Fire in the Hole! Trivia Quiz

Answer: inert

Though the description of a volcano's level of activity as extinct, dormant and active is viewed as simplistic by some experts, it is still widely used. In particular, there is no consensus among experts on what constitutes an active volcano. Some scientists consider a volcano "active" if it has erupted at least once in the past 10,000 years; others, instead, use "recorded history" as a frame of reference. It is estimated that there are over 1,500 potentially active volcanoes in the world - about two-thirds of which are concentrated in the geological area known as the Pacific Ring of Fire.

A dormant (or inactive) volcano is one that is likely to erupt again in the future, even if it has had no eruptive activity for thousands of years; a notable dormant volcano is Mount Kilimanjaro, Africa's highest mountain, whose last major eruption occurred over 300,000 years ago. On the other hand, a volcano is generally considered extinct when it no longer has a magma supply, which makes future eruptions unlikely; however, it is sometimes difficult for volcanologists to determine whether a volcano is extinct or dormant. A famous extinct volcano located in a region normally not associated with volcanism is Castle Rock in Edinburgh, Scotland.

The term "inert" is used in chemistry, and is not applied to volcanoes.

Answer: tephra

Also known as pyroclasts, tephra (from a Greek word meaning "ash") are airborne fragments ejected during a volcanic eruption. These fragments are classified according to size: ash refers to the smallest, fine-grained particles, while lapilli, or volcanic cinders. are pea- to walnut-sized (between 2 and 64 mm in diameter), and bombs and blocks are the largest. Ash tends to remain in the atmosphere for the longest time, while blocks fall to the ground relatively quickly. There are also specific kinds of tephra, such as the teardrop-shaped lapilli named "Pele's tears", and the fine filaments of basaltic glass known as "Pele's hair" (Pele being the Hawaiian goddess of fire).

Tephra can become compacted into tuff, a relatively soft, pale-coloured volcanic rock that contains from 25% to 75% of ash; tuff was widely used as construction material by the Romans, due to its abundant presence in many parts of Italy. Consolidated tephra containing coarser particles is known as breccia. The layers of tephra that settle on the ground after an eruption are used by various scientific disciplines - for example, to date the fossils of living organisms buried and preserved by the tephra. The perfectly preserved ruins of the legendary city of Pompeii were found buried under a layer of volcanic ash and pumice that was 4 to 6 m (13 to 20 ft) thick.

Answer: pyroclastic flows

The term Peléan comes from Mount Pelée ("bald mountain"), the volcano on the Caribbean island of Martinique whose catastrophic eruption of May 1902 - one of the deadliest in recorded history - utterly destroyed the town of Saint-Pierre, and caused the death of almost 30,000 people. The distinguishing feature of a Peléan eruption is the pyroclastic flows - called "nuées ardentes" (glowing clouds) in French, as they look like heavy, black clouds that glow in the dark - violently blown out of a volcano's crater. These ground-hugging clouds of gas, ash and other volcanic debris, with temperatures that can easily exceed 1,000º C (1,830 °F), can move at speeds of over 100 km/h (62 mph), and incinerate everything on their path.

Though Peléan eruptions are relatively rare, a number of them have occurred over the past 75 years; some - such as the eruptions of Mount Hibok-Hibok in the Philippines (1948-1951), and the eruption of Mount Lamington in Papua New Guinea (1951) - have caused considerable loss of life as well as material damage. The April 2021 eruption of the volcano La Soufrière on the Caribbean island of Saint Vincent was also classified as a Peléan eruption: fortunately, the population of the affected areas was evacuated in time.

Answer: Vesuvius

Though the term "Vesuvian eruption" is also occasionally used, the kind of violent, explosive eruption associated with Mount Vesuvius bears the name of Roman author and naturalist Pliny the Elder, who died during the volcano's infamous eruption of 79 AD. The trademark of a Plinian eruption is the huge column of hot gases and volcanic debris ejected from the crater high into the stratosphere. Numerous paintings and photos have captured this phenomenon, ominously resembling a nuclear mushroom cloud. Typical of stratovolcanoes, Plinian eruptions are also frequently accompanied by lightning strikes caused by the static electricity generated by colliding particles of ash within the eruption column. Pyroclastic flows are another hazard associated with Plinian eruptions: they were the cause of most of the deaths that happened in Pompeii, Herculaneum and Stabia in 79 AD.

