Page images

(Top) Sample bottles from a
sediment trap located 4
meters (13 feet) above the
bottom of Massachusetts Bay.
Each bottle represents
accumulations during about
9 days during the period from
October 1990 to February
1991. (Middle) Suspended
sediment concentration based
on light transmission shows
peaks in turbidity that
correlate well with sample
bottles. (The upward trend
beginning in December was
caused by algae fouling the
lenses of the turbidity
sensor.) (Bottom). There is a
clear correlation between the
four most intense periods of
wave activity and the peaks in
suspended sediment shown
by the upper graph and the
bottles. This correlation
indicates that waves are the
major cause of resuspension.
The samples in bottles are
also used to measure
attributes (such as sediment
characteristics and
contaminant levels) during
stormy and calm periods.

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discharge of wastes into the ocean con-
flicts with other uses of the marine envi-
ronment, such as recreation, fishing, and
Three-dimensional computer model-
ing of circulation in Massachusetts Bay,
which is a major component of the USGS
effort, not only has provided insight to
scientists but also has played a key role in
the debate about whether to complete the
new outfall that redirects treated sewage
effluent from the presently contaminated
harbor to a location 9 miles into Massa-
chusetts Bay. When the model was tested
under winter conditions, it showed excel-
lent agreement between what was
observed and what was predicted for cur-
rents in Massachusetts Bay. The model
results, which have been presented at a
number of public forums, in court, and
for a television documentary, have been
used to compare effluent dilution at the
present outfall site and the proposed site.
The model shows that the present outfall
maintains significant concentrations of

effluent throughout Boston Harbor and
southward along the shore of Massachu-
setts Bay. Effluent at equivalent concen-
trations from the deeper offshore outfall
does not reach Boston Harbor and affects
much less of the Massachusetts Bay
The amounts of heavy metals in bot-
tom sediment and suspended matter in
western Massachusetts Bay have also been
established and provide a baseline for
evaluating changes that may result from
the new ocean outfall. Maps showing
grain sizes of the sea floor in Boston Har-
bor and Massachusetts Bay have been
generated by using sidescan sonar, seis-
mic reflection, bottom photography, and
sediment sampling. Because contaminants
are commonly bound to fine-grained par-
ticles, maps that show particle sizes can be
used to indicate where contaminants are
most likely to accumulate. These maps
have been used by State agencies to
design baywide programs to monitor and


evaluate the environmental impacts of the new outfall.

Field measurements conducted around the future outfall site to determine the fate of particles show that surface waves during major winter storms are the principal agents in resuspending sediment. A time-series sediment trap used at a long-term instrumented mooring in Massachusetts Bay demonstrates the correlation between bottom currents caused by surface waves and sediment resuspension and provides material from individual storms for analysis. Fine particles that settle in western Massachusetts Bay during relatively tranquil summer periods may be eroded and redistributed to deeper waters of Stellwagen Basin during winter storms. Knowledge of these processes is critical to evaluating the longterm impacts of pollutants in this coastal area.

The USGS Massachusetts Bay studies are providing information that is applicable to other coastal regions and may serve as a model for studies to assess the environmental consequences of waste disposal and contaminant accumulation in the coastal ocean areas.

Michael Bothner and Bradford Butman have studied the geochemistry of shallow marine sediments for more than a decade

Richard P. Signell is a physical oceanographer specializing in numerical models of circulation

Surprising News of Recent Faulting in South San Francisco Bay

he USGS began acquiring ultra-high

resolution seismic reflection profiles in San Francisco Bay in 1992 as part of a long-term study of the geology and environment of the Nation's largest urban estuary. In cooperation with scientists from four Japanese universities, the USGS acquired profiles by sharing the use of a Japanese sonar system, which is capable of obtaining unusually precise records from layers as thin as 18 centimeters (7 inches) in the upper 20 meters (66 feet) of soft bay mud. Japanese scientists have used this instrument to study a large and active fault in Japan, called the Median Tectonic Line, and were inter

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bay had shown that long linear aeromagnetic anomalies were known to cross this part of the bay from northwest to southeast. USGS researchers suggested in the late 1970's that the anomalies delineate fault zones. These faults are exposed on the peninsula beneath the city of San Francisco in a mass of rock called the Franciscan Formation along the Hunters Point-Fort Point shear zone. Because the faults separate bodies of rock that are more than 65 million years old, they were thought to be old and inactive. The new seismic profiles confirmed earlier speculation that the faults extend offshore along the linear magnetic anomalies but also show that some faulting occurred less than 10,000 years ago. Two major fault zones have been identified, each 2 to 3 kilometers (1.3–1.8 miles) wide and consisting of dozens of strands (a fault strand is a short segment

