VOLCANO WATCH: Kīlauea’s East Rift Zone Eruption Turns 33

The Nov. 25, 2015, breakout that began as a rupture from the tube supplying the June 27 lava flow advanced slowly to the northeast of Pu‘u ‘Ō‘ō (background) and reached the forest in mid-December, but still poses no immediate threat to Puna communities. USGS image.

What do actor Mel Gibson, football quarterback Eli Manning, and Kīlauea Volcano’s ongoing East Rift Zone eruption at Puʻu ʻŌʻō have in common? They all share the same birthday!

In fact, Jan. 3, 2016, marks the 33rd anniversary of the start of the Puʻu ʻŌʻō eruption. While many people likely wish Mel and Eli a long life on their birthdays, Island of Hawai‘i residents who live downslope from Kīlauea’s persistent lava flows might not wish the same for Pu‘u ‘Ō‘ō.

After an unsettling 2014 and early 2015, when lava flows loomed above Pāhoa, the focus of Kīlauea’s surface activity shifted closer to Puʻu ʻŌʻō. This change, which occurred last March, allowed life in the island’s lower Puna District to return to some semblance of normalcy.

It’s important to remember, though, that the June 27 lava flow, the source of great stress from August 2014 to March 2015, remains active and continues to feed breakouts over a broad area up to about 6 km (4 mi) northeast of Puʻu ʻŌʻō. This means that surface flows are still active upslope from Puna communities.

But this scenario is better than many past ones. The eruption rate remains quite low—only about half as much lava is erupting now compared to a decade ago. It also repeatedly fluctuates in response to changes in summit pressurization.

One apparent consequence of these factors, probably combined with the gentle ground slope northeast of Puʻu ʻŌʻō, is the general inability of the disparate breakouts to organize into a single coherent flow. If these breakouts were to become organized, the flow would likely begin to advance downslope once again.

Instead, the few dozen small breakouts scattered across the flow field at any one time have repeatedly covered the same broad area. For example, during periods of increased discharge, any lava that breaks out can creep forward for days or weeks, filling in low spots on the flow field. But when the output falls to a level too low to support the lava’s continued advancement, the breakout dies.

This lava flow behavior is much like that recorded throughout 2013 and 2014, prior to the onset of the June 27 flow, when active lava was in roughly the same area as it is now. Today’s activity is also reminiscent of the behavior observed during late 2014 and early 2015, when the flow front at the edge of Pāhoa Marketplace widened, but failed to advance.

The relatively steady, non-threatening behavior of the June 27 lava flow in recent months has been a welcome relief. The most significant deviation from this behavior began on November 25, when a large breakout from the lava tube on the flank of Puʻu ʻŌʻō sent lava to the north.

This new flow lobe reached the forest north of Puʻu ʻŌʻō in mid-December. It has since been traveling northeast along the northern edge of the existing flow field. About 40 percent of the lava erupting from the vent feeds this lobe.

But for now, there’s no reason for Puna communities to worry. The breakout still has a few kilometers (about a mile) to go before it surpasses the most distal breakouts on the flow field. Assuming the flow lobe remains active, it will likely take weeks before lava reaches beyond other currently active breakouts.

USGS Hawaiian Volcano Observatory (HVO) scientists expect that this advancing lobe will eventually merge with and acquire the same stop-and-go behavior as other flows in the area, but are closely monitoring it. We will continue to report the lobe’s progress and all other Kīlauea activity through daily eruption updates posted on the HVO website.

We wish you all the best in the New Year and hope to see you at one of the many presentations offered by HVO scientists during Volcano Awareness Month in January.

Coming up next week are two talks about Kīlauea’s ongoing eruptions—first in Hawai‘i Volcanoes National Park on Jan. 5, then repeated at the University of Hawai‘i at Hilo on Jan. 7. Details are posted on the HVO website or call (808) 967-8844 for more information.

Also, happy birthday wishes to Mel, Eli and the Pu‘u ‘Ō‘ō eruption!

Volcano Activity Updates
Kīlauea continues to erupt at its summit and East Rift Zone. During the past week, the summit lava lake level varied between about 35 and 64 m (115–210 ft) below the vent rim within Halema‘uma‘u Crater. On the East Rift Zone, scattered lava flow activity remained within about 6 km (4 miles) of Puʻu ʻŌʻō.

Mauna Loa is not erupting. Seismicity remains elevated above long term background levels. In the last week, earthquakes occurred mostly beneath Mauna Loa’s upper Southwest Rift Zone at depths less than 5 km (3 miles). GPS measurements continue to show deformation related to inflation of magma reservoirs beneath the summit and upper Southwest Rift Zone of Mauna Loa.

No earthquakes were reported felt on the Island of Hawai‘i during the past week.

Visit the HVO website for past Volcano Watch articles, Kīlauea daily eruption updates, Mauna Loa weekly updates, volcano photos, recent earthquakes info and more; call for summary updates at (808) 967-8862 (Kīlauea) or (808) 967-8866 (Mauna Loa); email questions to [email protected].

Volcano Watch is a weekly article and activity update written by scientists at the U.S. Geological Survey`s Hawaiian Volcano Observatory.