Editing Mauna Loa (section)

==Geology==
===Setting===
{{multiple image | direction = horizontal | align=left| width1 = 187 | width2 = 200 |image1=Mauna Loa map.gif|caption1=Position of Mauna Loa on [[Hawaii (island)|Hawaiʻi island]]|image2=Island of Hawai'i - Landsat mosaic.jpg|caption2=[[Landsat]] mosaic; recent lava flows appear in black}}

Like all Hawaiian volcanoes, Mauna Loa was created as the [[Pacific Plate|Pacific tectonic plate]] moved over the [[Hawaii hotspot]] in the Earth's underlying [[mantle (geology)|mantle]].<ref name=usgs-map>{{cite web|title=Geologic Map of the State of Hawai'i|url=http://pubs.usgs.gov/of/2007/1089/Hawaii_expl_pamphlet.pdf|work=Open-File Report 2007–1089|publisher=[[United States Geological Survey]]|access-date=December 9, 2012|pages=50–51|year=2007|author1=David R. Sherrod |author2=John M. Sinton |author3=Sarah E. Watkins |author4=Kelly M. Brunt |name-list-style=amp}}</ref> The Hawaii island volcanoes are the most recent evidence of this process that, over 70&nbsp;million years, has created the {{convert|3700|mi|km|abbr=on}}-long [[Hawaiian–Emperor seamount chain]].<ref name="Watson">{{cite web|last=Watson|first=Jim|title=The long trail of the Hawaiian hotspot|url=http://pubs.usgs.gov/gip/dynamic/Hawaiian.html|publisher=United States Geological Survey|access-date=August 26, 2010|date=May 5, 1999}}</ref> The prevailing view states that the hotspot has been largely stationary within the planet's mantle for much, if not all of the [[Cenozoic]] Era.<ref name="Watson"/><ref>{{cite web|url=http://www.mantleplumes.org/Hawaii.html|title=The Emperor and Hawaiian Volcanic Chains: How well do they fit the plume hypothesis?|author1=Foulger, G.R |author2=Anderson, Don L.
|publisher=MantlePlumes.org|date=March 11, 2006|access-date=April 1, 2009}}</ref> However, while the Hawaiian [[mantle plume]] is well understood and extensively studied, the nature of hotspots themselves remains fairly enigmatic.<ref>{{Cite book|year=1987 |title=Volcanism in Hawaii: papers to commemorate the 75th anniversary of the founding of the Hawaii Volcano Observatory |chapter=The Hawaiian-Emperor Volcanic Chain – Geological Evolution |publisher=United States Geological Survey |volume=1 |series=Professional Paper 1350 |chapter-url=https://pubs.usgs.gov/pp/1987/1350/pdf/chapters/pp1350_ch1.pdf |page=32 |author1=Clague, David A. |author2=Dalrymple, G. Brent}}</ref>

