Geology and Ecology of National Parks

Geology of Hawai'i Volcanoes National Park

This photograph shows a flowing lava exit tube glowing in a bright red color amongst the black solidified lava rock near Kilauea

A flowing lava exit tube near Kilauea’s southern flank.

(Credit: Jeffrey Judd, USGS. Public domain.)

Hawaii Volcanoes National Park is located on the largest island of Hawaii, also known as the Big Island. The Hawaiian Islands are an archipelago, or group of islandsin the North Pacific Ocean, roughly 2,400 miles (3,862 km) off the coast of California.Although it is geographically separated from the mainland of the United States of America, Hawaii became a state in 1959.









This map shows the location of the Big Island of Hawaii, which lies in the Pacific Ocean, about about 2,400 miles east of the co

Location map of the Big Island, Hawaii. 

(Public domain.)

These islands are the exposed peaks of the Hawaiian-Emperor seamount chain, a volcanic mountain range mostly below sea level that extends over 3,700 miles. This chain is the result of hot spot volcanism, a type of volcanic activity with a heat source originating deep within the Earth’s mantle, unaltered by the shifting plate tectonics above. Hot spots are created by a localized source of high heat energy that eventually forms plumes and partially melts cooler overlying rock to form magma. This magma continues to rise, causing volcanic eruptions onto Earth’s surface and results in overlapping layers of volcanic rocks. The plume remains stationary as the Pacific Plate (in this case) migrates over the hot spot. The slow movement of the Pacific Plate over the Hawaiian hot spot forms young and active volcanoes above the plume.






This photograph shows a conceptual model of the movement of a tectonic plate over a hot spot plume, resulting in a volcanic chai

The formation of the seamount chain formed by the Hawaiian hot spot.

(Public domain.)

As the plate moves farther northwest and away from the hot spot, the displaced volcanoes become progressively older and less active, since there is no longer a source of fresh magma below its roots. As one island volcano becomes extinct, a new volcano is activated above the hot spot. Imagine holding a paper plate just above a candle on a birthday cake (don’t try this at home). The heat from the candle will make a small hole in the plate. If you blow it out right away, then move the plate slightly away from you and to your left, a new hole will be burned in the plate to the lower right (SE) of the first hole. The candle (hot spot) stays in the same place, but the (tectonic) plate experiences new volcanism directly above the heat source. This repetitive process explains the formation of the youthful Big Island of Hawaii and the remnants of dormant volcanoes observed as the underwater seamount chain extends to the northwest of the Hawaiian islands in the direction of plate motion. Scientists have used this seamount chain to calculate tectonic plate displacement and the rate of plate movement, as well as the relative ages of the islands of Hawaii. The Pacific Plate is currently moving an estimated 2-4 inches per year (6 cm/year) to the northwest. Hawaii’s oldest and most heavily eroded rocks are found on Kauai, the northwesternmost island, which dates back to 5.5 million years ago. This exposed land once was positioned in the same location where the Big Island is today, over the hot spot plume, and has since migrated with Pacific Plate to the northwest. The Big Island is home to Hawaii’s youngest and most active volcanoes, with the oldest rocks on the island dating only back to 0.7 million years old (this is considered to be very young on the geologic time scale)! Lō‘ihi is forming southeast of Kīlauea, indicating that the hot spot may be slowly creating a new island.

This map shows the location of the Hawaiian-Emperor Seamount Chain, located in the middle of the Pacific Ocean and reaching out

This map shows the location of the Hawaiian-Emperor Seamount Chain, located in the middle of the Pacific Ocean and reaching out towards the coast of Eastern Russia. The boundary of the Pacific Plate can be traced along the subduction zone/trench at the north and northwest portion of the map. The hotspot leaves volcanic remnants on Earth's surface as the plate moves northwest over it.  NPS

(Public domain.)

There are two major volcanoes within Hawaii Volcanoes National Park, Mauna Loa and Kīlauea. There are also three other volcanoes outside of the national park boundary: Mauna Kea, Hualālai, and Kohala. These volcanoes are older and much less active than the larger volcanoes. All five listed make up the Big Island of Hawaii, but this summary will focus on the two volcanoes within the national park.

This map shows the general boundaries of the five volcanoes located on the big island of Hawaii.

This map shows the general boundaries of the five volcanoes located on the big island of Hawaii.

(Public domain.)














Mauna Loa: Mauna Loa is the largest active volcano on our planet, growing to an elevation of 4,170 m (13,681 feet) above sea level with an additional depth of 9,144 m (30,000 feet) below sea level, which makes this shield volcano taller from base to top than Mount Everest. Mauna Loa makes up roughly 51% of the land mass on the Big Island, with a weight so heavy that it physically depresses the ocean floor beneath it. It is a shield volcano, which is a broad, gently sloping dome-like structure built almost entirely from fluid lava flows pouring out of a central vent(s). These types of volcanoes tend to display effusive eruption styles, or high fluidity and low-viscosity conditions when erupting. There are two effusive eruption subcategories that geoscientists use to describe lava flow type, pāhoehoe and ‘A‘ā. The accretion, or deposition, of highly fluid lava flows that we see on Mauna Loa can spread over great distances and eventually cool as thin,  low-angle dipping layers away from the summit. Lava can also erupt from vents along rift zones, or weak fracture points that develop on the flanks of the volcano.







