U.S. Department of the Interior

U.S. Geological Survey

USGS Fact Sheet 012-99

May 1999

Hawaii

Volcanic Eruptions and

Earthquakes

The long-lived eruption of Kilauea

Volcano on the island of Hawaii, now

in its seventeenth year, ranks as the

most voluminous outpouring of lava

on the volcano’s east rift zone in the

last two centuries, and the most

destructive eruption. Since the

eruption’s onset on January 3, 1983,

lava flows have added 570 acres of

new land to Hawaii and paved over

40 square miles that included rare

rainforest, treasured historical sites,

and several communities.

The character of the eruption changed

in 1986 from intermittent to continuous. The large amounts of noxious

sulfur dioxide gas released from the

erupting vents have created volcanic

air pollution, known locally as vog

(volcanic smog), and acid rain over

extensive areas downwind. To improve understanding and to evaluate

the hazards of vog, scientists from the

Hawaiian Volcano Observatory

(HVO) closely monitor the amount

and composition of gas emissions

from Kilauea. On average, about

2,000 tons of sulfur dioxide gas are

released each day into the atmosphere

from Kilauea’s erupting vent.

During the period of eruption, 28

earthquakes with a magnitude of 5 or

greater have shaken Hawaii, eight on

Kilauea alone. Some of these earthquakes have damaged houses and

other buildings and roads. The strong

earthquakes are related to structural

adjustments and faulting within

Mauna Loa and Kilauea Volcanoes.

Thousands of smaller earthquakes

also occurred on Kilauea, the direct

result of underground movement of

magma, but most were too small to be

felt or to cause damage. Large

earthquakes probably are the single

largest natural hazard on the island of

Hawaii. Events such as the magnitude

7.2 earthquake in 1975 and the

magnitude 7.9 earthquake in 1868 are

expected outcomes of the general

instability of the island. The USGS

maintains the HVO to study volcanic

and earthquake activity in Hawaii and

to consult with emergency-response

officials as they endeavor to protect

people and property. During eruptions, the HVO provides information

on lava movement that helps guide

decisions by Hawaii County Civil

Defense and Hawaii Volcanoes

National Park regarding evacuation,

road closures, and vantage points for

visitors. When lava nears inhabited

areas, scientists work around the

clock to provide up-to-date assessments of the eruption’s status and

lava-flow locations.

In the past year HVO scientists have

launched an aggressive campaign to

upgrade and expand the volcano- and

earthquake-monitoring networks for

the active volcanoes on Hawaii and at

Haleakala on Maui, the only other

island with an active volcano. New

instruments placed on Mauna Loa

Volcano will improve the capability

to detect early warning signs of its

next eruption and to approximate the

vent location before the eruption

starts. Mauna Loa poses a greater

hazard than the more active Kilauea,

because of its huge eruptions and

steep slopes.

Detailed geologic mapping of

Hawaii’s active volcanoes continues

to uncover important information

about past eruptions. This knowledge

is vital for preparing hazard assessments and for preparing the public

for the next eruption. In particular, the

increased use of geographic information system techniques for mapping

lava flows on Mauna Loa will yield

improved probabilistic hazard assessments.

A troubling recent discovery is that

Kilauea has erupted explosively many

times in the past 5,000 years, most

recently in 1924 and, with major loss

of life, in 1790. This discovery results

from geologic mapping and analysis,

which have found and dated several

Figure 1. A bench of shiny hot lava

flow builds Kilauea beyond the old

coastline in 1994. Lava spatters from

the roof of an active lava tube, which

carries lava from the vent area 7 miles

away.
science for a changing world

beds of explosive debris previously

unknown or poorly known.

Water Supply for Domestic Needs

A critical issue in the Hawaiian

islands is a reliable supply of freshwater. Although rainfall, streamflow,

and ground water generally are

abundant in Hawaii, most islands are

withdrawing water at rates close to

the estimated yield of aquifers near

the populated areas. In addition, most

proposed urban development is in the

dry, leeward areas of the islands.

The USGS, in cooperation with State

and local agencies, is conducting

studies to quantify the availability of

ground water in five of the six major

islands of Hawaii. As part of these

studies, the USGS has undertaken an

exploratory drilling program on

Hawaii, Oahu, and Kauai.

Studies and test drilling that have led

to the discovery and quantification of

developable ground-water resources

have been completed in the North

Kohala and Kona areas of the island

of Hawaii, north-central Oahu, and

southeastern Kauai. Similar studies

are underway for western Maui, and

northeastern Kauai.

