U.S. Department of the Interior

U.S. Geological Survey

Fact Sheet 2013–3116

 December 2013

The First Five Years of Kīlauea’s Summit Eruption in 

Halema‘uma‘u Crater, 2008–2013

Printed on recycled paper

On the afternoon of December 21, 

2011, U.S. Geological Survey (USGS) 

scientists at the Hawaiian Volcano 

Observatory (HVO) detected a small but 

distinctive earthquake in the summit area 

of Kīlauea Volcano. Real-time webcam 

images revealed that a large portion of the 

rim of “Overlook crater,” nested within 

Halemaʻumaʻu Crater, had collapsed into 

its lava lake, triggering a violent explosive eruption of gas and hot lava fragments. Donning helmets and gas masks, 

the scientists drove the five minutes from 

the observatory to Halemaʻumaʻu and set 

out to sample and map the new deposit. 

This episode was yet another explosive 

event in the ongoing eruption at Kīlauea’s 

summit that had begun more than 3 years 

earlier.

Kīlauea forms the southeast portion of the Island of Hawaiʻi, and most 

eruptions occur from its summit or down 

the flanks along its two “rift zones.” 

Since 1983, an ongoing eruption on the 

East Rift Zone, around Puʻu ʻŌʻō cone, 

has covered 48 square miles (124 square 

kilometers) with lava flows and destroyed 

more than 200 structures, including 

scores of homes. With the summit eruption ongoing since March 2008, it is the 

longest time in at least two centuries 

that eruptions of Kīlauea have occurred 

simultaneously at the summit and along a 

rift zone.

Eruption Chronology

Signs of unusual activity at 

Kīlauea’s summit began in late 2007. In 

November, ground vibrations known as 

seismic tremor that suggest underground 

movement of molten rock (magma) 

increased well above normal “background” levels, and by late December, 

sulfur dioxide (SO2

) gas emission rates 

had also started increasing. At the same 

time, however, the summit of Kīlauea 

was deflating, which often means a 

reduction of magma supply to the summit 

magma chamber. Thus, initial signs were 

conflicting, and renewed eruptive activity at the summit was far from certain. 

Increased gas emissions led the National 

Park Service to close visitor access 

to much of the Kīlauea Caldera floor, 

including the western portion of Crater 

Rim Drive, on February 20, 2008. By 

early March, both seismic tremor and SO2

emissions were several times higher than 

normal levels. On March 12, a vigorous 

high-temperature fuming area appeared 

on the south wall of Halemaʻumaʻu Crater, immediately below the closed visitor 

overlook. This fuming area glowed at 

night and was compelling evidence that 

magma was near the surface and might 

erupt soon. 

At 2:58 a.m. on March 19, 2008, a 

glowing, gaping crater, about 115 feet 

(35 m) wide, opened below the fuming 

area, and an explosive eruption threw 

hot fragments of rock onto the rim of 

Halemaʻumaʻu, breaking and burning the 

visitor overlook fencing. These initial 

ejecta were all solid and “lithic” (pieces 

of old, solidified lava from the floor and 

The eruption in Halema‘uma‘u Crater that began in March 

2008 is the longest summit eruption 

of Kīlauea Volcano, on the Island of 

Hawai‘i, since 1924. From the time 

the eruption began, the new “Overlook crater” inside Halema‘uma‘u 

has exhibited fluctuating lava lake 

activity, occasional small explosive events, and a persistent gas 

plume. The beautiful nighttime 

glow impresses and thrills visitors 

in Hawai‘i Volcanoes National 

Park, but the continuous emission 

of sulfur dioxide gas produces 

“vog” (volcanic smog) that can severely affect communities and local 

agriculture downwind. U.S. Geological Survey scientists continue 

to closely monitor the eruption and 

assess ongoing hazards.

An active lava lake fills the “Overlook crater,” about 525 feet (160 m) across, contained 

within Halema‘uma‘u Crater in the larger depression of Kīlauea Caldera at the summit of 

Kīlauea Volcano. The walls of Halema‘uma‘u show white in the middle distance, while 

the Hawaiian Volcano Observatory (HVO) and Jaggar Museum, perched on the edge of 

the caldera wall, are visible as a small bump on the horizon. USGS photo by David Dow.

