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. The United States Geological Survey maintains a 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.
Hazards
Mauna Loa
Mauna Loa | Hazards
It is a sudden, massive collapse of the volcano's flanks,  large earthquakes could trigger rapid flank collapses along these lines, creating massive landslides and possibly triggering equally large tsunamis. Large earthquakes could trigger rapid flank collapses along these lines, creating massive landslides and possibly triggering equally large tsunamis. It 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 A potentially greater hazard 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.
when was the last time mauna loa volcano erupted
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March 24 to April 15, 1984.
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what is the main entity?
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It is one of five volcanoes that form the Island of Hawaii in the U.S. state of Hawaiʻi in the Pacific Ocean.
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what is its weather like?
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It has a tropical climate with warm temperatures at lower elevations and cool to cold temperatures higher up year-round.
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who monitors this volcano?
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The Hawaiian Volcano Observatory, a branch of the United States Geological Survey.
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who founded it ?
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Thomas A. Jaggar.
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where is it located?
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A temporary offices located in Hilo on the Island of Hawaii.
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mention few volcanoes it monitors?
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Kīlauea, Mauna Loa, Hualālai, and Haleakalā.
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name few dangers of the second?
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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 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. 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.
Mauna Loa | Hazards
Hualālai is expected to erupt again in the near future, as a 200- to 300-year estimated pause in activity is coming to an end. This presents a distinct hazard to the communities around it as well; for example, in the event of an eruption similar to the 1801 event, Kailua-Kona, which is from the volcano's summit, could be covered completely in a matter of hours. According to the USGS lava-flow hazard zones, on a scale of 1 to 9, all of Hualālai is listed as threat level 4. For comparison, almost all of Kīlauea and Mauna Loa is listed as threat levels 1 through 3.
Hualālai | Future monitoring
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. Deep 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 landslides and possibly triggering equally large tsunamis. Undersea surveys have revealed numerous landslides along the Hawaiian chain and evidence of two such giant tsunami events: 200,000 years ago, Molokaʻi experienced a tsunami, and 100,000 years ago a megatsunami high struck Lānaʻi.
Mauna Loa | Hazards
In 2018, the United States Geological Survey National Volcanic Threat Assessment gave Kīlauea an overall threat score of 263, and ranked it first among volcanoes in the United States most likely to threaten lives and infrastructure. In June 2019, readings from USGS instruments indicated that Kīlauea's shallow summit magma chamber was slowly refilling with magma. The presence of the new water lake in Halemaʻumaʻu means that Kīlauea's next summit eruption could be explosive, if magma rises rapidly to the surface. However, this is uncertain, as there is plenty of underground water present at Kīlauea's summit, and yet, the volcano did not experience any explosive eruptions over the past century.
Kīlauea | Future threats
No recent eruptions of the volcano have caused fatalities, but eruptions in 1926 and 1950 destroyed villages, and the city of Hilo is partly built on lava flows from the late 19th century. Because of the potential hazards it poses to population centers, Mauna Loa is part of the Decade Volcanoes program, which encourages studies of the world's most dangerous volcanoes. Mauna Loa has been monitored intensively by the Hawaiian Volcano Observatory since 1912. Observations of the atmosphere are undertaken at the Mauna Loa Observatory, and of the Sun at the Mauna Loa Solar Observatory, both located near the mountain's summit.
Mauna Loa | Introduction
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. The United States Geological Survey maintains a 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.
Mauna Loa | Hazards
Other areas of Haleakala are rated comparable to the lava-flow hazards of Mauna Kea and Kohala (Hazard Zones 7 through 9). These high hazard estimates for Haleakala are based on the frequency of its eruptions. Haleakala has erupted three times in approximately the last 900 years. By way of comparison, both Mauna Loa and Kilauea have erupted more than a dozen times each in the last 90 years. Hualalai has an eruption rate comparable to Haleakala. All of Hualalai is rated as Hazard Zone 4. However, the frequency of eruption of a volcano is only one of the criteria on which hazards are based.
Haleakalā | Volcanic hazard
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; Mauna Loa's 1950 eruption emitted as much lava in three weeks as Kīlauea's 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. An earlier eruption in 1926 overran the village of Hoʻōpūloa Makai, and Hilo, partly built on lavas from the 1880–81 eruption, is at risk from future eruptions. The 1984 eruption nearly reached the city, but stopped short after the flow was redirected upstream.
Mauna Loa | Hazards
On the island of Hawaii, lava-flow hazards are rated on a scale of one through nine with one being the zone of highest hazard and nine being the zone of lowest hazard. For example, the summits and rift zones of Kilauea and Mauna Loa volcanoes are rated Hazard Zone 1. Using this same scale, preliminary estimates of lava-flow hazard zones on Maui made in 1983 by the U.S. Geological Survey rated the summit and southwest rift zone of Haleakala as Hazard Zone 3. The steep, downslope areas of the Kanaio and Kahikinui ahupuaa and the area north of Hana are rated as Hazard Zone 4.
Haleakalā | Volcanic hazard
The other important criterion is the lava flow coverage rate. Using the preliminary dates for Haleakala flows, only of lava flows have been emplaced in the last 900 years. In comparison, approximately of Hualalai are covered with flows 900 years old or younger and approximately on Kilauea and on Mauna Loa are covered by lavas less than 200 years old. Thus, Haleakala is a distant fourth in coverage rates.
Haleakalā | Volcanic hazard
It is even more poorly known than "N. wekiuicola", but appears to be in less danger since the summit of Mauna Loa is not under threat of development. Although it receives a large number of hikers, the area is largely made up of rocky lava rather than loose cinder, and is less vulnerable to human influence.
