The Science Behind Hawaii's Surprising 2018 Volcanic Eruption
Fountaining at Fissure 22 has reached as high as 160 feet (50 meters). This photo was taken May 22.
Credit: U.S Geological Survey

Kilauea volcano is spewing lava and belching hazardous gases on Hawaii's Big Island, forcing more than 1,700 people to evacuate their homes.

Eruptions aren't anything new on Kilauea. In particular, the Pu'u 'Ō'ō vent, where lava is exposed, has erupted almost continuously since January 1983. But the latest eruption took volcanologists by surprise when it invaded Leilani Estates, a residential area near Kilauea.

Signs of trouble began in mid-March, when increased magma in the system prompted the Pu'u 'Ō'ō vent to inflate in size, like when a chef pumps cream into a cream puff, Janet Babb, a geologist and Hawaiian Volcano Observatory spokesperson, previously told Live Science. This surge of magma ultimately caused Pu'u 'Ō'ō's crater floor to collapse on April 30. After this, the excess magma traveled southeast toward the residential Puna District, Babb said. [Kilauea Volcano: Facts About the 30-Year Eruption]

Small earthquakes had shaken the region all that week, but residents were taken aback by 5.0- and 6.9-magnitude earthquakes on May 3 and 4, respectively, which preceded lava eruptions. Now, newly opened fissures are bubbling with lava almost daily, and Hawaii County Civil Defense has warned sightseers to stay away for safety's sake.

A lava flow emerges from Fissure 22 on May 23. Notice how the lava is flowing downhill, from right to left in the photo.
A lava flow emerges from Fissure 22 on May 23. Notice how the lava is flowing downhill, from right to left in the photo.
Credit: U.S Geological Survey

Several lava fissures reactivated last night within the Leilani Estates and Lanipuna Gardens residential areas. These include fissures 2, 3, 7, 8, 14 and 21, which are spattering lava, meaning they're throwing chunks of molten rock into the air, according to the Hawaiian Volcano Observatory (HVO).

There are other hazards, too: The fissure eruptions are releasing hazardous volcanic gases, and the ground is still shaking with small earthquakes.

At Kilauea's summit, small ash emissions continue to hiccup out of the Overlook crater. In fact, ash plumes reached 6,000 feet (1,800 meters) during several energetic explosions, but this ash dispersed quickly, the HVO said.

Meanwhile, the HVO just reported that Leilani Estates saw eerie blue flames Tuesday night (May 22) as lava burned plants and shrubs, which in turn released methane, a blue-burning gas. [Read more: Why Eerie Blue Flames Just Erupted from Hawaiian Volcano]

Fountaining at Fissure 22 has reached as high as 160 feet (50 meters). This photo was taken May 22.
Fountaining at Fissure 22 has reached as high as 160 feet (50 meters). This photo was taken May 22.
Credit: U.S Geological Survey

Leilani Estates and Lanipuna Gardens are still home to intrusive guests: erupting lava and cracking ground. Just like yesterday, the middle part of the fissure system is sizzling, with fissures 5, 6, 19, 22 and 23 showing the most activity, the Hawaiian Volcano Observatory (HVO) said. Fissure 9 has a faint glow, but isn't producing any lava flows.

Overnight, methane burned in the area's road cracks, the HVO noted.

Lava is likely still pouring into the ocean, where it is producing small explosions, the HVO said. The lava channel there is now quite high — about 36 feet (11 meters) above ground. Meanwhile, volcanic gas emissions are still elevated from the fissure eruptions, and small earthquakes are still rocking the area from the active magma underground.

At Kilauea's summit, the Overlook crater is releasing small gas plumes. Winds are blowing these plumes to the southwest, meaning ash may fall in that area, HVO said.

A aerial view of a lava breakout on May 22.
A aerial view of a lava breakout on May 22.
Credit: U.S Geological Survey

The Leilani Estates residential area can't catch a break: Erupting lava and ground cracking continue to besiege the subdivision.