A cross-sectional diagram showing the typical internal structure of a shield volcano, with labels on the central magma reservior

 A basic shield volcano cross-sectional diagram.

(Credit: John Watson, USGS. Public domain.)


Mauna Loa has erupted 33 times since 1843 averaging once every five years, with its most recent eruption occurring in 1984. The eruptions tend to start at the summit, known as Moku‘āweoweo, and migrate toward rift zones located to the northeast, northwest, and southwest of the summit caldera. These rift zone eruptions can cause concerns of lava flow progression for cities such as South Kona and Hilo.

Color graphic showing Mauna Loa historical lava flows, hazard zones, and county districts

A map created by the USGS Hawaiian Volcano Observatory displaying the lava flows and hazard zones of Mauna Loa.

(Credit: K. Mulliken, HVO. Public domain.)

1984: Mauna Loa erupted for the first time in nine years from March 25th to April 15th of 1984, cascading with lava flows down to the island’s population center of Hilo. This eruption occurred in the wake of a series of earthquakes that began in September of 1983, approximately 3- 9 miles beneath the southeastern flank of Mauna Loa; the largest of which was a 6.6-magnitude quake in the Ka‘ōiki Fault System rupturing on November 16, 1983. The frequency of earthquakes continued to increase, causing deformation and inflation of the volcanic slopes. By March 24th, seismic activity began happening every 2-3 minutes, causing constant ground vibrations.

Lava Flow from 1984 Mauna Loa Eruption

Two images showing the progression of lava towards Hilo.

(Credit: J. D. Griggs, USGS. Public domain.)

At 1:25 a.m. on March 25th, the eruption began on Mauna Loa’s summit in the Moku‘āweoweo caldera and in less than four hours, lava fountains had quickly spread along the southeastern and northeastern rift zones stemming from the caldera center. As magma continued to move down the northeast rift zone at about 10:30 a.m., a 1 km-long lava fissure formed and began emitting steam at the 3,258- and 3,170-m elevation (10,690 and 10,400 ft). However, by 4:41 p.m. a new fissure had opened at 2,850 m elevation (9,350 ft), making way for a one-mile-long lava fountain. The lava emitted from this fountain formed four parallel flows moving at speeds between 300 to 700 feet (90 to 230 m) per hour directly toward the city of Hilo.

The morning of March 26th saw the lava advance 5.5 miles (roughly 9 km) toward Hilo, while a secondary flow pushed east toward Kulani Prison, getting as close as two miles from the facility, which was put on high alert. This flow ceased entirely after two days. As the narrow and swift flow moved lower in elevation toward Hilo, it also slowed and by March 29th, at an elevation of 3,000 feet (914 m), the flow had traveled 15.5 miles (25 km) from the caldera and was 4 miles (6.4 km) from outskirts of the city of Hilo. What happened next could be what saved this eruption from consuming Hilo.

On the morning of March 29th, a levee along the lava channel gave out, spreading the lava flow over a larger area and slowing its pace. A week later, on April 5th, another levee broke. There were now three subparallel lava flows slowing in speed and becoming more viscous as the flow from the source vents began to diminish. As the lava became more viscous, flow channels became blocked and more levees broke. By April 15th, the eruption ended. It is important to note the significance of the diversion of channelized ‘a‘ā flows due to natural levee failure, allowing for the viscous flow to sprawl out and slow down. Several other factors facilitated this natural slowing process, including relatively gentle slopes, dense vegetation through which the flows were transported, the relatively low temperature and high viscosity of the erupted lava, and the gradual decline of eruption rates.

This color photo shows a several lava fountains spewing out of vents and feeding into lava flows from the 1984 Mauna Loa eruptio

Lava fountains feeding lava flows from the 1984 eruption of Mauna Loa.

(Credit: J. D. Griggs , USGS. Public domain.)

1975: In 1975, Mauna Loa experienced its first eruption in over 25 years. In the late-night hours of July 5, lava fountains began erupting from the caldera and all along the northeast and southwest rift zones. It was a short-lived eruption though, all action near the caldera ended after only six hours. By the evening of July 6, all volcanic activity ceased.

1950: The 1950 eruption of Mauna Loa, spanning 23 days from June 1 to 23, had a discharge rate, or rate of lava flow, greater than any recorded eruption that scientists have seen before. 492 million cubic yards (about 376 million cubic meters) of lava poured from the southwest rift zone, with the fastest flow making the 15-mile (24 km) journey to the ocean in under 3 hours. Three of the six lava flows traveled into the ocean creating 10,000-foot-tall (3 km) steam clouds and destroyed structures along the way. This eruption followed a smaller eruption in 1949 when three groups of earthquake swarms shook the Big Island; with two more following at the end of March and May of 1950. The May event took place two days before the eruption and measured a magnitude of 6.4, which was enough to signal impending volcanic activity.

Ka‘apuna lava flow enters the ocean during Mauna Loa 1950 eruption....

A picture taken from a ship during the 1950 eruption of Mauna Loa.

(Public domain.)

