Volcano Watch: What a day! Eruptions, earthquakes, and a lower lava lake

  • An intrusion of magma into Kilauea Volcano’s lower East Rift Zone resulted in an eruption in Leilani Estates in the lower Puna District on the Island of Hawaii. The first four fissures to erupt in the subdivision are shown here on Friday, emitting copious amounts of hazardous sulfur dioxide gas. Pu‘u ‘O‘o (top center), which is about 20 km (12.4 mi) uprift of Leilani Estates, can be seen on the far horizon. As of Sunday, at least 10 fissures have erupted in the subdivision. (USGS photo by T. Neal.)
  • With each large earthquake, ground shaking causes an additional collapse within the Pu‘u ‘O‘o crater, sending a plume of reddish-brown ash skyward. The size and vigor of a plume depends on the size of the earthquake and subsequent collapse. This roiling ash plume followed the magnitude-6.9 earthquake on Friday. Much of the rock within the crater is rust in color, which is a result of heavy alteration by acidic volcanic gases. When the rock is pulverized by a collapse event, the resulting ash plume is pink to reddish-brown ash plume. (USGS photo by T. Neal.)
  • Over 500 earthquakes were located by the USGS Hawaiian Volcano Observatory between noon Friday and noon Saturday. A magnitude-6.9 earthquake at 12:32 p.m. on Friday was preceded by two foreshocks with magnitudes of 5.4 and 4.4 at 11:32 a.m. and 11:38 a.m., respectively, and followed by eight aftershocks with magnitudes greater than 4.0, including a magnitude-5.3 at 2:37 p.m. Moderate to strong aftershocks should be expected for weeks to months to come. The earthquakes are related to the ongoing intrusion into Kilauea’s East Rift Zone and reflect adjustments beneath the south flank of the volcano. (USGS map.)
  • Kilauea’s summit eruption within Halemaʻumaʻu did not initially respond to the volcano’s East Rift Zone activity (collapse of the Pu‘u ‘O‘o crater floor and magmatic intrusion into the rift zone) on April 30. But on Wednesday, the lava lake level began to drop in concert with summit deflation, suggesting that magma was moving from the summit into the East Rift Zone. By Friday, when this photo was taken, the lava lake level had dropped 85 m (279 ft). The lake continues to drop. Lava that spilled from the lake and onto the floor of Halemaʻumaʻu during April 21-27 formed the dark-colored flows that can be seen on either side of the lava lake. (USGS photo by J.Babb.)

The USGS Hawaiian Volcano Observatory was unable to issue Volcano Watch by its regular Thursday deadline on May 3 due to unfolding events on Kilauea Volcano. Little did we know that Friday would be even more hectic.

How it began

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Following a collapse of the Pu‘u ‘O‘o crater floor on Monday, April 30, an intrusion of magma migrated down Kilauea’s East Rift Zone, advancing below ground toward Highway 130 and communities in the lower Puna District on Hawaii Island. The possibility that the intrusion would lead to an eruption of lava became more likely as numerous small earthquakes shook the area over the next few days.

On Thursday, May 3, it happened. With little fanfare, steaming ground cracks were soon spewing lava in Leilani Estates.

By Friday morning, three additional fissures had opened in the subdivision, with lava traveling less than a few tens of meters from the vents.

Then, Kilauea really started rocking and rolling. It began with a magnitude-5.4 earthquake at 11:32 a.m. An hour later, a magnitude-6.9 earthquake, the strongest quake to strike Hawaii since 1975, rattled residents across the island and beyond, with felt reports from as far away as Kauai. Over the next 24 hours, more than 500 earthquakes — 13 with magnitudes of 4 or greater — shook the island.

In the meantime, the summit of Kilauea switched from inflation to deflation, and in concert with that deflation, the summit lava lake level began to drop.

Events of this notable day on Kilauea are summarized in a photo essay featuring images from Friday.

Volcano Activity Updates

This past week, Kilauea Volcano’s summit lava lake level dropped with summit deflation, and was about 160 m (525 ft) below the vent rim as of Saturday at 9:30 p.m. On the East Rift Zone, the 61g lava flow is no longer active. Episode 62 commenced on Kilauea’s lower East Rift Zone on May 3, with at least 10 fissures (as of Sunday) opening within the Leilani Estates subdivision in the lower Puna District. Both eruptions, summit and East Rift Zone, are dynamic, and additional changes will be reported on HVO’s website at https://volcanoes.usgs.gov/volcanoes/Kilauea/status.html.

Mauna Loa is not erupting. Rates of deformation and seismicity have not changed significantly over the past week.

More than 100 earthquakes were reported felt in Hawaii during the past week. The largest of these earthquakes was a magnitude-6.9 event located about 16 km (10 mi) southwest of Leilani Estates on Big Island at a depth of 5.0 km (3.1 mi). It occurred at 12:32 p.m. on Friday, and was one of 14 earthquakes with magnitudes of 4.0 or greater to occur that day.

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Please visit HVO’s website (https://volcanoes.usgs.gov/hvo) for past Volcano Watch articles, Kilauea daily eruption updates, Mauna Loa weekly updates, volcano photos, maps, recent earthquake info, and more. Call for summary updates at 967-8862 (Kilauea) or 967-8866 (Mauna Loa). Email questions to askHVO@usgs.gov.

Volcano Watch (https://volcanoes.usgs.gov/hvo/hvo_volcano_watch.html) is a weekly article and activity update written by U.S. Geological Survey Hawaiian Volcano Observatory scientists and affiliates.

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