Mauna Loa is one of five [[subaerial]]{{efn|occurring on or near the Earth's land surface as opposed to submarine (below the sea), sub-glacial (below a glacier), etc.}} volcanoes that make up the island of [[Hawaii (island)|Hawaiʻi]].<ref>{{cite book |editor1-last=Juvik |editor1-first=Sonia P. |editor2-last=Juvik |editor2-first=James O. |title=Atlas of Hawaiʻi |date=1998 |publisher=University of Hawaiʻi Press |isbn=0-8248-2125-4 |page=44 |edition=3rd |quote=Hawaiʻi Island. Hawaiʻi consists of five coalescent, subaerial (above sea level) volcanoes...}}</ref> The oldest volcano on the island, [[Kohala (mountain)|Kohala]], is more than a million years old,<ref>{{cite web |last1=Sherrod |first1=David R. |last2=Sinton |first2=James M. |last3=Watkins |first3=Sarah E. |last4=Brunt |first4=Kelly M. |title=Geologic Map of the State of Hawaiʻi |date=2007 |publisher=United States Geological Survey |location=Reston, Virginia |page=41 |url=https://pubs.usgs.gov/of/2007/1089/Hawaii_expl_pamphlet.pdf}}</ref> and [[Kīlauea]], the youngest, is believed to be between 210,000 and 280,000 years of age.<ref>{{cite web |title=Kīlauea: Geology and History |url=https://www.usgs.gov/volcanoes/kilauea/geology-and-history |website=U.S. Geological Survey |access-date=December 25, 2021}}</ref> [[Kamaʻehuakanaloa Seamount|Kamaʻehuakanaloa]] (formerly Lōʻihi) on the island's flank is even younger, but has yet to breach the surface of the Pacific Ocean.<ref>{{cite book |author1=David A. Clague |author2=David R. Sherrod |editor1-last=Poland |editor1-first=Michael P. |editor2-last=Takahashi |editor2-first=T. Jane |editor3-last=Landowski |editor3-first=Claire M. |title=Characteristics of Hawaiian volcanoes, Professional Paper 1801 |date=2014 |publisher=U.S. Geological Survey |location=Reston, VA |chapter=Growth and degradation of Hawaiian volcanoes|page=104|url=https://pubs.usgs.gov/pp/1801/downloads/pp1801_Chap3_Clague.pdf}}</ref> At 1&nbsp;million to 600,000 years of age,<ref name="USGS-Mauna Loa history">{{cite web|title=Mauna Loa: Earth's Largest Volcano|url=https://www.usgs.gov/volcanoes/mauna-loa/geology-and-history|publisher=Hawaiian Volcano Observatory – [[United States Geological Service]]|access-date=January 29, 2022}}</ref> Mauna Loa is the second youngest of the five volcanoes on the island, making it the [[List of volcanoes in the Hawaiian – Emperor seamount chain|third]] youngest volcano in the [[Hawaiian – Emperor seamount chain]], a chain of [[shield volcano]]es and [[seamount]]s extending from [[Hawaii]] to the [[Kuril–Kamchatka Trench]] in [[Russia]].<ref name="USGS Hotspots">{{cite book|url=http://pubs.usgs.gov/gip/dynamic/hotspots.html|title="Hotspots": Mantle thermal plumes|publisher=United States Geological Survey|edition=1.14|year=1996|isbn=978-0-16-048220-5|author1=W. J. Kious |author2=R. I. Tilling |name-list-style=amp |access-date=December 9, 2012}}</ref>

[[File:mauna loa from hilo bay.JPG|thumb|Mauna Loa from Hilo Bay, December 2017]]

Following the [[Evolution of Hawaiian volcanoes|pattern]] of Hawaiian volcano formation, Mauna Loa would have started as a [[submarine volcano]], gradually building itself up through underwater eruptions of [[alkali]] [[basalt]] before emerging from the sea through a series of [[surtseyan eruption]]s<ref name=hov-evolution>{{cite web|title=Evolution of Hawaiian Volcanoes|url=https://www.usgs.gov/news/volcano-watch-evolution-hawaiian-volcanoes|publisher=Hawaiian Volcano Observatory – United States Geological Survey|access-date=January 29, 2022|date=March 26, 1998}}</ref> about 400,000 years ago. Since then, the volcano has remained active, with a history of [[Hawaiian eruption|effusive]] and [[explosive eruption|explosive]] eruptions, including 34 eruptions since the first well-documented eruption in 1843.<ref name="hvo-loa">{{cite web |title=Mauna Loa |url=https://www.usgs.gov/volcanoes/mauna-loa |website=US Geological Survey |access-date=January 29, 2022}}</ref>

===Structure===
{{multiple image
| align     = right
| direction = vertical
| width     = 300
| image1    = Mauna Loa Observatory.jpg
| caption1  = Mauna Loa's summit, overlaid with {{convert|100|m|ft|0|abbr=on}} [[contour lines]]; its rift zones are visible from the air.
| image2    = Mokuaweoweo from the air.gif
| caption2  = Mokuʻāweoweo, Mauna Loa's [[caldera|summit caldera]], covered in snow.}}