Impacts of Introduced Avian

Diseases on Native

Honeycreepers

The introduction to Hawaii of avian

pox and avian malaria, along with

the Culex mosquitoes, which spread

these diseases, has had a severe

impact on native forest bird communities. Scientists at the USGS Pacific

Islands Ecosystems Research Center

have taken a leading role in evaluating the effects of these diseases on

highly susceptible Hawaiian honeycreepers, a unique and diverse group

of native birds.

USGS researchers have developed

new diagnostic tools for detecting the

diseases, conducted surveys to estimate the extent of disease and mosquito distribution, and tested habitat

management strategies for controlling

mosquito populations. Ongoing

investigations focus on achieving a

better understanding of disease and

mosquito ecology, and on the natural

evolution of disease resistance in

some honeycreeper species.

Conserving Native Hawaiian

Ecosystems Through a Unique

Partnership: The Olaa-Kilauea

Project

The Olaa-Kilauea Project is a multiagency cooperative partnership to

develop and implement management

programs to control alien species,

restore rare populations of plants

where necessary, and ensure the

survival of endangered plants,

animals, and insects. This partnership

offers an unparalleled opportunity to

preserve large, functioning native

ecosystems, and it serves as a model

for future protection efforts throughout the Hawaiian archipelago. The

32,000-acre section of land on the

windward western slope of Mauna

Loa Volcano on the island of Hawaii

represents a significant contiguous

block of some of the most intact

native montane wet and moist forest

on the island. The cooperators and

landowners in this endeavor are the

Kamehameha Schools-Bishop Estate,

the Hawaii Department of Public

Safety, the U.S. Fish and Wildlife

Service Pacific Islands ProgramEcosystem Region Office, the Department of Land and Natural Resources,

the U.S. Forest Service, the Hawaii

Volcanoes National Park, and the

USGS. Vocational training is a unique

feature of this partnership.

National Water-Quality

Assessment Program (NAWQA)—

Island of Oahu

To address the need for consistent and

scientifically sound information for

managing the Nation’s water resources, the USGS began a full-scale

National Water-Quality Assessment

(NAWQA) Program in 1991. The

NAWQA program is unique compared with other national waterquality assessment studies in that it

integrates the monitoring of the

quality of surface and ground waters

Figure 3. Feral pigs pose a major

threat to the native forests and

endemic species within the OlaaKilauea Management Area. About

10,000 acres have already been

enclosed with pig-free fencing

and are showing significant signs

of recovery.

Figure 2. Anianiau (Hemignathus

parvus) from the Alakai Wilderness

Preserve, Kauai. This species is

currently restricted to high elevation

montane rain forests on Kauai. Like

other native honeycreepers, Anianiau

are highly susceptible to avian pox

and malaria, and they have disappeared from former low elevation

habitats because of mosquitotransmitted avian diseases.
Hawaii

with the study of aquatic ecosystems.

The island of Oahu is one of several

NAWQA studies that began in

Federal fiscal year 1997.

The goals of the this program are to

(1) describe current water-quality

conditions for freshwater streams and

aquifers, (2) describe how water

quality is changing over time, and

(3) improve our understanding of the

primary natural and human factors

affecting water quality. The Program

also seeks to provide some of the

information needed by water-resource

managers to implement effective

water-quality management actions

and evaluate long-term changes in

water quality.

Ground water provides essentially all

municipal and domestic water for a

large and expanding population on

Oahu. The streams provide important

riparian and instream habitats for

many threatened and endangered

species. In addition, streams affect the

physical, chemical, and aesthetic

quality of receiving estuaries, bays,

and nearshore waters, which are

critical to the tourism-based economy

of the island. The Oahu NAWQA

study will examine the relationships

among natural factors, human activities, and water-quality conditions.

Major water-quality issues on Oahu

are: (1) water-use and water-quality

changes expected as a result of landuse changes from large-scale sugarcane plantations to urban and smallscale diversified agriculture, (2) the

potential for further water-quality

degradation of the principal drinkingwater supply aquifer in central Oahu,

(3) the potential loss of native aquatic

communities by degradation of

riparian and instream water quality

and habitat, and (4) sediment and

chemical loading in streams and

delivery to estuaries, bays, and

nearshore waters.

Topographic Map Revision

Among the most popular and versatile products of the USGS are its

1:24,000-scale topographic maps.

These maps show natural and cultural

features of the landscape, such as

lakes and streams, highways and

railroads, boundaries, and geographic

names. The State of Hawaii is covered by 127 maps at this scale.

