Ten Interesting Facts . . . Volcanoes
1.The biggest volcano in our solar system is on Mars. Olympus Mons is 600 km (373 miles) wide and 21 km (13 miles) tall.
2.Volcanoes are measured by the Volcano Explosivity Index.
|0||< 10,000 m³||Hawaiian||non-explosive||< 100 m||constant||Kilauea|
|1||> 10,000 m³||Hawaiian / Strombolian||gentle||100–1000 m||daily||Stromboli|
|2||> 1,000,000 m³||Strombolian / Vulcanian||explosive||1–5 km||weekly||StromboliGaleras, 1992|
|3||> 10,000,000 m³||Vulcanian / Peléan||severe||3–15 km||few months||Ruiz, 1985|
|4||> 0.1 km³||Peléan / Plinian||cataclysmic||10–25 km||≥ 1 yr||Pelée (1902), Eyjafjallajökull (2010)|
|5||> 1 km³||Plinian||paroxysmic||20–35 km||≥ 10 yrs||Vesuvius (79) St. Helens (1980)|
|6||> 10 km³||Plinian / Ultra-Plinian||colossal||> 30 km||≥ 100 yrs||Pinatubo (1991)|
|7||> 100 km³||Ultra-Plinian||mega-colossal||> 40 km||≥ 1,000 yrs||Tambora (1815)|
|8||> 1,000 km³||Supervolcanic||apocalyptic||> 50 km||≥ 10,000 yrs||Yellowstone (640,000 BC)|
3. Five Largest Volcanic Eruptions in Recent History
Explosivity Index (VEI)
|April 10, 1815||7|
island of Krakatoa
|Aug. 27, 1883||6|
|Novarupta||Alaska Peninsula||June 6, 1912||6|
|Pinatubo||Philippines||June 15, 1991||6|
|Santa Maria||Pacific coast of
|Oct. 24, 1902||6|
4. Volcanoes may be found on the ocean floor and under the icecaps.
5. Volcanic eruptions can send ash over 30 km (17 miles) into the atmosphere.
6. Erupting volcanoes can trigger tsunamis, flash floods, earthquakes, mud flows, and rock falls.
7. More than half of the 500 active volcanoes found on Earth are in a circle around the Pacific Ocean known as the “Ring of Fire.” The United States has active volcanoes in Hawaii, Alaska, California, Oregon, and Washington.
8. Volcanoes can be active, dormant, or extinct. Active means the volcano has had an eruption in the last few thousand years. Dormant means the volcano has the potential to erupt although it hasn’t erupted recently. Extinct means the volcano is not likely to erupt again.
9. The deadliest eruption in what is now the United States took place 200 years ago when Kilauea erupted on the Hawaiian Islands killing more than 400 people.
10.There are different kinds of volcanoes.
When the lava contains less gas, the eruption is gentler. Flow after flow of thin streams of lava flows out in all directions from the volcano’s vent creating a flat, dome-shaped mountain with broad slopes.
Lava domes are formed by small spherical masses of lava which are too thick to flow. The lava piles around the vent. Lava domes often grow larger by expansion within the volcano.
Composite or strata volcanoes contain a lot of gas mixed in with the lava. Because of the built-up gas, the eruptions are violent. The volcano spews out gases, ash, and hot lava. The lava doesn’t travel far, so it piles up creating a volcano that is built of many layers of ash and solidified lava.
Cinder cones are formed when a volcano violently erupts. The lava quickly congeals and falls around the vent in a circular shape.
Photo Mount St.Helens
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