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HPFZ = Hunters Point
Fault Zone

CPFZ = Coyote Point
Fault Zone

Magnetic anomaly

SFO = San Francisco
International Airport

SF = San Francisco

For more information about the Marine

and Coastal Surveys program, contact

Janet Morton at:
Telephone (703) 648–6509

For more information about the San
Francisco Bay study, contact:

Telephone (415) 354–3129
Internet mmarlow(a

of a fault). The northern fault zone, called the Hunters Point fault zone, is known to extend about 5 kilometers (3 miles) from the shear zones exposed on Hunters Point to the central part of the bay, but it may be longer; the shallow depth of the bay to the southeast prevented surveying there. The area will be surveyed this year by using a shallowdraft vessel on loan from San Francisco State University. The Hunters Point fault zone may be as long as 120 kilometers (75 miles) (as long as the adjacent Hayward fault) if it follows the regional extension of a pronounced magnetic anomaly. The second fault zone, called the Coyote Point fault zone, extends from the end of the runways of San Francisco International Airport to the southeast past Coyote Point and may extend into the shallow part of the bay or beyond. Separating the two fault zones is a large suspected fold

and thrust structure called the San Bruno Shoal anticline, which has uplifted the bay floor to less than a meter (3 feet) deep in the center of south San Francisco Bay.

A month after the surveys, the USGS began collecting a series of cores in the south-central bay to date the layers that have been offset by fault movement. Colleagues at Stanford University and the Lawrence Berkeley Laboratory have been assisting USGS scientists in dating shells found in some layers by means of a precise carbon-14 dating technique. The preliminary results indicate that all the faults in the bay offset layers that were deposited 5,000 years ago and that some of the faults offset beds deposited only 1,600 years ago. At least two fault strands offset the bay floor, an indication that faulting may have been active within the past 1,000 years, but further studies are needed to determine the actual age of faulting.

Because of the young age of the faulting and the proximity of the faults to large urban areas and critical infrastructure, the USGS has held a series of briefings with officials from the airport, city emergency and transportation services, and others to advise them of the newly mapped faults. Future plans include a cooperative study with the State transportation agency to assist in the analysis of deep borings (to bedrock) that will be collected near the bay bridges. USGS scientists have recently finished an extensive survey of the rest of the south San Francisco Bay. Other USGS scientists will extend the fault studies on land across the San Francisco Peninsula and into the Pacific Ocean. They hope to find the area where the San Andreas fault intersects these newly delineated faults, near the epicenter of the great 1906 San Francisco earthquake.

Michael S. Marlow has published extensively on tectonic processes at continental margins

Gary M. Mann studies the deformation caused by strike-slip faulting in young rocks in the Pacific Northwest and in San Francisco Bay

Roberto J. Anima specializes in combining high-resolution geophysical methods with sedimentology to study the shallow structural framework of San Francisco Bay


The U.S. Energy Mix

he energy consumption of the

United States continues to grow at a steady pace. Ninety-nine percent of the energy used in this country is based on natural, nonrenewable resources—91 percent on fossil fuels, including coal, oil, and natural gas, and 8 percent on nuclear power. The remaining 1 percent comes from hydroelectric, solar, and wind power and other renewable sources. The mix of energy used by the United States is the foundation of the Nation's infrastructure and economy and significantly influences the environment. The USGS Energy Program provides fundamental scientific knowledge on the abundance of energy resources and the environmental consequences of their use, information that is vital in order to effect any substantial changes in the energy mix of the Nation.

Energy Resources and the Economy

he bulk of domestic energy con

sumption comprises oil-based fuels. Domestic oil production satisfies only about half of the Nation's oil appetite, however, and domestic oil production is declining at an alarming rate. Imported oil accounts for a significant proportion of the national trade deficit. Natural gas and coal are alternatives to oil-based fuel and are considered to be abundant in the United States. Scientists do not have a comprehensive understanding of the geological occurrences of natural gas, however, and this lack of knowledge inhibits exploration and development of domestic natural gas resources. Domestic coal resources also are thought to be vast, but a comprehensive understanding of the quantity and quality of minable coal has still not been achieved. Moreover, the use of coal poses potential environmental hazards that must be addressed if coal is to remain a viable energy resource in coming decades. USGS scientists conduct scientifically based assessments of specific energy resources, including oil, natural gas, coal, uranium, and oil shale. In addition, they evaluate the Nation's energy mix on a regular basis. World assessments of oil, natural gas, and coal

