Editing Mauna Loa (section)

=== Recent history ===
[[File:Aa channel flow from Mauna Loa.jpg|thumb|Lava fountains and [[Lava#ʻAʻā|a'a]] channel flow from Mauna Loa, 1984]]
[[Ancient Hawaii]]ans have been present on Hawaiʻi island for about 1,500 years, but they preserved almost no records on volcanic activity on the island, beyond a few fragmentary accounts dating to the late 18th and early 19th centuries.<ref name=hvo-erupthist>{{cite web|title=Summary of Historical Eruptions, 1843–Present|url=http://hvo.wr.usgs.gov/maunaloa/history/historytable.html|publisher=Hawaiian Volcano Observatory – United States Geological Survey|access-date=January 24, 2013|date=September 17, 2004|archive-date=August 13, 2007|archive-url=https://web.archive.org/web/20070813100729/http://hvo.wr.usgs.gov/maunaloa/history/historytable.html|url-status=dead}}</ref>  Possible eruptions occurred around 1730 and 1750 and sometime during 1780<!-- according to a travel guide on the Wilkes expedition -  see the SOEST eruptive history reference --> and 1803.<ref>{{cite gvp|title=Mauna Loa: Eruptive History|vn=332020|vtab=Eruptions|access-date=January 24, 2013}}</ref> A June 1832 eruption was witnessed by a missionary on [[Maui]], but the {{convert|190|km|mi|0|abbr=on}} between the two islands and lack of apparent geological evidence have cast this testimony in doubt. Thus the first entirely confirmed historically witnessed eruption was a January 1843 event; since that time Mauna Loa has erupted 32 times.<ref name=hvo-erupthist />

Historical eruptions at Mauna Loa are typically [[Hawaiian eruption|Hawaiian]] in character and rarely violent, starting with the emergence of [[lava fountain]]s over a several kilometer long [[rift]] colloquially known as the "curtain of fire" (often, but not always, propagating from Mauna Loa's summit<ref name=science-stress>{{cite journal|title=Stress Control of Deep Rift Intrusion at Mauna Loa Volcano, Hawaii|journal=[[Science (journal)|Science]]|date=May 18, 2007|volume=316|issue=5827|pages=1026–30|doi =10.1126/science.1140035|first1=F.|last1=Amelung|first2 =S.H.|last2=Yun|first3 =T.R.|last3 =Walter|first4 =P.|last4 =Segall|first5 =S.W.|last5 =Kim|publisher=[[American Association for the Advancement of Science]]|bibcode = 2007Sci...316.1026A |pmid=17510364|s2cid=39726145}}</ref>) and eventually concentrating at a single vent, its long-term eruptive center.<ref name=nps-loa/><ref name=ajs-1980 /> Activity centered on its summit is usually followed by flank eruptions up to a few months later,<ref name=hvo-hist-loa /> and although Mauna Loa is historically less active than that of its neighbor Kilauea, it tends to produce greater volumes of lava over shorter periods of time.<ref name=usgs-hazard/> Most eruptions are centered at either the summit or either of its two major [[rift zone]]s; within the last two hundred years, 38 percent of eruptions occurred at the summit, 31 percent at the northeast rift zone, 25 percent at the southwest rift zone, and the remaining 6 percent from northwest vents.<ref name=soest-erupt>{{cite web|title=Mauna Loa Eruption History|url=http://www.soest.hawaii.edu/GG/HCV/mloa-eruptions.html|publisher=[[Hawaii Center for Volcanology]]|access-date=December 12, 2012|author1=Rubin, Ken|author2=Minicola, Rochelle|date=March 7, 2007}}</ref> 40 percent of the volcano's surface consists of lavas less than a thousand years old,<ref name=usgs-hazard>{{cite web|title=Lava Flow Hazard Zone Maps: Mauna Loa|url=http://pubs.usgs.gov/gip/hazards/mauna-loa.html|publisher=United States Geological Survey|access-date=December 12, 2012|author=John Watson|date=July 18, 1997|url-status=dead|archive-url=https://web.archive.org/web/20130115203408/http://pubs.usgs.gov/gip/hazards/mauna-loa.html|archive-date=January 15, 2013}}</ref> and 98 percent of lavas less than 10,000 years old.<ref name=hvo-erupt>{{cite web|title=Eruption History|url=http://hvo.wr.usgs.gov/maunaloa/history/main.html|publisher=Hawaiian Volcano Observatory – United States Geological Survey|access-date=December 16, 2012|date=February 2, 2006|archive-date=August 19, 2007|archive-url=https://web.archive.org/web/20070819083329/http://hvo.wr.usgs.gov/maunaloa/history/main.html|url-status=dead}}</ref> In addition to the summit and rift zones, Mauna Loa's northwestern flank has also been the source of three historical eruptions.<ref name=usgs-hazard/>

