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1 Zhdanov, MichaelQuasi-linear series in three-dimensional electromagnetic modelingWe have recently introduced a quasi-linear (QL) approximation for the solution of the three-dimension(a3l -D) electromagnetic modeling problem. In this paper we discuss an approach to improving its accuracy by considering the QL approximation so f the higher order. This approach can be considered th...1997-01-01
2 Zhdanov, MichaelQuasi-analytical boundary condition for three-dimensional finite difference electromagnetic modelingNumerical modeling of the quasi-static electromagnetic (EM) field in the frequency domain in a three-dimensional (3-D) inhomogeneous medium is a very challenging problem in computational physics. We present a new approach to the finite difference (FD) solution of this problem. The FD discretization ...2004-01-01
3 Zhdanov, MichaelThree-dimensional quasi linear electromagnetic inversionOne of the most challenging problems of electromagnetic (EM) geophysical methods is developing three-dimension(a3l- D) EM inversion techniques. This problem is of utmost importance in practical applications because of the 3-D nature of the geological structures.T he main difficulties in 3-D inversio...1996-01-01
4 Solomon, Douglas KipTracer applications of noble gas radionuclides in the geosciencesNoble gas radionuclides, including 81Kr (t1/2 = 229,000 yr), 85Kr (t1/2 = 10.8 yr), and 39Ar (t1/2 = 269 yr), possess nearly ideal chemical and physical properties for studies of earth and environmental processes. Recent advances in Atom Trap Trace Analysis (ATTA), a laser-based atom counting method...2014-01-01
5 Zhdanov, MichaelTwo-dimensional magnetotelluric inversion of blocky geoelectrical structuresThis paper demonstrates that there are alternative approaches to the magnetotelluric (MT) inverse problem solution based on different types of geoelectrical models. The traditional approach uses smooth models to describe the conductivity distribution in underground formations. In this paper, we pres...2002-01-01
6 Thorne, Michael S.Viterbi sparse spike detectionAccurate interpretation of seismic traveltimes and amplitudes in the exploration and global scales is complicated by the band-limited nature of seismic data. We discovered a stochastic method to reduce a seismic waveform into a most probable constituent spike train. Model waveforms were constructed ...2013-01-01
7 Chapman, David S.Techniques, analysis, and noise in a Salt Lake Valley 4D gravity experimentRepeated high-precision gravity measurements using an automated gravimeter and analysis of time series of 1-Hz samples allowed gravity measurements to be made with an accuracy of 5 μGal or better. Nonlinear instrument drift was removed using a new empirical staircase function built from multiple ...Gravity measurements2008
8 Jarrard, Richard D.Geometry of Pleistocene facies on the Great Barrier Reef outer shelf and upper slope - seismic stratigraphy of sites 819, 820, and 821Seismic stratigraphic analysis of the sedimentary succession intersected in Ocean Drilling Program (ODP) Sites 819, 820, and 821, on the outer shelf and upper slope seaward of the Great Barrier Reef, provides a clear indication of the importance of sediment supply and depositional base-level as two ...1993
9 Jarrard, Richard D.Sedimentary response to paleoclimate from downhole logs at Site 693, Antarctic Continental MarginThe first well logs collected below the Antarctic circle were obtained during Leg 113 at Site 693 on the Dronning Maud Land Margin (Antarctica) in the Weddell Sea. Gamma-ray, resistivity, and sonic logs were collected between 108.0 and 439.0 mbsf. The downhole logs show good agreement with the data...1990
10 Fernandez, Diego P.Near-criticality in dilute binary mixtures: distribution of azulene between coexisting liquid and vapor carbon dioxideThe equilibrium distribution of dilute solutes between vapor and liquid coexisting phases of near-critical solvents exhibits a simple dependence on the solvent's liquid density which extends over a wide temperature range; however, theory predicts this dependence only as an asymptotic limit. In order...Near-critical solvents; Azulene; Binary mixtures; Dilute solutions2002
11 Chapman, David S.Borehole temperatures and climate change: ground temperature change in south India over the past two centuriesVariations in surface g round temperature (SGT) at the Earth's surface diffuse downward in a predictable way causing systematic perturbations to the subsurface temperature field. The pioneering study of Lachenbruch and Marsh all [1986] in Alaska demonstrated that present-day borehole temperature-dep...2012-01-01
12 Brown, Francis HaroldA summary of the geology, geochemistry, and geophysics of the Roosevelt Hot Springs thermal area, Utah1978
13 Jarrard, Richard D.Seismic stratigraphy and history of deep circulation and sediment drift development in Baffin Bay and the Labrador SeaDrilling results and seismic-reflection records at and across Ocean Drilling Program (ODP) Sites 645 (western Baffin Bay), 646, and 647 (Labrador Sea) provide important constraints on the history of deep-water circulation and sedimentation in response to Cenozoic climatic change, as well as the tect...1989
