Geophysical Aspects Research Articles

Geological uncertainty and geophysical misfit: How wrong can we be?

Geophysical inversion employs numerical methods to minimise the misfit between three-dimensional petrophysical distributions and geophysical datasets. Inversion techniques rely on many subjective inputs to provide a solution to a non-unique problem, including use of an a priori input model or model elements (a contiguous volume of the same litho-stratigraphic package) and inversion constraints. Inversions may produce a result that perfectly matches the observed geophysical data but still misrepresents the geological system. A workflow is presented that offers objective methods to provide inputs to inversion. First, simulations are performed to create a model suite that contains a range of geologically possible models. Next, uncertainty analysis is performed using stratigraphic variability to identify low certainty model regions and elements. Geodiversity analysis is then conducted to determine the geometrical and geophysical extremes within the model space. Next, geodiversity metrics are then simultaneously analysed using principal component analysis to identify the geometrical and geophysical aspects that contribute most toward model suite variability. Principal component analysis determines which models exhibit common or diverse geological and geophysical characteristics, facilitating selection of models subjected to geophysical inversion. We apply this workflow to the Ashanti Greenstone Belt, southwestern Ghana in west Africa. The workflow described in this manuscript reduces the subjectivity during decision making, explores the range of geologically possible models and provides geological constraints to the inversion process with the aim of producing geologically and geophysically robust suites of models associated with an uncertainty grid.

The Argentinean National Network of Seismic and Strong-Motion Stations

The history of seismic studies in Argentina dates back to the first decades of the last century and is based on historical material and archeological evidence. The first institution in the country devoted to geophysical aspects (mainly seismology) was the Astronomic Observatory of La Plata, created in 1882. But it was not until 1906 that this institution included seismic observations by installing the first seismological equipment, consisting of a three‐component Vicentini seismograph, in 1907. Between 1913 and 1925 two more mechanical seismographs were installed by the Astronomic Observatory of La Plata. This institution started publishing its first annual bulletin in 1922. In 1951, two electromagnetic‐type seismographs were installed at the Observatory, which increased significantly the registration of seismic events. One of the stations of this Observatory became part of the World Wide Standardized Seismograph Network (WWSN) in 1962. In January 1944 a large earthquake ( M w 7.0; Alvarado and Beck, 2006) almost completely destroyed the city of San Juan, the capital of San Juan province, located in the west‐central part of Argentina, killing at least 5000 people. This earthquake was the trigger for seismological research and seismic observations in Argentina, especially in San Juan province. Following this earthquake in 1944, the Federal Government created the Consejo Nacional de Construcciones Antisismicas y de Reconstruccion de San Juan (CONCAR), an institution devoted to develop a new building code and to plan and carry out the reconstruction process of San Juan city. On 8 May 1972, the CONCAR was transformed into the National Institute for Seismic Prevention (INPRES). INPRES is a federal agency of the Argentine government depending on the Secretary of Public Services and is situated in the city of San Juan. Its main objective is to carry out the national policy for seismic prevention, operate the national network of seismic stations …

The New Geophysics

AbstractNew Geophysics of critically microcracked rock is a new understanding of fluid‐rock deformation that matches much of the behaviour of in situ rock observed throughout the Earth's crust and uppermost mantle. The behaviour of rock in New Geophysics: is self‐similar; can be monitored, calculated, predicted, even in principle controlled; prevails in almost all rocks; and has ‘butterfly‐effect’ sensitivity. All of these remarkable features (except controllability) have been observed, in some cases many times. However, New Geophysics is innovative, controversial, and currently “ridiculed” and “violently opposed” (Schopenhauer Stages 1 and 2), and is difficult to get published via consensus‐driven peer‐review. Consequently, in the last 10 years, various aspects of New Geophysics have been published in some 20 different journals and conference proceedings making it difficult to access by the general reader. This review presents a synopsis of what is believed to be a fundamental advance in solid Earth geoscience.

Geophysical aspects of the structure and genesis of the Ilyinets structure: Impact or volcano?

Geophysical aspects of the structure and genesis of the Ilyinets structure: Impact or volcano?

