De Physique Du Globe Research Articles

Honors

Pascal Richet, a faculty member of the Physique des Minéraux et des Magmas, Institut de Physique du Globe de Paris, has been selected as the recipient of a Humboldt Research Award. Given by the Alexander von Humboldt Foundation, this award is conferred in recognition of lifetime achievements in research.

Erratum to: Lava discharge during Etna’s January 2011 fire fountain tracked using MSG-SEVIRI

In the paper by Gouhier, M., Harris, A., Calvari, S., Labazuy, P., Guehenneux, Y., Donnadieu, F., Valade, S, entitled “Lava discharge during Etna’s January 2011 fire fountain tracked using MSG-SEVIRI” (Bull Volcanol (2012) 74:787–793, DOI 10.1007/s00445-011-0572-y), we present data from a Doppler radar (VOLDORAD 2B). This ground-based Lband radar has been monitoring the eruptive activity of the summit craters of Mt. Etna in real-time since July 2009 from a site about 3.5 km SSE of the craters. Examples of applications of this type of radar are reviewed by Donnadieu (2012) and shown on the VOLDORAD website (http://wwwobs. univbpclermont.fr/SO/televolc/voldorad/). Although designed and owned by the Observatoire de Physique du Globe in Clermont-Ferrand (OPGC), France, VOLDORAD 2B is operated jointly with the INGV-Catania (Italy) in the framework of a technical and scientific collaboration agreement between the INGV of Catania, the French CNRS and the OPGC-Universite Blaise Pascal in ClermontFerrand. The system also utilizes a dedicated micropatch antenna designed at the University of Calabria (Boccia et al. 2010) and owned by INGV. The objective of the joint acquisition of the radar data by INGV-Catania and the OPGC is twofold: (1) to mitigate volcanic risks at Etna by better assessing the hazards arising from ash plumes and (2) to allow detailed study of volcanic activity and its environmental impact. In the paper by Gouhier et al. (2012), we failed to highlight this important collaboration between the INGV Catania and the OPGC; a cooperation essential for the past, current and future generation of such valuable data sets. Specifically we wish to acknowledge the roles of Mauro Coltelli, Michele Prestifilippo and Simona Scollo for their important input into this project, and pivotal role in setting up, and maintaining, this collaborative deployment.

Quest for consistency, symmetry, and simplicity — The legacy of Albert Tarantola

On 6 December 2009, the distinguished Spanish-French physicist and geoscientist, Albert Tarantola, passed away at the age of 60. Born in Barcelona in 1949, he went to Paris where he lived most of his life, and worked as a professor at Institut de Physique du Globe de Paris. His extensive scientific production and remarkable achievements in inverse problem theory and geophysical data analysis established him as one of the most influential mathematical geoscientists of our time. He became the father of probabilistic inverse theory, a theory that he passionately defended against severe criticism and managed to propagate to a major part of the geophysical community. Another major achievement was his contributions to the theory of seismic waveform inversion—a work that right now is unfolding its potential in large-scale computations. Albert’s contributions were not limited to geoscience. He started his career in astrophysics, and later in his life he wrote several papers and books on physics and probability, including new formulations of fluid dynamics, elasticity theory, global positioning, and scientific inference. Albert possessed a unique combination of exceptional skills and remarkable mental energy. He was a veritable powerhouse with an unusual work ethic, and his passion for science will remain an ideal for all those who worked with him.

Magnetic Valley: A Knowledge Transfer Project

The knowledge transfer project called Magnetic Valley that was launched in 2009 is presented below. This project is funded by the Belgian government to investigate and develop products and services that will improve the socio-economic development in the area around the Centre de Physique du Globe de l'IRM.

