Skip to content

Plumbing the Depths of Pu‘u ‘Ō‘ō

January 2, 2015

The following is the weekly Volcano Watch article, written by scientists at the U.S. Geological Survey’s Hawaiian Volcano Observatory, with additional information about the Pāhoa Transfer Station lava viewing area added by staff at Hawai‘i Volcanoes National Park: 

Pu‘u ‘Ō‘ō

Fractures define the perimeter of a new, smaller crater within Pu‘u ‘Ō‘ō. Light-colored areas are parts of the original cinder-and-spatter cone that have not been buried by lava flows. USGS photo.

January 3, 2015, marks the 32nd anniversary of the ongoing Puʻu ʻŌʻō eruption on Kīlauea Volcano’s East Rift Zone. Over that time, Puʻu ʻŌʻō has changed dramatically with variations in the eruption.

At its highest in 1986, Puʻu ʻŌʻō stood 255 m (835 ft) above the pre-eruption landscape and was about 1 km (0.6 mi) across at its base. Today, Pu‘u ‘Ō‘ō is about 171 m (560 ft) high and nearly all sides of the cone have been buried by lava flows. These flows form a broad shield, 2 to 3 km (1 to 2 mi) across and up to 150 m (500 ft) thick, that almost completely encircles Puʻu ʻŌʻō. Of the original cone, only the northwest flank and a narrow sliver of the upper southeast flank remain exposed.

Puʻu ʻŌʻō’s summit is defined by a crater that is 450 m (490 yd) long and 300 m (330 yd) wide and is filled with solidified lava. Following the onset of the June 27th lava flow in 2014, a new crater about 240 m (260 yd) across and 30 m (100 ft) deep formed in the northeastern part of the older, filled crater. This new crater developed as magma beneath Puʻu ʻŌʻō drained away to feed the June 27th flank eruption and the overlying crater floor fell into the resulting void.

Lava rises close to the surface in several spots along a fracture system that defines the perimeter of the new, smaller crater.  Lava also erupts from a fracture lower on Puʻu ʻŌʻō’s northeast flank, feeding the active lava flow near Pāhoa. These surface vents are connected to a magma storage reservoir hundreds of feet below, probably by long, narrow conduits.

he leading part of the flow consisted of several small, active lobes this afternoon. The front of the lobe that crossed the firebreak was stalled, though breakouts were active about 50 m (55 yd) upslope. Another lobe (area of most visible smoke in center) was about 300 m (330 yd) upslope of the tip and 150 m (165 yd) upslope of the firebreak. A third lobe was 350 m (385 yd) upslope of the firebreak. The view is to the northeast. USGS Photo taken 12/30/14.

The leading part of the flow consisted of several small, active lobes this afternoon. The front of the lobe that crossed the firebreak was stalled, though breakouts were active about 50 m (55 yd) upslope. Another lobe (area of most visible smoke in center) was about 300 m (330 yd) upslope of the tip and 150 m (165 yd) upslope of the firebreak. A third lobe was 350 m (385 yd) upslope of the firebreak. The view is to the northeast. USGS Photo taken 12/30/14.

Mapping the shape of the magma storage reservoir and delivery system beneath Puʻu ʻŌʻō is critical to understanding current monitoring data and forecasting how the eruption might behave in the future. But, because the entire plumbing system cannot be observed, we must rely on inferences from geological, geophysical, and geochemical data to “see” beneath the crater floor.

Studies conducted more than a decade ago suggested that the magma storage reservoir beneath Puʻu ʻŌʻō had a vertical extent of about 300 m (1000 ft), with its top about 70 m (230 ft) below the pre-eruption ground surface.  The size and shape of the crater formed above this reservoir is thought to approximate the reservoir’s horizontal dimensions.

Many changes have occurred at Puʻu ʻŌʻō since those studies, including four major and several minor crater collapses and large fluctuations in magma supply, so the current shape of the Puʻu ʻŌʻō magma reservoir is not known.  However, the small size of the crater formed after the onset of the June 27th lava flow suggests that the reservoir may be relatively small.

The magma reservoir beneath Puʻu ʻŌʻō is connected to the much deeper East Rift Zone system that transports magma from Kīlauea’s summit to Puʻu ʻŌʻō. Earthquake locations and modeling of other geophysical data suggest that magma travels through the East Rift Zone at a depth of about 3 km (2 mi), which is about 2 km (1.2 mi) below sea level.

The active flow front from the June 27 lava flow, originating from Pu‘u ‘Ō‘ō, continues to advance downslope towards the northeast. USGS Photo, taken 12.12.14

The active flow front from the June 27 lava flow, originating from Pu‘u ‘Ō‘ō, continues to advance downslope towards the northeast. USGS Photo, taken 12.12.14

The simplified model presented here is inferred from a wide range of data and will evolve as the tools and techniques used to study eruptions improve. Moreover, the plumbing beneath Puʻu ʻŌʻō has changed dramatically through past decades, so aspects of the current view will have to be revised as the eruption changes over time. Regardless, this model provides some constraints for understanding how the plumbing system beneath Puʻu ʻŌʻō might work.

Using these insights, USGS Hawaiian Volcano Observatory scientists hope to better understand the plumbing system that feeds the June 27th lava flow—to connect what we observe at Puʻu ʻŌʻō to activity at the distal end of the lava flow near Pāhoa. This could eventually enable us to better forecast the behavior of threatening lava flows based on changes that occur at their sources—certainly an important goal given the ongoing crisis in Puna.

January is Volcano Awareness Month, during which HVO scientists will present a number of talks about Hawaiian volcanoes. Please email , or call 808-967-8844 for details about this week’s programs.

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

Remember: the June 27th lava flow is currently within the Kahaualeʻa Natural Area Reserve, which has been closed by the Hawai‘i State Department of Natural Land and Resources (DLNR) due to the ongoing volcanic hazards, and the Wao Kele o Puna Forest Reserve, also closed by DLNR and the Office of Hawaiian Affairs.  According to the Hawai‘i County Civil Defense website: “The public is reminded that the flow is not visible and cannot be accessed from any public areas.” However, the County opened the Pāhoa Transfer Station lava viewing area in December, enabling the public to witness the now-hardened flows that encroached upon it.

lil' thermal gun

Schoolchildren use a small thermal “gun” to measure heat from the recent flows that inundated the Pāhoa Transfer Station. (Photo courtesy of Darcy Bevens, Center for the Study of Active Volcanoes)

No comments yet

Leave a Reply

Fill in your details below or click an icon to log in:

Gravatar
WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Follow

Get every new post delivered to your Inbox.

Join 236,718 other followers

Build a website with WordPress.com
%d bloggers like this: