U.S. Geological Survey Open-File Research Articles

End Point Rate Tool for QGIS (EPR4Q): Validation Using DSAS and AMBUR

This paper presents the validation of the End Point Rate (EPR) tool for QGIS (EPR4Q), a tool built-in QGIS graphical modeler for calculating the shoreline change with the end point rate method. The EPR4Q tries to fill the gaps in user-friendly and free open-source tools for shoreline analysis in a geographic information system environment since the most used software—Digital Shoreline Analysis System (DSAS)—although being a free extension, it is created for commercial software. Additionally, the best free, open-source option to calculate EPR is called Analyzing Moving Boundaries Using R (AMBUR); since it is a robust and powerful tool, the complexity can restrict the accessibility and simple usage. The validation methodology consists of applying the EPR4Q, DSAS, and AMBUR with different types of shorelines found in nature, extracted from the US Geological Survey Open-File. The obtained results of each tool were compared with Pearson’s correlation coefficient. The validation results indicate that the EPR4Q tool acquired high correlation values with DSAS and AMBUR, reaching a coefficient of 0.98 to 1.00 on linear, extensive, and non-extensive shorelines, proving that the EPR4Q tool is ready to be freely used by the academic, scientific, engineering, and coastal managers communities worldwide.

Estimation of the source parameters of the Nepal earthquake from strong motion data

Kathmandu and its surrounding region were rocked recently by a devastating earthquake on April 25, 2015. This is the largest earthquake that has occurred in this region since the past eight decades. This earthquake was recorded on strong motion stations located about 470–522 km away from its epicenter. Records of accelerographs from these stations have been used to determine the location of this earthquake using hypo71 algorithm given by Lee and Lehr (HYPO71, a computer program for determining hypocenter, magnitude and first motion pattern of local earthquakes. US Geological Survey Open file report, 100, 1975). The recorded accelerograms have been corrected for site effects using site amplification curve obtained from ambient seismic noise recorded at each station. Site effect has been computed using H/V ratio method given by Nakamura (Q Rep RTRI 30(1):25–33, 1989) using ambient noise data. The corrected record is further used to obtain source displacement spectra. The source spectrum obtained from strong motion data is compared with theoretical source spectrum obtained from Brune’s (J Geophys Res 75:4997–5009, 1970) model for the horizontal components. The long-term flat level and corner frequency from source displacement spectra are used to calculate stress drop, source radius and seismic moment of this earthquake. The present study indicates that the Nepal earthquake originated 12.0 km below the epicenter located at 27.93°N, 84.70°E. The source radius, stress drop and seismic moment of this earthquake estimated from source displacement spectra are 44.13 ± 3.85 km, 18.68 ± 5.93 bars and 3.53 ± 0.28 × 1027 dyne cm, respectively.

Preliminary Non-Fuel Mineral Resource Assessment of Afghanistan-2007

Stephen G. Peters, Stephen D. Ludington, Greta J. Orris, David M. Sutphin, James D. Bliss, and James J. Rytuba, Editors, and the U.S. Geological Survey-Afghanistan Ministry of Mines Joint Mineral Resource Assessment Team. USGS Open-File Report 2007-1214 (http://pubs.usgs.gov/of/2007/1214/) and Afghanistan Geological Survey Open-File Report 2007-214. USGS Afghanistan Project Product no. 157. Version 1. Distributed in printed format (810 p. soft bound) and on CD-ROM assessment report (disc 1) & DVD-ROM containing data and GIS (disc 2). The U.S. Geological Survey (USGS) cooperated with the Afghanistan Geological Survey (AGS) of the Afghanistan Ministry of Mines to assess the undiscovered non-fuel mineral resources of Afghanistan between 2006 and 2007. The resulting publication, Preliminary Non-Fuel Mineral Resource Assessment of Afghanistan–2007 (the first book listed above) presents the results of this work and contains chapters describing and assessing the mineral resources of Afghanistan. A Geographical Information System (GIS) is provided on an accompanying disc that includes supporting data. Funding for this effort was provided by the United States Agency for International Development (USAID). Supporting geologic studies of mineralized systems and assessment areas, and reports on the methodology used in this study, although on-going, make this publication a must- read for everybody interested in the geology and mineral wealth of Afghanistan. Assessment results are available on the USGS Afghanistan website, http://afghanistan.cr.usgs.gov/, and the Afghanistan Geological Survey website, http://www.bgs.ac.uk/afghanminerals/ …