Singapore and the Nanyang Technological University—A young country with a young university on the move

Singapore is a unique environment for research and one that has become a global phenomenon and model for a country truly embracing the concept of the knowledge-based economy. Over the first 10 years of the 21st century, Singapore has advanced into the “Ivy League” of research by a sustained and high investment in research both in government research institutes, notably those of the Agency for Science, Technology, and Research A Star , and in the university sector. Unusually, for a country with its population of approximately 4.5 million, there are only four universities in Singapore with one only very recently established with two of these being very major and successful institutions, of which Nanyang Technological University NTU is one. It is a relatively young university still undergoing rapid evolution and development, yet has consistently been ranked among the top 100 universities worldwide. In the most established ranking system for universities that of the Quacquarelli Symonds World University Rankings , there are no younger universities in the top 100 category. It was originally founded in 1955 as a privately funded university Nanyang University teaching in Chinese and was the only such institution outside China and Taiwan. It aimed at serving the Chinese diaspora in South East Asia and it still retains strong links in China itself. Nanyang University was merged with the University of Singapore in 1980 to form the National University of Singapore NUS —the other major tertiary level institution—and in 1981, it was reformed as the Nanyang Technological Institute with the objective of providing training and education of engineering manpower and with the medium of instruction being English, the language of government and business in Singapore. It became a fully fledged university with its own charter in 1991. Since then, NTU has moved consistently and rapidly into the top echelon of high performing research intensive universities, especially during the 2000s Fig. 1 . Over the recent past, it has become a much more comprehensive university but still with engineering at its core and, indeed, engineering in all its guises remains two-thirds of the institution. As such, it is probably the world’s largest engineering-based institution on a single campus. Its route toward enlarging its portfolio started with the addition of the Nanyang Business School, now the top rated school in Singapore and also considered one of the best schools in the Asia-Pacific region. More recently, the addition of the College of Science, although new, is developing rapidly with a very international faculty, and the College of Humanities, Arts, and Social Sciences with a School of Art, Design, and Media housed in one of the university’s many iconic buildings, see Fig. 2 , Singapore’s only school of journalism, have added greatly to the educational and research opportunities at the university and provided the basis for a complex web of interdisciplinary activities. NTU includes the National Institute of Education NIE , responsible for the education and training of all of Singapore’s school teachers at all levels, and the Rajeratnam School of Strategic and International Studies RSIS , a graduate school and think-tank concentrating on security and, again, very highly regarded both in the region and globally. The move toward a more comprehensive institution will be completed following Prime Minister Lee’s announcement August 2010 that NTU has been entrusted with a new medical school, a joint venture offering a joint qualification with Imperial College London, which has also developed a medical school on what is a predominantly engineering base. Imperial College is now the largest medical school and hospital administrator within the British university medical system. NTU has also gained ground in other areas as we host two out of the five nationally awarded and prestigious Research Centres of Excellence RCEs —the Earth Observatory of Singapore EOS and the Singapore Centre for Environmental Life Sciences and Engineering SCELSE . The university is also a partner in one of the other RCEs— Mechanobiology—hosted at the NUS. The RCE scheme itself has promoted the rapid evolution of Singapore into the upper ranks in the world “league” of research in selected areas. For example, in 2007, top level Earth sciences hardly existed in the region, but by attracting world-leading researchers such as Kerry Sieh from California Institute of Technology Caltech Fig. 3 , Paul Tapponnier from Institut de Physique du Globe de Paris, and Chris Newhall from the U.S. Geological Survey a “dream team” of tectonicists and volcanologists , together with more than $S200 million in funding for EOS, we have leap-frogged into the premier league of Earth science research and embedded these new disciplines within the university in establishing a new division of Earth and environmental sciences.

Muon tomography: Plans for observations in the Lesser Antilles

The application of muon tomography to monitor and image the internal structure of volcanoes in the Lesser Antilles is discussed. Particular focus is directed towards the three volcanoes that fall under the responsibility of the Institut de Physique du Globe of Paris, namely La Montagne Pelée in Martinique, La Soufrière in Guadeloupe, and the Soufrière Hills in Montserrat. The technological criteria for the design of portable muon telescopes are presented in detail for both their mechanical and electronic aspects. The detector matrices are constructed with scintillator strips, and their detection characteristics are discussed. The tomography inversion is presented, and its distinctive characteristics are briefly discussed. Details are given on the implementation of muon tomography experiments on La Soufrière in Guadeloupe.

