Editing Mauna Loa (section)

===Hazards===
Mauna Loa has been designated a [[Decade Volcano]], one of the sixteen volcanoes identified by the [[International Association of Volcanology and Chemistry of the Earth's Interior]] (IAVCEI) as being worthy of particular study in light of their history of large, destructive eruptions and proximity to populated areas.<ref>{{cite web|url=http://vulcan.wr.usgs.gov/Volcanoes/DecadeVolcanoes/|title=Decade Volcanoes|work=[[Cascades Volcano Observatory]]|author=International Association of Volcanology and Chemistry of the Earth's Interior|publisher=United States Geological Survey|year=1998|access-date=January 25, 2013|author-link=International Association of Volcanology and Chemistry of the Earth's Interior}}</ref><ref>{{cite web|title=Decade Volcano Program IDNDR – IAVCEI – 1990/2000|url=http://www.sveurop.org/gb/program/program.htm|publisher=Société Volcanologique Européenne|author=Nick Varley|access-date=January 25, 2013}}</ref> The United States Geological Survey maintains a [[Lava Flow Hazard Zones|hazard zone mapping]] of the island done on a one to nine scale, with the most dangerous areas corresponding the smallest numbers. Based on this classification Mauna Loa's continuously active summit caldera and rift zones have been given a level one designation. Much of the area immediately surrounding the rift zones is considered level two, and about 20 percent of the area has been covered in lava in historical times. Much of the remainder of the volcano is hazard level three, about 15 to 20 percent of which has been covered by flows within the last 750 years. However, two sections of the volcano, the first in the [[Naalehu, Hawaii|Naalehu]] area and the second on the southeastern flank of Mauna Loa's rift zone, are protected from eruptive activity by local topography, and have thus been designated hazard level 6, comparable with a similarly isolated segment on [[Kīlauea]].<ref name="usgs-hazard" />

Although volcanic eruptions in Hawaiʻi rarely produce casualties (the only direct historical fatality due to volcanic activity on the island occurred at Kīlauea in 1924, when an unusually explosive eruption hurled rocks at an onlooker), property damage due to inundation by lava is a common and costly hazard.<ref name="usgs-hazard_all">{{cite web | author = John Watson | title = Volcanic and seismic hazards on the island of Hawaii | publisher = United States Geological Survey | url = http://pubs.usgs.gov/gip/hazards/hazards.html | date = July 18, 1997 | access-date = January 25, 2013 | archive-date = January 15, 2013 | archive-url = https://web.archive.org/web/20130115203420/http://pubs.usgs.gov/gip/hazards/hazards.html | url-status = dead}}</ref> [[Hawaiian eruption|Hawaiian]]-type eruptions usually produce extremely slow-moving flows that advance at walking pace, presenting little danger to human life, but this is not strictly the case;<ref>{{cite web|title=How Volcanoes Work: Hawaiian Eruptions|url=http://www.geology.sdsu.edu/how_volcanoes_work/Hawaiian.html|publisher=[[San Diego State University]]|access-date=January 25, 2013}}</ref> Mauna Loa's 1950 eruption emitted as much lava in three weeks as Kīlauea's [[Kīlauea#1983–2018|recent eruption]] produced in three years and reached sea level within four hours of its start, overrunning the village of Hoʻokena Mauka and a major highway on the way there.<ref name=hvo-1950 /> An earlier eruption in 1926 overran the village of Hoʻōpūloa Makai,<ref name="hvo-1926" /> and [[Hilo, Hawaii|Hilo]], partly built on lavas from the 1880–81 eruption, is at risk from future eruptions.<ref name=usgs-hazard/> The 1984 eruption nearly reached the city, but stopped short after the flow was redirected by upstream topography.<ref name="usgs-loa_hazards">{{cite web | url = http://hvo.wr.usgs.gov/maunaloa/hazards/main.html | title = Lava flow hazards on Mauna Loa volcano | publisher = Hawaiian Volcano Observatory – United States Geological Survey | date = February 2, 2006 | access-date = January 25, 2013}}</ref>

A potentially greater hazard at Mauna Loa is a sudden, massive collapse of the volcano's flanks, like the one that struck the volcano's west flank between 100,000 and 200,000 years ago and formed the present-day [[Kealakekua Bay]].<ref name=uh-landslides/> Deep [[Fault (geology)|fault lines]] are a common feature on Hawaiian volcanoes, allowing large portions of their flanks to gradually slide downwards and forming structures like the [[Hilina Slump]] and the ancient [[Ninole Hills]]; large earthquakes could trigger rapid flank collapses along these lines, creating massive [[volcanic landslide|landslides]] and possibly triggering equally large [[tsunami]]s. Undersea surveys have revealed numerous landslides along the Hawaiian chain and evidence of two such giant tsunami events: 200,000&nbsp;years ago, [[Molokai|Molokaʻi]] experienced a {{convert|75|m|ft|0|abbr=on}} tsunami, and 100,000&nbsp;years ago a [[megatsunami]] {{convert|325|m|ft|0|abbr=on}} high struck [[Lanai|Lānaʻi]].<ref name="Decker">{{Cite book|author=Robert and Barbara Decker|title=Volcanoes|url=https://archive.org/details/volcanoes00deck_0|url-access=registration|year=1997|publisher=W.H. Freeman & Co, Ltd|location=New York|isbn=978-0-7167-3174-0|edition=3rd}}</ref> A more recent example of the risks associated with slumps occurred in [[1975 Hawaii earthquake|1975]], when the Hilina Slump suddenly lurched forward several meters, triggering a 7.2 {{M|w}} earthquake and a {{convert|14|m|abbr=on}} tsunami that killed two campers at Halape.<ref>{{cite journal|title=Shallow Normal Faulting and Block Rotation Associated with the 1975 Kalapana Earthquake, Kilauea'|journal=[[Bulletin of the Seismological Society of America]]|year=2001|volume=91|issue=6|page=1553|doi=10.1785/0120000072|author1=Cannon, Eric C.|author2=Bürgmann, Roland|author3=Owen, Susan E.|publisher=[[Seismological Society of America]]|bibcode = 2001BuSSA..91.1553C}}</ref>