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Towards policy relevant environmental modeling: contextual validity and pragmatic models

"What makes for a good model?" In various forms, this question is a question that, undoubtedly, many people, businesses, and institutions ponder with regards to their particular domain of modeling. One particular domain that is wrestling with this question is the multidisciplinary field of environmental modeling. Examples of environmental models range from models of contaminated ground water flow
Authors
Scott B. Miles

Quantifying precambrian crustal extraction: The root is the answer

We use two different methods to estimate the total amount of continental crust that was extracted by the end of the Archean and the Proterozoic. The first method uses the sum of the seismic thickness of the crust, the eroded thickness of the crust, and the trapped melt within the lithospheric root to estimate the total crustal volume. This summation method yields an average equivalent thickness of
Authors
D. Abbott, D. Sparks, C. Herzberg, Walter D. Mooney, A. Nikishin, Y.-S. Zhang

A crustal model of the ultrahigh-pressure Dabie Shan orogenic belt, China, derived from deep seismic refraction profiling

We present a new crustal cross section through the east-west trending ultrahigh-pressure (UHP) Dabie Shan orogenic belt, east central China, based on a 400-km-long seismic refraction profile. Data from our profile reveal that the cratonal blocks north and south of the orogen are composed of 35-km-thick crust consisting of three layers (upper, middle, and lower crust) with average seismic velocitie
Authors
Chun-Yong Wang, Rong-Sheng Zeng, Walter D. Mooney, B. R. Hacker

Assessment of landslide hazards in Kaluanui and Maakua gulches, Oahu, Hawaii, following the 9 May 1999 Sacred Falls landslide

One of the injured hikers later died of injuries received in the landslide. Governor Ben Cayetano of Hawaii ordered that the park be closed due to concern about continuing landslide hazard near the falls. Subsequently, Bill Meyer, District Chief for the U.S. Geological Survey (USGS) Water Resources Division in Honolulu contacted Tim Johns, Chair of the Board of Land and Natural Resources of the Ha
Authors
R. W. Jibson, R.L. Baum

Timing of paleoearthquakes on the northern Hayward Fault: Preliminary evidence in El Cerrito, California

The Working Group on California Earthquake Probabilities estimated that the northern Hayward fault had the highest probability (0.28) of producing a M7 Bay Area earthquake in 30 years (WGCEP, 1990). This probability was based, in part, on the assumption that the last large earthquake occurred on this segment in 1836. However, a recent study of historical documents concludes that the 1836 earthquak
Authors
J. J. Lienkaemper, D. P. Schwartz, K. I. Kelson, W. R. Lettis, Gary D. Simpson, J. R. Southon, J. A. Wanket, P. L. Williams

Wide-angle seismic recordings from the 1998 Seismic Hazards Investigation of Puget Sound (SHIPS), western Washington and British Columbia

This report describes the acquisition and processing of deep-crustal wide-angle seismic reflection and refraction data obtained in the vicinity of Puget Lowland, the Strait of Juan de Fuca, and Georgia Strait, western Washington and southwestern British Columbia, in March 1998 during the Seismic Hazards Investigation of Puget Sound (SHIPS). As part of a larger initiative to better understand later
Authors
Thomas M. Brocher, Tom Parsons, Ken C. Creager, Robert S. Crosson, Neill P. Symons, George D. Spence, Barry C. Zelt, Philip T.C. Hammer, Roy D. Hyndman, David C. Mosher, Anne M. Tréhu, Kate C. Miller, Uri S. ten Brink, Michael A. Fisher, Thomas L. Pratt, Marcos G. Alvarez, Bruce C. Beaudoin, Keith E. Louden, Craig S. Weaver

Gas and Isotope Geochemistry of 81 Steam Samples from Wells in The Geysers Geothermal Field, Sonoma and Lake Counties, California

The Geysers geothermal field in northern California, with about 2000-MW electrical capacity, is the largest geothermal field in the world. Despite its importance as a resource and as an example of a vapor-dominated reservoir, very few complete geochemical analyses of the steam have been published (Allen and Day, 1927; Truesdell and others, 1987). This report presents data from 90 steam, gas,
Authors
Jacob B. Lowenstern, Cathy J. Janik, Lynne Fahlquist, Linda S. Johnson

Radioisotope tracer studies of inorganic carbon and Ca in microbially derived CaCO3

Microbial calcification significantly impacts the cycling and deposition of inorganic carbon. This research employs 45Ca and 14C techniques as radioisotopic tracers to examine the role of cellular cycling of Ca2+ and inorganic carbon in CaCO3 precipitation by the unicellular green alga Nannochloris atomus. Implications of the effects of these physiological aspects on CaCO3 precipitation and the ef
Authors
Kimberly K. Yates, Lisa L. Robbins

210Pb and 210Po, manganese and iron cycling across the O2/H2S interface of a permanently anoxic fjord: Framvaren, Norway

Vertical profiles of dissolved and particulate 201Po and 210Pb were measured across the redox transition zone at Station F1 in Framvaren Fjord, Norway. In this fjord, a sharp decrease in pH above the O2/H2S interface facilitates the aerobic dissolution of MnO2. In contrast, Fe(II) concentrations begin to increase only at the O2/H2S interface depth. Activity profiles reveal that dissolved 210Po an
Authors
Peter W. Swarzenski, Brent A. McKee, Kai Sorenson, James F. Todd

7Be as a tracer of flood sedimentation on the northern California continental margin

Sediment inventories of the cosmogenic radionuclide 7Be (t1/2=53 d) were measured on the Eel River shelf and slope (northern California continental margin) to investigate sedimentation processes associated with coastal river flooding. Seabed coring shortly after major riverflow events in 1995 and 1997 documented a shelf-wide flood deposit, and subsequent radionuclide studies determined 7Be to be a
Authors
C. K. Sommerfield, C. A. Nittrouer, C. R. Alexander
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