Mauna Loa is the largest active volcano on Earth and the planet's third largest volcano behind [[Gardner Pinnacles|Pūhāhonu]],<ref name=Garcia2020>{{Cite journal |last1=Garcia |first1=Michael O. |last2=Tree |first2=Jonathan P. |last3=Wessel |first3=Paul |last4=Smith |first4=John R. |date=2020-07-15 |title=Pūhāhonu: Earth's biggest and hottest shield volcano |journal=Earth and Planetary Science Letters |language=en |volume=542 |pages=116296 |doi=10.1016/j.epsl.2020.116296 |issn=0012-821X|doi-access=free |bibcode=2020E&PSL.54216296G}}</ref> which is also in the Hawaiian chain, and the [[Tamu Massif]].<ref name=tamu>{{cite magazine | magazine = National Geographic | title = New Giant Volcano Below Sea Is Largest in the World | url = http://news.nationalgeographic.com/news/2013/09/130905-tamu-massif-shatsky-rise-largest-volcano-oceanography-science/ | archive-url = https://web.archive.org/web/20130906013208/http://news.nationalgeographic.com/news/2013/09/130905-tamu-massif-shatsky-rise-largest-volcano-oceanography-science/ | url-status = dead | archive-date = September 6, 2013 | author = Brian Clark Howard | date = September 5, 2013}}</ref><ref name="ngs">{{Cite journal | journal = Nature Geoscience | volume = 6 | issue = 11 | pages = 976–981 | title = An immense shield volcano within the Shatsky Rise oceanic plateau, northwest Pacific Ocean | last = Sager |first=William W. |author2=Zhang, Jinchang |author3=Korenaga, Jun |author4=Sano, Takashi |author5=Koppers, Anthony A. P. |author6=Widdowson, Mike |author7= Mahoney, John J. | date = September 6, 2013 |doi=10.1038/ngeo1934 | bibcode= 2013NatGe...6..976S}}</ref> It covers a land area of {{convert|5271|km2|mi2|0|abbr=on}} and spans a maximum width of {{convert|120|km|mi|0|abbr=on}}.<ref name="hvo-loa"/> Consisting of approximately {{convert|65000|to|80000|km3|mi3|-2|abbr=on}} of solid rock,<ref name=nps-loa>{{cite web|title=Mauna Loa, Fiery Colossus of the Pacific|author1=G. Macdonald|author2=D. Hubbard|name-list-style=amp|orig-year=1951, 7th ed. revision December 1974|url=http://www.cr.nps.gov/history/online_books/hawaii-notes/vol4-2-7e.htm|publisher=[[National Park Service]]|access-date=December 9, 2012|date=March 24, 2006|url-status=dead|archive-url=https://web.archive.org/web/20131020022158/http://www.cr.nps.gov/history/online_books/hawaii-notes/vol4-2-7e.htm|archive-date=October 20, 2013}}</ref> it makes up more than half of the surface area of the island of Hawaiʻi. Combining the volcano's extensive submarine flanks ({{convert|5000|m|ft|-2|abbr=on}} to the sea floor) and {{convert|4170|m|ft|-1|abbr=on}} subaerial height, Mauna Loa rises {{convert|9170|m|ft|0|abbr=on}} from base to summit,<ref name="hvo-loa"/><ref name=soest-loa>{{cite web|title=Mauna Loa Volcano|url=http://www.soest.hawaii.edu/GG/HCV/maunaloa.html|author1=Rubin, Ken |author2= Minicola, Rochelle|publisher=Hawaiian Volcano Observatory – United States Geological Survey|date=March 20, 2009|access-date=December 12, 2012}}</ref> greater than the {{convert|8848|m|ft|0|abbr=on|disp=or}}<ref>{{cite news|title=Nepal in new bid to finally settle Mount Everest height|url=https://www.bbc.co.uk/news/science-environment-17191400|work=[[BBC News]]|access-date=December 10, 2012|author=Navin Singh Khadka|date=February 28, 2012}}</ref> elevation of [[Mount Everest]] from sea level to its summit. In addition, much of the mountain is invisible even underwater: its mass depresses the [[lithosphere|crust]] beneath it by another {{convert|8|km|mi|0|abbr=on}}, in the shape of an inverse mountain,<ref name="gspp">{{cite journal|url=https://books.google.com/books?id=wRosAQAAIAAJ&pg=PA95|title=Subsidence of the Hawaiian Ridge|author=J.G. Moore|journal=Volcanism in Hawaii: Geological Survey Professional Paper| volume= 1350 |issue= 1|year=1987}}</ref> meaning the total height of Mauna Loa from the start of its eruptive history is about {{convert|17170|m|ft|-3|abbr=on}}.<ref>{{cite web|title=How High is Mauna Loa?|url=http://hvo.wr.usgs.gov/volcanowatch/archive/1998/98_08_20.html|publisher=Hawaiian Volcano Observatory – United States Geological Survey|access-date=February 5, 2013|date=August 20, 1998}}</ref>

