Scientific and Technical Aerospace Reports Volume 38 July 28, 2000

The Leadville mining district, located at an elevation of 3000 in in the Central Colorado Rockies, has been mined for gold,
silver, lead and zinc for more than 100 years. This activity has resulted in the dispersal of waste rock and tailings, rich in pyrite
and other sulfides, over a 30 km area including the city of Leadville. Oxidation of these sulfides releases lead, arsenic, cadmium,
silver, and zinc into snowmelt and thunderstorm runoff, which drains into the Arkansas River, a main source of water for Front
Range urban centers and agricultural communities. The U.S. Environmental Protection Agency (EPA), U.S. Bureau of Reclamation
(USBR), contractors, and responsible parties are remediating the mined areas to curtail further releases of heavy metals into
various drainage tributaries of the Arkansas River. Mineral maps made by the U.S. Geological Survey (USGS) from AVIRIS data
collected over this mining district were used to focus remediation efforts by locating the point sources of acid drainage.
Derived from text
Environmental Cleanup; Geological Surveys; Spectroscopy; Remote Sensing; Mines (Excavations); Water Runoff; Colorado
20000065652 Scripps Institution of Oceanography, Inst. of Geophysics and Planetary Physics, La Jolla, CA USA
Distribution of Slip at the Northern Sumatran Fault System
Genrich, J. F., Scripps Institution of Oceanography, USA; Bock, Y., Scripps Institution of Oceanography, USA; McCaffrey, R.,
Rensselaer Polytechnic Inst., USA; Prawirodirdjo, L., Scripps Institution of Oceanography, USA; Stevens, C. W., Rensselaer
Polytechnic Inst., USA; Puntodewo, S. S. O., Badan Koordinasi Survey dan Permetaan Nasional, Indonesia; Subarya, C., Badan
Koordinasi Survey dan Permetaan Nasional, Indonesia; Wdowinski, S., Tel-Aviv Univ., Ramat-Aviv, Israel; May 04, 2000; 33p;
In English
Contract(s)/Grant(s): NAGW-2641; NSF EAR-88-17067; NSF EAR-90-04376; NSF EAR-89-08759; NSF EAR-91-14349
Report No.(s): Paper 1999JB990253; Copyright; Avail: Issuing Activity
We model spatial variations in horizontal displacements of 117 geodetic sites measured during annual surveys in 1989-1996
with the Global Positioning System (GPS) as elastic strain across a locked strike-slip fault to infer the contemporary slip rate,
locking depth, and location of the Sumatran fault (SF) in northern Sumatra (1 S-3 N). GPS-derived slip rate estimates increase
slightly northward from 23 plus or minus 3 mm/yr at 0.8 deg S to 26 plus or minus 2mm/yr at 2.7 N. They agree with geologic
estimates north of the Equator, but at 0.5 S they are about 10 mm/yr higher. Strain appears to be distributed asymmetrically about
the fault. South of 2 N, about 5 mm/yr of shear is required within the offshore forearc, west of the fault, to achieve a closer agreement
of fault locations inferred from GPS velocities with geologically identified traces of the SF. Locking depth estimates are on
the order of 10-20 km. The western branch of the major fault bifurcation near 1 N slips at a rate five times higher than the eastern
branch. The two main strands of the fault at the northwestern tip of Sumatra (5.5 N) appear to be nearly free of horizontal strain;
significant slip must occur away from the two strands, probably further east at two other geologically active branches. The Banda
Aceh embayment is extruded to the northwest at a rate of 5 plus or minus 2 mm/yr. Within the estimated velocity uncertainties
of several mm/yr, fault-normal deformation along the SF is insignificant. Almost strain free, the northern part of the back-arc basin
is part of a rigid Sunda shelf, while the northern forearc is subjected to 8 plus or minus 5 x 10 (exp -8)/yr of extension nearly parallel
to the arc.
Author
Geodesy; Annual Variations; Geodetic Surveys; Geological Faults; Spatial Distribution
20000066617 Naval Research Lab., Command Control Communications Computers and Intelligence, Washington, DC USA
Notes On Improved Exponential Troposphere Model Final Report
Choi, Junho; Kwak, Sung; Apr. 17, 2000; 42p; In English
Report No.(s): AD-A377195; NRL/MR/8140--00-8450; No Copyright; Avail: CASI; A03, Hardcopy; A01, Microfiche
Atmospheric data extraction and processing procedures are presented for four different Databases: ECM, HIRAS, MRF, and
FNL. Details of database utility are described for application of geolocation measure and semi-major/semi-minor axis EEP plot
generation with miss-distance calculation procedure. New improved Exponential troposphere model algorithm has great utility
reducing in processing time as well as improving geolocation accuracy by more than 50% for both performance and speed with
storage requirements of databases.
DTIC
Troposphere; Data Bases; Signal Processing; Miss Distance
20000067644 NASA Marshall Space Flight Center, Huntsville, AL USA
Multiple Satellite Observations of High-Latitude Ionospheric Outflows
Horwitz, J., NASA Marshall Space Flight Center, USA; Zeng, W., NASA Marshall Space Flight Center, USA; Stevenson, B. A.,
NASA Marshall Space Flight Center, USA; Wu, X.-Y., NASA Marshall Space Flight Center, USA; Germany, G. A., NASA Marshall
Space Flight Center, USA; Craven, Paul D., NASA Marshall Space Flight Center, USA; Rich, F. J., NASA Marshall Space
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