Editing Mauna Loa (section)

===Monitoring===
{{multiple image
| align     = right
| direction = horizontal
| image1    = Mauna Loa Summit Monitoring.jpg
| width1    = 205
| caption1  = [[GPS]] stations, [[tiltmeter]]s, and [[strainmeter]]s on Mauna Loa's summit. Not shown: a [[webcam]] and a [[gas detector]] positioned on the caldera rim.
| image2    = Mauna Loa Summit Inflation.jpg
| width2     = 225
| caption2  = Summit inflation as measured via [[GPS]] between June 2004 and April 2005; arrows denote between {{convert|1|and|10|cm|in|1|abbr=on}} of growth.
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Established on Kīlauea in 1912, the Hawaiian Volcano Observatory (HVO), presently a branch of the United States Geological Survey, is the primary organization associated with the monitoring, observance, and study of Hawaiian volcanoes.<ref name=hvo-hist-intro>{{cite web|title=Thomas A. Jaggar, Jr., and the Hawaiian Volcano Observatory|url=http://hvo.wr.usgs.gov/observatory/hvo_history.html|publisher=Hawaiian Volcano Observatory – United States Geological Survey|access-date=January 26, 2013|author=Russell A. Apple|date=January 4, 2005|archive-date=June 14, 2009|archive-url=https://web.archive.org/web/20090614054515/http://hvo.wr.usgs.gov/observatory/hvo_history.html|url-status=dead}}</ref> [[Thomas A. Jaggar]], the Observatory's founder, attempted a summit expedition to Mauna Loa to observe its 1914 eruption, but was rebuffed by the arduous trek required (see [[#Ascents|Ascents]]). After soliciting help from [[Lorrin A. Thurston]], in 1915 he was able to persuade the [[US Army]] to construct a "simple route to the summit" for public and scientific use, a project completed in December of that year; the Observatory has maintained a presence on the volcano ever since.<ref name=hvo-hist-loa>{{cite web|title=Mauna Loa|url=http://hvo.wr.usgs.gov/observatory/hvo_history_mloa.html|publisher=Hawaiian Volcano Observatory – United States Geological Survey|access-date=January 26, 2013|author=Russell A. Apple}}</ref>

Eruptions on Mauna Loa are almost always preceded and accompanied by prolonged episodes of seismic activity, the monitoring of which was the primary and often only warning mechanism in the past and which remains viable today. [[Seismograph|Seismic stations]] have been maintained on Hawaiʻi since the Observatory's inception, but these were concentrated primarily on Kīlauea, with coverage on Mauna Loa improving only slowly through the 20th century.<ref name=hvo-seismic>{{cite web|title=HVO Seismic Network|url=http://hvo.wr.usgs.gov/earthquakes/history/|publisher=Hawaiian Volcano Observatory – United States Geological Survey|access-date=January 26, 2013|date=June 18, 2001}}</ref> Following the invention of modern monitoring equipment, the backbone of the present-day monitoring system was installed on the volcano in the 1970s. Mauna Loa's July 1975 eruption was forewarned by more than a year of seismic unrest, with the HVO issuing warnings to the general public from late 1974; the 1984 eruption was similarly preceded by as much as three years of unusually high seismic activity, with [[volcanologist]]s predicting an eruption within two years in 1983.<ref name=hov-monitoring_data>{{cite web|title=Long-term Monitoring Data|url=http://hvo.wr.usgs.gov/maunaloa/current/monitoringdata.php|publisher=Hawaiian Volcano Observatory – United States Geological Survey|access-date=January 26, 2013|archive-date=February 17, 2013|archive-url=https://web.archive.org/web/20130217012832/http://hvo.wr.usgs.gov/maunaloa/current/monitoringdata.php|url-status=dead}}</ref>

The modern monitoring system on Mauna Loa consists not only of its local seismic network but also of a large number of [[GPS]] stations, [[tiltmeter]]s, and [[strainmeter]]s that have been anchored on the volcano to monitor [[Deformation (volcanology)|ground deformation]] due to swelling of Mauna Loa's subterranean [[magma chamber]], which presents a more complete picture of the events proceeding eruptive activity. The GPS network is the most durable and wide-ranging of the three systems, while the tiltmeters provide the most sensitive predictive data, but are prone to erroneous results unrelated to actual ground deformation; nonetheless a survey line across the caldera measured a {{convert|76|mm|in|0|abbr=on}} increase in its width over the year preceding the 1975 eruption, and a similar increase in 1984 eruption. Strainmeters, by contrast, are relatively rare.<ref name=hvo-monitoring_current>{{cite web|title=Mauna Loa Volcano, Hawai'i : Current Monitoring|url=http://hvo.wr.usgs.gov/maunaloa/current/currentmonitoring.php|publisher=Hawaiian Volcano Observatory – United States Geological Survey|access-date=January 26, 2013|archive-date=February 17, 2013|archive-url=https://web.archive.org/web/20130217005623/http://hvo.wr.usgs.gov/maunaloa/current/currentmonitoring.php|url-status=dead}}</ref> The Observatory also maintains two [[gas detector]]s at Mokuʻāweoweo, Mauna Loa's summit caldera, as well as a publicly accessible [http://hvo.wr.usgs.gov/cams/panorama.php?cam=MLcam live webcam] and occasional screenings by [[interferometric synthetic aperture radar]] imaging.<ref name=hov-monitoring_data/>