The 1843 event was followed by eruptions in 1849, 1851, 1852, and 1855,<ref name=hvo-erupthist /> with the 1855 flows being particularly extensive.<ref name=soest-erupt /> 1859 marked the largest of the three historical flows that have been centered on Mauna Loa's northwestern flank, producing a long lava flow that reached the ocean on Hawaii island's west coast, north of [[Kiholo bay|Kīholo Bay]].<ref name=usgs-hazard/> An eruption in 1868 occurred alongside the enormous [[1868 Hawaii earthquake]],<ref name=soest-erupt /> a [[moment magnitude|magnitude]] eight event that claimed 77 lives and remains the largest earthquake ever to hit the island.<ref>{{cite web|title=The Great Ka'u Earthquake of 1868|url=http://hvo.wr.usgs.gov/volcanowatch/archive/1994/94_04_01.html|publisher=Hawaiian Volcano Observatory – United States Geological Survey|access-date=January 24, 2013|date=March 26, 1998}}</ref> Following further activity in 1871, Mauna Loa experienced nearly continuous activity from August 1872 through 1877, a long-lasting and voluminous eruption lasting approximately 1,200 days and never moving beyond its summit.<ref name=hvo-erupthist /><ref>{{cite web|title=Eruptions of Hawaiian Volcanoes|url=http://pubs.usgs.gov/gip/hawaii/page15.html|publisher=United States Geological Survey|access-date=January 24, 2013|date=January 5, 1997}}</ref><ref name=hvo-1950>{{cite web|title=50th Anniversary of Mauna Loa's Most Spectacular Eruption|url=http://hvo.wr.usgs.gov/maunaloa/history/50_06_01/|publisher=Hawaiian Volcano Observatory – United States Geological Survey|access-date=January 24, 2013|date=September 17, 2004|archive-date=January 30, 2013|archive-url=https://web.archive.org/web/20130130173304/http://hvo.wr.usgs.gov/maunaloa/history/50_06_01/|url-status=dead}}</ref> A short single-day eruption in 1877 was unusual in that it took place underwater, in [[Kealakekua Bay]], and within a mile of the shoreline; curious onlookers approaching the area in boats reported unusually turbulent water and occasional floating blocks of hardened lava.<ref name=usgs-hazard/> Further eruptions occurred in 1879 and then twice in 1880,<ref name=hvo-erupthist /> the latter of which extended into 1881 and came within the present boundaries of the island's largest city, [[Hilo]]; however, at the time, the settlement was a shore-side village located further down the volcano's slope, and so was unaffected.<ref name=soest-erupt /><ref name=usgs-hazard/><ref>{{Cite book|url=https://books.google.com/books?id=YIE9AQAAIAAJ&q=carbonic+oxide|title=Scientific American|date=August 13, 1881|publisher=Munn & Company|pages=106|language=en}}</ref>

