 million years ago.

Date published: May 11, 2017

Magmas to Metals

No one wants to have an active volcano in their backyard (just ask Dionisio Pulido), but ancient eroded volcanoes can sometimes be literal goldmines for mineral ores.

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December 31, 2017

Kīlauea Summit Eruption | Lava Returns to Halemaʻumaʻu

In March 2008, a new volcanic vent opened within Halema‘uma‘u, a crater at the summit of Kīlauea Volcano in Hawaiʻi Volcanoes National Park on the Island of Hawaiʻi. This new vent is one of two ongoing eruptions on the volcano. The other is on Kīlauea’s East Rift Zone, where vents have been erupting nearly nonstop since 1983. The duration of these simultaneous summit and

video thumbnail: Lava Fountaining from a Dominant Vent
March 6, 2011

Lava Fountaining from a Dominant Vent

Video showing low fountaining from the dominant vent, near the southwest end of the fissure system adjacent to Napau Crater, active during the day on March 7.

Attribution: Natural Hazards
Image: Active Lava Flow
July 22, 2010

Active Lava Flow

Flows continue to be active south of the Kalapana access road, heading in a generally eastward direction. These breakouts were active just a few hundred meters east of the County lava viewing area.

Image: Lava Flow Entering Water
November 15, 2009

Lava Flow Entering Water

A small open channel of lava was entering the water at one of two entry points at the west Waikupanaha entry area.

June 23, 2008

What is the difference between "magma" and "lava"?

Listen to hear the answer.

video thumbnail: East Lae'apuki Lava Breakout (June 24, 2006)
June 23, 2006

East Lae'apuki Lava Breakout (June 24, 2006)

After sunset on June 24, 2006, lava burst from the East Lae'apuki lava tube about 50 meters (165 feet) inland from the older sea cliff behind the East Lae'apuki lava delta. Lava reached and began cascading over the sea cliff within a minute, and quickly spread across the lava delta below. The cascade was mostly crusted over by late afternoon on June 25, but intermittent

Lava splashes from a lava lake.
November 30, 2000

Lava Lake

View of Kīlauea Volcano, Halemaʻumaʻu Crater, Summit Vent Lava Lake.

A narrow stream of yellow-hot lava flows out of a lava tube, onto a small ledge, then cascades down to the ocean.
November 27, 1989

Kilauea lava flows from a tube into the sea, November 27, 1989

Lava flows from a lava tube into the sea near Kupapau Point on 11/27/1989. From the Kilauea East Rift Zone (ERZ) eruption, eruption pisode 48, Kupapau lava flow. Hawai'i Island.

A small stream of red hot lava spreads out in a smooth, ropy texture as it cools to black.
June 15, 1989

Pahoehoe from Kilauea eruption, 1989

Pahoehoe ropes form in the Wahaula Lava Flow across from Wahaula Visitor Center on Hawai'i Island during the Kilauea East Rift Zone (ERZ) eruption on 6/15/89.

Image: Lava flows on Mauna Loa
March 25, 1984

Lava flows on Mauna Loa

Erupting vents on Mauna Loa’s northeast rift zone near Pu‘u‘ula‘ula (Red Hill) on Mar. 25, 1984, sent massive ‘a‘ā lava flows down the rift toward Kūlani.

A stream of red hot lava arcs into the air and splatters down on cooler, black lava flows
February 25, 1983

Arching fountain of lava, Kilauea Volcano, 1983

Arching fountain of lava approximately 10 meters high issuing from the western end of the 0740 vents, a series of spatter cones 170 meters long, south of Pu'u Kahaualea on Hawai'i Island's Kilauea Volcano (episode 2). Episodes 2 and 3 were characterized by spatter and cinder cones, such as Pu'u Halulu, which was 60 meters high by episode 3.