SPICE benchmark for global tomographic methods

The existing global tomographic methods result in different models due to different parametrization, scale resolution and theoretical approach. To test how current imaging techniques are limited by approximations in theory and by the inadequacy of data quality and coverage, it is necessary to perform a global-scale benchmark to understand the resolving properties of each specific imaging algorithm. In the framework of the Seismic wave Propagation and Imaging in Complex media: a European network (SPICE) project, it was decided to perform a benchmark experiment of global inversion algorithms. First, a preliminary benchmark with a simple isotropic model is carried out to check the feasibility in terms of acquisition geometry and numerical accuracy. Then, to fully validate tomographic schemes with a challenging synthetic data set, we constructed one complex anisotropic global model, which is characterized by 21 elastic constants and includes 3-D heterogeneities in velocity, anisotropy (radial and azimuthal anisotropy), attenuation, density, as well as surface topography and bathymetry. The intermediate-period (>32 s), high fidelity anisotropic modelling was performed by using state-of-the-art anisotropic anelastic modelling code, that is, coupled spectral element method (CSEM), on modern massively parallel computing resources. The benchmark data set consists of 29 events and three-component seismograms are recorded by 256 stations. Because of the limitation of the available computing power, synthetic seismograms have a minimum period of 32 s and a length of 10 500 s. The inversion of the benchmark data set demonstrates several well-known problems of classical surface wave tomography, such as the importance of crustal correction to recover the shallow structures, the loss of resolution with depth, the smearing effect, both horizontal and vertical, the inaccuracy of amplitude of isotropic S-wave velocity variation, the difficulty of retrieving the magnitude of azimuthal anisotropy and so on. The synthetic data set can be used to validate and calibrate new processing methodologies and has been made available to the scientific community at the Institut de Physique du Globe de Paris (IPGP) website (www.ipgp.jussieu.fr/~qyl). Any group wishing to test their tomographic algorithm is encouraged to download the synthetic data.

Imperial Masochism: British Fiction, Fantasy, and Social Class by John Kucich (review)

