Editing Mount Erebus (section)

==Geology and volcanology==
[[File:Anorthoclase-219058.jpg|thumb|upright| [[Anorthoclase]] crystal (45 mm long) from Mount Erebus]]

Mount Erebus is the world's southernmost active volcano. It is the current eruptive centre of the [[Erebus hotspot]]. The summit contains a persistent convecting [[Phonolite|phonolitic]] lava lake, one of five long-lasting [[lava lake]]s on Earth. Characteristic eruptive activity consists of [[Strombolian eruption]]s from the lava lake or from one of several subsidiary vents, all within the volcano's inner crater.<ref>{{cite book |editor-last=Kyle |editor-first=P. R. |title=Volcanological and Environmental Studies of Mount Erebus, Antarctica |series=Antarctic Research Series |publisher=American Geophysical Union |location=Washington DC |year=1994 |isbn=0-87590-875-6|oclc=	1132108108 }}</ref><ref>{{cite journal |last1=Aster |first1=R. |last2=Mah |first2=S. |last3=Kyle |first3=P. |last4=McIntosh |first4=W. |last5=Dunbar |first5=N. |first6=J. |last6=Johnson |title=Very long period oscillations of Mount Erebus volcano |journal=[[Journal of Geophysical Research|J. Geophys. Res.]] |volume=108 |issue= B11|pages=2522 |doi=10.1029/2002JB002101 |year=2003 |bibcode=2003JGRB..108.2522A |doi-access=free }}</ref>  The volcano is scientifically remarkable in that its relatively low-level and unusually persistent eruptive activity enables long-term volcanological study of a Strombolian eruptive system very close (hundreds of metres) to the active vents, a characteristic shared with only a few volcanoes on Earth, such as [[Stromboli]] in Italy. Scientific study of the volcano is also facilitated by its proximity to [[McMurdo Station]] (U.S.) and [[Scott Base]] (New Zealand), both sited on [[Ross Island|the same island]] around 35&nbsp;km away.

Mount Erebus is classified as a [[Polygenetic volcanic field|polygenetic]] [[stratovolcano]]. The bottom half of the volcano is a shield and the top half is a stratocone. The composition of the current eruptive products of Erebus are [[anorthoclase]]-[[porphyritic]] [[tephritic phonolite]] and [[phonolite]], which are the bulk of exposed lava flow on the volcano. The oldest eruptive products consist of relatively [[igneous differentiation|undifferentiated]] and [[Viscosity|nonviscous]] [[basanite]] lavas that form the low broad platform shield of Erebus. Slightly younger basanite and [[phonotephrite]] lavas crop out on Fang Ridge{{snd}}an eroded remnant of an early Erebus volcano{{snd}}and at other isolated locations on the flanks of Erebus. Erebus is the world's only presently erupting phonolite volcano.<ref name="Burg2012">{{cite journal |last1=Burgisser |first1=Alain |last2=Oppenheimer |first2=Clive |last3=Alletti |first3=Marina |last4=Kyle |first4=Philip R. |last5=Scaillet |first5=Bruno |last6=Carroll |first6=Michael R. |title=Backward Tracking of Gas Chemistry Measurements at Erebus Volcano |journal=Geochemistry, Geophysics, Geosystems |date=November 2012 |volume=13 |issue=11 |page= |doi=10.1029/2012GC004243|bibcode=2012GGG....1311010B |s2cid=14494732 |url=https://hal-insu.archives-ouvertes.fr/insu-00771966/file/ggge2328.pdf }}</ref>

Lava flows of more viscous phonotephrite and [[trachyte]] erupted after the basanite. The upper slopes of Mount Erebus are dominated by steeply [[Strike and dip|dipping]] (about 30°) tephritic phonolite lava flows with large-scale flow levees. A conspicuous break in slope around 3,200 m ASL calls attention to a summit plateau representing a [[caldera]]. The summit caldera was created by an explosive [[Volcanic Explosivity Index|VEI]]-6 eruption that occurred 18,000 ± 7,000 years ago.<ref>{{cite web|url=http://www.bgs.ac.uk/vogripa/searchVOGRIPA.cfc?method=detail&id=2421|title=VOGRIPA|website=www.bgs.ac.uk}}</ref> It is filled with small volume tephritic phonolite and phonolite lava flows. In the center of the summit caldera is a small, steep-sided cone composed primarily of decomposed [[lava bomb]]s and a large deposit of [[anorthoclase]] crystals known as [[Erebus crystal]]s. The active lava lake in this summit cone undergoes continuous degassing.

Microscopic gold particles have been found up to 1000 kilometres from Mount Erebus, ranging in size up to 60 micrometres.  A 1991 paper shows that these particles condense from the volcano's emissions that include 80 grams of gold vapor daily. This amount of gold vapor is low compared to other volcanoes, but the condensation from vapor into gold particles is the first ever documented.<ref>{{Cite journal |last1=Meeker |first1=Kimberly A. |last2=Chuan |first2=Ray L. |last3=Kyle |first3=Philip R. |last4=Palais |first4=Julie M. |author-link4=Julie Palais |date=August 1991 |title=Emission of elemental gold particles from Mount Erebus, Ross Island, Antarctica |url= |journal=[[Geophysical Research Letters]] |volume=18 |issue=8 |pages=1405–1408 |doi=10.1029/91GL01928 |bibcode=1991GeoRL..18.1405M |quote=Although the flux of emitted Au is low compared to other volcanoes, crystalline particulate Au has been found in the plume near the crater, in ambient air up to 1000km from the volcano and in near surface samples.}}</ref><ref>{{Cite web |last=Hecht |first=Jeff |date=7 September 1991 |title=Science: Antarctic gold dust |url=https://www.newscientist.com/article/mg13117853-300-science-antarctic-gold-dust/ |access-date=2022-08-24 |website=[[New Scientist]] |language=en-US}}</ref>

Researchers spent more than three months during the 2007–08 field season installing an atypically dense array of [[seismometer]]s around Mount Erebus to listen to waves of energy generated by small, controlled blasts from explosives they buried along its flanks and perimeter, and to record scattered seismic signals generated by lava lake eruptions and local ice quakes. By studying the refracted and scattered seismic waves, the scientists produced an image of the uppermost (top few km) of the volcano to understand the geometry of its "plumbing" and how the [[magma]] rises to the lava lake.
<ref>{{cite web |title=Plumbing Erebus: Scientists use seismic technique to map interior of Antarctic volcano |url=http://antarcticsun.usap.gov/science/contenthandler.cfm?id=1355 }}</ref><ref>{{cite journal |last1=Zandomeneghi |first1=D. |last2=Aster |first2=R. |last3=Kyle |first3=P. |last4=Barclay |first4=A. |last5=Chaput |first5=J. |last6=Knox |first6=H. |title=Internal structure of Erebus volcano, Antarctica imaged by high-resolution active-source seismic tomography and coda interferometry |journal=[[Journal of Geophysical Research]] |volume=118 |issue=3 |year=2013 |pages=1067–1078 |doi=10.1002/jgrb.50073 |bibcode=2013JGRB..118.1067Z |s2cid=129121276 |doi-access=free }}</ref> These results demonstrated a complex upper-volcano conduit system with appreciable upper-volcano magma storage to the northwest of the lava lake at depths hundreds of meters below the surface.