<imagemap>
File:Hawaii Volcanoes Hazard Map.svg|thumb|right|275px|Clickable imagemap of the United States Geological Survey [[Lava Flow Hazard Zones|hazard mapping]] for Hawaii island; the lowest numbers correspond with the highest hazard levels.

poly 25 186 49 180 73 150 54 108 36 100 24 104 5 123 3 137 22 164 [[Hualalai]]
poly 54 64 99 63 113 40 78 23 74 12 46 5 37 21 41 44 [[Kohala (mountain)|Kohala]]
poly 247 157 236 157 203 198 172 202 149 230 128 277 173 250 193 248 249 226 287 186 259 173 [[Kilauea]]
poly 56 65 99 64 116 38 188 66 224 103 221 134 194 140 139 143 93 123 60 92 53 79 [[Mauna Kea]]

desc bottom-left
</imagemap>

Mauna Loa continued its activity, and of the eruptions that occurred in 1887, 1892, 1896, 1899, 1903 (twice), 1907, 1914, 1916, 1919, and 1926,<ref name=hvo-erupthist /> three (in 1887, 1919, and 1926) were partially [[subaerial]].<ref name=soest-erupt /> The 1926 eruption in particular is noteworthy for having inundated a village near Ho{{okina}}ōpūloa, destroying 12 houses, a church, and a small harbor.<ref name="hvo-1926">{{cite web|title=The Mauna Loa Eruption of 1926|url=http://hvo.wr.usgs.gov/volcanowatch/archive/1995/95_04_07.html|publisher=Hawaiian Volcano Observatory – United States Geological Survey|access-date=January 26, 2013|date=March 26, 1998}}</ref> After an event in 1933, Mauna Loa's 1935 eruption caused a public crisis when its flows started to head towards Hilo.<ref name=hvo-erupthist /> A bombing operation was decided upon to try and divert the flows, planned out by then-[[lieutenant colonel]] [[George S. Patton]]. The bombing, conducted on December 27, was declared a success by [[Thomas A. Jaggar]], director of the Hawaiian Volcano Observatory, and lava stopped flowing by January 2, 1936. However, the role the bombing played in ending the eruption has since been heavily disputed by volcanologists.<ref>{{cite web|title=Lava diversion in Hawai'i?|url=http://hvo.wr.usgs.gov/volcanowatch/archive/1997/97_11_28.html|publisher=Hawaiian Volcano Observatory – United States Geological Survey|access-date=January 24, 2013}}</ref> A longer but summit-bound event in 1940 was comparatively less interesting.<ref name=hvo-erupthist />

Mauna Loa's 1942 eruption occurred only four months after the [[attack on Pearl Harbor]] and the United States' entry into [[World War II]], and created a unique problem for the wartime United States. Occurring during an enforced nighttime [[Blackout (wartime)|blackout]] on the island, the eruption's luminosity forced the government to issue a [[gag order]] on the local press, hoping to prevent news of its occurrence spreading, for fear that the Japanese would use it to launch a bombing run on the island. However, as flows from the eruption rapidly spread down the volcano's flank and threatened the ʻOlaʻa [[flume]], [[Mountain View, Hawaii|Mountain View]]'s primary [[water source]], the [[United States Army Air Forces|United States Army Air Force]] decided to drop its own bombs on the island in the hopes of redirecting the flows away from the flume; sixteen bombs weighing between {{convert|300|and|600|lb|kg|0|abbr=on}} each were dropped on the island, but produced little effect. Eventually, the eruption ceased on its own.<ref>{{cite web|title=Shhh! Don't tell there is an eruption – Eruption of 1942|url=https://volcanoes.usgs.gov/observatories/hvo/hvo_volcano_watch.html?vwid=970|publisher=Hawaiian Volcano Observatory – United States Geological Survey|access-date=January 24, 2013|date=April 27, 1998}}</ref>