Giorgio Fiocco (1931–2012)

Giorgio Fiocco was found dead in the roof garden of his mother's house on 31 July 2012, with pliers and a screwdriver in his hands. He was apparently fixing the watering system for her flowers. The passion for laboratory work never left Giorgio, and his contributions to very different aspects of experimental geophysics will remain his most important legacy. Immediately after the invention of the laser, Giorgio was the first to demonstrate many applications using this technology. The most important was light detection and ranging (lidar), which is now one of the most important sounding techniques for the atmosphere. He pioneered the first Doppler lidar to measure wind and the development of a very long baseline laser interferometer to measure the strain rate of seismic faults or the detection of gravitational waves.

History of Geophysics Fellowship awarded

Inspired by an article in an issue of Eos from April 1970, Gabe Henderson discovered a legacy of correspondence from former AGU president Helmut Landsberg detailing his views in the early days of the climate science debate. Thanks to AGU donors and the creation of a new fellowship by AGU's History of Geophysics Committee, Henderson, a Ph.D. candidate at Michigan State University, is conducting research on Landsberg's papers at the University of Maryland, College Park, continuing his study of the broad history of geophysics and the link between the past and future of climate science. In April 1970, Henderson says, AGU president Helmut Landsberg called for S. Fred Singer to lead a special committee on environmental quality to evaluate the geophysical aspects of environmental problems, dispassionately (H. E. Landsberg,Eos Trans. AGU, 51, 243, doi:10.1029/EO051i004p00243). Because environmental problems were hardly given a second thought at that time, Landsberg's request could have faded from the consciousness of geoscientists and from the pages of history.

The velocity structure of the upper mantle and regional deep thermodynamics of the Baikal rift zone

The article is aimed at discussion of geological and geophysical aspects of the ‘asthenospheric’ interpretation of the ‘anomalous’ mantle layer that is revealed in the Baikal rift zone by deep seismic sounding (DSS) methods. Based on the analysis of the geoelectrical model, estimations of rheological properties, regional geothermal and deep petrological data, it is concluded that the ‘anomalous’ mantle phenomenon should be interpreted within the framework of solid-phase models. It is shown that the actual minimum depth to the top of the asthenosphere is about 60–70 km in the region under study, and temperatures at the surface of the Earth’s mantle varies from 600 to 900 °С. It is most probable that velocities are reduced in the ‘anomalous’ mantle layer due to the presence of hightemperature spinel-pyroxene facies of the mantle rocks.

Seismic assessment in southern Baromura hill, northeast India, considering geophysical aspects

This paper aims to assess the geophysical signatures like morphology and structure of a fault line, which is situated in a part of southern Baromura hill of Tripura, northeast India. In this work manual observations and technical applications were adopted for understanding the morphological and structural characters of the fault line. As tectonic mapping is one of the main objectives of this study, the remote sensing technique was used to prepare a tectonic map of the study area. Geothermal range of the area was measured by unsupervised classification of Landsat TM thermal infrared band (band 6). The classified thermal band was overlaid by another classified shortwave infrared band (band 7 of Landsat TM), which explains the structural evidences of the study area. In addition, an automated digital elevation model (DEM) was prepared to assess the morphological characters of the study area particularly near the confluence of R. Maharani and R. Gumti. To analyse the structural condition of the faulted zone, resistivity characters of the rocks were measured by “vertical electrical sounding” (VES) method. The electrical resistivity character of this area strongly supports that a displacement occurred in this place. Finally an attempt was made to explain the character of faulting on the basis of morphological signatures and structural evidences for future disaster management planning.