It began when a fissure 2.5-miles (4 km) long opened along the southwest rift zone near the Lua Hou pit crater. The lava flowed westward and advanced 5 miles (8 km) stopping just under 9,000-feet (14,484 km) of elevation. About an hour after the initial activity, fissures began to quickly propagate with lava fountains shooting molten earth up to 300 feet (91 m) in the air in strong bursts moving in a south-southeast direction. By the morning of June 2, the flow had reached the upper boundary of the Ka‘ū Forest Reserve.

The first flow to hit Highway 11 was the Honokua flow, which destroyed a gas station, post office and several other structures. In just under an hour, it reached the ocean. The Ka’ohe flow followed toward the ocean, destroying homes and a coconut grove on its way. The lowest fissure system between 8,200-7,810-feet (2,500- 2,380 km) yielded the Ka’apuna flow, which crossed the highway on June 2nd. Observatory personnel estimated this flow traveling between 10-30 miles per hour (16 -48 km/hour) before pouring into the ocean. The submarine flow was marked by a 2,625-foot-long (800 m) steam cloud over the surface of the ocean.

Compared to a preceding event in 1859, this eruption produced about the same amount of lava in about ten times as long in duration.  


Scientists looking into the bright glow of Mauna Loa's 1942 eruptiv...

Scientists looking into the bright glow of Mauna Loa's 1942 eruptive vent. Eruption occurred during WWII and was not publicized to prevent Japanese war planes from navigating to the island at night.

(Public domain.)

1942: Following the events of the Pearl Harbor attack on December 7, 1941 on the Hawaiian island of Oahu to the NW of the Big Island, Mauna Loa erupted with activity beginning on the western rim of the caldera on April 26, 1942. The lava flow shifted to the northeast rift zone and slowly worked its way toward the city of Hilo over the next 13 days. On May 9th, the eruption ended. The news coverage about this volcanic event was limited, so as to prevent the glow of the eruption from acting as another potential target to the Hawaiian Islands during the war.

1935: An eruption on Mauna Loa’s northeastern caldera rim began on November 21st, 1935 with lava flowing down the northeastern rift zone. Six days later, a vent on the northern flank erupted, flinging lava into the saddle between Mauna Loa and Mauna Kea before turning east toward Hilo at an alarming rate. A U.S. Army operation led by WWII general, General George S. Patton, was enacted to try and divert the lava flow by dropping bombs near the vent on December 27th. To this day it is disputed whether the operation was a success because the eruption ended six days later.




Color graphic showing Kīlauea historical lava flows, lava flow hazard zones, and county districts

A map showing lava flow extents and hazards zones on Kilauea volcano, Hawai'i.

(Credit: K. Mulliken, HVO. Public domain.)

Kīlauea: Kīlauea is the youngest and most active Hawaiian volcano. This 280,000-year-old volcano is a textbook shield volcano with long and shallow slopes, 90 percent of which have become covered with lava over the past 1,000 years. Aside from the main crater, the southwestern and eastern rift zones are also home to volcanic activity. The highly regular activity of Kilauea has made it difficult for geologists to map its eruptive history. Twenty percent of the slopes currently covered in lava flows are less than 200 years old. The oldest rock found above sea level is estimated to be between 50,000 and 70,000 years old while cores and sub-marine samples have yielded dates reaching as far back as 210,000 to 280,000 years.

Scientists believe that Kīlauea’s eruptions over the past 2,500 years are cyclical, switching between explosive and effusive eruptions. The explosive eruptions of Kīlauea occurred when groundwater came in contact with magma. When magma within a vent drops below the water table following the draining or exploding of the magma chamber, water can seep into the main conduit of the volcano creating a violent chemical reaction not unlike that of mixing cold water and hot oil in a skillet on stove. The water rapidly evaporates, and the steam pressurizes the magma chamber and lava column. Once any blockage above can no longer contain the pressure, the volcano explodes sending steam and debris skyward.

At Kīlauea, when the lava column drops below the water table, groun...

At Kīlauea, when the lava column drops below the water table, groundwater may come into contact with with magma or hot rocks, causing violent steam explosions.

(Public domain.)
















Stream of lava from Pu‘u ‘Ō‘ō flowing through the forest in the Roy...

A 3 m (10 ft) wide stream of lava from Pu‘u ‘Ō‘ō flowing through the forest in the Royal Gardens subdivision, February 28, 2008, Kīlauea Volcano, Hawai‘i.

(Public domain.)


Conversely, Kīlauea’s effusive eruptions are much less volatile. Though there are gases present in these eruptions, there is less pressure from overlying rock. This results in the rising magma to encounter less resistance on the path to the surface, were the surficial deposits of lava form either a lava lake or lava flow. Up until 2,200 years ago, these types of eruptions were considered to be normal.

This normal pattern shifted when the current caldera’s precursor collapsed to a depth of 2,030 feet (620m) and initiated a 1,200-year period of explosive eruptions. Between 850-950 CE, there was an eruption so explosive that it sent large rocks flying through the air more than 3 miles (5 km) from the summit, some weighing nearly 10 pounds (4.4 kg). Other rocks the size of golf balls fell near the coast, over 11 miles (18 km) away.