Nysius wekiuicola | Conservation
The last eruption of Mauna Kea was about 4,600 years ago (about 2600 BC); because of this inactivity, Mauna Kea is assigned a United States Geological Survey hazard listing of 7 for its summit and 8 for its lower flanks, out of the lowest possible hazard rating of 9 (which is given to the extinct volcano Kohala). Since 8000 BC lava flows have covered 20% of the volcano's summit and virtually none of its flanks. Despite its dormancy, Mauna Kea is expected to erupt again. Based on earlier eruptions, such an event could occur anywhere on the volcano's upper flanks and would likely produce long lava flows, mostly of aā, long.
Mauna Kea | Future activity
A more recent example of the risks associated with slumps occurred in 1975, when the Hilina Slump suddenly lurched forward several meters, triggering a 7.2 earthquake and a tsunami that killed two campers at Halape.
Mauna Loa | Hazards
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. 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. 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 volcanologists predicting an eruption within two years in 1983.
Mauna Loa | Monitoring
The flanks of the volcano do not pose a lower threat to the population than the area near the rift zones because the distance is short and the slopes are steep; lava poses as much of a threat as it does near its source. Since 1991, the Hawaiian Volcano Observatory (HVO) has maintained a seismic recording station east of Hualālai's summit to monitor the volcano. During this time, not a single earthquake swarm or harmonic tremor, indicative of activity at the volcano, has occurred. Although Hualālai does experience several magnitude-4 earthquakes per year, these are attributed to a deep source off the coast of the north-western rift zone and are not related to the movement of magma.
Hualālai | Future monitoring
Mauna Loa is the largest subaerial and second largest overall volcano in the world (behind Tamu Massif), covering a land area of and spans a maximum width of . Consisting of approximately of solid rock, it makes up more than half of the surface area of the island of Hawaiʻi. Combining the volcano's extensive submarine flanks ( to the sea floor) and subaerial height, Mauna Loa rises from base to summit, greater than the elevation of Mount Everest from sea level to its summit. In addition, much of the mountain is invisible even underwater: its mass depresses the crust beneath it by another , in the shape of an inverse mountain, meaning the total height of Mauna Loa from the start of its eruptive history is about .
Mauna Loa | Structure
Many farmers live in the paths of such possible destructive events. Although volcanic eruptions are notoriously chaotic in their frequency, some scientists warn that a large eruption is "overdue". Research from Massey University indicates that significant seismic activity is likely again in the next 50 years. Prevailing winds would probably blow ash east, covering much of the North Island, and disrupting air routes, power transmission lines and local water supplies.
Mount Taranaki | Hazards
Future eruptions from Nazko Cone are unlikely to cause many fatalities, due to the region's remoteness. There is active logging and ranching in the region, and people engaged in these activities are at some risk. Lava flows are likely to flow only a few kilometres from the volcano which could possibly start forest fires in the dry region. Any future eruption is likely to affect low flying air traffic only, since eruptions would likely be in the form of Hawaiian eruption- lava fountains that create small cinder cones and lava flows rather than voluminous ash clouds.
Nazko Cone | Hazards
The presence of an ice cap, and therefore the risk of incandescent volcanic rocks melting that ice, creates a hazard of lahars, or mudflows, such as those that in 1985 killed over 23,000 people at Nevado del Ruiz volcano in Colombia. The risk to life is further increased by Coropuna's steep slopes and by the concentration of people in nearby valleys. The terrain around the volcano has one of the greatest topographic reliefs in the world and a number of towns lie on the floor of the Majes valley, right down to the Pacific Ocean where the district capital Camaná with 20,000 inhabitants is situated.
Coropuna | Hazards and monitoring
Strainmeters, by contrast, are relatively rare. The Observatory also maintains two gas detectors at Mokuʻāweoweo, Mauna Loa's summit caldera, as well as a publicly accessible live webcam and occasional screenings by interferometric synthetic aperture radar imaging.
Mauna Loa | Monitoring
Data obtained from the Global Volcanism Program website.
List of Mauna Loa eruptions | Radiocarbon-dated eruptions
In 1790, Kīlauea exploded; it was the deadliest eruption known to have occurred in the modern era in what is now the United States. Up to 5,405 warriors and their families marching on Kīlauea were killed by the eruption. Volcanic activity and subsequent erosion have created impressive geological features. Hawaii Island has the second-highest point among the world's islands. On the flanks of the volcanoes, slope instability has generated damaging earthquakes and related tsunamis, particularly in 1868 and 1975. Steep cliffs have been created by catastrophic debris avalanches on the submerged flanks of ocean island volcanoes.
Hawaii | Geology
The volcanoes follow a distinct evolutionary pattern of growth and death. The chain includes the second largest volcano on Earth, Mauna Loa, which stands above sea level and reaches a further below the waterline and into the crust, approximately of rock. Kīlauea, meanwhile, is one of the most active volcanoes on Earth, with it's most recent eruption having lasted from January 1983 to 2018.
Shield volcano | Hawaiian Islands
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 basalts, like those of Mauna Kea, created through the mixing of primary magma and subducted oceanic crust. Mauna Loa's summit hosts three overlapping pit craters arranged northeast-southwest, the first and last roughly in diameter and the second an oblong feature; together these three craters make up the summit caldera Mokuʻāweoweo, so named for the Hawaiian ʻāweoweo fish ("Priacanthus meeki"), purportedly due to the resemblance of its eruptive fires to the coloration of the fish.
Mauna Loa | Structure
Renewed volcanism is likely to result in the creation of mafic cinder cones, with the latest such event having occurred with the eruption of Nazko Cone 7,200 years ago. However, eruptions of less mafic magma, typical of earlier activity of the Anahim hotspot, cannot be ruled out.
