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USGS Science at AGU: From Mars to Below the Earth
Released: 12/6/2002

Contact Information:
U.S. Department of the Interior, U.S. Geological Survey
Office of Communication
119 National Center
Reston, VA 20192
Catherine Puckett 1-click interview
Phone: 707-442-1329

Dale Cox
Phone: 916-997-4209

NOTE: During Dec. 6-10, at AGU: To arrange interviews, please contact Catherine Puckett (cell: 650-222-9750), Stephanie Hanna (cell: 206-331-0335) or Dale Cox (cell: 916-997-4209) or Stephanie Hanna or call them at the AGU press room, 415-905-1007

Scientists from the U.S. Geological Survey (USGS) will present new research on a variety of topics at the annual AGU meeting at the Moscone Center in San Francisco, December 6-10. A few highlights include:


Tweaking the Hydrologic Cycle

To satisfy the thirst of a growing population, southern California is storing water underground. Known as artificial groundwater recharge, the practice is accelerating the natural hydrologic cycle and having profound effects on the surface of the earth and changing the quality of drinking water. USGS scientists will discuss the benefits and consequences of groundwater recharge in southern California, from assuring a long-term water supply to potential aquifer contamination. (Talks dealing with this issue: G. Bawden Abstract G22A-11, "Optimizing GPS Arrays to Image Both Tectonic and Anthropogenic Deformation;" K. Belitz, Abstract H72C-0872, "Volatile Organic Compounds and Stable Isotopes in Groundwater as Tracers of Industrial-Age Recharge in the Southern California Coastal Plain;" Judy Densmore, Abstract H11F-11, "Identifying the Source of High-Nitrate Ground Water Related to Artificial Recharge in a Desert Basin;" Reichard Hansen, Abstract H51C-04, "Ground-water Modeling and the Installation of Deep Multiple-Well Monitoring Sites in the Central and West Coast Basins, Los Angeles County, California) Please Contact Dale A. Cox for interviews

El Nino, Floods, and the California Coast

Today, we find ourselves in a weak to moderate El Nino winter. Weak or strong, El Nino in southern California means one thing — bigger floods. USGS scientist Ned Andrews explains how flood magnitudes vary along the California coast in a north to south trend. Typically, in northern California flood magnitudes during an El Nino winter are forty percent smaller than in non-El Nino winters. However, in southern California the floods are typically ten times larger. (E.D. Andrews, Abstract H11B-0842, "Influence of ENSO on Flood Frequency Along the California Coast") Please contact Dale A. Cox for interviews

The Creeping Seafloor Off Greater Los Angeles

Visualize an impressive underwater fly-though of the seafloor off Los Angeles. USGS scientist James Gardner reveals a 3-D digital ocean landscape that show a large section of the coastal margin off Los Angeles to be slowly creeping downslope and demonstrates the advantages of 3-D digital visualization over flat maps. (James Gardner, Abstract U52A-03, "The Seafloor off Greater Los Angeles: Visualizing Gigabytes of Data") Please contact Dale A. Cox for interviews

The Massive Tea Bag Islands of the San Francisco Delta?

The islands of San Francisco Bay/Delta have been described (perhaps incorrectly) as massive tea bags emitting clouds of dissolved organic matter (DOM) into the Delta waters. When the tea-colored DOMs are pumped to southern California and disinfected with chlorine, byproducts like trihalomethanes (THMs), can form. THMs have been shown to cause cancer, mutations, and even miscarriages. However, not all islands are the same. Will the creation of new wetlands in the San Francisco Bay create more trouble for southern California? USGS scientists discuss the implication. (Talks dealing with this subject: J. Fleck, Abstract B22B-0758, "Restoration of a Freshwater Wetland on Subsided Peat Soils: Potential Effects on Release of Dissolved Organic Carbon and Disinfection Byproduct Precursors"; R. Fujii, Abstract B21C-06, "Carbon Dynamics Change Over Time in a Restored Freshwater Wetland in the Sacramento- San Joaquin Delta, California"; B. Bergamaschi, AN B22B-0763, "The Contribution of Natural and Restored Wetlands to Changes in the Concentration and Composition of Dissolved Organic Material in the Sacramento-San Joaquin Delta and San Francisco Estuary") Please contact Dale A. Cox for interviews