255 Reviews ers with numerous illustrations and quotations from the original literature. In brief, Bursting the Limits ofTime will constitute, for a long time, a basic reference book and a rich source of inspiration. Works Cited Voltaire. Des singularités de la nature. Basel, 1768. Cuvier, Georges. Recherche sur les ossements fossiles. Paris: Deterville, 1812. Pasca l R ichet Institut de Physique du Globe de Paris • Imperial Masochism: British Fiction,Fantasy,and Social Class by John Kucich; pp. 270. Princeton: Princeton UP, 2007. $35.00 cloth. With the publication of this (his fourth) book, John Kucich confirms his reputation as one of the most original voices in the study of Victorian literature . In a recent keynote address, he spoke of “shadow-discourses,” discourses that have gone (or been allowed to go) “dormant” in the cultural imagination.The chief virtue of Imperial Masochism is that it succeeds in coaxing out of intellectual hibernation not one but two shadow-discourses—those of masochism and of social class—that have largely dropped out of recent studies of nineteenth-century British imperial fiction. He analyzes acutely the interweaving of these two discourses in the work of four nineteenth-century Anglophone writers—Robert Louis Stevenson, Olive Schreiner, Rudyard Kipling, and Joseph Conrad—arguing that in the colonial fiction of all four, masochism “focused one particular conjunction more than any other: the relationship between imperial politics and social class” (1). Many postcolonial scholars have written about imperialism and its discontents—the anxieties, confusions, and ambivalences of the colonial subject—but Kucich’s approach is rare in linking the suffering of this subject to the category of class.The concepts of race, gender, and sexuality have served as lenses through which scholars have examined colonial literature, but class has largely been ignored as an analytical rubric. Lately, historians have tried to remedy the neglect of class in the study of imperial history—the best example being David Cannadine’s Ornamentalism: How the British SawTheir Empire—but, until Kucich, literary critics have been slow to explore this theme in the analysis of imperial literature. His book is thus a fresh and welcome development. Kucich has chosen to focus not on the predominant image of masochism— the Freudian model of sexual submission associated with the Oedipal stage—but on a“shadowy,” alternative masochism: the model, put forward by relational psychologists, of a narcissism linked to the pre-Oedipal stage of psychological victorian review • Volume 34 Number 2 256 development. According to the latter model, disruptions in the parent-child bond open a narcissistic wound in the child that finds its compensation in omnipotent fantasies of control over oneself and others. Kucich examines the metaphors generated by such masochistic fantasies, metaphors that, in latenineteenth -century Britain, often insinuated themselves into imperial narratives that glorified pain, victimization, and sacrifice.According to Kucich, the metaphoricity of masochistic fantasy received a class (usually middle-class) inflection within two discourses in particular—those of evangelicalism and professionalism—that often underwrote lateVictorian imperial narratives. He does not dismiss the heuristic usefulness of the concept of Oedipal masochism; indeed, he finds that in works of colonial fiction, fantasies of eroticized and non-eroticized masochism sometimes work together both to energize characters ’ relationships with one another and to galvanize the ideological configurations those relations embody. However, he asserts that pre-Oedipal masochism’s emphasis upon the relational (suffering as an imagined path to love and sympathy ) offers more diverse and nuanced interpretive possibilities than does the narrow emphasis on sexualized submission in Oedipal masochism that often dominates current psychoanalytical approaches to literature. Kucich argues that in the Scottish novels of the late 1870s and 1880s, Stevenson used bourgeois and anti-bourgeois doubles to disrupt the psychological economy of a pre-Oedipal masochism, thereby exposing the social incoherence of the Scottish middle class. In his South Pacific writings of the 1890s, however, Stevenson showed that through the self-martyrdom of a self-styled, evangelical anti-imperialism, he might overcome the psychosocial schisms that plagued the middle-class milieu of his earlier works. The chapter on Schreiner is the most controversial.There, Kucich contends that in both The Story of an African Farm and her later non-fiction, Schreiner...

CDSA: A New Seismological Data Center for the French Lesser Antilles

The Lesser Antilles, in the eastern Caribbean, is prone to a large seismic hazard due to the subduction of the Atlantic lithosphere beneath the Caribbean plate, with a slow convergence rate of 2 cm/yr (Demets et al. 2000; Mann et al. 2002). The largest historical earthquake in the region, in 1843 between Guadeloupe and Antigua, had a magnitude estimate of 7.5 to 8 (Bernard and Lambert 1988), but historical seismicity covers too short a period of time (less than three and one-half centuries) to estimate the recurrence time of strong events or their plausible maximum magnitude. The latest destructive earthquake, Les Saintes in Guadeloupe in 2004, had a magnitude 6.3 (Institut de Physique du Globe de Paris 2004; Bertil et al. 2004). To better understand the regional geodynamics and assess the related seismic hazard, we must improve our knowledge and our understanding of the area's present seismicity. Since the 1950s, several regional research institutes have monitored local seismicity. The Institut de Physique du Globe de Paris (IPGP) and Bureau de Recherches Geologiques et Minieres (BRGM) have set up various seismological and accelerometric arrays to monitor the French islands of Guadeloupe and Martinique. As a consequence, several large datasets with very different formats and time spans exist, scattered among several sites. Providing a more integrated database for the seismicity of the Lesser Antilles arc was the primary motivation for creating the French Antilles Seismological Data Base (Centre de Donnees Sismologiques des Antilles, CDSA). The aim of this paper is to introduce the newly created CDSA and to illustrate its capacity for improving our knowledge of the region's seismicity. In the first part of this study, we present the various arrays, waveform databases, and seismicity catalogs used by the CDSA. In the second part, we present and discuss new …