Explosive eruption column from Halema‘uma‘u Crater 11:15 a.m. May 1...

The Explosive eruption column from Halema‘uma‘u , May 18, 1924, Kīlauea Volcano, Hawai‘i.

(Credit: Maehara, K. Public domain.)

1924: The largest crater in the Kīlauea caldera named Halema’uma’u became highly active for half of the month of May in 1924. This activity resulted from the draining of a nearby lava lake and subsequent earthquakes that occurred in February near lower Puna, about 31 miles (50 km) to the east of the rift zone. This sparked seismic activity throughout the month of April. By the end of the month, hundreds of earthquakes and ground shattering faulting became normal occurrences. On April 29, the crater floor began collapsing, increasing the depth from 377 ft (115 m) to 690 ft (210 m) by May 7th. The first reports of explosive eruptions came on the night of May 9th. May 13th saw larger and more frequent explosions taking place a few hours apart, the largest of which occurred on May 18th. These explosions were caused by the expulsion of steam pressure. Volcanologists believe that a conduit of magma kept collapsing beneath the water table and allowed cold water to make contact with the hot magma. This was happening while the wall and floor structure of the Halema’uma’u crater were also crumbling, thereby obstructing the ventilation and exit of steam vapor. As the subsurface pressure built up more and more, it overpowered the weight of the blockage, eventually ending in violent hydrothermal explosions. This extensive activity made Halema’uma’u grow 200 million cubic meters in volume (about 71 million cubic ft). Another event caused by the crater floor and walls collapsing was a massive dust cloud, which at its highest was estimated to reach 5.5 miles tall (9 km). Despite strong trade winds, wet ash fell over lower Puna and travelled as far as 10 miles (16 km) away. In Glenwood, the roof of a store could not bear the weight of the muddy ash and collapsed. It is believed the that an eruption like this could happen again specifically due to the fact that this major event in 1924 took place during an effusive period of Kīlauea’s history.

1955: This 88-day eruption in the lower east rift zone of the Kilauea volcano was a 4-phase eruption that began from a phase of swelling at the summit of Kïleuea, superseding a small 4-day eruption in 1954 and a total of 700 earthquakes measured in February of 1955 alone. At 8:00 a.m. on February 28, 1955 to the east of Pāhoa, the first phase of the eruption began with massive staggered fissures shooting walls of lava 25-40 feet in the air. Phase two began on March 2nd when a crack crossing the Pāhoa-Kapoho Road widened due to earthquakes. Fault scarps spreading to the northeast began appearing near Kapoho Village. The following day, four new vents opened spewing lava 500 feet into the air with new fountains opening closer to town. By March 7th, the whole village was essentially cut off by what became the Kii lava flow. Phase three consisted of many vents, fountains, pit craters and fissures opening and exploding in several locations around the lower Puna region endangering villages, farms, and infrastructure. From March 12th to the beginning of April, there was no end in sight with continuous earthquakes at the summit of Kïleuea and Lilewa Crater continuing to erupt and feed major lava flows. Those flows destroyed the agriculture in their paths and the Kehena flow, in particular, reached the ocean and demolished several homes on the coast. April 8th looked like the end of volcanic activity in lower Puna and rebuilding efforts were well underway in the area. However, the Lilewa crater was not done yet, as its vents began ejecting lava intermittently until May 16th. It was then that the volume of lava began to grow and before they knew it, residents of the lower Puna area had yet another massive lava flow on the way that was 12 feet (3.6 m) high and 700 feet (213 m) wide. It never reached the ocean like the previous Kii flow, but more structures were destroyed through the month of May. Finally, on May 26th, when the Iwasaki camp was consumed by lava (it had escaped destruction in phase two), a harmonic tremor signaled the end of the eruption.

1959: This was a highly explosive and short-lived volcanic event of the the Kīlauea Iki Crater that took place in November and December of 1959, the foreshadowing of which was witnessed a few months prior. In August of that year, seismographs at the Hawaiian Volcano Observatory recorded several earthquakes deep beneath the surface of the volcano. By October, silt surveys of the caldera documented inflation of the ground surface, indicating new magma was filling the chamber from below. From mid-September to November 1st, shallow quakes were a regular occurrence with as many as 1,000 quakes per day being measured. Activity intensified on the 14th as a 5-hour tremor shook the summit of Kīlauea and kicked off the eruption. The fissure system at the Kīlauea Iki Crater spewed lava fountains 15 to 30 m (50 to 100 ft) high, with the cascading lava forming a lava lake at the bottom of the crater. Within a day, the erupting lava spewed from many vents down to one single vent, with an increased lava fountain height of 60 m (200 ft). By November 17th, a new cinder cone formed from residual cinder, spatter, and pumice (tephra). This excess of rock content fed into the lava lake at the bottom of the crater, rising the lake level throughout the eruptive period. On November 21st, within 40 seconds, the single lava fountain ceased spewing lava and quieted down to a few gas bubbles.