Kīlauea Caldera (summit)

Halema‘uma‘u

Crater Pu‘u ‘Ō‘ō

Summit

magma

chamber

Conduit from mantle

Conduits

ERZ

Simplified cartoon of Kīlauea Volcano’s 

magmatic “plumbing” system that brings 

magma from depth to surface vents, 

showing the connection between the 

summit and East Rift Zone (ERZ).
wall of Halemaʻumaʻu). Several days 

later, however, “juvenile” liquid particles 

were ejected, originating from fresh, 

gas-rich lava deep in the new pit, now 

informally called the “Overlook crater.” 

Over the next few months, several 

more weak explosive events hurled lava 

fragments around the Halemaʻumaʻu 

Overlook. But the lava was still not visible in the fume-filled crater. Finally, during a helicopter overflight on September 

5, 2008, HVO staff glimpsed a roiling, 

spattering lava lake deep in the Overlook 

crater—the first direct view of molten 

lava at Kīlauea’s summit since 1982.

For the next year and a half, the 

lava remained deep in the crater and was 

only occasionally seen. During day-long 

periods of summit inflation, lava would 

rise into view as a small lava lake but 

then quickly drain and disappear once 

the summit deflated. Two large collapses 

of the crater wall, in December 2008 and 

June 2009, choked the vent with rubble 

for several weeks, but each time lava 

eventually crept back into the bottom of 

the Overlook crater. 

But in mid-February 2010, a permanent lava lake appeared within the 

Overlook crater as the summit began to 

inflate. This lake has persisted into late 

2013, with only one brief interruption—

in March 2011, the Kamoamoa eruptive 

event on the East Rift Zone depressurized 

the summit-east rift magmatic system, 

causing the lava lake to drain out of view 

for about a week.

Normally the lava lake in the Overlook crater circulates placidly. Fresh lava 

wells up at the north lake margin and 

slowly migrates across the lake, cooling 

at the surface to form plates of thin black 

crust separated by jagged, red, incandescent cracks. The lava sinks back down 

at the south margin, where a persistent 

spattering source emits a plume of gas 

and often throws spatter about 15–35 feet 

(5–10 m) in the air.

How Far Down Is the Lava?

The level of the lava lake fluctuates 

constantly. From hour to hour, the lava 

can undergo rise and fall cycles (sometimes called “gas pistoning”) driven by 

gas buildup within the lava that pushes 

the surface up as much as 65 feet (about 

20 m), before the gas rapidly escapes and 

the lava drops down again. From day to 

day, cycles of deflation and inflation of 

the summit magma reservoir can cause 

the level to rise and fall over a range of 

as much as 165 feet (50 m). Finally, over 

weeks and months, broad changes in 

pressure in the summit magma reservoir can cause the lava level to change 

gradually. The level of the lava lake has 

been as high as 72 feet (22 m) below the 

Overlook crater rim (that is, below the 

floor of Halemaʻumaʻu Crater) and, at its 

lowest, has dropped more than 720 feet 

(220 m) below the rim. During 2013, the 

lava level was generally 100–165 feet 

(30–50 m) below the rim. 

Will the lava ever rise and flood 

the floor of Halemaʻumaʻu Crater—or 

even fill Halemaʻumaʻu and flow onto 

the caldera floor, as lava did in the early 

!

!

!

!

!

!

ERZ

SWRZ

Puʻu ʻŌʻō

flow field

(1983-now)

Mauna

Loa

Hilo

Waimea

Pāhala

Volcano

Nā‘ālehu

Kailua-Kona

Kohala

Mauna

Kea

Hualālai

Kīlauea

summit

"

" Kīlauea Caldera

(floor of caldera closed)

Halema‘uma‘u

Crater

Overlook

crater

Kīlauea Iki

Kīlauea

Military

Camp Park

Visitor

Center

Hawaiian

Volcano

Observatory

Volcano Village

Volcano

Golf Course

Subdivision

Hawai‘i Volcanoes

National Park

Mauna Loa Estates

Ka‘ū Desert

Hawai‘i Volcanoes

National Park

Mauna Loa

Strip Road

Highway 11

Hawai‘i Volcanoes

National Park

Highway 11

Overlook

(closed)

4500

4000

3500

4000

3500

3500

Chain of Craters Road

Crater Rim Drive (closed)

Roads and trails in red are currently closed.

Crater Rim

Drive

0 1 miles

0 1 kilometers

0 20 miles

0 20 kilometers

!

!

!

!

!

!