New Energy Assessment Underway

The USGS, in cooperation with the Minerals Management Service (MMS), is currently conducting a new assessment of U.S. oil and gas resources. The USGS assesses all onshore lands and State offshore waters; the MNMS assesses Federal offshore waters. The assessment provides an independent, scientifically based set of hypotheses concerning the amounts of oil and gas that could be added to U.S. reserves. The new assessment includes (1) undiscovered, conventionally recoverable oil and natural gas; (2) selected recoverable, unconventional resources of oil and natural gas; and (3) reserve appreciation (field growth). The USGS assessment will be completed by January 1995; results will be published early in 1996.

All results of the new assessment will be released in digital form, including on CD-ROM's. The geographic information system approach—being used for the first time in this assessment—allows results to be identified in relation to specific geologic provinces and geographic areas. For example, resource estimates will be available for individual Federal land-management areas, sedimentary basins, or States. This capability will make it easier for Federal landmanagement agencies, State agencies, and industry to use the assessment results. Moreover, it will provide a base of digital information that will be the foundation of continuing USGS efforts to improve assessment results.

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For more information about the Energy Resources Surveys program, contact David Houseknecht at:

Telephone (703) 648–6470 Internet dhousekna

Coal-Quality Data Base Sets Standards

The Environmental Protection Agency has recently designated the USGS coal-quality data base as the sole data base on which policy recommendations concerning trace-metal emissions from coalburning powerplants will be made. The electric power industry also has recognized the uniqueness of this data base and the high quality of information it contains. Representatives of the Electric Power Research Institute, the Edison Electric Institute, and the Utility Air Regulations Group recently expressed a strong desire to work cooperatively with the USGS to expand the coverage of the coal-quality data base. These developments establish the USGS coal-quality data base as the primary source of independent scientific data recognized and used by both regulators and industry to address airquality issues.

to predict the occurrence of relatively clean fossil fuels and to develop technology for removing hazardous elements from fuels before use. Increased use of natural gas in place of coal and oil-based fuels would significantly reduce the amounts of greenhouse gases and hazardous elements released to the atmosphere. Expanded research on natural gas will build a comprehensive understanding of this vital resource. Research topics of particular interest include the volume and distribution of economically and technically recoverable domestic natural gas resources and the earth-science background needed for the optimal development of those resources. The results of this research will establish a scientific basis for evaluating the environmental impacts of various energy-use scenarios and will provide predictive models to use in exploring for environmentally benign energy resources. An added benefit is an improved understanding of geological constraints in designing technology for removing harmful elements from fossil fuels before use.

Energy Resources and Cooperation

he USGS is a partner with the Min

erals Management Service and the Bureau of Mines in oil and gas assessment activities and coal assessment activities, respectively. Because a large proportion of undiscovered energy resources resides on federally managed lands, the

USGS maintains formal liaisons with the U.S. Forest Service and with other Department of the Interior bureaus, including the Bureau of Land Management, the National Park Service, and the Bureau of Indian Affairs. Results of energy-resource assessments are shared with the Bureau of Mines and incorporated into the National Energy Strategy, largely through cooperation among various agencies in the U.S. Department of Energy, including the Energy Information Administration, the Office of Oil and Gas Exploration and Development, and the Office of Basic Energy Sciences. Similarly, the environmental impact assessments conducted by the USGS are cooperative ventures with the Bureau of Reclamation, the Bureau of Mines, and the Environmental Protection Agency. Interaction with agencies in every State having oil, natural gas, or coal potential is an essential part of most Energy Program research.

David Houseknecht coordinates the USGS Energy Resource Surveys program and has published extensively on various aspects of petroleum geology

Reducing Hazards from Landslides

andslides are among our Nation's

most costly and destructive geologic hazards, causing billions of dollars of economic losses and significant loss of life. In some areas, expanding urban development onto landslide-prone hillsides has increased the number of landslide disasters and escalated costs of Federal disaster relief. An understanding of landslide processes and their consequent hazards can lead to nationwide reduction of landslide losses through proper planning and effective engineering.

Practical Planning for Hawaiian Landslides

I. the aftermath of a severe rainstorm that struck Honolulu, Hawaii, on December 31, 1987, and caused massive debris flows and landslides, the USGS began a multiyear project that was completed in 1993 and that provided practical information to local officials on how

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