1960: The 1959 Kīlauea Iki eruption came to an end on December 21st, but the reservoir beneath the summit of the volcano got plugged by magma, resulting in more pressure build up than before the eruption began. There was minimal activity throughout the rest of the year. On January 12th, 1960, over 1,000 earthquakes were recorded near Kapoho Village, about 47 km from the summit. The earthquakes grew in size and frequency, creating large fractures along the Kapoho Fault overnight. The ruptures along the Kapoho Fault and the nearby Koa’e fault resulted in a 3-4 foot (1 m-1.2 m) graben, a landscape structure formed by extensional processes where a central block of land drops and the two adjacent side blocks shift upward along relatively parallel faults.

This color image shows residents of the Kapoho Village standing on an uplift block along major fractures running through the str

Ground fractures and uplift in Kapoho Village, Hawai‘i, caused by subsurface magma movement only hours before the January 13th eruption in 1960.

(Public domain.)

The 1960 eruption began on the night of January 13th, characterized by loud blasts from methane explosions and lava fountains as high as 330 feet (100 m) erupting along a 3,000 foot-long (900-m-long) fissure. ‘A‘ā lava flows consumed nearby vegetation and migrated to the northeast, all while groundwater began seeping into the conduits. The reaction with water sent violent steam blasts shooting into the sky, resulting in dark gray billowing clouds carrying large amounts of ash. The steam blasts subsided by noon the next day, but ‘a‘ā lava flows continued to spew despite blockages from fallout accumulation. Throughout the following week, concentrated lava fountains sent tephra 300 m (984 ft) into the air and lava flowed throughout the graben and towards the ocean, covering nearby recreation sites on its path. Despite barrier efforts to divert the progression, the lava flows encompassed the Warm Springs picnic area and reached the ocean on January 15th, ultimately extending new land 100 m (328 ft) beyond the old shoreline. By January 28th, lava had covered the Kapoho cemetery, enveloped the Kapoho School, and destroyed Coast Guard residences near Cape Kumukahi. The Koa’e Village also fell victim to lava flow progression, losing the community hall, a local church, and one residence. On January 30th, lava fountain temperatures increased 20-50 degrees Celsius (about 70- 130 F) due to a batch of hotter magma from Kīlaueas summit mixing with a storage reservoir of cooler magma beneath the Kapoho area since before 1955. High-spewing fountains continued through February 15th and steadily declined until eruptions came to an end on February 19th. By the end of the eruption, lava flows covered more than 10 km2 (4 mi2), including 2 km2 (0.75 mi2) of new land beyond the original shoreline. The volume of lava erupted is conservatively estimated as 122 million m3 (160 yd3) with an additional 7.5 million m3 (10 yd3) of pyroclastic material. Simultaneously, Kīlauea’s summit began experiencing increased earthquake activity beginning on January 23rd. The Halema‘uma‘u Crater floor began deflating in early February, as magma left the storage reservoir to feed into the Kapoho eruptions downhill. The final collapse of the Halema‘uma‘u crater floor occurred on March 11th, and the total volume of collapse was about 22 million m3 (29 million yd3).

1969- 1974: The Mauna Ulu eruption started on May 24th 1969 on Kīlauea's east rift zone after only a few hours of increased seismicity. Three brief eruptions occurred within the nine months preceding the main event. Kīlauea's summit also displayed noticeable signs of swelling due to magma filling the underground reservoir. The eruption began along a 4-km- (2.5-mi-) long fissure system, where Mauna Ulu (“growing mountain”) formed between the ‘Ālo‘i and ‘Alae pit craters. Twelve fountaining events took place in the summer of 1969, shooting lava as high as 540 m (1,770 ft) and building tephra mounds downwind of the vent from volcanic fallout. Lava flowed over fountain deposits resulting in chaotic landscapes and spilled into the ocean about 12 km (7.5 mi) away. By August 4th, ‘Alae Crater overfilled and cracked, allowing lava to cascade down 80 m (260 ft) in about 30 minutes. Between each fountaining event, a process known as gas pistoning occurred, in which lava rose and fell rhythmically and eventually created a lava shield that matured into the present-day Mauna Ulu edifice.

Lava falls higher than American Falls at Niagara begin to fill ‘Ala...

Lava falls higher than American Falls at Niagara began to fill ‘Alae Crater on August 5, 1969.

(Public domain.)

From December 1969 to June of 1971, Mauna Ulu experienced a major edifice-building sequence. A new fissure appeared on April 9th, allowing lava to start filling the crater. In July, the walls of the summit fissure gradually collapsed and widened, resulting in a lava lake that fed underground lava flows. Mauna Ulu went into hibernation through mid-October, marked by the draining of the lava lake and showing no signs of eruptive behavior. Activity picked up again in February of 1972 as Kīlauea's summit inflated, indicating pressurization of the volcano’s plumbing system. For the next 15 months, the Mauna Ulu summit experienced sequences of overflowing lava flow events reaching ‘Alae Crater, Makaopuhi Crater, and the sea. December of 1973 to July of 1974 was marked by short-lived, low fountains of about 40-80 m (130-260 ft) high alternated with slow outpourings of lava from the crater. These quiet overflows contributed to the growth of the shield to its maximum height of 121 m (397 ft) above the pre-eruption base. The lava lake slowly disappeared, and the end of the eruption was declared on July 22nd, 1974.

