Volcano Watch — Can we control volcanic hazards?

A hazard is a potentially destructive process or source of danger. Risk is the possibility of loss, such as life, property, or productive capacity, within an area subject to the hazard. Which can we fix-the hazard or the risk?
In the case of vog, people are looking for ways to stop Kīlauea's gas emissions at their sources-in other words, to control the hazard. Aside from the fact that both Pu`u `Ō`ō and Halema`uma`u vents are within Hawai`i Volcanoes National Park and are, therefore, legally immune to any development, controlling gas emissions from an active volcano seems an interesting idea. Let's explore some possibilities.

One suggestion has been to cap or contain gas emissions from Kīlauea using a structural barrier. It sounds reasonable but is problematic. Magma and gas must exploit existing weaknesses or create new ones within a volcano in order to get to the earth's surface. Thus, any structure designed to cap or contain gases would have to do what miles of subsurface volcanic rock have not. It's unlikely that a few more feet of concrete would stop an erupting vent for long.

Even if it were feasible, containment is not a good idea. Volcanoes are all about releasing pressure. When gases are easily released, non-threatening eruptions typically occur. If gases cannot easily escape, devastating explosive eruptions can happen, like those at Mount St. Helens. So, if we were to cap a vent, it almost certainly would have disastrous results. Pressure would build until it breaches the cap either in the same place or at another location.

Another possibility is scrubbing sulfur from gas emissions with water. This seems reasonable, because HVO scientists have long observed that torrential rainfall during winter storms temporarily subdues sulfur dioxide (SO₂) emissions from Kīlauea's summit. For instance, heavy rainfall in February 2008 reduced summit SO₂ emissions from about 1,000 tonnes per day to about 500 tonnes per day. Interestingly, this same storm had no apparent effect on Pu`u `Ō`ō emissions.

Halema`uma`u Crater is home to Pele, the Hawaiian goddess of volcanoes. It might be wise to note here that Pele's nemesis, Kamapua`a, once tried to defeat her by inundating the crater with water-he didn't succeed.

This storm dropped more than 0.5 m (20 in) of rain in less than four days. To simulate the effects of this amount of rainfall on Halema`uma`u Crater, we would need at least 18,000 gallons of water per minute. If the water is trucked from Kea`au, it would require more than 5,000 runs per day at an estimated cost exceeding $1 million a day.

If efforts to control or stop vog, a volcanic hazard, are not plausible or are cost-prohibitive, what can be done? We can still minimize the risk it poses to island residents. This is how we deal with other hazards. We cannot stop earthquakes, hurricanes, or tsunami, but we can implement improved building codes and land-use zonation to minimize the risk to people and property posed by those events.

County, State, and Federal agencies are working hard to address the risk of vog to public health, lifestyles, agriculture, and the economy. Their approach is a tried-and-true one that has worked with other hazards-minimizing the effects of vog through public education and responding to the hazard through improved vog monitoring.

For more information, visit our Frequently Asked Questions list online. Hawai`i County has advisories and a mitigation brochure on their website. The state of Hawai`i also has online information.

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Volcano Activity Update

Kīlauea Volcano continues to be active. A vent in Halema`uma`u Crater is erupting elevated amounts of sulfur dioxide gas and very small amounts of ash. Resulting high concentrations of sulfur dioxide in downwind air have closed the south part of Kīlauea caldera and produced occasional air quality alerts in more distant areas, such as Pahala and communities adjacent to Hawai`i Volcanoes National Park during kona wind periods. There have been several small ash-emission events, lasting only minutes, in the last week. These are preceded by small seismic events, and are probably caused by tiny rockfalls within the vent. On Friday, August 1, a portion of the vent's rim fell into the conduit. As a result, juvenile spatter and other debris were blasted out of the vent and deposited on the crater's rim between the Halema`uma`u overlook and the parking area

Pu`u `Ō`ō continues to produce sulfur dioxide at even higher rates than the vent in Halema`uma`u Crater. Trade winds tend to pool these emissions along the West Hawai`i coast, while Kona winds blow these emissions into communities to the north, such as Mountain View, Volcano, and Hilo. Incandescence continues to be observed at night inside Pu`u `Ō`ō and suggests minor activity from vents within the crater.

Lava continues to erupt from fissure D of the July 21, 2007, eruption and flows toward the ocean through a well-established lava tube. No breakouts have been observed in the past week anywhere on the flow field. Lava continues to flow into the ocean at Waikupanaha, however, where minor-to-moderate explosive activity has been observed. A deformation event at Kīlauea's summit, starting on Tuesday, August 5, at least partly choked off the supply of lava to the east rift zone eruption site. The ocean entry plume was dead, except for occasional small puffs, by Wednesday morning, and remains inactive at the time of this writing (Thursday, August 7). If this summit deformation event follows previous patterns, then it is likely that the eruption and ocean entry will have resumed by the time you read this.

Be aware that lava deltas could collapse at any time, potentially generating large explosions. This may be especially true during times of rapidly changing lava supply conditions, as have been seen lately. Do not venture onto the lava deltas. Even the intervening beaches are susceptible to large waves generated during delta collapse; avoid these beaches. In addition, steam plumes rising from ocean entries are highly acidic and laced with glass particles. For viewing hours at the coast, check the Civil Defense Web site or call 961-8093 for viewing hours.

Mauna Loa is not erupting. Three earthquakes were located beneath the summit this past week. Continuing extension between locations spanning the summit indicates slow inflation of the volcano.

Two earthquakes beneath Hawai`i Island were reported felt within the past week. A magnitude-3.2 earthquake occurred at 01:25 a.m. on Friday, August 1, 2008, H.s.t., and was located 25 km (16 miles) south of Kaupo, Maui, at a depth of 15 km (9 miles). A magnitude-2.7 earthquake occurred at 7:20 a.m. on Monday, August 4, and was located 23 km (14 miles) northeast of Laupahoehoe at a depth of 6 km (4 miles).

Visit our Web site for daily Kīlauea eruption updates, a summary of volcanic events over the past year, and nearly real-time Hawai`i earthquake information. Kīlauea daily update summaries are also available by phone at (808) 967-8862. Questions can be emailed to askHVO@usgs.gov. skip past bottom navigational bar