The most active fissures are in the middle of the fissure system, including fissures 5, 6, 19, 22 and 23, although fissure 17, in the northeastern part of the fissure system is still weakly active, according to the Hawaiian Volcano Observatory (HVO). Fissures 6 and 22 are feeding lava flows, and fissures 5 and 23 have fountaining lava in the eastern part of Leilani Estates, the HVO said. Moreover, the flow of magma underground continues to cause small earthquakes in the region.

At the summit, the Overlook crater is burping out small ash clouds.

A bird's-eye view of lava erupting out of fissure 22. Photo courtesy of Volcano Helicopters.
A bird's-eye view of lava erupting out of fissure 22. Photo courtesy of Volcano Helicopters.
Credit: U.S Geological Survey

A small explosion tore through Halema'uma'u, the lava lake at Kilauea's summit, early this morning, at 12:55 a.m. Hawaii Standard Time. The blast produced an ash plume reaching about 7,000 feet (2,133 meters) above sea level, according to the Hawaiian Volcano Observatory. This plume is big, but not as large as the 30,000-foot-high (9.1 kilometers) plume that the volcano belched out last week, following an even larger explosion at the summit.

A geologist with the Hawaiian Volcano Observatory stands next to cracks on Nohea Street in Leilani Estates yesterday (May 17).
A geologist with the Hawaiian Volcano Observatory stands next to cracks on Nohea Street in Leilani Estates yesterday (May 17).
Credit: U.S Geological Survey

The lava isn't taking a break. A "moderate-level" of lava continues to erupt from the active fissure system in the residential Puna District, which sits next to Kilauea volcano, according to the Hawaiian Volcano Observatory (HVO).

There is spattering (airborne chunks of lava) from fissures 15, 17, 18, 20, 21 and 22, as well as pahoehoe lava — smooth undulating or ropy masses of lava — flowing from fissures 17, 18 and 20, the HVO said.

Volcanic gas levels are still high, and weak winds today mean that other areas on the Big Island might be affected. Click here for forecast information. Moreover, lava moving underground (where it's called magma) continues to cause small earthquakes in the area.

The summit is somewhat calmer than yesterday, when an explosion sent ash 5.6 miles (9.1 kilometers) into the sky. But there is some activity: A "robust plume of gas and steam is billowing out of the Overlook vent and drifting generally southwest," the HVO reported.

Webcams that operate 24/7 faithfully recorded the ashy cloud that reached as high as some commercial airplanes fly.
Webcams that operate 24/7 faithfully recorded the ashy cloud that reached as high as some commercial airplanes fly.
Credit: U.S Geological Survey

The summit at Kilauea exploded today as boulders and a volcanic cloud, more than 5 miles high, spewed out of the Overlook vent at the top of the volcano.

The explosion happened shortly after 4 a.m. Hawaii Standard time, and sent a plume about 30,000 feet (5.6 miles, or 9.1 kilometers) into the sky, an altitude where commercial airplanes fly, according to the Hawaiian Volcano Observatory.

There are no reports of injuries, but the National Weather Service issued an ashfall advisory. Also, due to high levels of sulfur dioxide, several local schools are closed. [Read more: Kilauea Spews Boulders in 5-Mile-High Eruption]

Civil Air Patrol flight CAP20 reported plumes as tall as 9,500 feet (2900 meters), with the dispersed plume rising as high as 11,000 feet (3,300 m) on May 15. Ash from this plume fell on communities downwind of Kilauea.
Civil Air Patrol flight CAP20 reported plumes as tall as 9,500 feet (2900 meters), with the dispersed plume rising as high as 11,000 feet (3,300 m) on May 15. Ash from this plume fell on communities downwind of Kilauea.
Credit: U.S Geological Survey

Lava flows escaping from Fissure 17 are slowing down, only advancing about 100 yards (91 meters) in the last 24 hours, according to the Hawaiian Volcano Observatory (HVO). Meanwhile, high levels of volcanic gas are being emitted downwind of the volcanic vents, and trade winds hitting Hawaii today may bring these hazardous gasses to other parts of the island, the HVO said.