1983- 2018: The longest and most voluminous known outpouring of lava from Kīlauea Volcano's East Rift Zone in over 500 years was the eruption of Pu‘u ‘Ō‘ō. This eruption began in 1983 and lasted 35 years, resulting in a volume of 4.4 km3 (1.1 mi3) of erupted lava which covered about 144 km2 (55.6 mi2) of land from lava flows, and added 177 hectares (439 acres) of new land to Kīlauea's southeastern shore.

Lava fountain erupts from Pu‘u ‘Ō‘ō, Kīlauea Volcano, Hawai‘i...

Lava fountain from the Pu‘u ‘Ō‘ō eruption, Kīlauea Volcano, Hawai‘i.

(Public domain.)

Scientists have condensed the 61 episodes of eruptive activity into five broad time periods, each separated by the style of the eruption and the location of the erupting vent. The first phase took place between January 1983 to July 1986 and was recorded as a growing period for the volcano, Pu‘u ‘Ō‘ō. During this three year phase, a series of 44 lava fountains continuously fed thick ‘a‘ā flows over the surrounding landscape, slowly building the main edifice of the cinder-and-spatter cone to a maximum height of 255 m (835 ft) above the pre-1983 surface. The next eruptive period spanned from July of 1986 to February of 1992, represented by a continuous effusion of pāhoehoe lava flows that cut through a coastal community, covered a portion of Highway 130, and eventually reached the ocean. The overflow material contributed to the building of Kupaianaha, a broad, low shield that grew above the vent to a height of 56 m (180 ft) in less than a year. The most destructive period of this eruption took place from March to December of 1990, when lava spilled out of a burst lava tube and migrated through the Kalapana community, covering several historic sites, homes, and black sand beaches beneath 15-25 m (50-80 ft) of lava. Shortly after, the discharge of lava from Kupaianaha began to decline as new fissures and eruptive activity increased in Pu‘u ‘Ō‘ō. This eruption phase came to an end on February 7th 1992 and a new phase officially began at Pu‘u ‘Ō‘ō ten days later. This next eruption lasted from February 1992 to June 2007 and was recorded as a quiet and continuous effusion of pāhoehoe lava that built a broad shield 130 m (425 ft) tall and a series of lava deltas on Kīlauea's southeast coast, extending the land mass about 169 ha (418 acres). This period experienced several collapses that ultimately enlarged the crater diameter, lowered the rim elevation, and formed many smaller pits and craters on the flanks of the cone. The magma reservoir beneath Pu‘u ‘Ō‘ō depressurized on June 17th, 2007, resulting from a magma intrusion from Kīlauea's upper East Rift Zone. The intrusion caused a brief eruption and collapse of the crater, followed by a 12-day pause in eruptive activity.

Lava cascades out of perched lava channel into lower channel, Pu‘u ...

A view of an erupting fissure, which created a perched lava flow on the east flank of Pu‘u ‘Ō‘ō in 2007.

(Credit: J. Kauahikaua, USGS. Public domain.)

The next period spanned from July 2007 to March 2011, when a fissure on the northeastern flank of Pu‘u ‘Ō‘ō halted the rising magma in the crater and dispersed ‘a‘ā flows that reached as far as 6 km (4 mi) to the northeast. Growing concern for the safety of downslope communities from this eruption resulted in the creation of a new hazard assessment by HVO scientists as an effort to determine diversion options. Three houses, previously built atop of earlier Kalapana flows, could not be spared. As eruptive activity lulled, the Pu‘u ‘Ō‘ō crater once again began to fill indicating that the system was repressurizing. On March 5th, a new intrusion generated the 5-day Kamoamoa fissure eruption uprift from Pu‘u ‘Ō‘ō, closing out the end of this eruption period. The final period spanned from April 2011 to April 2018 and involved an eruption series displaying a sequential pattern between rapid filling of the Pu‘u ‘Ō‘ō crater, lava overflowing from the rim, downslope lava flows and spreading, and new fissure formations allowing for depressurization of the central magma chamber. This sequence occurred about three times during this eruption phase and eventually ended on April 30th, 2018, when the crater floor and lava lake of Pu‘u ‘Ō‘ō catastrophically collapsed.

2008- 2018: The 25 years that followed the 1982 eruptive activity at the Kilauea summit were relatively quiet. The overlook at the crater’s rim became a popular tourist destination where visitors could observe the steam cloud up close. However, in November of 2007, new activity began to reveal itself in the form of seismic tremors and sulfur dioxide emissions that had increased beyond their normal levels. For safety purposes, the western part of the crater closed to the public on February 20, 2008. Superficial signs of volcanic activity became visible on March 12, 2008 after a fumarolic area appeared on the south wall of the previously popular Halema’uma’u overlook and formed a huge gas plume which glowed in the night. Seven days after the fumarolic plume formed, a small earthquake at the summit of Kilauea occurred at 2:58 a.m. on March 19, 2008 and triggered an eruption near the overlook. Blocks of lithic lava were broken loose from the crater and the vent at the summit reopened. Despite the thick gaseous emissions around the crater, geologists at the Hawaii Volcanic Observatory were able to identify fresh lava deep within the crater that occasionally spewed fresh lava bombs, in addition to the explosions caused by the lithic deposits. A helicopter passing over the crater on September 5, 2008 provided a clear view of a bubbling lava pond beneath the crater’s rim, a phenomenon typically only visible as a lingering orange glow from distant viewing areas. Throughout 2009, the lava level in the crater continuously rose and fell, creating sporadic, small lava ponds and causing the floor of the crater rim to fall into the vent. Geologists were able to observe the crater more clearly during this time with help from thermal imaging. They laser scanned the area which allowed them to measure the depth of the crater which, at its deepest, was 220 meters (220 yards). The fluctuating lava ponds of 2009 became a steadily growing lava lake in 2010 after the overlook crater floor experienced a large collapse in February. Crustal plates were visible on the lake’s surface, but spattered lava often impaired geologists’ observations. Gas pistoning events were common during this time, allowing the lake level to rise around 20 m (65 ft) due to subsurface gas accumulation. Following rapid and volatile spattering at the surface, the depressurization would then cause the lava lake level to fall again.