14 Jarrard, Richard D.Results of borehole televiewer observations in the Celebes and Sulu SeasBorehole televiewer data were collected during Ocean Drilling Program Leg 124 to investigate stress orientations in the Sulu and Celebes sea basins. At Site 768C, in the Sulu Sea, televiewer logs were collected from 809-870 and 950-1250 meters below sea floor (mbsf). At Site 770C, in the Celebes Se...1991
15 Zhdanov, Michael S.Rigorous 3D inversion of marine CSEM data based on the integral equation methodMarine controlled-source electromagnetic (MCSEM) surveys have become an important part of offshore petroleum exploration. However, due to enormous computational difficulties with full 3D inversion, practical interpretation of MCSEM data is still a very challenging problem. We present a new approach ...2007
16 Zhdanov, Michael S.Three-dimensional quasi-linear electromagnetic modeling and inversionThe quasi-linear (QL) approximation replaces the (unknown) total field in the integral equation of electromagnetic (EM) scattering with a linear transformation of the primary field. This transformation involves the product of the primary field with a reflectivity tensor, which is assumed to vary slo...1999-01-01
17 Chapman, David S.Global warming - just hot air?We know from weather station records that Earth's surface temperature has increased on average by 0.6 degrees C in the last 100 years. The 1990s have been the warmest decade on record. Over the same period, global sea level has increased by 10-20 cm. We know also that planet Earth has an atmosphere ...Greenhouse Effect; Climate change1998
18 Jarrard, Richard D.Velocity and density of carbonate-rich sediments from northeastern Australian margin: integration of core and log dataDuring Ocean Drilling Program (ODP) Leg 133, shipboard scientists obtained a remarkable quantity of both core and log measurements of the physical properties of carbonate-rich sediments. This suite of measurements provides a unique opportunity to evaluate the robustness of each measurement technique...1993
19 Jarrard, Richard D.Resistivity/porosity/velocity relationships from downhole logs: an aid for evaluating pore morphologyRelationships between downhole resistivity/velocity logs and porosity styles, controlled by cementation/dissolution/recrystallization, are investigated using core and downhole logging data from the carbonate-rich sediments encountered during Leg 133 of the Ocean Drilling Program (ODP), northeastern ...1993
20 Zhdanov, Michael S.3-D magnetic inversion with data compression and image focusingWe develop a method of 3-D magnetic anomaly inversion based on traditional Tikhonov regularization theory. We use a minimum support stabilizing functional to generate a sharp, focused inverse image. An iterative inversion process is constructed in the space of weighted model parameters that acce...2002-01-01
21 Brown, Francis HaroldMagnetostratigraphy of the shungura and usno formations, Southwestern Ethiopia: new data and comprehensive reanalysis1978
22 Zhdanov, MichaelResistivity imaging by time domain electromagnetic migration (TDEMM)One of the most challenging problems of electrical geophysical methods is the interpretation of time domain electromagnetic (TDEM) sounding data in the areas with the horizontally inhomogeneous geoelectrical structures. This problem is of utmost importance in mining exploration and environmental stu...1995
23 Brown, Francis HaroldRadiometric dating and tuff mineralogy of omo group depositsThrough the efforts of the Omo Research Expedition and the East Rudolf Research Group, a large number of vertebrate fossils have been collected from the sedimentary deposits near the northern end of Lake Rudolf in Kenya and in the lower Omo valley in Ethiopia. The hominid fossils collected in this a...1976
24 Chapman, David S.; Harris, Robert N.Mid-Latitude (30°-60° N) climatic warming inferred by combining borehole temperatures with surface air temperaturesWe construct a mid-latitude (30°-60° N) reduced temperature-depth profile from a global borehole temperature database compiled for climate reconstruction. This reduced temperature profile is interpreted in terms of past surface ground temperature change and indicates warming on the order of 1°C...Surface air temperature; Surface ground temperature; Borehole temperatures; Geothermal observations2001
25 Brown, Francis HaroldGombe group basalts and initiation of pliocene deposition in the Turkana depression, northern Kenya and southern EthiopiaA little before 4 Ma ago, deposition of Pliocene and Pleistocene strata described as the Omo Group began in the Turkana and Omo basins of northern Kenya and southern Ethiopia. Soon after, basaltic magma erupted as thin lava flows, and intruded as dykes into the oldest Pliocene strata of the basin. T...2004
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