At the summit of Kilauea, enormous ash plumes — some reaching as high as 10,000 feet (3,000 m) above sea level — astonished onlookers yesterday (May 15). These plumes came from the Overlook vent, where the lava lake Halema'uma'u sits. It's likely that rockfall into the lava lake led to these plumes, the HVO said. The ash from these clouds dusted communities from Pahala to Discovery Harbor with ash and made it hazardous to operate aircraft in the area.

The surprises didn't end there. Two-foot-wide (60 centimeters) ballistic blocks were found in the parking lot, just a few hundred yards from Halema'uma'u.

"These reflect the most energetic explosions yet observed and could reflect the onset of steam-driven explosive activity," the HVO said. "Additional such explosions are expected and could be more powerful."

Steam jets out of Fissure 17 on May 14.
Steam jets out of Fissure 17 on May 14.
Credit: U.S Geological Survey

Lava continues to pour from several active fissures. Lava flows crept forward at about 20 yards per hour (0.01 kilometer per hour) from Fissure 17 last night, according to the Hawaiian Volcano Observatory.

Meanwhile, a new fissure opened this morning in the Lanipuna Gardens subdivision, northeast of Fissure 19. And volcanic gas emissions are still high, especially in areas downwind of the volcanic vents. Little earthquakes, many of them magnitude 2 to 4, continue to shake the region as magma roils underground.

At Kilauea's summit, a plume from the Overlook vent — where the lava lake Halema'uma'u is housed — is "steady and gray" because of volcanic ash, the Hawaiian Volcano Observatory said. This plume is enormous — it's rising several thousand feet above ground and drifting southeast. Ashfall is already falling down to earth in the upper Ka'u Desert and downwind of the summit.

At 8 a.m. Hawaii Standard Time (HST) on May 13, a slow and sticky flow emerges from a new fissure — No. 17 — northeast at the end of Hinalo Street.
At 8 a.m. Hawaii Standard Time (HST) on May 13, a slow and sticky flow emerges from a new fissure — No. 17 — northeast at the end of Hinalo Street.
Credit: U.S. Geological Survey

There was a stupendous lava show this morning from Fissure 17 (the cracks that have opened up during this eruption are numbered, starting with No. 1), with lava fountaining and explosions of spatter that are being hurled more than 100 feet (30 meters) into the air. Fissure 17 also had lava flowing from it. Meanwhile, Fissure 18, which opened yesterday, is only weakly active now and Fissure 19 is emitting a sluggish lava flow, according to the Hawaii Volcano Observatory. [Photos: Fiery Lava from Kilauea Volcano Erupts on Hawaii's Big Island]

Although Pu'u 'Ō'ō is getting much of the public's attention, geologists have also been monitoring the lava lake at Kilauea's summit. This lava lake — called Halema'uma'u — is dropping dramatically, and if it goes below the water table, there could be a steamy and rocky explosion, geologists said. [Read more: Kilauea Volcano Could Launch 10-Ton Ballistic Boulders in a Dramatic Explosion]

A total of 10 volcanic fissures have opened, pouring lava into the residential area of Leilani Estates. Fires from the lava have burned down 35 structures — mostly homes. Volcanic air pollution known as "vog" has prompted authorities to caution that people with breathing problems should stay inside and use air purifiers if needed. [Read more: Incredible Video Shows the Fiery Toll of Kilauea on Hawaii's Big Island]

A magnitude-5.0 earthquake that struck the Big Island on May 3 was followed by lava eruptions that sounded as loud as a jet engine. This prompted mandatory evacuations of the Leilani Estates and Lanipuna Gardens subdivisions. [Read more: Hawaii's Kilauea Volcano Erupts Dramatically After a 5.0-Magnitude Quake]

More than 600 earthquakes have rattled Hawaii's Big Island over the past four days as magma from Kilauea volcano moves toward the residential area of Leilani Estates. [Read more: Do Hundreds of Earthquakes in Hawaii Mean Kilauea Could Blow?]

Original article on Live Science.