Through inspection of recent aerial

imagery, it was found that 66 of the

State’s topographic maps needed to

be updated. The National Imagery

and Mapping Agency and the USGS

are cooperatively funding the revision

of these maps. In an effort to convert

all national data to the more accurate

North American Datum of 1983

(NAD83), all maps being revised will

be reprojected from the Old Hawaiian

Datum to NAD83. To provide a

consistent map coverage for the State,

the remaining 61 maps that do not

need revision will be reprojected to

the new datum through cooperative

partnerships.

Many different sources of information are required to update the variety

of map features. The USGS recognizes that in many areas the best

geographic data are produced by local

agencies. The City and County of

Honolulu was the best source for street

and park boundary data for the island

of Oahu. A data-exchange agreement

between the two agencies allowed the

USGS to use city and county largescale data to update the maps. This

cooperation helps the USGS avoid

duplicating the local mapping effort so

that more can be done at lower cost,

and provides the public with a smallerscale version of the best source of

street and parks data for Oahu. Furthermore, the data exchange agreement establishes a mechanism for

future cooperation between the USGS

and the City and County of Honolulu.

Along with topographic maps, digital

line graph (DLG) files and digital

raster graphics (DRGs) also are being

revised, reprojected, or both. The DLG

data are digital representations of

cartographic features found on topographic maps. A DRG is a scanned,

georeferenced image of a topographic

map. Both products are useful for a

variety of computer mapping functions

such as a backdrop for orienting users

or for combining with other digital

data.

The map revision effort is intended to

provide more up-to-date maps and

digital data where they are needed. All

maps and data are accessible to the

broad range of scientific, government,

military, and private agencies and

individuals interested in the State.

157° 156° 155°

19°

20°

21°

22°

160° 159° 158°

Niihau

Kauai

Oahu

Molokai

Lanai

Maui

Kahoolawe

Hawaii

Map revision and 

 reprojection to NAD83

Reprojection to NAD83 only

Figure 5. Hawaii topographic map

Figure 4. In the urban area of revision and reprojection projects.

Honolulu, runoff affects several

streams, the Ala Wai Canal estuary,

and nearshore water of the major

tourism center of Waikiki. (Photo by

Douglas Peebles.)
Printed on recycled paper

USGS office locations USGS State Representative

677 Ala Moana Blvd.

Suite 415

Honolulu HI 96813

(808) 522-8290

FAX (808) 522-8298

USGS Home Page:

http://www.usgs.gov

Reports and products:

1-888-ASK-USGS

Coastal Erosion and Sand

Resources

Coastal erosion is widespread and

locally severe in Hawaii and other

low latitude areas. For example,

about 25 percent of the sand beaches

on Oahu have been lost or severely

degraded during the last 60 years. To

understand the shoreline’s history and

plan for future use, USGS coastal

scientists are documenting the

coastal-erosion history of Hawaii.

They will determine the causal

factors of erosion, provide highquality data for other “end-users” in

applied studies (such as coastal

engineers, planners, and managers),

and increase the general understanding of low-latitude coastal geologic

development. The research approach

is to quantify the magnitude and

locations of serious erosion problems,

and then monitor coastal change in

critical areas. Selected field sites have

been identified for detailed processoriented studies to understand the

complex relations among reef carbonate production, sediment dispersal,

and the interaction of artificial

structures with sediment movement

along the shore. This information will

be used to develop general guidelines

for sediment production, transport,

and deposition of low-latitude coasts.

Related research is being conducted

to evaluate the quantity and usefulness of offshore sand deposits for

replenishing eroded beaches.

Interactions Among Alien and

Native Snappers

Scientists at the Hawaii Cooperative

Fishery Research Unit of the USGS

are assisting the Hawaii Division of

Aquatic Resources (HDAR) in

studying predation and competition

between an introduced alien snapper,

the taape, and the native deepwater

snappers that form the basis of a

dwindling commercial and recreational handline fishery. Taape have

thrived and spread since their

intentional introduction 40 years

ago. Through an analysis of the gut

contents of collected fish and by

visual observations from piloted

submersibles of habitat use, researchers are gaining an understanding of current and potential future

ecological interactions among

snapper species. This information

will help the HDAR devise effective

strategies for managing and restoring

the depleted native fishery.

Figure 6. The blueline snapper (taape)

is an alien fish introduced to Hawaii

more than 40 years ago. Taape have

formed large populations that share

habitat with native fishery species

and that may affect important

fisheries of the native species.

Hilo

Honolulu Kahului

Lihue

Hawaii Volcanoes 

National Park

The USGS has 121

employees in Hawaii