View of the lava surface within the Overlook vent showing a crusted...

View within the Overlook vent showing the crusted lava surface with spattering from a single source, Kīlauea Volcano, Hawai‘i. April 7, 2009.

(Public domain.)

In 2011, for the first time in this series of eruptive events, the surface of the consistently growing lava lake was visible from the Halema’uma’u Overlook. In March, the surface was a mere 60 m (197 ft) away. This growth was due to the crater walls breaking away, which was an event accompanied by a cacophony of loud cracks and rumbles. As more and more spatters and explosions occurred, it was made clear that they were triggered by rock fall at the rim of the crater. All of this activity meant that the magma system beneath the crater’s surface was pressurizing. The building pressure opened up new vents along the East Rift Zone to the west of Pu’u ‘Ō’ō cone on March 5, 2011. This is was the site of the Kilauea eruption that had been ongoing since 1983. The creation of those vents caused a massive pressure drop in the lava lake near the overlook, and what resulted was a massive draining of the lava lake to a depth of 140 m (460 ft). The lava fountains near Pu’u ‘Ō’ō were active for five days, and upon the loss of flow in that area, the fountains ceased and the lake at the Overlook began to refill over several months. That sequence of events repeated itself two more times until the end of 2011. The second pressurization was released, and the lake drained via a new vent on the East Rift Zone on August 3rd. The third draining and depressurization exited through yet another new vent on the East Rift Zone, occurring on September 21st, 2011. The activity in Kilauea during 2012 can be categorized by one acronym: DI, which stands for deflation-inflation. Throughout the whole year, the lake levels inside of the crater were falling (deflating) up to 10 m (33 ft) and rising (inflating) again. A sudden and rapid rise in October 2012 came 20 m (66 ft) from the floor of Halema’uma’u and yielded some of the best views of the lake yet. In 2013 the lava lake’s level at Halema’uma’u remained high; 30-60 meters (98-197 ft) with lava upwelling in the north end of the lake and slowly moving south. On the south end, the lava sank as it approached the edges where spattering was common. Deflation-inflation cycles continued to affect the levels of the lake and the crustal tectonic plates, which were separated by incandescent spreading zones. Those spreading plates traveled from north to south at 10-20 cm (4-8 inches) per second, all while falling chunks of the crater wall continued to contribute to spattering. In April of 2015, lava spilled over the rim of Halema’uma’u for the first time during this current eruption event and covered nearly a quarter of the crater floor in new lava flows. This was also the first time there was an ability to see lava flows with the naked eye from the several public viewing areas surrounding the crater. On May 10th, a deflation event occurred dropping the lake level back below the crater’s rim, and out of view from observation points.

Sunset view of the lava lake in Halema‘uma‘u crater about 33 m (110...

A sunset view of the lava lake in Halema‘uma‘u crater about 33 m (110 ft) below the crater floor, Kīlauea Volcano, Hawai‘i. October 23, 2012.

(Public domain.)

In the beginning of 2016, after a constant rise of lava, the surface of the lake became visible from the Jagger Overlook and remained at high levels for the rest of the year. Data collected during this time helped geologists determine a rough dimension of the lake at roughly 250 meters long (820 ft) and 190 meters wide (623 ft); dimensions that were not far from the crater itself. The lake continued to rise and fall into 2017 becoming visible at the different overlooks in the area. The Jagger Museum was a popular tourist destination; especially when the lava lake glowed at dusk. The lake in Halema’uma’u crater is one of merely a handful of persistent lava lakes on Earth and is closely matched only by the Nyriagongo Volcano in the Democratic Republic of the Congo. That was until just after the 10-year anniversary of eruption’s inception a new eruption at Kilauea’s East Rift Zone drained the lava lake at the summit. Following this massive draining, the crater experienced the largest collapse in 200 years.

