Lava-Flow Hazard Zones
|10. How and why is the Lava-Flow Hazard Zone Map used by home insurance or mortgage companies?
As stated in #4 above, the map was designed for general planning purposes only. The following statement is included on the published map (USGS Miscellaneous Field Studies Map 2193):
Hazard-zone boundaries are approximate and gradational. These boundaries are not specific enough to determine the absolute degree of danger at any particular site. Lava-flow hazard maps are designed to show relative hazard across the Island of Hawai'i and are meant to be used for general planning purposes only.
|11. What can a home owner do if a company uses the map to set elevated insurance or mortgage rates?
An option is to contact the State of Hawai'i Department of Commerce and Consumer Affairs.
The USGS Lava-Flow Hazard Zone Map is meant to convey relative volcanic hazard rather than risk (see "Hazard versus Risk" box).
A published study indicating the relative risk of lava inundation in Zones 1 and 2 is not available at this time, so inquiries or complaints about increased rates should go to the respective insurance or mortgage companies.
The question of who will create risk maps for Hawai'i and other states with active, or potentially active, volcanoes is currently a topic of great interest.
|12. What can a home owner do if a lava-flow hazard zone is used as a reason for non-renewal of a home owner's insurance policy?
An option is to contact the State of Hawai'i Department of Commerce and Consumer Affairs. Their Website states that they investigate insurance-related complaints.
|13. How does location near a rift zone affect lava-flow hazards?
A rift zone is marked by vents through which lava is erupted. In other words, it is the first place that lava appears out of the ground and, therefore, the starting point of lava flows that can then travel downhill.
Kilauea has two rift zones: the east rift zone and the southwest rift zone (the latter is almost totally within Hawai'i Volcanoes National Park). Mauna Loa has a northeast rift zone and a southwest rift zone. Hawai'i Island rift zones are shown in gray on the map at right.
|14. Why is an area freshly covered by lava designated as Zone 2, while another area not recently threatened by lava is designated as Zone 1?
Lava-flow hazard zones reflect the long-term hazard of lava flows, not the short term hazard. Rate of lava coverage—not how recently lava covered an area—is the basis of long-term lava flow hazard.
Zone 1: "Includes the summits and rift zones of Kilauea and Mauna Loa (left) where vents have been repeatedly active in historic time." These areas are the most dangerous because all, or nearly all, erupted lava first emerges from the ground within Zone 1.
Zone 2: "Areas adjacent to and downslope of active rift zones." These areas are also hazardous, but somewhat less so, because it takes some time for lava from Zone 1 to reach Zone 2
As Kilauea's current (and ongoing) middle east rift zone eruption has proven, damage from lava flows will be greater in Zone 1 than in any other zone over the long term. When the eruption began in January 1983, lava flows immediately and repeatedly covered Zone 1 areas. Zone 2 areas have also been covered by lava during the eruption, but not immediately or repeatedly. In other words, it took some time for lava flows to reach Zone 2 areas, and the threat was not continuous—it depended on which direction and how fast the lava flows moved downslope.
|14a. As a specific example, why is Kalapana in Zone 2, while Leilani Estates is in Zone 1?
Kalapana is about 13 km (8 mi) downslope of Kilauea's east rift zone. During Kilauea's current east rift zone eruption, lava flows took 6 years to first reach Kalapana (in 1989) before the area was more completely inundated with lava over a period of about 9 months in 1990. Lava flows then spared this area for 20 years, until they once again threatened Kalapana Gardens in 2010-2011.
Leilani Estates, on the other hand, is located entirely on Kilauea's lower east rift zone, and the next eruption in this area could start within, or immediately adjacent to, the subdivision. The most recent lower east rift zone eruptions were in 1955 (left), when one of the vents erupted lava along the southernmost boundary of Leilani Estates, and in 1960, when lava inundated the village of Kapoho.
There is evidence of eruptive vents both north and south of Leilani Estates. But, unfortunately, many of the volcanic features indicative of the active rift zone—craters, cinder cones, steaming vents—are disguised by lush vegetation or have been removed by quarrying or grading, which leads to a false sense of security.
The concern is that when—not "if"—the next eruption occurs on Kilauea's lower east rift zone, active vents and lava flows will directly impact Lelani Estates, and will do so for as long as the eruption continues. Thus, the Zone 1 designation for the subdivision is appropriate.
|15. Have lava-flow hazard zone maps been prepared for the other Hawaiian islands?
In the Hawaiian Islands, there are six volcanoes classified as active: Kilauea, Mauna Loa, Hualalai, and Mauna Kea on the island of Hawai'i; Lo'ihi, a submarine volcano southeast of Hawai'i Island; and Haleakala, on the island of Maui. These two islands—Hawai'i and Maui—are the only ones for which lava-flow hazard zone information is available.
Lava-flow hazard zone maps are not available, and not needed, for the islands of Kaua'i, Ni'ihau, O'ahu, Moloka'i, Lana'i, and Kaho'olawe.
|16. Where can Maui residents find lava-flow hazard zone information?
For East Maui, which includes the active volcano Haleakala (right), the most current lava-flow hazard zone map can be found in a 2006 paper by D.R. Sherrod and others, available online. The Lava-Flow Hazard Zone classification used for Maui is similar to that used to classify lava-flow hazards on Hawai'i Island, but, because Haleakala erupts far less frequently than either Mauna Loa or Kilauea, the relative hazards on Maui are lower.
A lava-flow hazard zone map is not available or needed for West Maui.
|17. How do Maui lava-flow hazard zone numbers compare to those on Hawai'i island?
The principal author of the 2006 paper by D.R. Sherrod and others, suggests that Maui Zone 1 is roughly equivalent to Hawai'i Island Zone 3, Maui Zone 2 is roughly equivalent to Hawai'i Island Zone 4, and Maui Zone 3 is roughly equivalent to Hawai'i Island Zone 6. These comparisons are not explicitly stated in the paper, but Sherrod affirms how Maui lava-flow hazard zone numbers compare to Hawai'i Island lava-flow hazard zone numbers, which were established by Mullineaux and others (1987). In other words, no place on Maui has volcanic hazards equivalent to Lava-Flow Hazard Zones 1 and 2 on Hawai'i Island.
|18. Where can I read more about lava-flow hazard zones in Hawai'i?
The following two papers contain more detailed information about lava-flow hazards:
Mullineaux, D.R., Peterson, D.W., and Crandell, D.R., 1987, Volcanic hazards in the Hawaiian Islands, chap. 22 of Volcanism in Hawaii, Decker, R.W., Wright, T.L., and Stauffer, P.H., eds.; U.S. Geological Survey Professional Paper 1350, v. 1, p. 599-621.
Other sources of information about volcanic hazards:
Tilling, R.I., Heliker, C., and Swanson, D.A., 2010, Eruptions of Hawaiian Volcanoes—Past, Present, and Future: U.S. Geological Survey General Information Product 117, 62 p.
USGS Volcano Hazards Program—Types of Volcanic Hazards