U.S. Geological Survey Fact Sheet 152-00
Online Version 1.0
Viewing Lava Safely - Common Sense is Not Enough
Kilauea Volcano has been erupting almost continuously since 1983. Although it is noted for its approachable lava flows, the volcano undergoes many changes that can be unpredictable and life threatening. Without knowledge of the landscape and the processes that form it, visitors can find themselves in dangerous, even deadly, situations. Understanding volcanic hazards and taking the right equipment are keys to safely exploring volcanic landscapes.
|PLEASE READ CAREFULLY-YOUR LIFE MAY DEPEND ON IT|
|The image above shows car-sized bubbles of lava from a lava-formed "bench" at the water's edge. Ocean water enters the lava tube, flashes to steam, and blows through the roof of the tube. The image to the left shows an explosive fountain throwing hot lava spatter and basket-ball sized rocks 300 feet (100 m) in the air; the fountain resulted when a piece of a lava-filled bench collapsed and exposed hot rock into the ocean.|
The current eruption of Kilauea Volcano began in 1983 with spectacular lava fountaining at a new vent, named Puu Oo, high on the volcano's east rift zone. Although surface flows have been common in this eruption, most of the lava from the vent travels concealed in lava tubes until it reaches the ocean.
When lava moves through the landscape and into the ocean, we see how the Hawaiian Islands are built. The experience of witnessing rock in its bright molten state and watching land being formed has fascinated and inspired everyone who has been lucky enough to see it. Seeing lava for the first time is captivating and often lures the viewer closer, but it is also beguiling and dangerous.
When hot lava enters the water, it bursts into pieces, building new land at the ocean edge from the fragmental material. This pile of rubble is then covered with a veneer of lava flows, forming a "bench" that gives a false impression of solid ground.
Without experience drawn from years of watching the behavior of this volcano, the casual visitor cannot know all the hazards and may easily underestimate them. Unfortunately, warning signs cannot always be posted near hazardous areas. This is because the positions of lava flows and lava tubes change frequently.
The information in this pamphlet has been gathered from the experiences of Earth scientists working on Kilauea. Heeding its lessons can help you safely enjoy your visit.
What are the Volcanic Hazards Facing you?
Plus, be prepared for personal hazards such as:
New Land, Shoreline Collapse, and Explosions
|Formation of bench and unstable land|
|An area of new, unstable land, commonly called a "bench", forms where the lava enters the ocean. Although most activity consists of sluggish submarine flows and mild spattering, sudden landslides can cause the bench to collapse and trigger violent explosions that throw lava and rocks 300 feet (100 m) inland.|
|This lava covered bench looks solid from above but can collapse unexpectedly. Be alert to cracking or booming sounds.|
|Such collapse can trigger a series of strong explosions that blasts lava spatter and large rocks and send waves of scalding water onshore.|
|This lava covered bench looks solid from above but can collapse unexpectedly. Be alert to cracking or booming sounds.|
What is a tephra jet?
When waves splash the open steam of lava, they "explode" in a cloud of steam, hot water, and tephra (molten spatter, tiny glass fragments, and long glass filaments known as "Pele's hair") called a "tephra jet."
A tephra jet is the most common type of explosion a visitor is likely to witness when an active lava tube opens to the sea.
A littoral fountain (above) produces bursts if molten lava and steam from a lava tube at or below sea level. As water enters the 2,120°F (1,160°C) lava tube, it immediately flashes to steam. The resulting explosions of molten lava, bombs, and small tephra pieces can reach higher than 300 feet (100 m) and builds a steep cone on the bench.
What causes the explosions?
Collapse of a bench exposes hot, newly solidified lava flows to sea water. The water heats to steam and can trigger a type of explosion called a steam blast. Visitors standing anywhere near a bench or on cliffs from a previous bench collapse can be hit by flying rocks.
April 1993: A person on the bench died when it suddenly collapsed. Twelve people who were near the bench needed medical attention after being hit by flying debris.
|Scalding Water, Steam Plume, and Bad Air|
Is the water hot near ocean entry sites of lava?
In 1994, two people standing near the water's edge at an ocean entry site of lava were caught off guard by a sudden wave. They were severely scalded and had to be hospitalized.
When hot lava touches the ocean, it evaporates some water, forming an impressive steam plume, and heats the surface water to temperatures capable of causing third-degree burns. Visitors should stay away from the water near the bench, because unexpected waves from natural tides or high surf, as well as from sudden bench collapses, can splash hot water onto shore!
Why are steam plumes considered a hazard?
Avoid walking under plumes of "laze" (lava haze) formed when hot lava makes seawater boil and vaporize. Chloride in the sea salt combines with hydrogen in the water to form hydrochloric acid in the plumes. Clouds of laze produce "acid rain," which can fall on people and land along the coast during onshore winds. The rain, with a pH between 1.5 and 3.5 (pure water has a neutral pH of 7), has the corrosive property of battery acid. The plume cloud also contains tiny glass fragments that can irritate the eyes and, in rare cases, cause permanent damage.
Avoid walking under steam plumes!
|Onshore winds can blow the steam plume from lava entering the ocean into the path of hikers, creating a whiteout. This plume hides deep cracks in the middle ground of the photograph.|
What is a "whiteout"?