2018: On April 30th, 2018, the Pu‘u ‘Ō‘ō vent collapsed, before  a massive eruption that followed in May 2018. Eruptive fissures along the eastern rift zone in cohesion with an earthquake [moment magnitude (Mw) 6.9] on May 4th caused roughly 5 m (16 ft) of fault slip. This quick release of built-up pressure cleared the path for lava to erupt at rates exceeding 100 cubic meters (131 cubic yards) per second, eventually covering 35.5 square kilometers (14 square miles). This partial draining of the summit magma system led to minor explosions and seismic events of a magnitude (Mw) 4.7 to 5.4 that eventually began to decline in frequency on August 4th. The 2020 crater dimensions measure to about 1600 feet (487 m) deep and 1.5-miles (2.4 km) wide, whereas before the eruption it was 280-feet (85 m) deep and 0.5 miles (0.8 km) wide. A never-before-seen lake at the bottom of Kilauea’s crater was confirmed on August 1st, 2019 which, as of July 2020, was 128-feet (39 m) deep, 430-feet (131 m) wide, and 800-feet (244 m) long, with a water temperature of about 158-degrees Fahrenheit (70-degrees Celsius).

image related to volcanoes. See description

An aerial view of the fissure 8 lava flow moving down open channels to the central coastal flow field southeast of Kapoho Crater on July 30th, 2018.

(Public domain.)

The 2018 eruption was meticulously observed, and scientists utilized previous knowledge of eruptive patterns and behavior to accurately predict potential hazards associated to this event. This eruption was closely monitored, with hazard assessments, public information, and FAQs about deformation and earthquakes being published throughout the eruption in May, June, and July. Detailed photo and video chronology of the 2018 volcanic activity at Kilauea and additional relevant publications and maps were released to the public after the event. There are also several video presentations created by the USGS explaining seismicity, chemistry, geology and monitoring associated with Kīlauea. Additional video footage and photography of the 2018 eruption of Kilauea can be located on the USGS multimedia site.

Two color photograph's of lake

Comparison of images showing growth of Kīlauea's summit water lake over the past year. The left image, taken on August 2, 2019, shows a small green pond that was approximately 6 ft (2 m) deep. The right image, taken on July 21, 2020, shows a lake more than 130 ft (40 m) deep with shades of tan to brown and a sharp color boundary often cutting across the lake. Hawaiian Volcano Observatory scientists continue to monitor the lake, and Kīlauea's summit. 

(Credit: USGS. Public domain.)

From July to December of 2019, ponded water first appeared at the bottom of Halema‘uma‘u crater at the summit of Kīlauea Volcano. Volcanic interaction with water has the potential to produce catastrophic eruptions, which has led to further research and close monitoring of water levels by USGS scientists today.

Color photograph of volcanic vent

Low fountaining continues to supply lava to the lake through January 15th at the western fissure in Kīlauea's summit.

(Public domain.)

2021: Kīlauea has been displaying volcanic activity more recently as observed by increases in inflationary tilt, or swelling of the land, at the summit and elevated emissions of sulfur dioxide. The volcano is erupting, with lava activity currently confined to a vent on the northwestern side of the Halemaʻumaʻu crater. Real-time webcam footage has assisted the monitoring of the rising lake level in the perched western end of the lava lake, while the lower eastern portion of the lake continues to show minimal rising. USGS scientists on the island are producing ongoing hazard analyses and updating details on the volcano’s status as the eruption unfolds.







USGS Hawaiian Volcano Observatory

The Hawaiian Volcano Observatory (HVO) was founded in 1912 and, until 2018, was located on the rim of Kilauea’s caldera with the sole purpose of monitoring volcanic activity on the Hawaiian Islands. Any activity, volcanic or otherwise as well as hazards, are investigated and assessed in this facility in the name of research. Reports are generated by the site’s findings and distributed among government agencies, the public, and scientific community to further humanity’s knowledge of geologic activity and how to adequately respond to Mother Nature. After increased volcanic activity in 2018 that damaged the building, the HVO was moved to the nearby city of Hilo where it is still located today. Plans are in place to construct new facilities in the city as well as in the National Park.

This color air photo shows the USGS Hawaiian Volcano Observatory sitting to the west of the Mauna Loa caldera in in Hawai‘i Volc

The USGS Hawaiian Volcano Observatory was the first volcano observatory in the United State and is located on the west rim of Kīlauea Volcano's summit caldera in Hawai‘i Volcanoes National Park.

(Public domain.)

When HVO became the first of five USGS-supported volcanic observatories, the HVO had only one geologist: Thomas A. Jagger. Today, there are 30 researchers, all of whom specialize in a wide array of geologic fields as well as media and communications. The HVO also receives help from volunteers, students, and visiting scientists and currently employs over 200 pieces of sensory equipment which work around the clock including seismometers, GPS, gas detectors, thermal imaging, and more to understand and prepare for hazards such as earthquakes, geologic deformation, and volcanic gassing events. More specifically, HVO’s monitoring program allows geoscientists to report seismic updates, track active lava flows, detect ground elevation changes and temperature fluctuations, and analyze volcanic gasses and subsurface magma movement to inform and warn the public ahead of a disastrous event.

Both volcanoes can be observed by the public via live webcams and USGS updates of current conditions on the National Park Service “Plan Your Visit” webpage. A detailed 2009 geologic report was also conducted at this park to further explain Hawaiian geology and a Geodiversity Atlas was published by the National Park Service to provide a Geologic Resources Inventory, a Soil Resources Inventory, and information on geoconservation programs in the park.