Anahim hotspot | Volcanic hazards
Based on the history of Tutupaca, a future eruption can be envisaged where renewed activity causes another collapse of the volcano. In this case, about 8,000–10,000 people, as well as neighboring geothermal power and mining infrastructure, would be in danger. Several small towns, diversion dams, irrigation canals, and the two roads IloDesaguadero and TacnaTarataCandarave would also be vulnerable. Other dangers are ballistic rocks, pyroclastic flows, scoria avalanches, ash and pumice rains, volcanic gas and lahars. The Peruvian Instituto Geológico, Minero y Metalúrgico (INGEMMET) has published a volcano hazard map for Tutupaca, but the volcano itself was not monitored since it is not active.
Tutupaca | Hazards
Long periods of activity could build a cinder cone at the source. Although not likely in the next few centuries, such an eruption would probably result in little loss of life but significant damage to infrastructure.
Mauna Kea | Future activity
The modern monitoring system on Mauna Loa is constituted not only by its locally seismic network but also of a large number of GPS stations, tiltmeters, and strainmeters that have been anchored on the volcano to monitor ground deformation due to swelling in 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 increase in its width over the year preceding the 1975 eruption, and a similar increase in 1984 eruption.
Mauna Loa | Monitoring
Birdwatching is also common at lower levels on the mountain. A popular site is "Kīpuka Puu Huluhulu", a kīpuka on Mauna Kea's flank that formed when lava flows isolated the forest on a hill. Mauna Kea's great height and the steepness of its flanks provide a better view and a shorter hike than the adjacent Mauna Loa. The height with its risk of altitude sickness, weather concerns, steep road grade, and overall inaccessibility make the volcano dangerous and summit trips difficult. Until the construction of roads in the mid-20th century, only the hardy visited Mauna Kea's upper slopes; hunters tracked game animals, and hikers traveled up the mountain.
Mauna Kea | Recreation
Hawaii Volcanoes National Park covers the summit and the southeastern flank of the volcano, and also incorporates Kīlauea, a separate volcano.
Mauna Loa | Introduction
Mazama is considered dormant, but it remains monitored by the United States Geological Survey Cascades Volcano Observatory. Future eruptions would likely take place near the western side of the complex and within the caldera rim; they could occur underwater. The ejection of lava rich in gas from shallow water could produce huge ash columns, but submarine eruptions at deeper depths may decrease the explosiveness of the event. Nonetheless, the rapid mixing of water and lava could produce dangerous pyroclastic surges, which are more gaseous and less solid than pyroclastic flows. Such flows could pass over topographic barriers, move rock fragments at , and travel several miles from their vent.
Mount Mazama | Recent activity and potential hazards
Although there is no evidence of past mudflows of such size, lahars could reach as far as the coast, affecting a number of towns and infrastructure such as roads, antennas and small hydropower plants. According to the 2007 census, 110,481 people lived in the provinces that span Coropuna and lie downstream of it. Lava flows are also a potential danger at Coropuna. Other hazards with lesser probabilities are directed volcanic blasts, lava dome collapses, fast-moving massive pyroclastic flows and flows of pumice and volcanic ash, lava bombs and shock waves from volcanic explosions.
Coropuna | Hazards and monitoring
With a warming climate, increased rain and increasing glacial meltwater may accelerate edifice collapse. This has potential implications for more landslide hazards in the area of the volcano, and tsunami risks in the lake area.
Yate (volcano) | Future Dangers
The island of Hawaiʻi is built from five separate shield volcanoes that erupted somewhat sequentially, one overlapping the other. These are (from oldest to youngest): Geological evidence from exposures of old surfaces on the south and west flanks of Mauna Loa led to the proposal that two ancient volcanic shields (named Ninole and Kulani) were all but buried by the younger Mauna Loa. Geologists now consider these "outcrops" to be part of the earlier building of Mauna Loa. Because Mauna Loa and Kīlauea are active volcanoes, the island of Hawaii is still growing. Between January 1983 and September 2002, lava flows added to the island.
Hawaii (island) | Volcanism
No unusual activity was noted on the Mauna Loa seismograms during the early evening of July 5; seismicity was at relatively low levels. At 23:18 HST, however, seismic alarms, signifying prolonged high-amplitude volcanic tremor, were activated in homes of Hawaiian Volcano Observatory (HVO) staff. The tremor had been first recorded by three seismometers near Moku‘āweoweo at 22:51 HST. Staff reached HVO at 23:30 HST and saw that harmonic tremor was being recorded on all Mauna Loa and Kīlauea seismographs. Hawaiʻi Volcanoes National Park and civil defense authorities were alerted to the imminent probability of a Mauna Loa eruption.
1975 eruption of Mauna Loa | Precursors
The oldest volcano on the island, Kohala, is more than a million years old, and Kīlauea, the youngest, is believed to be between 300,000 and 600,000 years of age. Lōʻihi Seamount on the island's flank is even younger, but has yet to breach the surface of the Pacific Ocean. At 1 million to 700,000 years of age, Mauna Loa is the second youngest of the five volcanoes on the island, making it the third youngest volcano in the Hawaiian – Emperor seamount chain, a chain of shield volcanoes and seamounts extending from Hawaii to the Kuril–Kamchatka Trench in Russia. Following the 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 eruptions about 400,000 years ago.
Mauna Loa | Setting
Minor hydrothermal explosions could still potentially be dangerous, as the ejection of ballistic blocks or tall waves could threaten people standing near the lake, traveling at speeds from . Landslides could threaten visitors to the national park or researchers by creating tsunami-sized waves, also potentially damaging infrastructure surrounding the lake.
Mount Mazama | Recent activity and potential hazards
Three of the earliest recorded observers of the volcanoes were the Scottish scientists Archibald Menzies in 1794, James Macrae in 1825, and David Douglas in 1834. Just reaching the summits proved daunting: Menzies took three attempts to ascend Mauna Loa, and Douglas died on the slopes of Mauna Kea. The United States Exploring Expedition spent several months studying the islands in 1840–1841. American geologist James Dwight Dana was on that expedition, as was Lieutenant Charles Wilkes, who spent most of the time leading a team of hundreds that hauled a pendulum to the summit of Mauna Loa to measure gravity.