Global factors in dynamics of petrophysical processes

In classical description of structural-tectonic fragments of earth crust vast territories of ancient platforms are represented as geodynamically passive elements of lithosphere. That is why nature of various phenomena occurring on platform (landslides and karst-suffosion processes, rock bursts and gas explosions in mines, pipeline breaks, etc.) is usually associated solely with processes of exogenous changes in geological environment, formed by rocks of sedimentary cover [Natural Hazards in Russia, 2002]. However, results of many years investigations of geodeformation regimes of geodynamically (seismically) active and platform regions allowed experimentally establish [Rudakov, 2009] that in preparation of catastrophic geodynamic phenomena (earthquakes and volcanic eruptions) prominent role played by processes of global change of stress-strain state of lithosphere due to processes of self-organization under influence of Earth velocity rotation variations. In particular, it was shown that these processes are reflected in changes of fluid dynamic regimes of fault structures of East European Platform (EEP), influencing processes of exogenous geological environment transformation, and, appearing in rocks of sedimentary cover by local geodynamic processes and phenomena. For example, it was found that dynamics of accidents on routes of gas pipeline networks of EEP is connected with wave motion of platform, as well as with processes of cyclic fluid transmission in fault transcontinental and regional tectonic formations that form dynamics of karst-suffosion processes in territories of Moscow depression [Rudakov, 2008]. Continuing to investigate links in chain of cause-effect dependence of local geodynamic phenomena and processes from processes of global change in stress-strain state of earth's crust, we made spectral and correlation analysis of a half century (49 years) time series of mean annual cases of karst gap formation in Dzerzhinsk, Nizhny Novgorod region in comparison with variations of water level in Oka River, which flows in area, variations in Earth's rotation and change in solar activity. It allowed to trace development of karst-suffosion processes influenced by changes in fluid dynamic regimes in region controlled by variations in stress-strain state of earth's crust in region associated with variations in Earth's rotation and changes in solar activity, controlling climate changes on Earth as a whole, and in each particular region of planet. Note that problem of assessing influence of solar-terrestrial relationships in processes of terrestrial atmosphere, hydrosphere, and even biosphere, after A.L. Chizhevsky concerned by many researchers [Rivin, 1989] but geological and geophysical aspects of this problem are practically not affected. Especially not enough investigated processes that control in platform conditions development of exogenous processes, such as karst-suffosion. And in this respect opportunity to examine longterm observations, of the Dzerzhinsk karst observatory” of Nizhny Novgorod region allowed, as it seems to us, to take another step toward assessing extent of planetary processes influence on dynamics of geodynamic processes of local scale. Fig. 1 shows original time series of mean annual variations of Earth's rotation velocity (relative value), solar activity (Wolf numbers), cases of karst gaps in Dzerzhinsk and water level in Oka river, which were analyzed on basis of calculation spectral-temporal and correlation characteristics of these time series and their components identified by energy filtering. Fig. 2 shows calculated values of cross-correlation function (CCF) between analyzed time series.

Does astrobiology inclu de human space flight?

Katinka Apagyi and Mark J Burchell argue that aspects of astronautics overlap with astrobiology, in the same way that aspects of geophysics and planetary science do. The gap between these disciplines is an artificial separation that should be overcome.

The architecture of climate economics: Designing a global agreement on global warming

The natural sciences are doing an admirable job of describing the geophysical aspects of climate change. The science behind global warming is well established. But designing an effective political and economic strategy to control climate change will require the second culture—the social sciences—to analyze how to harness our economic and political systems to achieve our climate goals effectively and at low cost. This second task requires examining questions such as the impacts on the economy and on non-market activities, the costs of slowing or mitigating climate change, the strength and timing of emissions reductions with an eye to the costs and benefits of slowing climate change, the risks of asymmetric and irreversible damages, and the policy instruments for implementing such emissions reductions. The author addresses this final question: how to devise policy instruments. The 2009 United Nations Climate Change Conference in Copenhagen meeting failed to reach a consensus on a successor agreement to the Kyoto Protocol, the global agreement that provides for emissions reductions for participating countries. This agreement has not resulted in global emissions reductions; its model creates inefficient and opaque mechanisms, akin to mortgage-backed securities, that have to date produced minimal emissions reductions. Only a harmonized global price on carbon—most easily implemented by a carbon tax—can achieve significant emissions reductions by sending a consistent signal to the governments, innovators, corporations, and individual consumers across all sectors and geographic boundaries.