ERZ

SWRZ

Puʻu ʻŌʻō

flow field

(1983-now)

Mauna

Loa

Hilo

Waimea

Pāhala

Volcano

Nā‘ālehu

Kailua-Kona

Kohala

Mauna

Kea

Hualālai

Kīlauea

summit

"

" Kīlauea Caldera

(floor of caldera closed)

Halema‘uma‘u

Crater

Overlook

crater

Kīlauea Iki

Kīlauea

Military

Camp Park

Visitor

Center

Hawaiian

Volcano

Observatory

Volcano Village

Volcano

Golf Course

Subdivision

Hawai‘i Volcanoes

National Park

Mauna Loa Estates

Ka‘ū Desert

Hawai‘i Volcanoes

National Park

Mauna Loa

Strip Road

Highway 11

Hawai‘i Volcanoes

National Park

Highway 11

Overlook

(closed)

4500

4000

3500

4000

3500

3500

Chain of Craters Road

Crater Rim Drive (closed)

Roads and trails in red are currently closed.

Crater Rim

Drive

0 1 miles

0 1 kilometers

0 20 miles

0 20 kilometers

The Island of 

Hawai‘i, known as 

the Big Island, is 

the southernmost 

Hawaiian island. 

It is formed from 

five overlapping 

volcanoes, 

delineated by the 

dashed gray lines, 

with Mauna Loa 

and Kīlauea being 

the most active in 

recent times. Kīlauea’s summit area is shown by the 

red dot, and the East Rift Zone (ERZ) and Southwest 

Rift Zone (SWRZ) are shown by dashed red lines. 

The area covered by lava during the ongoing eruption on 

the East Rift Zone is shown in orange. Selected towns 

are shown with black dots.

The large 

depression of 

Kīlauea Caldera, 

within Hawai‘i 

Volcanoes National 

Park, dominates 

the summit region 

of Kīlauea Volcano. 

Embedded within 

the caldera is 

Halema‘uma‘u 

Crater, in a corner 

of which is the 

currently active 

vent called the 

Overlook crater 

(red dot). Several 

residential subdivisions form the village of Volcano (pop. 

2,575). Trails and roads in red have been closed by the 

Park because of volcanic hazards.

The lava level in the active vent (“Overlook crater”) in Halema‘uma‘u Crater 

fluctuates constantly. On January 10, 2010 (left), the lava is at one of its lowest 

stands, about 720 feet, or 220 m, below the floor of Halema‘uma‘u. On March 3, 

2011 (right), the lava is at a relatively high level, only about 200 feet (60 m) below 

the Overlook crater rim. Both photos look northwest from the (now closed) 

Halema‘uma‘u Overlook. USGS photos by Tim Orr.

FLUCTUATING LAVA LEVELS
1900s? The lava level today is lower 

than it was in the early 1900s, likely 

because the ongoing eruption at Puʻu 

ʻŌʻō, on Kīlauea’s East Rift Zone is also 

tapping the summit magma reservoir. 

If the magma supply to this East Rift 

Zone eruption were to end, the lava in 

Halemaʻumaʻu would likely rise to higher 

levels than we see today. 

Collapses, Explosions, and Ejecta

The Overlook crater has grown 

considerably over the years as a result 

of collapses of its rim and walls. When 

this vent opened on March 19, 2008, the 

crater was about 115 feet (35 m) wide. 

As of late 2013, the crater had grown to 

about 525 feet (160 m) wide by 700 feet 

(215 m) long. Heat from the molten lava 

cracks and weakens the walls, causing 

pieces to fall into the lake, widening the 

crater. The rumble and sharp cracks of 

rockfalls and rock breaking can sometimes be heard from the Jaggar Museum 

overlook, adjacent to HVO. It is not 

known how large the Overlook crater 

could eventually grow, but it will almost 

certainly continue enlarging for some 

time. 

Explosive events at Overlook crater 

are triggered by collapses of the crater 

walls—massive blocks dropping into 

the lava lake cause violent gas release 

and splashing of the liquid lava. Of 

the hundreds of small explosive events 

since March 2008, about two dozen have 

hurled lava fragments and rock material 

(collectively called ejecta) outside of the 

Overlook crater. These explosive events 

also produce a brown plume of volcanic 

ash (ejecta less than 2 mm [0.08 in] in 

diameter), and the largest have thrown 

blocks (lithic ejecta larger than 6.4 cm 

[2.5 in]) and bombs (juvenile ejecta 

larger than 6.4 cm) as far as 1,000 feet 

(300 m) from the vent. 