Onshore winds can blow steam plumes onto the land, causing visibility to be limited. This can be disorienting and could cause you to walk into risky areas. Move away from a whiteout when the winds shift.
Heavy rain can also produce dense fog that limits visibility.
What is "vog" and who is at risk breathing it?
"Vog" (volcanic smog) is the visible haze that forms when irritating sulfur dioxide and other volcanic gases combine and interact chemically with oxygen, moisture, dust, and sunlight. Kilauea emits about 2,000 tons of sulfur dioxide each day during eruption, now mainly from the still-open vent at Puu Oo.
Trade winds commonly disperse the volcano's gases, so that the concentration is not generally hazardous. However, sulfur dioxide fumes can be concentrated near ground cracks along and down-wind from lava tubes.
Concentrated sulfur dioxide fumes put all people at risk, but particularly those persons with breathing problems (such as asthma and chronic obstructive pulmonary disease) and heart difficulties, pregnant women, infants, and young children. If sulfur-fume concentrations begin to cause you physical distress, you should leave the area.
|The current eruption of Kilauea, which began in 1983 at Puu Oo on the volcano's eastrift zone, has covered many square miles with lava flows and added new land along the Island of Hawai'i's south coast. Insert shows a 1986 high-fountaining event at Puu Oo. Such fountaining built a cone 835 ft (255 m) high, but the cone has lost much of its to because of collapses since 1986.|
|Stay Alert, Stay Alive. Plan Ahead Before Going to the Lava Flows.|
|Typical irregular surface of pahoehoe. Red glowing areas in the foreground show that this flow is still active.|
How long does it take to walk there?
The hummocky surfaces of pahoehoe lava flows are unlike anything most people have walked on. Because of their surface irregularities, you should allow twice the time you think the walk might take. If a ranger tells you it is 3 miles (5 km) to the flows, consider it the equivalent of walking 5 to 6 miles (8-10 km) on a smoother surface. (Also, don't forget that the return trip always seems twice as long!)
I am only going for a few hours. Why do I need a flashlight?
Many people who walk out just for a day hike get caught in the dark. This can happen because (1) they didn't estimate their speed properly, (2) they were engrossed in the scenery and didn't pay attention to the time, or (3) darkness falls more quickly near the equator than in temperate locales; when the sun sets, there is less than an hour of twilight left.
WHAT IS A SKYLIGHT?
scientist from the Hawaiian Volcano Observatory probes into a lava tube
through a "skylight" near the coast. Lava in the tube has a temperature
of about 2,120°F (1,160°C). The steam plume in the background is created
where lava from this tube reaches the ocean.
Large volumes of lava commonly travel in lava tubes beneath the congealed surface of recent flows. "Skylights" form when the roof of a lava tube collapses, revealing the molten lava flowing beneath. It is important to stand well back from these holes, which form where the roof of the tube is thin and unstable.
What do I need to take with me when I visit the lava-flow field?
Shown below are the items that the National Park advises taking when visiting the lava-flow field. They are arranged from the essential ("very important") items at the top to recommended items at the bottom.
No services are available at the end of Chain of Craters Road. Purchase any needed items before you drive to this area.
Isn't some of this equipment unnecessary?
Most injuries are not directly due to the eruption. Intense sunlight and high temperatures can lead to dehydration, heat exhaustion, or sunstroke. Take sunscreen and a hat and drink more water than you think you need. Air temperatures near lava flows can exceed 120°F (49°C), depending on cloud cover and wind conditions. At higher elevations, wind and rain can chill you and lead to hypothermia (low body temperature).
Injuries from falling are common. It is easy to break through a thin, overhanging crust of lava or trip on a crack and fall on the abrasive, glassy surface. U.S. Geological Survey (USGS) scientists always wear long pants, sturdy boots, and sometimes gloves when working near the flows-never shorts and slippers!
Before trying to visit the lava field, check with Park Rangers for current conditions there and for the best approach route. Park Rangers do not recommend that you attempt the hike to the coast if you are unprepared or uninformed. The area is remote, has no shade or water source, and is seldom patrolled.
By informing the public about hazards in Hawai'i Volcanoes National Park, the USGS and the National Park Service help visitors safely enjoy the park's attractions. The work of the Hawaiian Volcano Observatory is part of the U.S. Geological Survey's efforts to understand volcanoes and help protect people's lives and property from volcano hazards in all of the volcanic regions of the United States, including Hawai'i, Alaska, Wyoming, California, and the Pacific Northwest.
Banner Design by Bobbie Myers
For more information contact:
Hawai'i Volcanoes National
P.O. Box 52
Hawai'i National Park, HI 96718-0052
Visit the Hawaiian Volcano Observatory web site at:
For current volcanic activity:
Related Fact Sheets
Living on Active Volcanoes - The Island of Hawai'i
Volcanic Air Pollution - A Hazard in Hawai'i
Explosive Eruptions at Kilauea Volcano, Hawai`i?
U.S. GEOLOGICAL SURVEY-REDUCING THE RISK FROM VOLCANO HAZARDS
Learn more about volcanoes
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URL of this page: https://pubs.usgs.gov/fs/2000/fs152-00/
Maintained by: Michael Diggles
Last modified: December 2, 2004-00 (mfd)