{{anchor|Mokuaweoweo}}
[[File:Mauna Loa summit in snow 2016.jpg|thumb|upright=1.36|Snow-covered Moku‘aweoweo caldera in 2016]]
Mauna Loa is a typical [[shield volcano]] in form, taking the shape of a long, broad dome extending down to the ocean floor whose slopes are about 12° at their steepest, a consequence of its extremely fluid lava. The shield-stage lavas that built the enormous main mass of the mountain are [[tholeiitic basalt]]s, like those of [[Mauna Kea]], created through the mixing of primary [[magma]] and [[subduction|subducted]] oceanic crust.<ref>{{cite journal|author=Claude Herzberg| title = Petrology and thermal structure of the Hawaiian plume from Mauna Kea volcano| journal = [[Nature (journal)|Nature]]| publisher = [[Nature Publishing Group]]| volume = 444| issue = 7119| pages = 605–09| date = November 30, 2006| pmid = 17136091| doi = 10.1038/nature05254 |bibcode = 2006Natur.444..605H | s2cid = 4366221}}</ref> Mauna Loa's summit hosts three overlapping [[pit crater]]s arranged northeast–southwest, the first and last roughly {{convert|1|km|mi|1|abbr=on}} in diameter and the second an oblong {{convert|4.2|x|2.5|km|1|abbr=on}} feature; together these three craters make up the {{convert|6.2|by|2.5|km|mi|1|abbr=on}} summit caldera Mokuʻāweoweo,<ref name=hvo-caldera>{{cite web|title=When did Moku'aweoweo (the summit caldera of Mauna Loa) form?|publisher=Hawaiian Volcano Observatory – United States Geological Survey|url=http://hvo.wr.usgs.gov/volcanowatch/archive/2001/01_03_22.html|access-date=December 11, 2012|date=March 28, 2001}}</ref> so named for the Hawaiian ʻāweoweo fish (''[[Priacanthus meeki]]''), purportedly due to the resemblance of its eruptive fires to the coloration of the fish.<ref>{{cite web|title=Place Names of Hawaii – Moku-ʻāweoweo|url=http://www.wehewehe.org/gsdl2.5/cgi-bin/hdict?a=q&r=1&hs=1&e=q-0hdict--00-0-0--010---4----den--0-000lpm--1haw-Zz-1---Zz-1-home---00031-0000escapewin-00&q=mokuaweoweo&j=pp&hdid=0&hdds=0|archive-url=https://archive.today/20121228082508/http://www.wehewehe.org/gsdl2.5/cgi-bin/hdict?a=q&r=1&hs=1&e=q-0hdict--00-0-0--010---4----den--0-000lpm--1haw-Zz-1---Zz-1-home---00031-0000escapewin-00&q=mokuaweoweo&j=pp&hdid=0&hdds=0|url-status=dead|archive-date=December 28, 2012|publisher=Ulukau – Hawaiian Electronic Library|access-date=December 11, 2012}}</ref> Mokuʻāweoweo's caldera floor lies between {{convert|170|and|50|m|0|abbr=on}} beneath its rim and it is only the latest of several calderas that have formed and reformed over the volcano's life. It was created between 1,000 and 1,500 years ago by a large eruption from Mauna Loa's northeast rift zone, which emptied out a shallow [[magma chamber]] beneath the summit and collapsed it into its present form.<ref name=hvo-caldera/> Additionally, two smaller pit craters lie southwest of the caldera, named Lua Hou (New Pit) and Lua Hohonu (Deep Pit).<ref name=nps-loa />

Mauna Loa's summit is also the focal point for its two prominent [[rift zone]]s, marked on the surface by well-preserved, relatively recent lava flows (easily seen in satellite imagery) and linearly arranged [[Fracture (geology)|fracture lines]] intersected by [[cinder cone|cinder]] and [[splatter cone]]s.<ref name=ajs-1980/> These rift zones are deeply set structures, driven by [[dike (geology)|dike]] intrusions along a [[décollement|decollement fault]] that is believed to reach down all the way to the volcano's base, {{convert|12|to|14|km|0|abbr=on}} deep.<ref name=science-stress /> The first is a {{convert|60|km|mi|0|abbr=on}} rift trending southwest from the caldera to the sea and a further {{convert|40|km|mi|0|abbr=on}} underwater, with a prominent 40° directional change along its length; this rift zone is historically active across most of its length. The second, northeastern rift zone extends towards [[Hilo, Hawaii|Hilo]] and is historically active across only the first {{convert|20|km|mi|0|abbr=on}} of its length, with a nearly straight and, in its latter sections, poorly defined trend.<ref name=ajs-1980>{{cite journal|title=The Southwestern Rift Zone of Mauna Kea: Implications for Structural Evolution of Hawaiian Volcanoes|journal=[[American Journal of Science]]|year=1980|volume=280-A|pages=752–76|author=Peter W. Lipman|publisher=American Journal of Science}}</ref> The northeastern rift zone takes the form of a succession of cinder cones, the most prominent of which the {{convert|60|m|ft|0|abbr=on}} high Puu Ulaula, or Red Hill. There is also a less definite northward rift zone that extends towards the Humuula Saddle marking the intersection of Mauna Loa and Mauna Kea.<ref name=nps-loa />