Although very small compared to 

explosive eruptions at other volcanoes, 

such as Mount St. Helens in Washington, 

several of these explosive events could 

have injured or killed anyone standing 

nearby on the Halemaʻumaʻu Crater rim. 

The area around the vent has been closed 

to the public, so that the explosive events 

now pose no threat to visitors. 

Even between explosive events, 

the continuous eruption plume carries 

up countless liquid lava droplets, mostly 

smaller than 2 mm (0.08 in), wafted 

upwards in thermal updrafts. These 

quickly chill to form glassy threads 

(“Pele’s hair”), teardrop-shaped blebs 

(“Pele’s tears”), and tiny hollow spherules. The plume also carries small rock 

particles from frequent collapses of the 

Overlook crater walls. Small amounts of 

fine ash and Pele’s hair can sometimes be 

blown into nearby residential areas, particularly when the wind is from the south.

How the Eruption Affects People 

and Agriculture

In addition to the juvenile lava and 

rock particles, the eruptive plume is made 

up of water vapor, carbon dioxide, sulfur 

dioxide, and smaller amounts of other 

gases, including hydrogen chloride and 

hydrogen fluoride, along with entrained 

air. The 500–5,000 metric tons (1.1–11 

million pounds) of sulfur dioxide emitted 

from the Overlook crater each day react 

in the atmosphere and, with the other 

gases and particles, form “vog” (volcanic smog) downwind. Vog is a respiratory irritant that can affect residents in 

downwind communities, such as Pāhala, 

Nā‘ālehu, and towns on the west side of 

the Island of Hawaiʻi. With less common 

wind conditions, vog can spread across 

the island and affect other areas such as 

Hilo, and even drift north and reach the 

other Hawaiian Islands. 

Common reactions to vog include 

sore throat, eye irritation, headaches, 

coughing, and breathing difficulties. 

Symptoms are especially pronounced 

for those with preexisting respiratory 

conditions such as asthma or chronic 

obstructive pulmonary disease (COPD). 

In addition, the tiny droplets of sulfuric 

acid in vog cause acid rain, which can 

leach lead and other metals from roofing 

and plumbing materials. Leached lead 

can pose a health hazard if it contaminates drinking water, such as in rooftop 

rainwater-catchment systems.

The impact of vog on agriculture has 

been severe on the Island of Hawaiʻi, and 

particularly in the Ka‘ū district, which 

most of the time is directly downwind of 

Kīlauea’s summit. Farmers report major 

economic losses due to vog damage to 

A plume of volcanic gases, tiny particles, and droplets rises from the active 

vent in Halema‘uma‘u Crater and drifts southwest in the tradewinds. This 

volcanic smog (“vog”) plume can be harmful to humans, agricultural crops, and 

machinery. The Hawaiian Volcano Observatory (HVO) is about 1.2 miles (1.9 km) 

from the vent. USGS photo by Mike Poland. Upper right: Both native plants and 

introduced species can be chemically burned by this acidic volcanic pollution. 

Photo by Scot Nelson, University of Hawai‘i at Mānoa. Lower right: Farm and 

ranch infrastructure, such as fences and gates, have shown increased corrosion 

due to vog. USGS photo by Tamar Elias.

Overlook crater size

•	 Initial, March 2008: 115 feet 

(35 m) diameter; late 2013: 525 

feet (160 m) wide; 700 feet 

(215 m) long

Lava lake

•	 Dimensions: variable, as large 

as 525 feet (160 m) wide; 740 

feet (225 m) long

•	 Distance below rim: highly 

variable, between 72 feet (22 

m) and 720 feet (220 m) below 

Overlook crater rim (floor of 

Halema‘uma‘u Crater)

Explosions

•	 Number of explosive events 

throwing blocks or bombs out 

of Overlook crater: about two 

dozen

•	 Maximum distance blocks 

or bombs thrown from vent: 

1,000 feet (300 m)

Gas emission

•	 Typical SO2

 emission rate: 

500–5,000 metric tons (1.1–11 

million pounds) per day

SUMMIT ERUPTION STATISTICS 

2008 TO 2013
vegetable and orchard crops, flowers, and 

foliage. Ranchers also report detrimental 

effects to range grasses and livestock and 

increased corrosion of metal fencing and 

other infrastructure. As a result of these 

impacts, the U.S. Department of Agriculture provided Federal disaster assistance 

to farmers and ranchers on the Island of 

Hawaiʻi from 2008 through 2011. The 

impacts of vog on the agricultural industry and on human health remain areas of 

ongoing concern and study.