The Fundamental Economic Issues of Petroleum Geological Explorations in Croatia

The Section of Geology, Geophysics and Geochemistry of th e Scie ntifi c Cou ncil for Petroleum of th e Croatian Academy or Sciences and Arts has already o rgani sed scientific meetings on seve ra l occasio ns. These meetings were almost witholl t exception concerning geological -geophysical aspects of explo rati on for oil and gas as we ll as the application of spec ifi c exp loration methods. Thi s was unde rstandabl e given the socia-economic conditions present a l those times. The change in social envi ronment gave the economical aspect of ex ploration and production far g reater importance for it can significantly influcnce the final resu lt as well as knowledge on gcologic-geophysical conditions. Bccause not many in Croatia have occu pied themselves wi th such and re lated matters it was our a im to inform [he broade r profess ional publi c wi th how thi s was applied in other oil -produc ing coulltries. T he parti ci pation o f inte rnational ex perts gave thi s sympos ium an international character. Approxi mate ly two years ago, the management o f the INA-Nn fLaplin company mentioned the possi bility of orga ni s ing an advi sory mccting to discuss the economi c factors re levant to the exploration of petroleum. Both the Min istry o f Science and Technology and Minis try of Economic Affa irs showed the ir iIllerest. l NA-NafLap lin is the national oil -company of C roat ia. It covers a wide spectrum of activ it ies expected of any such oil company from basic exploration and geophys icalmeasuremenls to the drilling and production of hydrocarbons both inland and abroad. Numerous exploration s have been carried o ut in foreign count ries such as Angola, Tunisia , Albania, Egypt, Libya, and a significant ex pansion of th ese activi ties is ex pected in the future. Othe r bus iness agreement s wit h in ternational partners have been made, one example being the most recen t arrangement on gas production with the Italian company Agip. All o f these s llccess ful business re lations creatc a need fo r the Croatian petroleum economy to systemati ca ll y enhance its bonds with the world and to be connecled to the world-wide ci rculation of scientific information. Croatia is a counlry in tran sition. Not the only

Pulmonary Hypertension in Latin America: Pulmonary Vascular Disease: The Global Perspective

Latin America is here defined as all of the Americas south of the United States. In the setting of pulmonary hypertension, there are social inequalities and geophysical aspects in this region that account for a high prevalence of certain etiologies. This review aimed to analyze some of these factors. Data were collected from the existing literature. Information also was obtained from local tertiary-care centers to where patients with pulmonary hypertension generally are referred. Further, local experience and expertise was taken into consideration. Three etiologies of pulmonary hypertension were found to be the most prevalent: schistosomiasis (approximately 1 million affected people in Brazil), high altitude (particularly in the Andes), and congenital heart disease (late diagnosis of congenital left-to-right shunts leading to development of pulmonary vasculopathy). The diversity in terms of ancestries and races probably accounts for the differences in phenotype expression of pulmonary hypertension when a given region is considered (eg, schistosomiasis-, high-altitude-, or congenital heart disease-associated pulmonary hypertension). Governmental measures are needed to improve social and economic inequalities with an obvious impact on certain etiologies, such as schistosomiasis and congenital heart disease. Early diagnosis of pulmonary hypertension and access to medication remain important challenges all over Latin America.

Geological and geophysical aspects of the underground CO2 storage

Observed impact of carbon dioxide (CO2) emissions on the climate changes resulted in significant intensification of the research focused on the development of the technologies, which would enable CO2 capture from the flu gases and its safe storage in the adequately selected geological formations. The member countries of the European Union (UE-27) worked out special CCS (CO2 Capture and Storage) directive concerning industrial application of this technology. It must be emphasized, that extremely important and difficult from the technical point of view is its final stage connected with CO2 storage process itself. The paper presents key geological problems, which may occur during above mentioned stage of CCS technology, it draws also attention on the problem of monitoring the locations selected for CO2 storage. It points out significant role of geophysical methods for effective application in this domain.