Simplified geophysical models of Mauna Loa's [[magma chamber]] have been constructed, using [[interferometric synthetic aperture radar]] measures of [[Deformation (volcanology)|ground deformation]] due to the slow buildup of lava under the volcano's surface. These models predict a {{convert|1.1|km|mi|0|abbr=on}} wide magma chamber located at a depth of about {{convert|4.7|km|mi|0|abbr=on}}, {{convert|0.5|km|mi|0|abbr=on}} below [[sea level]], near the southeastern margin of Mokuʻāweoweo. This shallow magma chamber is significantly higher-placed than Mauna Loa's rift zones, suggesting magma [[intrusion]]s into the deeper parts and occasional dike injections into the shallower parts of the rift zone drive rift activity; a similar mechanism has been proposed for neighboring [[Kīlauea]].<ref name=science-stress /> Earlier models, based on Mauna Loa's 1975 and 1984 eruptions, made a similar prediction, placing the chamber at {{convert|3|km|mi|1|abbr=on}} deep in roughly the same geographic position.<ref>{{cite web|title=What's up with Mauna Loa?|url=http://hvo.wr.usgs.gov/volcanowatch/archive/2001/01_10_18.html|publisher=Hawaiian Volcano Observatory – United States Geological Survey|access-date=December 16, 2012|date=October 23, 2001|url-status=dead|archive-url=https://web.archive.org/web/20120919133433/https://hvo.wr.usgs.gov/volcanowatch/archive/2001/01_10_18.html|archive-date=September 19, 2012}}</ref>

Mauna Loa has complex interactions with its neighbors, [[Hualālai]] to the northwest, [[Mauna Kea]] to the northeast, and particularly [[Kīlauea]] to the east. Lavas from Mauna Kea intersect with Mauna Loa's basal flows as a consequence of Kea's older age,<ref name="pp1557">{{cite book|author1=E. W. Wolfe|author2=W. S. Wise|author3=G. B. Dalrymple|title=The geology and petrology of Mauna Kea volcano, Hawaii : a study of postshield volcanism|url=https://pubs.er.usgs.gov/djvu/PP/pp_1557.djvu|series=Professional Paper 1557|year=1997|publisher=United States Geological Survey|access-date=December 12, 2012|archive-date=June 15, 2011|archive-url=https://web.archive.org/web/20110615111115/http://http/|url-status=dead}}</ref> and Mauna Kea's original [[rift zone]]s were buried beneath post-shield volcanic rocks of Mauna Loa;<ref name="usgs-database">{{cite web|title=Complete Report for Mauna Kea Volcano (Class B) No. 2601 |url=http://gldims.cr.usgs.gov/webapps/cfusion/sites/qfault/qf_web_disp.cfm?disp_cd=C&qfault_or=5107&ims_cf_cd=cf |publisher=United States Geological Survey |access-date=December 12, 2012 |author1=E. C. Cannon |author2=R. R. Bürgmann |name-list-style=amp |date=October 26, 2009 |url-status=dead |archive-url=https://web.archive.org/web/20120305184251/http://gldims.cr.usgs.gov/webapps/cfusion/sites/qfault/qf_web_disp.cfm?disp_cd=C&qfault_or=5107&ims_cf_cd=cf |archive-date=March 5, 2012}}</ref> additionally, Mauna Kea shares Mauna Loa's gravity well, depressing the [[oceanic lithosphere|ocean crust]] beneath it by {{convert|6|km|mi|0|abbr=on}}.<ref name="pp1557"/>  There are also a series of [[normal fault]]s on Mauna Loa's northern and western slopes, between its two major rift zones, that are believed to be the result of combined circumferential tension from the two rift zones and from added pressure due to the westward growth of neighboring Kīlauea.<ref name=osu-rifts>{{cite web|title=Rift Zones|url=http://volcano.oregonstate.edu/book/export/html/124|publisher=[[Oregon State University]]|access-date=December 13, 2012}}</ref>