Thermal and Magmatic Evolution of the Moon

Research Article| January 01, 2006 Thermal and Magmatic Evolution of the Moon Charles K. Shearer; Charles K. Shearer 1Inst. of Meteorites, University of New Mexico, Albuquerque, New Mexico, U.S.A. Corresponding author e-mail: Charles K. Shearer <cshearer@unm.edu> Search for other works by this author on: GSW Google Scholar Paul C. Hess; Paul C. Hess 2Dept. of Geol. Sci., Brown University, Providence, Rhode Island, U.S.A. Search for other works by this author on: GSW Google Scholar Mark A. Wieczorek; Mark A. Wieczorek 3Institut de Physique du Globe de Paris, Paris, France Search for other works by this author on: GSW Google Scholar Matt E. Pritchard; Matt E. Pritchard 4Dept. of Earth & Atmospheric Sci., Cornell University, Ithaca, New York, U.S.A. Search for other works by this author on: GSW Google Scholar E. Mark Parmentier; E. Mark Parmentier 2Dept. of Geol. Sci., Brown University, Providence, Rhode Island, U.S.A. Search for other works by this author on: GSW Google Scholar Lars E. Borg; Lars E. Borg 1Inst. of Meteorites, University of New Mexico, Albuquerque, New Mexico, U.S.A. Search for other works by this author on: GSW Google Scholar John Longhi; John Longhi 5Lamont-Doherty Earth Observatory, Palisades, New York, U.S.A. Search for other works by this author on: GSW Google Scholar Linda T. Elkins-Tanton; Linda T. Elkins-Tanton 2Dept. of Geol. Sci., Brown University, Providence, Rhode Island, U.S.A. Search for other works by this author on: GSW Google Scholar Clive R. Neal; Clive R. Neal 6Dept. of Civil Eng. & Geol. Sci., Univ. of Notre Dame, Notre Dame, Indiana, U.S.A. Search for other works by this author on: GSW Google Scholar Irene Antonenko; Irene Antonenko 7University of Toronto, Toronto, ON, Canada Search for other works by this author on: GSW Google Scholar Robin M. Canup; Robin M. Canup 8Dept. of Space Studies, Southwest Research Institute, Boulder, Colorado, U.S.A. Search for other works by this author on: GSW Google Scholar Alex N. Halliday; Alex N. Halliday 9Dept. of Earth Sciences, University of Oxford, Oxford, United Kingdom Search for other works by this author on: GSW Google Scholar Tim L. Grove; Tim L. Grove 10Dept. of Earth, Atmospheric, & Planetary Sci., MIT, Cambridge, Massachusetts, U.S.A. Search for other works by this author on: GSW Google Scholar Bradford H. Hager; Bradford H. Hager 10Dept. of Earth, Atmospheric, & Planetary Sci., MIT, Cambridge, Massachusetts, U.S.A. Search for other works by this author on: GSW Google Scholar D-C. Lee; D-C. Lee 11Academica Sinica, Institute of Earth Sciences, Taipei, Taiwan Search for other works by this author on: GSW Google Scholar Uwe Wiechert Uwe Wiechert 12Eidgenossische Technische Hochschule, Zurich, Switzerland Search for other works by this author on: GSW Google Scholar Reviews in Mineralogy and Geochemistry (2006) 60 (1): 365–518. https://doi.org/10.2138/rmg.2006.60.4 Article history first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Charles K. Shearer, Paul C. Hess, Mark A. Wieczorek, Matt E. Pritchard, E. Mark Parmentier, Lars E. Borg, John Longhi, Linda T. Elkins-Tanton, Clive R. Neal, Irene Antonenko, Robin M. Canup, Alex N. Halliday, Tim L. Grove, Bradford H. Hager, D-C. Lee, Uwe Wiechert; Thermal and Magmatic Evolution of the Moon. Reviews in Mineralogy and Geochemistry 2006;; 60 (1): 365–518. doi: https://doi.org/10.2138/rmg.2006.60.4 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyReviews in Mineralogy and Geochemistry Search Advanced Search As with all science, our continually developing concepts of lunar evolution are firmly tied to both new types of observations and the integration of these observations to the known pool of data. This process invigorates the intellectual foundation on which old models are tested and new concepts are built. Just as the application of new observational tools to lunar science in 1610 (Galileo’s telescope) and 1840 (photography) yielded breakthroughs concerning the true nature of the lunar surface, the computational and technological advances highlighted by the Apollo and post-Apollo missions and associated scientific investigations provided a new view of the thermal... You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Geophysical investigation of a recent shallow fault