Many of history's most destructive eruptions have been of the Plinian type - including those of Mount Tambora (1815), Krakatoa (1883), and Mount St Helens (1980). The summits of both Tambora and Mount St Helens were blown off by the violence of the eruptions, substantially reducing the mountains' elevations; in the case of Krakatoa, most of the island where the volcano was located disappeared, probably by collapsing into an empty magma chamber.

Answer: Surtseyan

Surtseyan eruptions (also known as hydrovolcanic) are classified as phreatomagmatic eruptions because they involve water as well as magma. The name of this type of eruption comes from the island of Surtsey, located off the southern coast of Iceland, and formed on 14 November 1963 in an eruption that began 130 metres (430 feet) below sea level. Surtsey ("Surtr's island") was fittingly named after Surtr, the fire giant of Norse myth who will set fire to the world at the end of Ragnarök. The submarine volcanic vents responsible for the formation of the island are part of the Mid-Atlantic Ridge, a fissure on the floor of the Atlantic Ocean that separates the North American Plate from the Eurasian and the African ones. The formation of Surtsey was accompanied by fierce explosive activity, caused by the meeting of hot lava and icy cold sea water; eruptive activity continued until 1966, then ceased. Another famous instance of Surtseyan eruption is the island of Ferdinandea in the Mediterranean Sea, which appeared in 1831 and disappeared the following year because of erosion.

Hawaiian eruptions are of the effusive type, with very fluid lava and hardly any explosive activity. Strombolian eruptions are characterized by spectacular lava and tephra jets, and Vulcanian eruptions by dense clouds of gas exploding from the crater, as well as volcanic bombs and blocks. Stromboli and Vulcano are both located in the Aeolian Islands, a volcanic archipelago north of Sicily.

Answer: steam

Also known as steam-blast eruptions, phreatic eruptions are driven by the steam produced by cold ground or surface water coming into contact with lava or magma (often because of an earthquake), and evaporating instantaneously. Steam, water and tephra spew out of the rocks fractured by the expansion of steam. Sometimes a phreatic eruption can be a precursor of a future volcanic event - as happened in the case of the 1980 eruption of Mount St Helens, which was preceded by hundreds of steam explosions.

Though generally not as strong as magmatic or phreatomagmatic eruptions, phreatic eruptions can be violent and cause a lot of damage, especially when they occur without any warning. One of the biggest dangers of these eruptions are the rocks hurled by the explosion, as well as emissions of gases such as hydrogen sulfide. The 2014 eruption of Mount Ontake, on the Japanese island of Honshu, caused the death of 63 people, most of them hikers. Another recent, deadly phreatic eruption occurred on 9 December 2019 the island of Whaakari (White Island), off the east coast of New Zealand's North Island, which resulted in the death of 22 people.

Answer: lahars

A word of Javanese origin, "lahar" denotes a thick slurry of water and volcanic debris (such as ash and rock fragments) flowing down the slopes of a volcano, often at very high speed. Lahars can be over 100 m (328 ft) deep, and hundreds of metres wide, covering very large areas: a large enough lahar can destroy everything in its path, and it is practically impossible to escape on foot. In 1985, the town of Armero in Colombia was completely buried by massive lahars that followed the eruption of Nevado del Ruiz, causing the death of 23,000 people.

In general, lahars are one of the most hazardous phenomena associated with Plinian eruptions, when pyroclastic flows running down the sides of a volcano melt snow or ice (as in the case of Nevado del Ruiz). Lahars can also be triggered by heavy rainfall or floods mixing with pyroclastic material. Because of the presence of large amounts of glacial ice, Mount Rainier (Washington, USA) - one of the 16 highly monitored volcanoes known as Decade Volcanoes - is considered particularly prone to lahars.