Kailash Nath Khattri (1934-2007)

Kailash Nath Khattri was born on 9 June 1934 in Banaras, India, and was involved in teaching and research in almost all aspects of geophysics, including seismology for more than 40 years when he died on 24 April 2007 in Dehradun. He was 73 years old. Professor Khattri got his primary education in Lucknow. He took his B.Sc. with honors in geophysics from the Indian Institute of Technology, Kharagpur, in 1956. He was awarded M.S. and Ph.D. degrees in 1968 and 1969 respectively from St. Louis University in the United States. He started his career as a geophysicist with the Oil and Natural Gas Commission, the national oil company of India; he then switched over to teaching and joined Roorkee University as a reader …

Temporal persistence and stability of surface soil moisture in a semi-arid watershed

Satellite soil moisture products, such as those from Advanced Microwave Scanning Radiometer (AMSR), require diverse landscapes for validation. Semi-arid landscapes present a particular challenge to satellite remote sensing validation using traditional techniques because of the high spatial variability and potentially rapid rates of temporal change in moisture conditions. In this study, temporal stability analysis and spatial sampling techniques are used to investigate the representativeness of ground observations at satellite scale soil moisture in a semi-arid watershed for a long study period (March 1, 2002 to September 13, 2005). The watershed utilized, the Walnut Gulch Experimental Watershed, has a dense network of 19 soil moisture sensors, distributed over a 150 km 2 study region. In conjunction with this monitoring network, intensive gravimetric soil moisture sampling conducted as part of the Soil Moisture Experiment in 2004 (SMEX04), contributed to the calibration of the network for large-scale estimation during the North American Monsoon System (NAMS). The sensor network is shown to be an excellent estimator of the watershed average with an accuracy of approximately 0.01 m 3/m 3 soil moisture. However, temporal stability analysis indicated that while much of the network is stable, the soil moisture spatial pattern, as represented by mean relative difference, is not replicated by the network mean relative difference pattern. Rather, the network is composed of statistical samples. Geophysical aspects of the watershed, including topography and soil type are also examined for their influence on the soil moisture variability and stability. Soil type, as characterized by bulk density, clay and sand content, was responsible for nearly 50% of the temporal stability. Topographic effects were less important in defining representativeness and stability.

Analysis of variations in the thermal neutron flux at an altitude of 1700 m above sea level

The results of detection of thermal neutron flux by a large open scintillation detector of thermal neutrons are reported. Detailed analysis of the experimental data is performed. Meteorological, astronomical, and geophysical aspects of the variations observed are considered.

Edmond Halley and Early Geophysics

Summary Edmond Halley, primarily an astronomer, was also a pioneer in some aspects of geophysics. In particular he carried out original work on geomagnetism, on the aurora, the behaviour and cause of the trade winds, and made some scientific attempts to determine the age of the Earth. A brief sketch is given of his work, which opened a new chapter in the study of the Earth as a physical body.

Does SEG need another peer-reviewed technical journal?

Perhaps SEG has reached another crossroads in publishing. Perhaps the Society needs to provide practicing geophysicists with a peer-reviewed journal companion to Geophysics focusing on applications and techniques. The Society publishes two highly successful technical journals, The Leading Edge (TLE) and Geophysics. TLE is a general-interest publication about all aspects of geophysics designed for nonspecialists. It features widely read special sections on the latest technical developments and communicates SEG activities to the Society's members. Geophysics is the premier peer-reviewed archival journal of applied geophysics. What appears in Geophysics is the foundation of future theoretical advances and technical solutions for the applied-geophysics community.

Neutrino Tomography – Learning About The Earth’s Interior Using The Propagation Of Neutrinos

Because the propagation of neutrinos is affected by the presence of Earth matter, it opens new possibilities to probe the Earth’s interior. Different approaches range from techniques based upon the interaction of high energy (above TeV) neutrinos with Earth matter, to methods using the MSW effect on the oscillations of low energy (MeV to GeV) neutrinos. In principle, neutrinos from many different sources (sun, atmosphere, supernovae, beams etc.) can be used. In this talk, we summarize and compare different approaches with an emphasis on more recent developments. In addition, we point out other geophysical aspects relevant for neutrino oscillations.