Hawaii hotspot | Modern studies
Tiltmeters installed on the volcano's north side displayed a northwest trending tilt for that side of the mountain, and a southwest trending tilt was observed on the south side. Worried that the amount of pressure on the magma underground was increasing, scientists analyzed gases by the crater, and found high traces of sulfur dioxide. After this discovery, they began to regularly check the fumarolic activity and monitor the volcano for dramatic changes, but none were observed. Disheartened, they instead opted to study the growing bulge and the threat an avalanche could have for humans relatively near the volcano. An evaluation of the threat was carried out, concluding that a landslide or avalanche in the Toutle River could spawn lahars, or mudflows, downstream.
David A. Johnston | Final signs and primary blast
Beginning in late March 2015 demonstrators halted construction crews near the visitors center, again by blocking access of the road to the summit of the mountain. Heavy equipment had already been placed near the site. Daniel Meisenzahl, a spokesman for the University of Hawaii, stated that the 5 tractors trailers of equipment that were moved up the mountain the day before had alerted protesters that began organizing the demonstrations. Kamahana Kealoha of the group Sacred Mauna Kea stated that over 100 demonstrators had traveled up to the summit to camp overnight, to be joined by more protesters in the early morning to blockade crews.
Thirty Meter Telescope protests | Second Mauna Kea blockade and arrests, 2015
Due to the relatively non-explosive nature of Kīlauea's volcanic eruptions for many years, scientists could study ongoing eruptions in proximity without being in extreme danger. Also located at the shuttered main site was the public Thomas A. Jaggar Museum. In May 2018 the Kilauea caldera facility buildings were closed and the property permanently evacuated due to structural damage resulting from collapse explosions at Halemaʻumaʻu and earthquakes related to the 2018 lower Puna eruption, which also led to the months-long closure of the Kīlauea unit of Hawaii Volcanoes National Park.
Hawaiian Volcano Observatory | Introduction
These rift zones are deeply set structures, driven by dike intrusions along a decollement fault that is believed to reach down all the way to the volcano's base, deep. The first is a rift trending southwest from the caldera to the sea and a further 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 and is historically active across only the first of its length, with a nearly straight and, in its latter sections, poorly defined trend. The northeastern rift zone takes the form of a succession of cinder cones, the most prominent of which the high Puu Ulaula, or Red Hill.
Mauna Loa | Structure
Data obtained from the Global Volcanism Program website.
List of Mauna Loa eruptions | Historically-observed eruptions
Another major hazard of an eruption on Taveuni is the lava being shot into the air. In some cases lava has been ejected about 1.8 kilometers into the air, and the sheer force of the lava falling can easily destroy any structure on the island that it hits.
Mount Taveuni | Ballistic Ejection
Volcanic gases are another major hazard to Taveuni, as they can easily cause respiration problems, poison water, and corrode metal. Most of the gases include: and a few others.
Mount Taveuni | Volcanic Gases
Mauna Loa ( or ; Hawaiian: ; ) is one of five volcanoes that form the Island of Hawaii in the U.S. state of Hawaiʻi in the Pacific Ocean. The largest subaerial volcano in both mass and volume, Mauna Loa has historically been considered the largest volcano on Earth, dwarfed only by Tamu Massif. It is an active shield volcano with relatively gentle slopes, with a volume estimated at approximately , although its peak is about lower than that of its neighbor, Mauna Kea. Lava eruptions from Mauna Loa are silica-poor and very fluid, and they tend to be non-explosive.
Mauna Loa | Introduction
Since then, the volcano has remained active, with a history of effusive and explosive eruptions, including 33 eruptions since the first well-documented eruption in 1843. Although Mauna Loa's activity has been overshadowed in recent years by that of its neighbor Kīlauea, it remains active.
Mauna Loa | Setting
The substantial ice body in the caldera means that there is a significant risk of mudflows or glacier bursts in the case of renewed activity. Conversely, a retreat of the caldera-filling glacier might facilitate the onset of explosive eruptions at Sollipulli. A repeat of the Alpehué eruption would be a regional catastrophe, comparable to the 1991 eruption of Cerro Hudson volcano. The Chilean geological service Sernageomin monitors the volcano and publishes a hazard index for it. The towns of Cunco, Melipeuco and Villa García are close to the volcano. Melipeuco has devised a Volcanic Emergency Plan to deal with future eruptions of Llaima or Sollipulli.
Sollipulli | Hazards
More than 9,000 people live in the danger zone. Ash fall from an eruption could extend southeastward to the border with Chile]and affect the towns of Candarave, Ilabaya, Pachia, Palca and Tarata. Volcanic earthquakes like the 1999 Ticsani earthquakes at a volcano farther north and volcanic gases constitute additional dangers.
Yucamane | Hazards
In April 2005, the Directorate of Volcanology and Geological Hazard Mitigation raised an alert, forbidding visitors from going up the volcano. "Sensors on the slopes of the two mountains - Anak Krakatoa on the southern tip of Sumatra Island and Tangkuban Perahu in Java - picked up an increase in volcanic activity and a build-up of gases, said government volcanologist Syamsul Rizal." On the mountain's northern flank is Death Valley, which derives its name from a frequent accumulation of poisonous gases.
Tangkuban Perahu | Introduction
The Chilean SERNAGEOMIN geological service monitors the volcano and shows a volcano hazard level for it. It also publishes a hazard map for Taapaca, which shows risk areas for lava bomb falls, pyroclastic flows and tephra fallout.
Taapaca | Threats and preparedness
In February of that year Menzies, two ships' mates, and a small group of native Hawaiian attendants attempted a direct course for the summit from Kealakekua Bay, making it inland by their reckoning (an overestimation) before they were turned away by the thickness of the forest. On a second visit by the expedition to the island in January of the next year Menzies was placed in charge of exploring the island interior, and after traversing the flanks of Hualālai he and his party arrived at the high plateau separating the two volcanoes. Menzies decided to make a second attempt (above the objections of the accompanying island chief), but again his progress was arrested by unassailable thickets.