Past, Present, and Future

Halemaʻumaʻu Crater has long 

hosted lava lake activity and, according to native Hawaiian tradition, is the 

current home of the volcano deity Pele. 

A lava lake was nearly continuous in 

Halemaʻumaʻu from the time of the first 

written record in 1823 until 1924. Mark 

Twain remarked in 1866 that the view 

was like “gazing at the sun at noon-day” 

and the sight “fascinated the eye with its 

go on for decades. In the meantime, the 

eruption provides beautiful sights and 

opportunities for scientific study, but also 

a chronic impact on air quality in downwind communities. USGS scientists with 

the Hawaiian Volcano Observatory will 

continue to monitor the eruption closely 

and alert the public and emergency managers to volcanic hazards. This work is 

only part of the USGS Volcano Hazards 

Program’s ongoing efforts to protect 

people’s lives and property in all of the 

volcanic regions of the United States.

For more information contact:

U.S. Geological Survey

Hawaiian Volcano Observatory

P.O. Box 51

Hawai‘i National Park, HI 96718

(808) 967–7328

http://hvo.wr.usgs.gov/

or

Hawai‘i Volcanoes National Park

P.O. Box 52

Hawai‘i National Park, HI 96718

(808) 965–6000

http://nps.gov/havo/

See also The ongoing Pu‘u‘O‘o eruption of 

Kilauea Volcano, Hawai‘i—30 years of eruptive 

activity (USGS Fact Sheet 2012–3127) and 

other USGS volcano Fact Sheets

http://volcanoes.usgs.gov/Products/sproducts.

html

This Fact Sheet and any updates available to it 

are available online at:

http://pubs.usgs.gov/fs/2013/3116

Matthew Patrick, Tim Orr, A. Jeff Sutton, 

Tamar Elias, and Don Swanson

Edited by Peter H. Stauffer

Graphic design by Vivian Nguyen and David 

Dow

Visitors pose in front of a circular and overflowing lava lake in Halema‘uma‘u Crater 

in 1893. This “perched” lava lake was elevated by walls (levees) built from solidified 

overflows. Lava lake activity was usually present in Halema‘uma‘u Crater until 

explosions and crater collapse in 1924 ended that continuous phase of activity. Photo 

by unknown photographer, reproduced courtesy of Hawai‘i State Archives.

INNOVATIONS IN VOLCANO MONITORING

Scientists at HVO use advanced technology to monitor the vent and its hazards. Left: A thermal camera keeps constant watch 

on the lava lake and can “see” through thick volcanic fume. Center: Periodic laser scans of the crater and lava lake help track 

the evolving crater geometry. Image by Todd Erickson, University of Hawai‘i at Mānoa. Right: A Fourier transform infrared (FTIR) 

spectrometer measures the composition of gas emissions. These tools are part of a robust monitoring network maintained by HVO 

that includes seismometers, tiltmeters, Global Positioning System (GPS) sensors, gas monitoring sensors, and webcams. Some of 

the real-time data can be seen on the HVO Web site (http://hvo.wr.usgs.gov).

unapproachable splendor.” Other early 

visitors mention the smell of volcanic 

gas far downwind, suggesting that vog 

has been a common product of eruptions 

on Kīlauea. The near-constant summit 

eruption during the early 1900s, allowing continuous observation of volcanic 

activity, was the impetus for founding 

the Hawaiian Volcano Observatory on 

the caldera rim in 1912. A collapse of 

Halemaʻumaʻu Crater with violent steam 

explosions that killed one person ended 

that long-lived lava lake in 1924. For the 

remainder of the 1900s, Kīlauea’s summit 

eruptions were only occasional and usually short, lasting days or weeks—in one 

case, 9 months. 

Now in its sixth year, the current 

summit eruption harks back to the persistent lava lake in Halemaʻumaʻu during 

the 1800s and early 1900s, suggesting 

that it has the potential to last for many 

years. Thus far, there are no signs that 

the eruption is either slowing down or 

ramping up. It could end tomorrow or 

ISSN 2327–6916 (print)

ISSN 2327–6932 (online)

http://dx.doi.org/10.3133/fs20133116