Exposed Water Ice Discovered Near the South Pole of Mars

Surface water in the form of ice exposed near the edge of Mars’s southern perennial polar cap has been discovered for the first time, according to U.S. Geological Survey research released this week in the journal Science and to be presented at AGU in San Francisco on. There is evidence that the surface water ice in this region may be widespread – from a half-mile to six miles around the entire southern polar ice cap.

U.S. Geological Survey space scientist Timothy Titus and his colleagues Hugh Kieffer of USGS and Philip Christensen of Arizona State University noted that although it has long been known that water ice should be present in the southern polar region of Mars, until recently little evidence for water ice had been found. Previously, surface water ice had been documented on the northern polar cap of Mars, but this is the first time exposed water ice has been documented on the southern polar cap of the solar system’s fourth planet. To here more about this discovery, attend "Exposed Water Ice Discovered Near the South Pole of Mars," at 2:10 p.m. on Dec 8 (Abstract P72C-03), by Timothy Titus, Hugh Kieffer, and P. Christensen. This subject will also be part of the press conference "New Results From Mars Odyssey," on Dec. 8, 2 p.m., RM 114 Moscone Convention Center.

Hang-Gliding Over Mars: New Mapping Techniques Allow Scientists to See Mars (Almost) Up Close and Personal

USGS scientists and others are applying state-of-the art digital mapping techniques to the latest images of Mars to produce topographic maps of the planet at higher resolutions than has ever been possible before. Stereo analysis of images from the Mars Orbiter Camera now flying on the Mars Global Surveyor spacecraft yield 3-D views that resolve features 5-10 m across, while other techniques take the topographic models to the limit of image resolution. Topographic data at these resolutions are starting to reveal some of the processes (such as the retreat of layers in the polar caps to form "swiss cheese" terrain) that are shaping the martian surface at the present day and are also a crucial part of assessing the safety of landing sites for the next set of Mars missions, the Mars Exploration Rovers that will be launched next year. These same techniques, when applied to images from the next generation of Mars cameras will yield topography at even higher resolutions. Not quite as good as being there, but meter-scale 3-D models will give scientists about the view they would have hang-gliding over Mars, for hundreds of locations rather than a handful of landing sites. To hear more, and see a virtual flyover of the martian polar caps, attend the presentation, "Topographic Mapping of Mars: Approaching the Human Scale," by USGS scientist R. Kirk, Abstract Number P22D-10

A Thousand Grand Canyons? Fluvial Erosion on Mars Driven by Volcanism

Mars shows evidence for some of the most dramatic erosional events in the Solar System, which is quite unexpected considering it has a frozen surface and thin atmosphere. Thus, scientists do not expect, for example, martian torrential downpours and hurricanes that lead to big floods and lots of erosion as on Earth. Many of the eroded canyons and depressions on Mars appear to have formed near and at about the same time when volcanic centers and other features suggestive of local heating were active. USGS scientists believe that apparently, when molten rock rose near the surface, the heating of ice and water in the rock resulted in unstable conditions in which either modest spring discharges to catastrophic floods or debris flows (rocky debris lubricated by fluid) were released. USGS researchers have compiled results from previous studies performed by USGS and others to develop a historical picture of these events. Most of this activity occurred within the first billion years or so of Mars geologic history, resulting in erosion of rock that might have filled the equivalent of a thousand Grand Canyons on Earth. Over the final 3 billion years of Mars’ history, several additional events occurred of more modest size (each one equivalent to tens of Grand Canyons). These findings show that Mars has been greatly prone to erosion, wherever and whenever large doses of heat arrived near the surface. To hear more, attend "Mars: Fluvial Erosion Driven by Magmatism," by Kenneth Tanaka, James Skinner, and Mary Chapman (See Abstract P51B-0360)