Mauna Loa | European summiting attempts
Mauna Kea ( or , ) is a dormant volcano on the island of Hawaii. Its peak is above sea level, making it the highest point in the state of Hawaii. Most of the volcano is underwater, and when measured from its underwater base, Mauna Kea is the tallest mountain in the world, measuring in height. Mauna Kea is about a million years old, and has thus passed the most active shield stage of life hundreds of thousands of years ago. In its current post-shield state, its lava is more viscous, resulting in a steeper profile. Late volcanism has also given it a much rougher appearance than its neighboring volcanoes due to construction of cinder cones, decentralization of its rift zones, glaciation on its peak, and weathering by the prevailing trade winds.
Mauna Kea | Introduction
Various towns with a total population of about 11,800 people are located at the feet of extinct vents, but usually at a distance from the youngest volcanoes although shifts in vent location during the course of an eruption could bring hazards to these towns. Explosive eruptions could result in fallout of lava bombs, tephra and volcanic ash, but the impact would be limited to the surroundings of the vent, probably less than . The volcanic field however also produced lava flows in the past, which can reach larger distances and also infrastructure such as the Mantaro-Socabaya power line and could also bury the ground for perhaps thousands of years.
Andagua volcanic field | Hazards from future eruptions
Mauna Kea can be ecologically divided into three sections: an alpine climate at its summit, a "Sophora chrysophylla"–"Myoporum sandwicense" (or māmane–naio) forest on its flanks, and an "Acacia koa"–"Metrosideros polymorpha" (or koa–ōhia) forest, now mostly cleared by the former sugar industry, at its base. In recent years, concern over the vulnerability of the native species has led to court cases that have forced the Hawaii Department of Land and Natural Resources to eradicate all feral species on the volcano. With its high elevation, dry environment, and stable airflow, Mauna Kea's summit is one of the best sites in the world for astronomical observation.
Mauna Kea | Introduction
The volcano continues to pose a serious threat to nearby towns and villages. The most likely hazard is small-volume eruptions, which might destabilize glaciers and trigger lahars. Despite the significant retrenchment of the volcano's glaciers, the volume of ice atop Nevado del Ruiz and other volcanoes in the Ruiz–Tolima massif remains large. Melting merely 10% of the ice would produce mudflows with a volume of up to —similar to the mudflow that destroyed Armero in 1985. Such lahars can travel up to along river valleys in a matter of few hours. Estimates show that up to 500,000 people living in the Combeima, Chinchiná, Coello-Toche, and Guali valleys are in danger, and 100,000 of these are considered to be at high risk.
Nevado del Ruiz | Current threats and preparedness
The important natural preserve that is the Lauca National Park could suffer significant disruption from renewed eruptions of Parinacota.
Parinacota (volcano) | Present-day activity and hazards
Halemaumau continued to intermittently emit high levels of volcanic gases, ash, spatter, Pele's Tears, and Pele's Hair until the second episode.
Halemaʻumaʻu | Beginning of the eruption
Unlike many other volcanoes, the largest hazard from Taveuni is actually its lava flows, which are exceptionally hot (940-1125 degrees Celsius). Because Taveuni is heavily forested, fires can spread fast and easily, but mainly the southern flank of the island will be directly affected by the lava.
Mount Taveuni | Lava Flows
Testing also determined Mauna Kea to be superb for nighttime viewing due to many factors including the thin air, constant trade winds and being surrounded by sea. Jefferies would build a 2.24 meter telescope with the State of Hawaii agreeing to build a reliable, all weather roadway to the summit. Building began in 1967 and first light seen in 1970.
Opposition to the Mauna Kea Observatories | Background
Hawaiian eruptions are considered less dangerous than other types of volcanic eruptions, due to the lack of ash and the generally slow movement of lava flows. However, they can still cause injuries or deaths. In 1993, a photographer attempting to take pictures of a lava ocean entry died, and several tourists were injured, when a lava bench collapsed. In 2000, two people were found dead near a lava ocean entry from Kīlauea, likely killed by laze. Sulfur dioxide emissions can also be fatal, especially to people suffering from respiratory ailments. In 2018 lava spatter from Kīlauea broke a man's leg, and another 23 people on a tour boat were injured by a steam explosion at a lava ocean entry from the same eruption.
Hawaiian eruption | Safety
According to John Ewert and Ed Miller in a 1995 publication, "a great majority of the world's potentially active volcanoes are unmonitored". Of the historically active volcanoes in the world, less than one fourth are monitored. Only twenty-four volcanoes in the entire world are thoroughly monitored for activity. They also state that "seventy-five percent of the largest explosive eruptions since 1800 occurred at volcanoes that had no previous historical eruptions". By monitoring the seismic and geological activity, the USGS can warn people ahead of time about impending danger. These volcanologists measure the size of an eruption in two ways: the eruption magnitude (by the volume or mass of magma erupted) and eruption intensity (by the rate of magma erupted).
Volcanic hazards | Monitoring and mitigation
The volcano has an approximate rock generation rate of , lower than other arc associated volcanoes. Nevertheless, with eruptive episodes being separated by gaps of about 40,000 years between the last episodes, dangerous eruptive activity in the future is possible. However, the region surrounding the volcano is thinly populated, so major damage to infrastructure or danger to human life is unlikely.
Nevado Tres Cruces | Hazards
"It's a big problem. I think the first violation of the zero casualty (record) will be a dead tourist," said Salceda. Speaking about thrill-seekers finding their way into the area, Salceda warned, "At the moment of the eruption, the local guides will have better chance of getting out. The helpless tourist will be left behind."
