Earthshots: Satellite Images of Environmental Change

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» Kīlauea, Hawaii, USA
 

In 2018, Hawaii was in the news as fresh lava covered 13.7 square miles (35.5 km2) at the eastern end of the Big Island. Of course, lava flows in Hawaii are nothing new. Satellite imagery shows evidence of many lava flows from the past, appearing like dark curtains draped across the southern coast of the island.

The lava flows on this part of the island are from Kīlauea, the youngest volcano on the Island of Hawai‘i. Almost all of Kīlauea’s surface is made up of rock that is less than 1,000 years old. It’s on the southeastern flank of Mauna Loa but has its own magma plumbing system, so it’s a separate volcano. This shield volcano is one of the world’s most active.

Map of the featured area.

The 2018 eruption was part of an ongoing eruption sequence that started on January 3, 1983, with fissures breaking out along the East Rift Zone.

Over the next 3 years, constant fountaining from one vent built a cone named Pu‘u ‘Ō‘ō. Eruptive activity continued from this vent until 2018, the longest East Rift Zone eruption ever recorded.

Landsat images show the area around Pu‘u ‘Ō‘ō. The 2018 lava flow emerged farther along the East Rift Zone to the northeast.

The Pu‘u ‘Ō‘ō eruption took a destructive turn in March 1990. Breakouts from a lava tube spread lava into the Kalapana community. Images show the entire community, known for its historic sites and black sand beaches, being completely covered with lava. Bright spots in the 1989 and 1991 images are active lava flows.

A church, store, and more than 100 homes were buried under 15–25 m of lava. The devastating event finally ended in late 1990 when a new lava tube diverted lava away from Kalapana and back into Hawai‘i Volcanoes National Park.

On June 27, 2014, new fissures erupted just east of Pu‘u ‘Ō‘ō crater and lava advanced rapidly to the east. By late October, lava had advanced 20 km toward Pāhoa. The flow eventually stalled 1,800 feet (550 m) from the Pahoa police and fire stations. It also reached within 500 feet (150 m) of Pāhoa’s main street before stopping. By mid-December, the lava flow threatened the Pāhoa Marketplace shopping center but no damage was done there. The entire flow extended 13.5 miles (21.7 km).

Landsat imagery shows this flow as ragged, dark lines protruding from the main lava flows around Pu‘u ‘Ō‘ō. An image from the European Space Agency’s Sentinel-2 satellite shows the lava flow and Pāhoa in slightly higher resolution and makes it clear just how closely the flow approached the community.

On April 30, 2018, rapid changes in the East Rift Zone were detected. The Pu‘u ‘Ō‘ō crater floor collapsed. Ground deformation toward the east indicated magma intrusion approaching the Leilani Estates neighborhood, 20 km from Pu‘u ‘Ō‘ō.

Based on numerous geological, geochemical, and geophysical instruments, the USGS Hawaiian Volcano Observatory and other scientists determined that magma had drained from below Pu‘u ‘Ō‘ō crater. It then intruded through underground tunnels and emerged at eruptive vents, or fissures, in the lower East Rift Zone.

On May 3, the first of 24 fissures along a 6-km line opened within Leilani Estates. Fissure 8 became the dominant vent on May 28. It shot lava tens of meters into the air and sent a vigorous flow toward the coast, ultimately entering the ocean near the eastern tip of the island.

This series of images shows the progression of the lava flows throughout the summer of 2018. Clouds often obscure views of the island, but numerous observations from Landsat, Sentinel-2, and Resourcesat offered peeks through the clouds to the location of fresh lava. Some of the images also show “laze.” When lava mixes with seawater, it creates a noxious gas plume that looks like clouds or smoke. The word is a blend of the words lava and haze. Laze can cause skin and eye irritation and breathing difficulties.

This flow ended abruptly on August 4, 2018. By this time, lava had destroyed more than 700 structures, covered 13.7 square miles (35.5 km2) of land, and added about 741 acres (300 hectares) of land to the island. Lava was a couple hundred meters thick in some places.

Meanwhile, at the summit of Kīlauea, the Halema‘uma‘u crater and surrounding caldera floor subsided throughout the summer of 2018. Kīlauea has something like a plumbing system connecting Halema‘uma‘u crater at the summit to the lower flanks of the volcano. The collapse at Halema‘uma‘u suggests the underlying magma reservoir largely drained into the lower East Rift Zone to feed the lava flows.

Magma draining from the summit hints at the possibility of a quiet interlude at Kīlauea for several years. While April 30, 2018, marked the beginning of the recent lava flow event, it also marked the end of the continuous eruptive activity at Pu‘u ‘Ō‘ō that started in 1983.

Although lava flowed from the East Rift Zone and devastated the Leilani Estates neighborhood, the April 30 collapse of Pu‘u ‘Ō‘ō crater left this eruption site devoid of lava. Since lava did not return to the crater after August 4, the USGS has said the Pu‘u ‘Ō‘ō eruption is over.

However, the USGS Volcano Hazards Program says Kīlauea is still active and will erupt again. Volcano hazards in the area remain the same. Based on historical data, it’s unlikely that lava will erupt again from Pu‘u ‘Ō‘ō, but the East Rift Zone still has magma underneath, and it will erupt again through another vent. It may take several years for enough magma to accumulate again, but Kīlauea and the East Rift Zone remain very active.

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