USGS Studies Cast Major Doubts on Geologic Theory of How Volcanic Regions Created: Mantle Plumes May Be Nonexistent After All

Standard fare in geology textbooks and school classrooms across the world is that the hot springs, geysers and volcanoes of Yellowstone National Park, Hawaii, Iceland, and many other volcanic regions were "created" by plumes of hot rock that rise from near the Earth’s core. New results from recently published U.S. Geological Survey research hint, astonishingly, that such plumes may not exist at all. Results from seismic tomography, a method that uses earthquake waves to "CAT scan" the Earth’s secretive goings-on, suggest that the magma system beneath Yellowstone is only skin deep – shallower than 120 miles, far less than the 1,750 miles scientists would expect if the magma arose from near the Earth’s molten core as has been thought for decades. The results of USGS scientists Bob Christiansen, Gillian Foulger and their colleagues research on purported mantle plumes beneath Yellowstone and Iceland were published in the October edition of the Bulletin of the Geological Society of America and will be presented at the American Geophysical Union’s meeting in San Francisco. Abstract Number S71D-05.

Forecasting Volcanic Activity

Reliable forecasts of volcanic activity would be a significant contribution from earth scientists to the public. USGS scientists Timothy Masterlark and Zhong Lu introduce a combination of computer modeling and satellite radar imagery that allows visualization of the dynamic processes that occur inside of a volcano. This method is used to image the interactions between magma and groundwater in the interior of Seguam Island, an active volcano in the Aleutian islands of Alaska. These interactions may provide clues to the timing of future volcanic activity. Hear more about this topic at Poster G51A-0950 on Dec. 6, Moscone Convention Center, Hall C. Abstract Number 3926.

Report From the Fault Line: The 7.9 Denali Earthquake

AGU is hosting a press conference on the 7.9 Denali earthquake that occurred on Nov. 3, 2002, in Alaska, as well as its Oct. 23, 2002, foreshock of 6.7. USGS scientist Peter Haeussler will provide an overview of geologic studies that have occurred since the earthquake, including the mapping of surface faults that ruptured during the earthquake, the discovery of a previously unknown thrust fault, the distribution of slip along the fault, and landslides and liquefaction features caused by the quake. Roger Hansen, a state seismologist with the Univ. of Alaska, will present an overview of the earthquake seismology, analysis of the slip along the fault trace, strong ground motions and stress transfers before and after the quake. Jeff Freymueller of the Univ. of Alaska Geophysical Institute will provide an overview of geodetic studies conducted before, during, and after the earthquakes; this data should provide some of the best information to date on how the Earth’s crust deforms between, during, and after earthquakes along strike-slip faults. To hear more, attend the press conference in RM 114 Moscone Convention Center at 8 a.m. on Dec. 8 and attend the poster session on the Denali Earthquake from 1:30 to 4:30 p.m. on Dec. 8.

Historic Earthquakes

Attend the AGU press conference on Historic Earthquakes on Dec. 8 at 3 p.m. and learn more about why historic earthquakes that occurred more than a thousand years ago are an extremely important tool in learning about present earthquakes and their hazards. Panelists will discuss recently published information about "fossil" earthquakes on the San Andreas Fault, as well as other studies. USGS scientist Susan Hough will participate in the press conference with experts from many other institutions.


Dinosaur Extinctions Caused by Asteroid May Have Begun 2 Million Years Before Scientists Thought: Asteroid or Comet Hits Earth 2 Million Years Before Chicxulub Asteroid "Wiped Out" the Dinosaurs

Deep-sea sediment cores from the Pacific Ocean indicate that a large asteroid or comet hit Earth about 2 million years before the Chicxulub asteroid impact in Mexico. Researchers generally believe that the Chicxulub impact wiped out the dinosaurs during the Cretaceous-Tertiary (K-T) mass extinction about 65 million years ago. Mineral grains and spherules were found in the cores. Spherules are small melt droplets ejected from an impact site and the mineral grains are inferred to have condensed from the cloud of vaporized target material over the impact site. These small particles are found several meters below the sediment horizon containing similar impact debris associated with the Chicxulub impact. The K-T extinction, therefore, might have lasted much longer than previously believed – beginning two million years before the Chicxulub event and ending with the Chicxulub event. Abstract Number A12B-0148, Dec. 10, Hall D)

