Equations for the estimation of strong ground motions from shallow crustal earthquakes using data from Europe and the Middle East : vertical peak ground acceleration and spectral acceleration

This article presents equations for the estimation of vertical strong ground motions caused by shallow crustal earthquakes with magnitudes M w 5 and distance to the surface projection of the fault less than 100km. These equations were derived by weighted regression analysis, used to remove observed magnitude-dependent variance, on a set of 595 strong-motion records recorded in Europe and the Middle East. Coefficients are included to model the effect of local site effects and faulting mechanism on the observed ground motions. The equations include coefficients to model the observed magnitude-dependent decay rate. The main findings of this study are that: short-period ground motions from small and moderate magnitude earthquakes decay faster than the commonly assumed 1/r, the average effect of differing faulting mechanisms is similar to that observed for horizontal motions and is not large and corresponds to factors between 0.7 (normal and odd) and 1.4 (thrust) with respect to strike-slip motions and that the average long-period amplification caused by soft soil deposits is about 2.1 over those on rock sites

A Modeling Approach to Assess the Water Balance of a Typical Southern Piedmont Catchment under Long-Term No-Till Usage

Proceedings of the 2003 Georgia Water Resources Conference, held April 23-24, 2003, at the University of Georgia.We used the Root Zone Water Quality Model to simulate runoff and seepage below the root zone from a 2.7 hectare watershed to look at rates of ground water recharge under long-term, no-till crop production systems in the Piedmont of Georgia. The watershed is located at the USDA-ARS-JPCNRCC (J. Phil Campbell Sr., Natural Resource Conservation Center) in Watkinsville, Georgia. It has been in crop production under no-till and winter cover cropping management practices since 1974. The model over predicted soil moisture and slightly over predicted runoff, however, the pattern of deep seepage to ground water was distinctly different for rainfall patterns that were small and consecutive versus large rain events. Ground water depth immediately responded when root zone soil moisture was at field capacity or greater. This indicates that under saturated or field capacity soil moisture conditions, larger rain events of short duration (> 15 cm and < 30 hours in this case) are recharging ground water rather than creating significant runoff. Simulations of watershed management practices such as long-term no-till and cover cropping can serve as a useful tool to show the effects of long-term management on potential surface water contamination

Conservation tillage in Georgia: economics and water resources

Conservation tillage systems have proven effective in reducing soil erosion, but additional benefits to agricultural production, water quality and quantity, and on- and off-site impacts of water loss are often ignored. In spite of known benefits, no specific mention has been made of the use of conservation tillage in the development of the current statewide comprehensive water use plan. We estimate that water savings from the use of conservation tillage on cropland currently in conventional tillage could result in potentially enough water to support 2.8 million people annually in Georgia, and that off-site benefits associated with reduced erosion and improved water quality could be as great as $245 million annually. Based upon these potential benefits, conservation tillage needs to be considered in the formulation of the current policy to conserve and protect the state’s water supply for the future. Conservation tillage warrants recognition as a cost-effective practice to conserve Georgia’s water resources.Sponsored by: Georgia Environmental Protection Division U.S. Geological Survey, Georgia Water Science Center U.S. Department of Agriculture, Natural Resources Conservation Service Georgia Institute of Technology, Georgia Water Resources Institute The University of Georgia, Water Resources Facult