Mayon | Government response
Layers of carbonized organic material at the bottom of Kīlauea ash deposits are evidence of the many times the volcano has wrought destruction on its own ecosystem and that of its neighbor Mauna Loa, and parts of the volcano present a dichotomy between pristine montane forest and recently buried volcanic "deserts" yet to be recolonized. Kīlauea's bulk affects local climate conditions through the influence of trade winds coming predominantly from the northeast, which, when squeezed upwards by the volcano's height, result in a moister windward side and a comparatively arid leeward flank. The volcano's ecology is further complicated by height, though not nearly as much as with its other, far taller neighbors, and by the local distribution of volcanic products, making for varied soil conditions.
Kīlauea | Background
After studying photos for NASA's Apollo program that contained greater detail than any ground-based telescope, Gerard Kuiper began seeking an arid site for infrared studies. While he first began looking in Chile, he also made the decision to perform tests in the Hawaiian Islands. Tests on Maui's Haleakalā were promising but the mountain was too low in the inversion layer and often covered by clouds. On the "Big Island" of Hawaii, Mauna Kea is considered the highest island mountain in the world. While the summit is often covered with snow the air itself is extremely dry. Kuiper began looking into the possibility of an observatory on Mauna Kea.
Opposition to the Mauna Kea Observatories | Background
After testing, he discovered the low humidity was perfect for infrared signals. He persuaded then-Governor John A. Burns to bulldoze a dirt road to the summit where he built a small telescope on Puu Poliahu, a cinder cone peak. The peak was the second highest on the mountain with the highest peak being holy ground, so Kuiper avoided it. Next, Kuiper tried enlisting NASA to fund a larger facility with a large telescope, housing and other needed structures. NASA, in turn decided to make the project open to competition. Professor of physics, John Jefferies of the University of Hawaii placed a bid on behalf of the university.
Opposition to the Mauna Kea Observatories | Background
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. 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). 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.
Mauna Loa | Monitoring
As well as the direct effects of explosions, lava, and pyroclastic flows, volcanoes pose various hazards to the New Zealand populace. These include tsunamis, break-out floods and lahars from volcanically dammed lakes, ashfall, and other far field effects. For instance, the Tangiwai disaster occurred on 24 December 1953 when the Tangiwai railway bridge across the Whangaehu River collapsed from a lahar in full flood, just before an express train was about to cross it. The train could not stop in time, and 151 lives were lost. This was ultimately caused by Ruapehu's 1945 eruption, which had emptied the crater lake and dammed the outlet with tephra.
Volcanism of New Zealand | Hazards
New cones and lava fields have formed inside the caldera, all of which have been submerged except for Wizard Island. Mapping the caldera floor with high-resolution multibeam echo sounders, vehicle-motion sounders and navigators, and a dual-differential global positioning system (DGPS), scientists from the US government and universities detected volcanoes and landslide deposits under the water. Between 7,700 and 7,200 years ago, the central lava platform, the Merriam Cone, and Wizard Island were produced, as well as lava flows. These eruptions produced of andesitic lava, half of that in the Wizard Island cone. Wizard Island lava interacted with water to form breccia piles, and as the water levels rose, only the top of the Wizard Island edifice stayed above the water.
Mount Mazama | Recent activity and potential hazards
Taranaki is unusual in that it has experienced at least five of its major eruptions by the method of cone collapse. Few volcanoes have undergone more than one cone collapse. The vast volume of material involved in these collapses is reflected in the extensive ringplain surrounding the volcano. There is also evidence of lahars being a common result of eruption. Much of the region is at risk from lahars, which have reached as far as the coast. A volcanic event is not necessary for a lahar: even earthquakes combined with heavy rain or snow could dislodge vast quantities of unstable layers resting on steep slopes.
Mount Taranaki | Hazards
In addition to the volcanic hazards that could possibly occur, one volcano did erupt in the 20th century in LVNP: (Lassen Peak). Lassen's eruptions (1914–21, though most activity occurred between 1914–17) were very small compared to the 1980 eruption of Mount St. Helens.
Mount Tehama | Recreation
The first is the formation of long debris avalanches or pyroclastic flows that could reach the which is just away from the volcano. The second hazard is formed by a large explosive eruption resulting in ash fall and the emplacement of ignimbrites; the whole region could be affected if the eruption column is over high. A few seismic stations monitor earthquake activity at San Pedro. The Chilean SERNAGEOMIN publishes a volcano hazard level for the volcano.
San Pedro (Chile volcano) | Historical activity
The population is thought to be between 1,505 and 52,734. Accurate numbers are hard to estimate due to cloud coverage over its range. Some of its natural threats include birds, snakes, and the giant civet. Mount Awu can also be considered a natural threat as well, since it is an active and deadly volcano on the island. Anthropogenic causes include habitat loss or fragmentation, the introduction of cats and dogs to the island, population density increases in its territory, and pet trade.
Sangihe tarsier | Threats
Kīlauea was the most affected by the lateral displacement associated with the earthquake, as it did not have another major eruption until 1919. It also disrupted the magma system beneath Mauna Loa, as is shown both in reduced lava volumes and an abrupt change in the lava chemistry.
1868 Hawaii earthquake | Effect on volcanic eruptions
The forested zone on the volcano, at an elevation of , is dominated by māmane ("Sophora chrysophylla") and naio ("Myoporum sandwicense"), both endemic tree species, and is thus known as māmane–naio forest. Māmane seeds and naio fruit are the chief foods of the birds in this zone, especially the palila ("Loxioides bailleui"). The palila was formerly found on the slopes of Mauna Kea, Mauna Loa, and Hualālai, but is now confined to the slopes of Mauna Kea—only 10% of its former range—and has been declared critically endangered. The largest threat to the ecosystem is grazing by feral sheep, cattle ("Bos primigenius"), and goats ("Capra hircus") introduced to the island in the late 18th century.