Base surges are similar to pyroclastic flows, though they contain more gas than debris; lava tubes are formed by the crusting over of lava channels; fumaroles are vents from which volcanic gas escapes.

Answer: famine

As its name implies, volcanic winter is a sharp drop in temperatures due to clouds of volcanic ash and sulfur aerosols reflecting a portion of incoming sunlight; this phenomenon occurs after a particularly violent explosive eruption. In recent times, the global climate has occasionally been affected by one of those events - most significantly after the Pinatubo eruption of 1991, when temperatures worldwide cooled for several years. However, in the past volcanic winter may have caused more deaths than the eruptions themselves.

The most egregious example was the aftermath of the disastrous Tambora eruption: 1816 has become known in history as "The Year Without a Summer", which badly affected many countries in Europe and elsewhere. Crop failures and major weather disruptions led to widespread unrest, and rampant epidemics of various diseases sharply increased the fatality rate in Europe. Even worse happened in 1783, when the eruption of the Laki fissure in Iceland released huge amounts of sulfur dioxide into the atmosphere, killing most of the island's livestock, and causing one-fifth of the island's population to die of starvation. The Laki eruption triggered a series of extreme weather events throughout most of Europe; some historians blame the ensuing famine and poverty for the outbreak of the French Revolution. Even further back in history, the Hekla 3 (also in Iceland) eruption of about 1,000 BC has been associated with the famines that occurred during the Late Bronze Age collapse.

Answer: Pinatubo, Philippines

With a VEI of 6 (described as Colossal), Mount Pinatubo's 1991 eruption was one of the three largest of the 20th century - the other two being Novarupta (Alaska, 1912) and Santa Maria (Guatemala, 1902). However, the three supervolcanic eruptions listed as wrong answers were several orders of magnitude stronger: in fact, they are all classified as Ultra-Plinian, and described as Mega-Colossal. All these catastrophic events happened during the Pleistocene geological epoch: the oldest was the creation of the Yellowstone Caldera, which occurred around 630,000 BC, while both the Toba eruption (about 74,000 BC) and the first Lake Taupo eruption (about 26,000 BC) happened much later. No other VEI-8 eruptions occurred during Holocene, the current geological epoch. The Mount Tambora eruption of 1815, the most powerful in recorded history so far, was a VEI-7 (Ultra-Plinian, Super-Colossal) event.

The Yellowstone Caldera eruption, also known as Lava Creek eruption, was the last of three that occurred in the past 2.1 million years. The Toba eruption - the largest of the three - is believed to have been particularly violent: some scientists believe that the volcanic winter that ensued almost led to the extinction of the Earth's human population, though this theory has been hotly debated. The Oruanui eruption of Taupo on New Zealand's North Island created the caldera that eventually filled with water to became Lake Taupo. A second eruption, known as Hatepe (VEI-7), occurred between 180 and 233 AD.

Answer: obsidian

Formed from the rapid cooling of lava, which prevents the growth of a crystalline structure, obsidian is considered a mineraloid rather than a true mineral. Also known as volcanic glass, this hard, brittle material, usually black in colour, is formed from felsic lava - that is, rich in lighter elements such as oxygen, silicon and sodium. Consisting mostly of silicon dioxide (SiO2), obsidian breaks into razor-thin pieces with curved surfaces and extremely sharp edges: as obsidian blades can be much sharper than surgical steel, the material is still used today to make high-precision scalpels.

Though archaeological evidence of various tools and objects manufactured from obsidian has been found in most continents, it was in pre-Columbian America that it came into its own as a material for the making of sophisticated implements. One of these was the deadly weapon known as "macuahuitl", a wooden club with obsidian blades embedded around its sides that was the Aztecs' version of a sword. The name "obsidian" comes from Obsidius, a Roman explorer who, according to Pliny the Elder's "Natural History", discovered the material in Ethiopia and brought samples back to Rome.

Pumice is a very light volcanic rock formed from lava with a high gas and water content. Granite is also a felsic igneous rock with a high silica content, while basalt is formed from mafic lava (rich in magnesium and iron).