Following a 1949 event, the next major eruption at Mauna Loa occurred in 1950. Originating from the volcano's southwestern rift zone, the eruption remains the largest rift event in the volcano's modern history, lasting 23 days, emitting 376&nbsp;million cubic meters of lava, and reaching the {{convert|24|km|mi|0|abbr=on}} distant ocean within 3 hours. The 1950 eruption was not the most voluminous eruption on the volcano (the long-lived 1872–1877 event produced more than twice as much material), but it was easily one of the fastest-acting, producing the same amount of lava as the 1859 eruption in a tenth of the time.<ref name=hvo-1950/> Flows overtook the village of Hoʻokena-mauka in [[South Kona, Hawaii|South Kona]], crossed [[Hawaii Belt Road|Hawaii Route 11]], and reached the sea within four hours of eruption. Although there was no loss of life, the village was permanently destroyed.<ref>{{cite web|title=The 1950 eruption of Mauna Loa: a nightmare that could reoccur|url=https://www.usgs.gov/center-news/volcano-watch-1950-eruption-mauna-loa-a-nightmare-could-reoccur|publisher=Hawaiian Volcano Observatory – United States Geological Survey|access-date=February 2, 2021|date=May 14, 2001}}</ref> After the 1950 event, Mauna Loa entered an extended period of dormancy, interrupted only by a [[1975 eruption of Mauna Loa|small single-day summit event in 1975]]. However, it rumbled to life again in 1984, manifesting first at Mauna Loa's summit, and then producing a narrow, channelized [['a'a|ʻaʻā]] flow that advanced downslope within {{convert|6|km|mi|0|abbr=on}} of Hilo, close enough to illuminate the city at nighttime. However, the flow got no closer, as two natural levees further up its pathway consequently broke and diverted active flows.<ref>{{cite web|title=The Mauna Loa Eruption of 1984|url=http://hvo.wr.usgs.gov/volcanowatch/archive/1994/94_03_25.html|publisher=Hawaiian Volcano Observatory – United States Geological Survey|access-date=January 24, 2013|date=March 26, 1998}}</ref><ref>{{cite web|title=1984 Eruption: March 25 – April 15|url=http://hvo.wr.usgs.gov/maunaloa/history/1984.html|publisher=Hawaiian Volcano Observatory – United States Geological Survey|date=September 17, 2004|access-date=January 24, 2013|archive-date=January 31, 2013|archive-url=https://web.archive.org/web/20130131132038/http://hvo.wr.usgs.gov/maunaloa/history/1984.html|url-status=dead}}</ref>

From 1985 to 2022, the volcano had its longest period of quiet in recorded history.<ref name=hvo-erupthist/><ref name="npsbrochure">{{cite web |author-link1=Gordon A. Macdonald |author1=Gordon A. Macdonald |author2=Douglass H. Hubbard |title=Volcanoes of the National Parks of Hawaii |url=http://www.nps.gov/history/history/online_books/hawaii-notes/vol4-2-7d.htm |publisher=[[National Park Service]] |date=March 24, 2006 |access-date=January 24, 2013}}</ref> Magma had been accumulating beneath Mauna Loa since the 1984 eruption, and the U.S. Geological Survey in February 2021 reported that although an eruption "did not appear to be imminent," the volcano had shown elevated signs of unrest since 2019, including a slight increase in the rate of inflation at the volcano's summit.<ref>{{cite web |title=Volcano Watch — When will Mauna Loa erupt next? |url=https://www.usgs.gov/observatories/hvo/news/volcano-watch-when-will-mauna-loa-erupt-next |website=U.S. Geological Survey |date=February 25, 2021}}</ref>

