Head For the Hills Trivia Quiz

Answer: Ash plume

An ash plume is formed when pockets of gas contained in molten magma reach the surface and explode violently into the atmosphere. Ash is technically ejected matter that is less than 2mm (0.079 inches) in diameter, but common usage includes all ejected material, whatever the size, in the term "ash".

Answer: Shield

These volcanoes are so named for their resemblance to a warrior's shield lying on the ground. Easy flowing, fairly liquid, lava forms these large, low volcanoes. This Icelandic volcano is named "Skjaldbreiđur", meaning "Broad" (breiđur) "Shield" (skjald).

Answer: Fumarole

Fumaroles are often formed as subterranean magma heats ground water to the boiling point. The high-temperature water is forced to the surface and when it enters an area of lower pressure, flashes into steam. Gases and minerals that may be dissolved in the water precipitate out, sometimes forming solid chimneys such as those pictured.

Answer: Cascades

The Cascades extend from southern British Columbia, Canada to northern California. All of the continental U.S. volcanic eruptions in the last 200 year have come from them, and another like Mt. St. Helens in 1980 would pose a serious threat to air travel.

Answer: Lava dome

The silica-rich magma that forms lava domes is very viscous and doesn't flow very far once it is extruded from the volcano. Domes may be several hundred meters in height and some have been growing for centuries, such as on Mt. Merapi in Indonesia.

Answer: Cinder cone

Cinder cones are formed of small pieces of volcanic rock that build up around a vent. Some cones form after only one eruption, although some cinder cones, such as that pictured, result from multiple eruptions. Pictured is Izalco in El Salvador, which formed in 1770 and regularly erupted until 1958, so regularly that it became known as the "Lighthouse of the Pacific".

Answer: Stratovolcano

The strata, or bands of different materials, gives the name "stratovolcano" to these classic volcano shapes. The layers are made up of ash, lava and cinders that are built up, layer upon layer, over the long life of these volcanoes.

Answer: Submarine volcanoes

"Submarine" means simply "below water". The Mid-Atlantic Ridge is an area of active volcanism and sea-floor spreading. The island of Surtsey, off the southern coast of Iceland, began as a submarine volcano over 400 feet (130 meters) under water that finally broke the surface in November 1963.

Answer: Ice

Tuyas are also rarely referred to as "mobergs", a portmanteau word made up of "mountain" and "iceberg". These volcanoes erupted under ice sheets, and gained their characteristic flat-topped and vertical-sided shapes from the rapidly cooling lava. The name comes from Tuya Butte in British Columbia; pictured is a tuya in Iceland, and these forms have also been found in Antarctica.

Answer: Mud volcano

True mud volcanoes are extrusions of slurries formed by heated water, subterranean mineral deposits and gases. A typical mud volcano may include cones of mud up to 2 meters high and 2 meters circumference, or it may be a wide, flat pool of warm mud. The largest mud volcanic feature is from Lusi in Indonesia, a mud shield 10 kilometers (6 miles) in diameter.