Mauna Kea | Māmane–naio forest
The Peruvian geological agency INGEMMET has published ash fall, lava flow and pyroclastic flow hazard maps for Yucamane, and additional hazard maps are available on its website. According to these the western, eastern and southern flanks could be threatened by lava flows, whereas the older volcanoes protect much of the northern flank. Hazards from pyroclastic flows extend farther, down to the Laguna Aricota lake southwest of the volcano. Hazards from lava flows derive from their ability to bury land and to ignite flammable materials, as well as the possible creation of lava dams on rivers and outburst floods when they break, while the high speed and temperatures of pyroclastic flows threatens people with asphyxiation, burial and burns.
Yucamane | Hazards
Its rate of advance slowed as it moved downslope, but by March 29 the flow had moved to an elevation of . At this time, the flow front was about from the outskirts of Hilo. Smoke from burning vegetation, loud explosions caused by methane gas along the advancing flow front and the intense glow at night all contributed to a growing concern among Hilo's residents.
1984 eruption of Mauna Loa | Eruption
Charles Wilkes camped in this area on the United States Exploring Expedition in 1840, on his way to Mauna Loa. About 1846 a primitive one-room grass shelter was constructed at the rim of the Kīlauea crater by Benjamin Pitman, the first hotel to call itself "Volcano House". Sometimes visitors would show up after the long journey and nobody would be home. A more substantial wood frame structure was built in 1866 with four bedrooms, parlor, and dining room. Mark Twain stayed here, and wrote about his visit in the book "Roughing It".
Volcano House | Early visitors
Additionally, only small areas of Oahu are likely to be affected by an eruption. Any future eruption is likely to occur in the southeastern sector of Oahu and will be of small volume, involving the emplacement of cinders, lava flows and mudflows with characteristics similar to those of past Honolulu Volcanics eruptions:
Honolulu Volcanics | Youngest activity and hazards
The Hawaiian Volcano Observatory (HVO) is an agency of the U.S. Geological Survey, with temporary offices located in Hilo on the Island of Hawaii. The former volcano observatory clifftop facility and HVO offices, closed due to structural damage in 2018, is located at Uwekahuna Bluff on the rim of Kīlauea Caldera. The observatory staff and equipment monitors four active Hawaiian volcanoes: Kīlauea, Mauna Loa, Hualālai, and Haleakalā. Because Kīlauea and Mauna Loa are significantly more active than Hualālai and Haleakalā, much of the observatory's research is concentrated on the former two mountains. HVO has a worldwide reputation as a leader in the study of active volcanism.
Hawaiian Volcano Observatory | Introduction
A number of celebrity activists of Native Hawaiian descent, both local and national, began campaigning over social media, including "Game of Thrones" star Jason Momoa who urged Dwayne Johnson (The Rock) to join the protests with him on top of Mauna Kea. Construction was halted for one week at the request of Hawaii state governor David Ige on April 7, 2015 after the protest on Mauna Kea continued and demonstrations began to appear over the state. Project Manager, Gary Sanders stated that TMT agreed to the one-week stop for continued dialogue. Kealoha Pisciotta, president of "Mauna Kea Anaina Hou" viewed the development as positive but said opposition to the project would continue.
Thirty Meter Telescope protests | Second Mauna Kea blockade and arrests, 2015
On March 19, 2008, there was a small explosion in Halemaʻumaʻu, the first explosive event since 1924 and the first eruption in the Kīlauea caldera since September 1982. Debris from the explosion was scattered over an area of . A small amount of ash was also reported at a nearby community. The explosion covered part of Crater Rim Drive and damaged Halemaʻumaʻu Overlook. The explosion did not release any lava, which suggests to scientists that it was driven by hydrothermal or gas sources. This explosion event followed the opening of a major sulfur dioxide gas vent, greatly increasing levels emitted from Halemaʻumaʻu.
Hawaiʻi Volcanoes National Park | Recent events
Pisciotta also stated that the protests would continue to be within a Kapu Aloha; "moving in Aloha with steadfast determination".
Thirty Meter Telescope protests | Second Mauna Kea blockade and arrests, 2015
Future eruptions from Volcano Mountain would probably be lava flows, since there is a lack of pyroclastic material. The main hazards from Volcano Mountain are forest fires started by the lava flows and poisonous gases. Older volcanic deposits south of Volcano Mountain indicate that lava flows may have once partly blocked or at least altered the course of the Yukon and Pelly Rivers. Any future activity in this area could disrupt the course of both of these major rivers and could have a serious impact on people living or working downstream.
Volcano Mountain | Volcanic hazards
There are 169 young volcanoes in the United States, many of which are considered hazardous due to their proximity to populated areas. The USGS considers many of the more dangerous volcanoes to be under-monitored, lacking adequate scientific instruments on the ground to measure activity and potential threats. Many volcanoes lack any instruments, and the seismometers at other sites are inadequate for useful analysis. One of the most active volcanoes in Washington, Glacier Peak, only has a single seismometer. Improved monitoring capabilities can provide more timely warnings for evacuations and emergency response coordination, and mitigate the impacts of the travel disruptions.
National Volcano Early Warning and Monitoring System | Background
According to Charles Mandeville, the program coordinator for the USGS Volcano Hazards Program, the USGS is "somewhere between 30-40 percent of the way to having an ideal monitoring network for those volcanoes”. As of 2018, only three "very high risk" volcanoes are categorized as "well monitored": Kilauea, Mount St. Helens, and Long Valley Caldera.
National Volcano Early Warning and Monitoring System | Background
A former summit caldera may have been filled and buried by later summit eruption deposits. Mauna Kea is over in volume, so massive that it and its neighbor, Mauna Loa, depress the ocean crust beneath it by . The volcano continues to slip and flatten under its own weight at a rate of less than per year. Much of its mass lies east of its present summit. Mauna Kea stands above sea level, about higher than its neighbor Mauna Loa, and is the highest point in the state of Hawaii. Measured from its base on the ocean floor, it rises over , significantly greater than the elevation of Mount Everest above sea level.