The quiet period ended at 11:30&nbsp;pm [[Hawaii–Aleutian Time Zone|HST]] on November 27, 2022, when [[2022 eruption of Mauna Loa|an eruption]] began at the volcano's summit in Moku‘āweoweo (Mauna Loa's caldera).<ref name=hvo-loa-2022/> Lava flows emanating from the caldera became visible from [[Kailua-Kona]] in the hours immediately following the eruption. The eruption remained confined to the caldera until approximately 6:30&nbsp;am HST on November 28, when the Hawaiian Volcano Observatory observed that the eruption had migrated from the summit to the Northeast Rift Zone.<ref>{{Cite web |title=HAWAIIAN VOLCANO OBSERVATORY VOLCANO OBSERVATORY NOTICE FOR AVIATION Monday, November 28, 2022, 17:20 UTC USGS Hazard Notification System (HANS) for Volcanoes |url=https://volcanoes.usgs.gov/hans2/view/notice/DOI-USGS-HVO-2022-11-28T09:00:26-08:00 |access-date=2022-11-29 |website=volcanoes.usgs.gov}}</ref> Three fissures were initially observed in the rift zone, with the first two becoming inactive by 1:30 PM on the 28th. Before becoming inactive, the two upper fissures fed lava flows that moved downslope, however those flows stalled approximately {{convert|11|mi|km}} from [[Saddle Road]]. [[Lava|Lava fountains]] were also observed emanating from the fissures, with the tallest reaching up to {{convert|200|ft|m}} into the air.<ref>{{Cite web |title=HAWAIIAN VOLCANO OBSERVATORY STATUS REPORT Tuesday, November 29, 2022, 02:55 UTC USGS Hazard Notification System (HANS) for Volcanoes |url=https://volcanoes.usgs.gov/hans2/view/notice/DOI-USGS-HVO-2022-11-28T18:29:33-08:00 |access-date=2022-11-30 |website=volcanoes.usgs.gov}}</ref> As lava flows from the third fissure expanded, they cut off the road to the [[Mauna Loa Observatory]] at approximately 8&nbsp;pm on the 28th. Activity in the rift zone continued on the 29th, with a fourth fissure that opened at approximately 7:30&nbsp;pm on the 28th joining the third in releasing lava flows. The main front of the third fissure's lava flows also continued to move, and was located approximately {{convert|2.7|mi|km}} from Saddle Road at 7&nbsp;am on December 2. 

As the eruption approached its second week, indications of a reduction in activity began to appear. On December 8, the lava flows feeding the main front began to drain, and the main flow front stalled approximately {{convert|1.7|mi|km}} from Saddle Road. The flows continued to drain on the 9th, and the third fissure's lava fountains also began to grow shorter. On the 10th, the lava fountains were replaced by a lava pond, and the stalled flow front was declared to no longer be a threat. Based on these factors and data on past eruptions, the HVO determined that the eruption may end soon and reduced the [[Volcano warning schemes of the United States|volcano alert level]] from Warning to Watch at 2:35&nbsp;pm on the 10th. However, there was a small possibility that the eruption would continue at a very low rate.<ref>{{Cite web |title=HAWAIIAN VOLCANO OBSERVATORY VOLCANO ACTIVITY NOTIFICATION Sunday, December 11, 2022, 00:35 UTC USGS Hazard Notification System (HANS) for Volcanoes |url=https://volcanoes.usgs.gov/hans2/view/notice/DOI-USGS-HVO-2022-12-10T16:24:56-08:00 |access-date=2022-12-11 |website=volcanoes.usgs.gov}}</ref> The eruption officially ended at 7:17&nbsp;am on the 13th, and the HVO lowered the volcano alert level to Advisory.<ref>{{Cite web |title=HAWAIIAN VOLCANO OBSERVATORY VOLCANO OBSERVATORY NOTICE FOR AVIATION Tuesday, December 13, 2022, 17:17 UTC USGS Hazard Notification System (HANS) for Volcanoes |url=https://volcanoes.usgs.gov/hans2/view/notice/DOI-USGS-HVO-2022-12-13T08:57:10-08:00 |access-date=2022-12-16 |website=volcanoes.usgs.gov}}</ref>