East Hawaii News

HVO Explains Possible Kilauea Scenarios

May 18, 2015, 7:32 AM HST
* Updated May 18, 8:23 AM
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A decrease in the lava lake level of the Kilauea Summit Overlook crater also leaves other aspects of the summit’s activity changing.

Hawaiian Volcano Observatory has continuously noted change in recent weeks with summit area deformation pattern and concentrated earthquake activity, especially in the southern part of the caldera and the upper Southwest Rift Zone.

Beginning on April 28, the lava lake in the Overlook crater, which is Kilauea’s summit vent, began to overflow. An increased height of about 25 feet above Halema’uma’u Crater was formed from overflows and splatter on May 8. Just one day later, the lava lake levels began to drop. On Sunday morning, eight days later, HVO reported that the lava levels have continued to drop, noting that the levels had remained steady at 165 feet below the original crater floor.

As the lava lake has continued to decrease, other areas have been impacted. This includes changes in summit deformation and seismicity. HVO says that the inflationary trend noted as the summit lava lake rose has quickly changed to a deflationary trend that is centered in the area of Halema’uma’u Crater. In addition, HVO reported on May 13 that the focus of deformation changed to the southern part of Kilauea’s summit caldera and upper Southwest Rift Zones. These areas experienced rapid and localized inflationary tilt.

Earthquake activity changes were a result of the change in deformation. HVO reports that activity that was previously focuses on Kilauea’s summit, upper East Rift Zones, and upper Southwest Rift Zone instead began to focus on the southern part of Kilauea’s caldera and upper Southwest Rift Zone. As of Friday, May 15, HVO had reported that small earthquakes were occurring every couple of minutes.

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HVO says that summit activity at heightened levels has led to no obvious change in the eruption

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Despite the inability to understand the full extent of what is next to come, HVO has outlined a few possible scenarios:

1. Magma continues to accumulate in the southern part of Kilauea’s summit caldera and upper Southwest Rift Zones at shallow depths, but then stops with no eruption.

2. Magma continues to accumulate in the southern part of the caldera at shallow depths and leads to a rapid intrusion into the Southwest Rift Zone. Such an intrusion could remain within the rift zone or erupt along the rift zone. A rift zone intrusion would be indicated by a swarm of shallow earthquakes, seismic tremor, and large, rapid changes in the deformation of the ground surface.

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3. Magma continues to accumulate in the southern part of the caldera, rises toward the surface, and erupts in the upper Southwest Rift Zone and/or in the caldera. With this scenario, we would expect to see even stronger earthquake activity and/or seismic tremor in the southern part of the caldera, as well as ground cracks.

HVO continues to maintain close observation of Kilauea Volcano. Monitoring includes watching for signs of unrest that may lead to a new lava breakout, changes in activity at Puʻu ʻŌʻō, as well as at the summit, and constant communication with Hawai’i Volcanoes National Park and Hawai’i County Civil Defense.

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