March 1, 1996

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

Natural Hazards; Aloha, Dave Clague

I will end my series of these columns with some thoughts about preparedness for future disasters and some personal thank-yous.

The single geologic event with the potential for widespread destruction on the Big Island is clearly earthquakes. As we have witnessed with the Loma Prieta and Northridge earthquakes in California and the Kobe earthquake in Japan, earthquakes can cause widespread damage to property and infrastructure and can result in many injuries and deaths.

In the types and extent of areal damage, destruction from earthquakes is similar to that from hurricanes, whereas damage from lava flows are more similar to that from tornadoes. Here in Hawai'i, Hurricane 'Iniki caused widespread damage on Kaua'i in 1992, and also highlighted the importance of well-constructed buildings in reducing the damage.

Nearly all of the building requirements to withstand earthquake shaking are the same ones required to reduce damage from strong winds. Therefore, if we construct houses to withstand hurricane winds, we will also protect ourselves from earthquake damage. If we construct appropriately strong buildings, we will dramatically reduce the losses from both the next earthquake and the next hurricane. To this end, it is important that appropriate building codes are adopted everywhere in Hawai'i and that the counties enforce those building codes vigorously.

In the past few years, in response to the damage from Hurricane 'Iniki, the County of Hawai'i has adopted modern building codes (1991 Uniform Building Code) and has increased enforcement of the code. This is the key to reducing the losses from future earthquakes and hurricanes, and the County should be commended for its actions.

The recurrence interval between large, damaging earthquakes on Hawai'i Island is about one every eight years and is far shorter than the recurrence interval for hurricanes anywhere in the islands. Because of the frequency of large earthquakes on Hawai'i, the Hawai'i State Civil Defense, following the advice of the Hawai'i State Earthquake Advisory Board, has recently requested that the earthquake zone for the County of Hawaii be increased from zone 3 to zone 4 (the highest zone, equivalent to the zone in much of California).

The rest of the Hawaiian Islands are not immune from earthquakes either. Large, damaging earthquakes occurred near Maui and near Lana'i in 1871 and in 1938, respectively. These earthquakes, though occurring far less frequently than those on Hawai'i, were large enough to cause damage in Honolulu.

The hazards from earthquakes are clearly greater for Hawai'i and decrease to the northwest, whereas hazards from hurricanes are generally thought to be fairly constant throughout the islands, even though the last two hurricanes hit Kaua'i. If we combine these hazards, it is clear that all of the Hawaiian Islands should have equally stringent building codes. The sooner such zoning, code changes, and enforcement begin in earnest throughout the Islands, the less will be the damage from future disasters.

The insurance industry and the Federal Emergency Management Agency (FEMA) have paid for enormous losses in the past few years. Such huge losses reflect the severity of the events (floods, earthquakes, hurricanes, etc.) that have occurred, but they also reflect the expansion of communities into areas with higher hazards (flood plains, slopes of active volcanoes, coastal zones) and the poor design and construction of many of these homes.

In the future, insurance rates are likely to reflect how well communities have worked to reduce future losses through such means as appropriate land-use planning, building codes, and enforcement of codes. Those communities that work to reduce the future losses will be rewarded with lower premiums while those that do not will pay higher premiums to compensate for the increased risk caused by their inaction.

Likewise, FEMA is rapidly moving towards insuring risks, rather than paying for reconstruction from catastrophic hazards, such as floods, with tax dollars. In the future, other catastrophic hazards, like hurricanes and earthquakes, may well be covered with national insurance plans. Their future programs are also likely to include reconstruction only outside the areas of increased hazard. These policies are being developed following reconstruction of the same houses in floodplains in the midwest after repeated floods only a few years apart. We have also seen the results of these policies in Hawai'i, where homeowners whose residences were destroyed by lava flows from Kilauea have not been reimbursed to rebuild in the same high-hazard areas.

In summary, I think that Hawai'i is on the right track in reducing the losses from future natural events. With each passing year, the number of houses that have been built to withstand the forces of earthquakes and hurricanes should grow and the future losses, reduced. It will, however, take many years before the existing inventory of houses inappropriately designed and built is reduced to the point that large natural events will not cause significant damage.

Aloha

Finally, I want to thank a number of individuals and groups who have worked closely with the Hawaiian Volcano Observatory. It has been a pleasure to work with Harry Kim and the Hawai'i County Civil Defense Agency. They have rapidly acted upon our updates about earthquakes and changes in eruptive activity. In addition, they have served to effectively communicate that information to the public and the media.

It has likewise been a pleasure to work with Jim Martin, Superintendent of Hawaii Volcanoes National Park, and his entire staff. They have always been responsive to our reports of changes in activity. They have a difficult job, providing access for the general public to the active flows, while at the same time trying to insure public safety. These two goals are often contradictory, and Jim and his staff do a superb job in walking the line between them.

I have also worked closely with the Hawai'i State Office of Civil Defense and have been an active participant in the Earthquake Advisory Board. I shall miss working with Brian Yanagi, Don Gransback (now retired), and Roy Price at State Civil Defense, and Gary Chock and the rest of the Earthquake Advisory Board. These groups are dedicated to the difficult task of planning for future disasters and reducing the risks to the citizens of Hawai'i.

The Geology Department at the University of Hawai'i at Hilo, and the Center for the Study of Active Volcanoes (CSAV) located there, have been important partners with the Observatory. The public seminars on geologic hazards and their mitigation, organized and run by CSAV, have been a fine public service to the community.

Finally, and most importantly, I want to thank the entire staff of the Hawaiian Volcano Observatory. I have not encountered any other group more responsible and dedicated to their work, more willing to give up their personal time when the volcanic activity dictated it, or been more of a pleasure to work with. I want to thank Jane Takahashi, who has edited all these columns. Without her effort, the message would frequently have been lost in my too-scientific prose. Arnold Okamura has been an able and enthusiastic Deputy Scientist-in-Charge. His experience and level- headedness saw us through many a crisis. It was always reassuring when I was away from the Observatory, knowing that I had left things in such capable hands. Dr. Margaret Mangan, former staff geologist at HVO, has graciously agreed to become the Acting Scientist-in-Charge until such time as the U.S. Geological Survey finds a longer-term replacement. I wish her well in what is one of the most interesting and challenging jobs I have experienced.

Thanks to you all for making these four years exciting, productive, and fun.

Aloha, Dave Clague.