LAVA FLOW HAZARD ZONE MAPS |
Maps showing volcanic hazard zones on the island of Hawaii were first prepared in 1974 by Donal Mullineaux and Donald Peterson of the U.S. Geological Survey and were revised in 1987. The current map divides the island into zones that are ranked from 1 through 9 based on the probability of coverage by lava flows. Other direct hazards from eruptions, such as tephra fallout and ground cracking and settling, are not specifically considered on this map; however, these hazards also tend to be greatest in the areas of highest hazard from lava flows.
[ Kilauea || Mauna Kea-Kohala || Hualalai || Mauna Loa ]
Hazard
zones from lava flows are based chiefly on the location and frequency of both
historic and prehistoric eruptions. "Historic eruptions" include those for which
there are written records, beginning in the early 1800's, and those that are
known from the oral traditions of the Hawaiians. Our knowledge of prehistoric
eruptions is based on geologic mapping and dating of the old flows of each
volcano. The hazard zones also take into account the larger topographic features
of the volcanoes that will affect the distribution of lava flows. Finally, any
hazard assessment is based on the assumption that future eruptions will be
similar to those in the past.
HAZARD ZONES FOR LAVA FLOWS | |||
---|---|---|---|
Zone |
Percentage of area covered by lava since 1800 |
Percentage of area covered by lava in last 750 years |
Explanation |
1 |
greater than 25 |
greater than 65 |
Includes the summits and rift zones of Kilauea and Mauna Loa where vents have been repeatedly active in historic time. |
2 |
15-25 |
25-75 |
Areas adjacent to and downslope of active rift zones. |
3 |
1-5 |
15-75 |
Areas gradationally less hazardous than Zone 2 because of greater distance from recently active vents and/or because the topography makes it less likely that flows will cover these areas. |
4 |
about 5 |
less than 15 |
Includes all of Hualalai, where the frequency of eruptions is lower than on Kilauea and Mauna Loa. Flows typically cover large areas. |
5 |
none |
about 50 |
Areas currently protected from lava flows by the topography of the volcano. |
6 |
none |
very little |
Same as Zone 5. |
7 |
none |
none |
20 percent of this area covered by lava in the last 10,000 yrs. |
8 |
none |
none |
Only a few percent of this area covered in the past 10,000 yrs. |
9 |
none |
none |
No eruption in this area for the past 60,000 yrs. |
There may be abrupt changes, however, in the
relative hazard because of the local topography. For example, the hills behind
Ninole stand high above the adjacent slopes of Mauna Loa and consequently are at
a much lower risk from lava flows than the surrounding area, even though the
entire area is included in a single zone. To determine the hazard differences
within a single zone, more detailed studies are required.
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