[[File:Volcano in Moonlight.jpg|thumb|right|upright=1.6|Captured from Maunakea, this Image features a skyscape of Mauna Loa.<ref>{{cite news|title=Volcano in Moonlight|url=https://noirlab.edu/public/images/iotw2234a/?nocache=true|access-date=26 December 2022|newspaper=NOIRLab}}</ref>]]
Because Kīlauea lacks [[topographical prominence]] and appears as a bulge on the southeastern flank of Mauna Loa, it was historically interpreted by both native Hawaiians and early geologists to be an active satellite of Mauna Loa. However, analysis of the chemical composition of lavas from the two volcanoes show that they have separate [[magma chamber]]s, and are thus distinct. Nonetheless, their proximity has led to a historical trend in which high activity at one volcano roughly coincides with low activity at the other. When Kīlauea lay dormant between 1934 and 1952, Mauna Loa became active, and when the latter remained quiet from 1952 to 1974, the reverse was true. This is not always the case; the [[1984 eruption of Mauna Loa]] started during an eruption at Kīlauea, but had no discernible effect on the Kīlauea eruption, and the [[2022 eruption of Mauna Loa]] occurred during an eruption of Kīlauea. Geologists have suggested that "pulses" of magma entering Mauna Loa's deeper magma system may have increased pressure inside Kīlauea and triggered the concurrent eruptions.<ref name="hvo-loa_kilauea">{{cite web|title=Inflation of Mauna Loa Volcano slows|publisher=Hawaiian Volcano Observatory – United States Geological Survey|work=Volcano Watch|date=January 28, 2003|url=http://hvo.wr.usgs.gov/volcanowatch/2003/03_01_23.html|access-date=January 30, 2012}}</ref>

Mauna Loa is slumping eastward along its southwestern rift zone, leveraging its mass into Kīlauea and driving the latter eastward at a rate of about {{convert|10|cm|in|0|abbr=on}} per year; the interaction between the two volcanoes in this manner has generated a number of large earthquakes in the past, and has resulted in a significant area of debris off Kīlauea's seaward flank known as the [[Hilina Slump]]. A system of older faults exists on the southeastern side of Mauna Loa that likely formed before Kilauea became large enough to impede Mauna Loa's slump, the lowest and northernmost of which, the Kaoiki fault, remains an active earthquake center today. The west side of Mauna Loa, meanwhile, is unimpeded in movement, and indeed is believed to have undergone a massive slump collapse between 100,000 and 200,000 years ago, the residue from which, consisting of a scattering of debris up to several kilometers wide and up to {{convert|50|km|mi|0|abbr=on}} distant, is still visible today. The damage was so extensive that the headwall of the damage likely intersected its southwestern rift zone. There is very little movement there today, a consequence of the volcano's geometry.<ref name="uh-landslides">{{cite web |author=Ken Hon |author-link=Ken Hon |title=Giant Landslides: Kilauea and Mauna Loa: GEOL 205: Lecture Notes |url=http://hilo.hawaii.edu/~kenhon/GEOL205/Landslides/default.htm |access-date=December 16, 2012 |publisher=[[University of Hawaii at Hilo]]}}</ref>

[[File:Mauna Loa taken from the 9300 ft level on the ascent of Mauna Kea.JPG|thumb|right|upright=1.6|A view of Mauna Loa taken from a hill near The Onizuka Center for International Astronomy Visitor Information Station at the {{convert|9,300|ft|m|abbr=on}} level of Mauna Kea.]]
Mauna Loa is tall enough to have experienced [[glaciation]] during the last ice age, 25,000 to 15,000 years ago.<ref name=usgs-map /> Unlike Mauna Kea, on which extensive evidence of glaciation remains even today,<ref>{{cite web|url=http://hvo.wr.usgs.gov/volcanowatch/archive/2001/01_10_18.html|title=Glaciers on Mauna Kea? You crazy? In the middle of the Pacific? YES!|publisher=Hawaiian Volcano Observatory – United States Geological Survey|access-date=December 16, 2012|date=October 22, 2007}}</ref> Mauna Loa was at the time and has remained active, having grown an additional {{convert|150|to|300|m|ft|0|abbr=on}} in height since then and covering any glacial deposits beneath new flows; strata of that age don't occur until at least {{convert|2000|m|ft|0|abbr=on}} down from the volcano's summit, too low for glacial growth. Mauna Loa also lacks its neighbor's summit [[permafrost]] region, although sporadic ice persists in places. It is speculated that extensive [[phreatomagmatic eruption|phreatomagmatic]] activity occurred during this time, contributing extensively to [[volcanic ash|ash]] deposits on the summit.<ref name=usgs-map />
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