Faulting mechanisms and stress regime at the European HDR site of Soultz-sous-Forêts, France

The state of stress and its implications for shear on fault planes during fluid injection are crucial issues for the HDR (Hot Dry Rock) or EGS (Enhanced or Engineered Geothermal System) concept. This is especially true for hydraulic stimulation experiments, aimed at enhancing the connectivity of a borehole to the natural fracture network, since they tend to induce the shearing of fractures, which is controlled by the local stress regime. During the 2000 and 2003 stimulation tests at Soultz-sous-Forêts, France, about 10,000 microearthquakes were located with a surface seismological network. Hundreds of double-couple (DC) focal mechanisms were automatically determined from first-motion polarities using the FPFIT program [Reasenberg, P.A., Oppenheimer, D., 1985. FPFIT, FPPLOT and FPPAGE: Fortran computer programs for calculating and displaying earthquake fault-plane solutions. US Geological Survey Open-File Report 85-739, 25 pp.]. The majority of these mechanisms indicate normal-faulting movement with a more or less pronounced strike-slip component. Some quasi-pure strike-slip events also occurred, especially in the deeper part of the stimulated rock volume, at more than 5 km depth. Although we found a double-couple solution for all events, we tried to observe and quantify the proportion of the non-double-couple (NDC) component in the seismic moment tensor for several microseisms from the 2003 data. The study shows that the NDC is higher for the events in the vicinity of the injection well than for the events far from the well. We used the method of Rivera and Cisternas [Rivera, L., Cisternas, A., 1990. Stress tensor and fault-plane solutions for a population of earthquakes. Bull. Seismol. Soc. Am. 80, 600–614.] to perform the inversion of the deviatoric part of the stress tensor from P-wave polarities. This method was applied to different datasets from the 2000 test, taken from the shallower and deeper parts of the stimulated region. The results show a stable, horizontal, NE-SW-oriented trend of the minor horizontal stress, but a rotation of the major stress from a sub-vertical direction (top of the stimulated region) to a sub-horizontal one (bottom of the stimulated region). This implies a change from a normal-faulting to a strike-slip regime, in agreement with our fault-plane solutions. Finally, we applied the stress components to the nodal planes of several events and were able to determine their fault plane and obtain a 3D image of the fracture network, based on real data.

Vitrinite Reflectance Study of the Upper Cretaceous Fruitland Formation, San Juan Basin, New Mexico

In 1988, a cooperative project between the New Mexico Oil conservation Division and US Geological Survey was established to better understand the thermal maturity of coal beds in the Upper Cretaceous Fruitland Formation throughout the New Mexico portion of the San Juan basin. The first product of this project was US Geological Survey Open-File Report 90-290, which presented vitrinite reflectance values for 125 coal samples. More recently, 300 additional vitrinite reflectance samples from wells throughout the area have been analyzed. Vitrinite isoreflectance maps, structure contour maps,and cross sections, which combine the old and new data, were constructed to illustrate thermal maturation patterns of the Fruitland Formation across the San Juan basin in New Mexico. Vitrinite reflectance (R{sub m}) values for the Fruitland Formation increase from south to north and generally follow the structural configuration of the basin. This pattern is directly related to depth of burial in the basin and indicates that maximum maturity (0.40% along the southern margin of the basin to 1.30% near the New Mexico-Colorado border) was established prior to final uplift. In the New Mexico part of the San Juan basin, Fruitland Formation coals produce methane at maturities corresponding to R{sub m} values between 0.60% andmore » about 1.30% at depths of approximately 3,000 to 4,000 ft (915 to 1,220 m), respectively. Using vitrinite reflectance data, the authors have mapped areas of optimum potential for coal-bed methane production in the New Mexico portion of the San Juan basin that generally include the areas between R4-10W and from T27N northward to the New Mexico-Colorado border.« less