Geologically, the Big Island is the most interesting island in the state. It features active volcanoes (one of the most popular visitor attractions in the State).
– Market Feasibility Study
Ernest Watari, Pannell Kerr Forster
Just with respect to the Police Department, we are talking to them about the possibility of locating a police substation in the support community, and for a number of reasons, one of which was the volcanic hazard, they would … prefer to remain — have a substation in Na`alehu.
– William Moore, Deputy Planning Director
County of Hawai`i
Many people have compared the Ka`u area proposed as the site for the Hawaiian Riviera Resort to the Kohala Coast before it was built up with hotels and resorts. Superficially there is some semblance. Both areas are typified by extensive flows of barren lava. Otherwise, they are vastly different. Calm waters and sunny days are typical of the Kohala resort area. Choppy seas and overcast days are the rule in Ka`u.
And, whereas the granddaddy of the Kohala resorts — the Mauna Kea Beach Hotel — is in volcanic hazard zone 8 (of nine such zones designated by the U.S. Geological Service, with zone 1 being the most dangerous), the Ka`u site is in hazard zone 2. As Tom Wright, scientist in charge of the U.S.G.S. Hawai`i Volcano Observatory described it, Hazard Zone 2 is “a relatively high hazard … higher being defined, say, by the area adjacent to where the lava is currently going into the ocean at Kilauea.”
The Land Use Commission was presented with much testimony concerning the wisdom of developing a major resort destination and support community in an area prone to lava flows and other geologic disturbances. In recognition of this, the Commission included in its conditions of approval certain requirements related to the site’s geological character.
The Commission acknowledged that the Southwest Rift Zone of Mauna Loa, on which the Riviera site is located, has produced seven eruptions in historic times, with the most recent in 1950. “Three of the lava flows — 1868, 1887, and 1907 — entered on or near the property,” the Commission states in its findings of fact attached to the approval. “The 1907 flow terminated at the makai [oceanside] boundary of the Hawaiian Ocean Ranchos subdivision,” adjacent to the resort property, it noted.
However, it accepted the developers’ argument that “the 1887 flow … along the eastern side of the property … serves as a natural barrier against lava flows approaching the proposed resort from the east.” (No similar protection is afforded the support community, which will be built on top of the 1868 and 1887 flows.)
It also went along with the developers’ argument that because the eruptive activity of Mauna Loa has been diminishing in the last 40 years, one could safely predict that the area would not be as prone to lava inundation in the future as it had been in the past.
The Commission’s findings are at variance with testimony presented to them by the developers’ own expert witnesses. Thomas E. Jensen, an employee of the Dames & Moore engineering firm who was put forward as an expert witness in geology and engineering geophysics, stated under questioning by the developers’ attorney that “within the specific area of the site with which we are dealing, we don’t see reason to anticipate an inundation within a 40 to 50 year time span.”
Michael Garcia, a professor of geology at the University of Hawai`i hired to testify on behalf of the developers, also attested to the difficulty of predicting Mauna Loa’s behavior. When asked whether it was safe to base assumptions of risk on the brief, 200-year historical record of Mauna Loa’s activity, Garcia replied: “I cannot answer that question… For Mauna Loa one does run a risk, because of the time period being so short to look at… You may have a very biased viewpoint of the activity of Mauna Loa if you focus in on just the historic record.”
The Ground Cracks
The world’s greatest known concentration of ground cracks occurs in the area that is the proposed site of the Palace Resort’s hotels and commercial activity center. “Averaging about 1.5 feet in width and up to 3 feet high, their length varies from about 30 feet to 1,800 feet, with an average length of about 1,300 feet,” according to the environmental impact statement prepared by Belt Collins & Associates. “The cracks tend to be generally parallel with the shoreline. Most of the cracks appear to have a slight vertical offset, although some are offset up to 2 feet, that is, one side of the crack is as much as 2 feet lower than the opposite side.”
The EIS went on to state that although exact causes of the cracks were not known, they were thought to be related to a geological phenomenon known as “slumping,” which occurs when gravity finally pulls into the sea large masses of land that cling tenuously to steep slopes. As Dames & Moore explained in a 1987 report, drawn on in the EIS, “the seaward flank of the growing volcano [Mauna Loa] is unbuttressed and sloped at a relatively steep angle… The inflation and deflation of the magma chamber in the rift zone causes gravitational tensional movement along the flank and causes the area between the two faults [Kealakekua, to the north, and Kahuku, to the east] to break into large regional slump blocks. These regional blocks are moveable and have slumped downwards relative to each other.”
Wright, from the Hawai`i Volcano Observatory, agreed with that interpretation. Recent offshore mapping had provided even more evidence of “submarine landslide deposits” in an area extending from the Kealakekua Fault, some 30 miles up the coast from the resort site, to the Kahuku Fault, which lies less than 10 miles to the south. Wright explained that the cracks were likely “a long-term response to weakness in the submarine part of the volcanic pile.”
By the time of the Land Use Commission hearings, the developers’ geologists were proposing a quite different interpretation of the cause of the ground cracks. The cracks had nothing to do with the “slumping” phenomenon, reported S.K. Djou, principal engineer of Dames & Moore’s Honolulu office. Rather, they resulted from “simple tensional fracturing associated with the relief of deformational stresses due to densification and readjustment of materials underlying the lava flows.”
In any case, according to Dames & Moore’s engineers, construction techniques could eliminate the risk. First, they suggested buildings not be sited “within 500 feet of the longitudinal extension” of significant cracks, nor should buildings “straddle a significant crack unless the building foundation is separated from bedrock by a layer of granular cushion fill.” Controlled blasting could be used to allow buildings within the 500-foot setback from “the crack terminus.”
Insuring Folly
Given the natural hazards of the area, insurance might prove difficult to obtain — not necessarily for the developer, but for the future residents of the support community. As was noted in the testimony of Robin Campaniano, the state’s insurance commissioner, homeowner’s insurance on the Big Island has been made more expensive by ongoing volcanic activity in the Puna area. Until recently, the relatively low cost of land in the area allowed people to buy houses without obtaining a mortgage. Now, however, with land values increasing, more and more people were having to purchase insurance as a requirement to obtaining a mortgage.
The people purchasing house lots or condominiums at the resort site itself are not necessarily going to be inconvenienced by this. The sort of clientele targeted for the resort residences will not likely be needing insurance as a condition of financing their purchase.
The potential market for the so-called “affordable” houses in the support community are a different matter, however. According to the Office of State Planning, the federal Department of Housing and Urban Development has said it will not be involved in underwriting loans on any residences built in this area. With prices for housing in the support community estimated to run between $55,000 and $165,000 for a unit, the need for commercially available insurance is essential.
The Land Use Commission acknowledged this in its conditions of approval. Before the developers may apply to the county for rezoning of the site, the Commission has ordered it to present to the Commission “evidence to demonstrate the availability at reasonable rates of insurance coverage to insure residential structures for the support community against the perils of earthquake, volcanic eruption, fire, flood, and tsunami damage.”
Volume 1, Number 12 June 1991
Leave a Reply