Mauna Kea | Geology
The stability of wēkiu bug populations has been a matter of controversy. Development of the summit area of Mauna Kea for telescopes has adversely affected the ecology of the area, including compaction of the loose cinder and traffic from tourism. Beyond the immediate vicinity of the summit the bugs inhabit other cones that are well removed from activity. Surveys by the University of Hawaii have shown populations to be stable with population variations driven by precipitation on the summit area. As a result of ongoing population monitoring a request to list the species as endangered was declined in 2011. The common name is also used to refer to the closely related "Nysius aa", which occupies the same niche on Mauna Loa.
Nysius wekiuicola | Conservation
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 ongoing inflation of Mauna Loa's summit, indicative of a future eruption, began the same day as new lava flows at Kīlauea's Puu Ōō crater. In 2002, Kilauea experienced a high-volume effusive episode at the same time that Mauna Loa began inflating. This unexpected communication is evidence of crustal-level interactions between Mauna Loa and Kīlauea, even though these two volcanoes are thought to be fairly independent of each other. 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.
Kīlauea | Structure
The eruption started as a fissure between two pit craters, Āloi and Alae, where the Mauna Ulu shield would eventually form. Both pāhoehoe and aā lava erupted from the volcano. Early on, fountains of lava burst out as much as 540 meters (1772 ft) high. In early 1973, an earthquake occurred that caused Kīlauea to briefly stop erupting near the original Mauna Ulu site and instead erupt near the craters Pauahi and Hiiaka.
Kīlauea | 1952 to 1982
Early warnings are particularly critical for air traffic control, which needs to be made aware of ash-producing eruptions in time to reroute airplanes. The USGS assesses each volcano against a 24-factor hazard and exposure matrix, and assigns a threat level of "very low", "low", "moderate", "high", or "very high". In 2018, 18 volcanoes were rated as "very high" risk, and 39 volcanoes were rated as "high" risk. The "very high" risk volcanoes are in Alaska, Washington, Oregon, California, and Hawaii, with the most dangerous being Kilauea. Some volcano monitoring has been performed by the Volcano Hazards Program, directed by the USGS, but the program lacks sufficient funding to properly close the monitoring gap.
National Volcano Early Warning and Monitoring System | Background
With the exclusion of flood basalts, mature shields are the largest volcanic features on Earth: the summit of the largest subaerial volcano in the world, Mauna Loa, lies above sea level, and the volcano, over wide at its base, is estimated to contain about of basalt. The mass of the volcano is so great that it has slumped the crust beneath it a further ; accounting for this subsidence and for the height of the volcano above the sea floor, the "true" height of Mauna Loa from the start of its eruptive history is about . Mount Everest, by comparison, is in height.
Shield volcano | Structure
The extent of tephra deposits would depend on wind strength and directions. However, given the sudden nature of rockfall-avalanches, these would be more dangerous than pyroclastic flows or tephra, as they could occur without warning, seriously endangering life within of the Crags. The Chaos Crags are monitored for movement in case of future rockslides by the United States Geological Survey; GPS receivers have been in place to monitor deformation within the Lassen volcanic center since 2008. 13 seismometers in the vicinity, first installed in 1976 and since updated each decade, continually survey earthquakes within the locale.
Chaos Crags | Potential hazards and monitoring
Hiking Olomana can be hazardous especially in wet conditions between the second and third peak. In 2004 Jacqueline Turner, fell 150 feet but survived. Also on that day, another hiker, Mel Yoshioka, also fell while descending the backside of Olomana's second peak. He, too, survived. In April 2011, 44-year-old Ryan Suenaga, an experienced hiker, fell to his death in this same area and in January 2014, 27-year-old off duty Honolulu Fireman Mitchell Kai fell to his death along the same section. In June, 2015 a 52-year-old retired Navy man fell approx. 200 to his death, making it the 3rd casualty in 4 years on Olomana.
Olomana (mountain) | Accidents
A lava dome emerged inside the collapse scar subsequently. 1818 an eruption formed a block lava flow over half a year that travelled 2.5 km eastward. Lahars and further explosive activity are potential hazards from this volcano.
Almolonga | Introduction
"We have already prepared alternative routes for all flights," he said. "It may cost more and use up more fuel, but safety comes first."
2010 eruptions of Mount Merapi | Air travel disruption
The bulk of information about Lōʻihi comes from dives made in response to the 1996 eruption. In a dive conducted almost immediately after seismic activity was reported, visibility was greatly reduced by high concentrations of displaced minerals and large floating mats of bacteria in the water. The bacteria that feed on the dissolved nutrients had already begun colonizing the new hydrothermal vents at Pele's Pit (formed from the collapse of the old ones), and may be indicators of the kinds of material ejected from the newly formed vents. They were carefully sampled for further analysis in a laboratory. An OBO briefly sat on the summit before a more permanent probe could be installed.
Lōʻihi Seamount | 1996 to present
The volcano has potential to produce huge debris avalanches that could inundate large areas of the Pacific coastal plain. In areas around the volcanoes and downslope toward the coastal plain, more than 100,000 people are potentially at risk from these and other flowage phenomena.
Acatenango | Volcanic hazards
Rock fall would affect the area close to the summit domes, as would pyroclastic flows; these would be a further hazard to the valleys draining the volcano. The presence of an ice cap is an additional source of danger, as its melting during a volcanic eruption could form hazardous lahars, although the small volume of the ice cap limits their damage potential. The Majes River and Sihuasi River drainages would be threatened by such mudflows in case of an eruption; the former is the site of a major irrigation project. Other dangers from eruptions at Sabancaya are tephra fallout, which can impact the health of people; and lava flows, which however are not much of a threat to humans owing to their slow speed.
Sabancaya | Hazards