Editing Caldera (section)

==Extraterrestrial calderas==
Since the early 1960s, it has been known that volcanism has occurred on other planets and moons in the [[Solar System]]. Through the use of crewed and uncrewed spacecraft, volcanism has been discovered on [[Venus]], [[Mars]], the [[Moon]], and [[Io (moon)|Io]], a satellite of [[Jupiter]]. None of these worlds have [[plate tectonics]], which contributes approximately 60% of the Earth's volcanic activity (the other 40% is attributed to [[hotspot (geology)|hotspot]] volcanism).<ref name = "Wilson">{{Cite book | last1 = Parfitt | first1 = L. | last2 = Wilson | first2 = L.  | title = Fundamentals of Physical Volcanology | url = https://archive.org/details/fundamentalsphys00parf | url-access = limited | place = Malden, MA | publisher = [[Blackwell Publishing]]| date= 19 February 2008| chapter = Volcanism on Other Planets| pages = [https://archive.org/details/fundamentalsphys00parf/page/n211 190]–212| chapter-url = http://google.com/books?id=ptpCiNkwLj8C&printsec=frontcover| isbn = 978-0-632-05443-5 | oclc = 173243845}}</ref> Caldera structure is similar on all of these planetary bodies, though the size varies considerably. The average caldera diameter on Venus is {{cvt|68|km|||}}. The average caldera diameter on Io is close to {{cvt|40|km|||}}, and the mode is {{cvt|6|km|||}}; [[Tvashtar Paterae]] is likely the largest caldera with a diameter of {{cvt|290|km|||}}. The average caldera diameter on Mars is {{cvt|48|km|||}}, smaller than Venus. Calderas on Earth are the smallest of all planetary bodies and vary from {{cvt|1.6–80|km|0||}} as a maximum.<ref>{{cite book |doi=10.1016/S1871-644X(07)00008-3 |chapter=Magma-Chamber Geometry, Fluid Transport, Local Stresses and Rock Behaviour During Collapse Caldera Formation |title=Caldera Volcanism: Analysis, Modelling and Response |volume=10 |pages=313–349 |series=Developments in Volcanology |year=2008 |last1=Gudmundsson |first1=Agust |isbn=978-0-444-53165-0 }}</ref>

===The Moon===
{{Further|Volcanism on the Moon}}
The [[Moon]] has an outer shell of low-density crystalline rock that is a few hundred kilometers thick, which formed due to a rapid creation. The craters of the Moon have been well preserved through time and were once thought to have been the result of extreme volcanic activity, but are currently believed to have been formed by meteorites, nearly all of which took place in the first few hundred million years after the Moon formed. Around 500&nbsp;million years afterward, the Moon's mantle was able to be extensively melted due to the decay of radioactive elements. Massive basaltic eruptions took place generally at the base of large impact craters. Also, eruptions may have taken place due to a magma reservoir at the base of the crust. This forms a dome, possibly the same morphology of a shield volcano where calderas universally are known to form.<ref name = "Wilson"/> Although caldera-like structures are rare on the Moon, they are not completely absent. The [[Compton–Belkovich Thorium Anomaly|Compton-Belkovich Volcanic Complex]] on the [[far side of the Moon]] is thought to be a caldera, possibly an [[Pyroclastic flow|ash-flow]] caldera.<ref name="Compton-Belkovich">{{cite journal |last1=Chauhan |first1=M. |last2=Bhattacharya |first2=S. |last3=Saran |first3=S. |last4=Chauhan |first4=P. |last5=Dagar |first5=A. |title=Compton–Belkovich Volcanic Complex (CBVC): An ash flow caldera on the Moon |journal=Icarus |date=June 2015 |volume=253 |pages=115–129 |doi=10.1016/j.icarus.2015.02.024 |bibcode=2015Icar..253..115C }}</ref>

===Mars===
{{Further|Volcanism on Mars}}
The volcanic activity of [[Mars]] is concentrated in two major provinces: [[Tharsis]] and [[Elysium (volcanic province)|Elysium]]. Each province contains a series of giant shield volcanoes that are similar to what we see on Earth and likely are the result of mantle [[Hotspot (geology)|hot spots]]. The surfaces are dominated by lava flows, and all have one or more collapse calderas.<ref name = "Wilson"/> Mars has the tallest volcano in the Solar System, [[Olympus Mons]], which is more than three times the height of Mount Everest, with a diameter of 520&nbsp;km (323 miles). The summit of the mountain has six nested calderas.<ref>Philip's World Reference Atlas including Stars and Planets {{ISBN|0-7537-0310-6}} Publishing House Octopus publishing Group Ltd p. 9</ref>

===Venus===
{{Further|Volcanism on Venus}}
Because there is no [[plate tectonics]] on [[Venus]], heat is mainly lost by conduction through the [[lithosphere]]. This causes enormous lava flows, accounting for 80% of Venus' surface area. Many of the mountains are large [[shield volcano]]es that range in size from {{cvt|150–400|km|round=5||}} in diameter and {{cvt|2–4|km|||}} high. More than 80 of these large shield volcanoes have summit calderas averaging {{cvt|60|km|||}} across.<ref name = "Wilson"/>

===Io===
{{Further|Volcanism on Io}}
Io, unusually, is heated by solid flexing due to the [[Tidal force|tidal]] influence of [[Jupiter]] and Io's [[orbital resonance]] with neighboring large moons [[Europa (moon)|Europa]] and [[Ganymede (moon)|Ganymede]], which keep its orbit slightly [[orbital eccentricity|eccentric]]. Unlike any of the planets mentioned, Io is continuously volcanically active. For example, the NASA ''[[Voyager 1]]'' and ''[[Voyager 2]]'' spacecraft detected nine erupting volcanoes while passing Io in 1979. Io has many calderas with diameters tens of kilometers across.<ref name = "Wilson"/>