Signs of Asteroid Impact Found Preserved in Badlands National Park (South Dakota)

Recent investigations in Badlands National Park (South Dakota) have yielded discoveries that suggest that catastrophic geologic deposition features associated with the Cretaceous-Tertiary (K-T) boundary impact (or impacts) are preserved in the park. These deposits occur in marine sediments that were deposited in the Western Interior Seaway, a great shallow inland sea that existed at the time of the dinosaurs and extended along the eastern side of the Rocky Mountains from the Gulf of Mexico to Alaska. In the Badlands region, deposits below the K-T boundary are rich in Cretaceous marine fossils including ammonites ("squids with shells") and giant swimming reptiles called mosasaurs. The K-T boundary interval itself consists of materials that were ripped up and transported in from other parts of the seaway region. The chaotic mix of sediments in the K-T interval suggests that great asteroid-impact generated earthquakes must have occurred and that tsunamis must have swept through the seaway in the region that is now Badlands National Park. After the catastrophe, slow steady marine sedimentation resumed in the seaway, but most of the ancient life forms that had thrived in the Cretaceous had vanished. (Abstract Number PP11A-0300)


New USGS Map Shows Landslide Susceptibility of Silicon Valley (Santa Clara County)
A new map drawn by computer at a scale one inch to the mile shows landslide susceptibility, or relative likelihood of slope failure, for all of Santa Clara Co., Calif. This is the first quantitatively prepared map of the landslide hazard ever to cover so large an area at such fine detail and is the first in a planned USGS series of county-scale landslide-susceptibility maps for the San Francisco Bay area. The new map has implications for land use and development.

Bay area hillsides, including those bordering Santa Clara ("Silicon") Valley, are prone to earthquake- and rainfall-triggered landslides, the kinds of landslides anticipated by this map and not smaller, shallow slides that occur suddenly in a single very heavy rainstorm. Like earthquakes, landslides are difficult to predict in both space and time. Hillsides also differ vastly in their resistance to landsliding and the types of landslides expected. Among large areas of highest susceptibility shown on the new map are the hills flanking Santa Clara Valley immediately to the east of the cities of San Jose, Milpitas, and Morgan Hill, as well as terrain in the Santa Cruz Mountains to the west. All of these are known from prior experience by local geologists and soils engineers to be quite vulnerable to landsliding. (USGS scientist Richard Pike, Abstract Number H12D-0956)

Deserts on the Move: Dust Storms and Their Effect on Humans and the Environment

Wind-induced dust emission from sources in the southwestern United States is not a major contributor to global dust flux, but it is important on a regional and national scale because of its effects on air quality, human health and safety, as well as ecosystem dynamics. Integrated remotely sensed satellite, airborne, and ground-based image data have strong potential to detect and monitor active dust storms and map areas vulnerable to wind erosion. Since 1999, USGS scientists have used such data to detect, monitor, and analyze the location, size, frequency, duration, and transport patterns of large dust storms in the central Mojave Desert. One of the biggest dust storms of this past decade occurred on April 15, 2002, when at least several million metric tons of dust were emitted from the central Mojave Desert alone. During this storm, satellite images documented the arrival of two very large dust plumes into the Las Vegas area, and within 30 minutes the particulate matter had increased to a level considerably above what is considered unhealthy for anyone. USGS results indicate that at mid-afternoon the amount of dust in the air over the Las Vegas area was about 1.2 million tons. Because of the very poor air quality and visibility conditions the Las Vegas airport was closed for several hours and local air quality groups implemented dust reduction procedures, not realizing that the major problem was caused by regional not local dust sources. (Abstract Number A12B-0148)

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