October 14, 2010
A weekly feature provided by scientists at the Hawaiian Volcano Observatory.
Death Happens: Respect coastal entry hazards and stay alive
Humans seem to have a limited ability to remember disasters. Some researchers who study disaster preparedness and risk mitigation speculate that, ironically, the pace of the Internet and other forms of instant news has recently caused our disaster memory to grow even shorter. The dwindling oral traditions that once passed information down generations were actually more effective than the Web in preserving our active long term disaster memory.
In Hawai`i, the oral tradition part of our culture is still strong enough that we can help each other remember our local tragedies, especially ones that were preventable.
Early next month it will be 10 years to the day that the badly burned bodies of a Volcano resident and her mainland guest were found next to the active coastal lava entry point, which at that time, was within the Hawai'i Volcanoes National Park, just a few miles from the current ocean entry at Kalapana. The medical examiner determined that one had died as a result of pulmonary edema and the other from pulmonary edema and laryngeal edema—both caused by inhalation of steam from the coastal entry eruption plume. They unwisely accepted a risk by choosing to enter an area the National Park had closed because of known—and posted—eruption hazards.
Recently, HVO staff who regularly monitor hazards at the Kalapana coastal eruption site have noted an increase in the number of people entering the area that has been closed by the county to avoid the same hazards that killed the two hikers. Even some organized groups are recklessly venturing out onto the hazardous lava delta, and others, unwary of the hazards, tag along, trusting the tour"leaders".
Lava deltas, like the currently active one at Kalapana, grow as molten lava enters the sea, fragments, and piles up along shore. As it forms, especially in its earliest stages of growth, a delta is extremely fragile. This rubble is eventually welded together by thin layers of lava, giving the delta a deceivingly stable appearance. Delta growth, produced by continuing eruption, competes with collapse, induced by gravity and ocean wave action.
As these active deltas become larger (the current one is about 25 acres in size), they appear, to the untrained eye, to be stable. However, years of experience studying delta collapse, has shown us that failure can occur with little or no warning, resulting in many acres of newly formed coastal land rapidly collapsing into the sea.
In 1993, despite a well-posted closure in the National Park, a Kona photographer was swept out to sea and lost during a lava delta collapse. In the same incident, over a dozen park visitors who had also entered the closed area were injured when they attempted to flee the hot rocks, spatter, and debris hurled out during the collapse.
Severe injuries, or worse, can result even if an active lava delta is stable. In a separate Park incident in 1998, a Laupahoehoe resident entered a closed area at night and disappeared after falling 25 feet from the top of a cinder cone onto the lava delta at the water's edge.
The extreme heat of molten lava can evaporate seawater to dryness, forming a dense, superheated plume composed of steam, hydrochloric acid, and entrained rock fragments. It is quite possible that such a plume, caused by an ocean wave washing over hot lava and flashing to steam, is responsible for the deaths of the two hikers in 2000.
Current conditions at the Kalapana coastal eruption site are nearly identical to those that resulted in the tragic loss 10 years ago and those before. In addition to the hazards previously noted, the current volcanic behavior of frequent deflation/inflation events is producing rapid changes in the ongoing eruption—stops, starts, and adjustments—that repeatedly impact the already unstable coastal delta.
Every person should heed the county's wise closure of hazardous areas and observe the eruption from safe locations provided at the road's end. Hawai`i residents have a responsibility to help each other—and visitors—by keeping our local disaster memory sharp and learning the lessons provided by tragic events of the past.
Kīlauea Activity Update
Lava continues to enter the lava tube system and is carried downslope to Puhi-o-Kalaikini lava delta, near Kalapana, where it enters the ocean and creates a large steam plume. Lava breakouts from the tube fed small surface flows that were active near the end of Highway 130, just west of Kalapana, through much of the week. Lava flows were active sporadically within the Pu`u `O`o crater through the week as well.
At Kīlauea's summit, the circulating lava lake deep in the collapse pit within the floor of Halema`uma`u Crater has been visible via Webcam throughout the past week. The circulation pattern was interrupted sporadically by abrupt increases in the height of the lava surface. These periods of high lava level have been short-lived, lasting up to several hours, and each ended with a sudden drop of the lava surface back to its previous level. Volcanic gas emissions remain elevated, resulting in high concentrations of sulfur dioxide downwind.
No earthquakes beneath Hawai`i Island were reported felt during the past week.
Visit our Web site (http://hvo.wr.usgs.gov) for detailed Kīlauea and Mauna Loa activity updates, recent volcano photos, recent earthquakes, and more; call (808) 967-8862 for a Kīlauea activity summary; email questions to askHVO@usgs.gov.
Updated: November 6, 2010 (pnf)