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Volcanowatch

February 22, 2001

A weekly feature provided by scientists at the Hawaiian Volcano Observatory.


Can we just move the city?

Several scientists from the Hawaiian Volcano Observatory and the University of Hawai?i attended the Cities on Volcanoes II conference held in Auckland, New Zealand, last week. Auckland is truly a city on a volcano - 48 volcanoes, to be precise, ranging in age from 40,000 years to a startling 600 years. For those who seek possible trends, the youngest volcano is also the largest! Several of these volcanic vents produced lava flows that look very similar to our own beloved `a`a and pahoehoe flows. But, for the most part, the Auckland eruptions produced a lot of cinder that still underlies much of the city.

Those aren?t the only volcanoes Aucklanders need to worry about. Fine ash deposits up to 15 m (50 feet) thick from the Taupo volcanic zone some 200 km (125 miles) to the south occur within the city limits. Another volcano in that zone, Ruapehu, erupted in 1996 but had no significant impact within Auckland.

The conference focused on volcanic hazards to cities built within or on the flanks of active volcanoes. The frequency of a volcanic event might be fairly low, but the consequences of an eruption within or near a large city could be very high. What can be done to minimize the effects of such a volcanic event?

Clearly, removing the city from the volcano is not an option if eruptions occur only every few hundred years. It would be equally impractical and unadvisable to seek ways to stop the eruptions. Living with the hazard seems the only option.

How do we do that? We can improve volcanic surveillance and prediction methods, ready governmental response such as evacuation plans, and strengthen recovery options such as property insurance.

People who study the insurance industry pointed out limitations in current business practices that greatly burden local property insurance companies for long disasters. Most local insurance companies are themselves insured by larger insurance companies (insurance insurance companies). During a disaster, local insurance companies would only pay benefits up to whatever their deductible is, and the insurance insurance company would pay out the balance of the benefits. This works well for most disasters, such as hurricanes, tornadoes, floods, and earthquakes.

However, if the disaster lasts longer than a certain period, commonly 72 hours, then the local insurance company must again pay benefits up to their deductible! For a disaster like lava entering Kalapana Gardens in 1990 and destroying 105 homes in 12 months, the local insurance companies would have to pay most of the benefits, and the insurance insurance company might not pay any. Such a disaster could bankrupt the local insurance companies. Efforts are under way to get volcanic disasters underwritten in a different manner to avoid this problem. New Zealand offers another solution - governmental insurance of NZ$112,500 to individual homeowners for an annual premium of NZ$67.50.

The final speaker, Dan Miller from the USGS Cascades Volcano Observatory, pointed out that volcano prediction is far from an accurate science and that land-use planning is a tool that should be used far more than it currently is. In fact, he could cite no examples of land-use planning for minimizing volcano hazards. It?s true for most natural disasters. People still build their homes in river flood plains and periodically get wiped out by flooding. The only difference is that they are probably required to buy flood insurance if they want to build there.

Hilo has a fine example of land-use planning to minimize tsunami damage. No, it?s not the breakwater ? it?s the system of state and county parks that now occupy areas where private property was damaged in the 1946 and 1960 tsunamis. Structures within this zone, like the Nihon Restaurant and the Hilo Hawaiian Hotel, must be constructed so that tsunami surge can pass through the ground floor and minimize structural damage.

In July 2003, Cities on Volcanoes III will be held on the Big Island. Either Hilo or Kailua-Kona would qualify as city hosts. Much progress, we hope, will be made by that time.

Eruption Update

Eruptive activity of Kilauea Volcano continued unabated at the Pu`u `O`o vent during the past week. Active `a`a and pahoehoe flows are descending Pulama pali, and budding and inflating pahoehoe straddles the eastern boundary of Hawai`i Volcanoes National Park adjacent to the Royal Gardens subdivision. Lava is pooling on the coastal flats and advancing slowly seaward, but none is entering the ocean at this time. The closest active flow is about 1 km (0.6 mi) away from the sea coast.

Four earthquakes were reported felt in Hawai`i during the week ending on February 22. At 9:53 p.m. on the 15th, a magnitude 3.5 earthquake was felt from Glenwood to Kealia; it was located about 17 km (10 miles) northwest of Kilauea caldera. The next day, residents from Waimea to Fern Forest and Hawaiian Ocean View Estates reported a magnitude 3.9 shake at 5:44 p.m., located in about the same area as the earlier earthquake. Both earthquakes were felt widely because they were deep, about 23 km (14 miles). In contrast, a small (M 2.3) but shallow (less than 1 km (0.6 mile) deep) earthquake from 5 km (3 miles) east of Pu`ulena Crater was felt by our sensitive reporters in Leilani Estates at 6:06 a.m. on February 18. Finally, a M 3.8 earthquake shook HVO and Volcano at 1:18 p.m. on the 20th; it was located only 5 km (3 miles) southeast of HVO at a depth of 2.7 km (1.6 miles).


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Updated: February 26, 2001