This is the second in a series of articles about living near Kilauea, Hawaii's most active volcano. In the previous post, I mentioned that Kilauea, which has been erupting continuously since early 1983, recently had entered a more vigorous eruptive phase.
Kilauea's usual style of erupting is to ooze lava more or less continuously from several vents. Typically, the lava first pools near the vent; eventually the pools overflow, sending rivers of lava down the flanks of the volcano to the sea. In addition, the volcano emits steam and gases, which diffuse into the atmosphere as aerosols, i.e. tiny droplets.
Among the gas emissions are several that are potentially toxic, most notably, sulfur dioxide (SO2). Kilauea also emits considerable amounts of carbon dioxide, plus smaller amounts of carbon monoxide, hydrogen, hydrogen sulfide, and hydrogen chloride. Gas emissions mix with smoke and particulate matter from the volcano to form a kind of smog. Here in Hawaii, this volcano-generated smog is called "vog."
Vog is Hawaii's dirty little secret. When the prevailing northeast trade winds are blowing, most of Kilauea's vog plume goes out to sea, where it diffuses further over the open ocean, and eventually passes into the upper atmosphere. When the winds are light, however, or blowing onshore, various parts of the island become blanketed with vog.
Sometimes the vog is barely perceptible; at other times it can be so thick that it forms a visible haze in the air. When it is at its worst, it actually smells bad -- but worse still, it poses a health hazard to people, pets, livestock and wildlife, and can damage plant life.
The greatest vog hazard comes from the SO2 component, which can irritate mucous membranes. Those of us who live here can tell when the concentration of SO2 in the air is on the rise. Our throats get scratchy, our eyes itch, and the insides of our noses burn whenever we spend any time outdoors. Some people (myself included) get mild but frequent nosebleeds during voggy periods. Those with preexisting asthma and pulmonary disorders have even more difficulty breathing than they usually do.
Many residents become sensitized to the vog over time, and develop persistent respiratory disorders. I became one of those in the late 1990s, during an episode of increased volcanic emissions. During this period the vog reached notable levels, and stayed that way for weeks. I was spending a lot of time outdoors, in my garden and at the beach, oblivious to the damage that was being done to my respiratory system until it was too late.
First I developed a sore throat and a mild cough -- annoying, but not serious, I thought. Then one day I woke up with a fever. My mild cough got worse, and I began to wheeze. I made an appointment with my doctor, and by the time I got there the wheeze had progressed to a sort of gurgle, and I felt like I was not getting enough air. That is not a nice feeling!
It turned out that I had bronchitis and pneumonia, all at once. Apparently what happens is that the SO2 (and perhaps the hydrogen chloride -- which mixes with water vapor to form an aerosol of hydrochloric acid) irritates the mucous membranes in the nose and throat, making them inflamed and raw, and giving opportunistic infections a perfect medium for growth. Bingo! You're done for.
I spent more than a week in bed, with a HEPA air filter running continuously in the room. I recovered with the help of antibiotics, anti-inflammatory drugs, and an inhaled bronchodilator. Fortunately, the vog dissipated while I was recovering.
Ever since that experience, I am more sensitive to vog. I keep an inhaler on hand at all times now, and on a number of occasion I have had to make use of it when my bronchial tubes constricted and I began to wheeze. When there is a lot of vog, I stay indoors as much as possible, with the air-conditioning and HEPA filters running full tilt. Several times over the past decade -- and twice during recent months -- I have left the island for a week at a time, just to get away from the vog. In this respect, I am more fortunate than some who suffer from the vog. I have the means to leave, and somewhere to go. Many other people are not so fortunate.
The bright side of this situation has been that, for most of the past 25 years, the level of vog-producing emissions from Kilauea has been moderate, i.e., below harmful levels, for most of the Big Island. The situation changed last month when a new vent opened in Halemaumau Crater at Kilauea's main caldera. The vent began to spew prodigious amounts of steam and gas -- mostly SO2.
Reports from the Hawaii Volcano Observatory, summarized on the Kilauea page of the Smithsonian Institution's Global Volcanism Program website, had this to say:
Sulfur dioxide emission rates from the summit area have been elevated at 2-4 times background values since early January.
The emission rate abruptly increased on 12 March and fluctuated between 1,600-2,500 tonnes per day during 12-16 March, compared to a background rate of 150-200 tonnes per day.
On 16 March, emission rates reached 2,500 tonnes per day, the highest recorded at Kilauea's summit since measurements began in 1979.
Then, in the wee hours of March 19, 2008, there was
an explosive eruption in Halemaumau Crater, which scattered debris over an area of about 75 acres. This was Kilauea's first explosive event since 1924.
Since that time, Kilauea has continued to produce high levels of gas emissions, steam and ash, and SO2 emissions remained well above 'background' rates of 150-200 tonnes per day.
- 18-23 March: 1,200 - 2,200 tonnes per day
- 26-31 March: 700-1,500 tonnes per day
Although emissions have diminished somewhat from their mid-March peak, they are still at least ten times greater than background rates.
No one can say how much longer SO2 and other gases will continue to be emitted at these high rates. No one knows if the situation will improve, worsen, or remain stable. All of us here on the Big Island are paying close attention to Kilauea. We are paying attention as well to the direction and strength of the wind as summer approaches. In summer, the trade winds typically diminish, allowing whatever vog is produced to settle over the island instead of being blown out to sea. This year, that could present an intolerable situation. I may be spending the summer of 2008 away from Hawaii.
About the Photo: Big Island Mayor Harry Kim, and Danny Ziemann of the National Park Service at a
press briefing on the recent increase in SO2 emissions, as Halemaumau Crater spouted fumes behind them.
Honolulu Star-Bulletin, March 27, 2008.
More information:
Kilauea's Halemaumau Crater web cam - Hawaii Volcano Observatory
Volcanic Gases and Their Effects - USGS
Long-lasting Eruption of Kilauea Volcano, Hawai`i Leads to Volcanic-Air Pollution - USGS
Explosive eruption in Halema`uma`u Crater, Kilauea Volcano, is first since 1924 - USGS HVO News Release, March 19, 2008
Kilauea Weekly Volcanic Activity Reports - Global Volcanism Program, Smithsonian Institution
This Wednesday's found images feature flowers, waters, and birds. (I really, really, really like nature photography!)