Since 1994 the students of the third year of the Ecole de Physique du Globe de Strasbourg (EPGS) start their last school year (roughly in mid-September) by performing a geophysics field camp. Students (including teachers) participate in hands-on geophysical studies using the methods of seismic reflection and refraction, gravity, magnetics, electrical resistivity, electromagnetics, and ground penetrating radar (GPR). They collect data with modern equipment; they process, model, and interpret the data with workstation and PCs; and they present their results in both oral and written form.

CRUSTAL DEFORMATIONS FROM SPARCE GEODETIC DATA

During the last decade, the Higher Geodesy Laboratory of NTU and the Seismology Department of the Institut de Physique du Globe de Paris have carried out a research program concerning the evaluation of the tectonic behaviour of the Gulf of Corinth, in Greece, based on geodetic data. The area being one of the densely populated, seismically active parts of Greece, was considered suitable for monitoring deformations. Thus, a geodetic GPS control network of 193 points, spread over a broad area (of about 10000 km2) on both sides of the Gulf, was established within seven years. During this period several points were reoccupied. Thus the GPS data acquired are sparse both in space and time. In order to estimate the deformation over longer periods of time 142 of the network points were chosen to belong to the Hellenic triangulation network. In the present paper, statistically acceptable strain parameters are evaluated via a multi-epoch deformation model using GPS data alone as well as in combination with positional information from old geodetic surveys.

CRUSTAL DEFORMATIONS FROM SPARCE GEODETIC DATA

During the last decade, the Higher Geodesy Laboratory of NTU and the Seismology Department of the Institut de Physique du Globe de Paris have carried out a research program concerning the evaluation of the tectonic behaviour of the Gulf of Corinth, in Greece, based on geodetic data. The area being one of the densely populated, seismically active parts of Greece, was considered suitable for monitoring deformations. Thus, a geodetic GPS control network of 193 points, spread over a broad area (of about 10000 km2) on both sides of the Gulf, was established within seven years. During this period several points were reoccupied. Thus the GPS data acquired are sparse both in space and time. In order to estimate the deformation over longer periods of time 142 of the network points were chosen to belong to the Hellenic triangulation network. In the present paper, statistically acceptable strain parameters are evaluated via a multi-epoch deformation model using GPS data alone as well as in combination with positional information from old geodetic surveys.

Paleomagnetic directions and K/Ar dating of 0 to 1 Ma lava flows from La Guadeloupe Island (French West Indies): Implications for time‐averaged field models

Twenty‐six lava flows spanning the last million years were sampled in La Guadeloupe, French West Indies. Because of the lack of continuous volcano‐stratigraphic sections in La Guadeloupe, dating is necessary in order to describe the temporal evolution of the geomagnetic field in this time interval. New K/Ar ages ranging from 50 ka to 1 Ma have been obtained on andesites using the Cassignol‐Gillot technique at the Université Paris Sud‐Institut de Physique du Globe de Paris Orsay laboratory. Additional flows (with K/Ar ages obtained using the same dating technique) were also sampled for paleomagnetic investigations. More than 200 samples were analyzed using both alternating field AF and thermal stepwise demagnetization techniques. Duplicate samplings of two flows at three different sites demonstrate that within‐flow dispersion is negligible for the andesitic lava flows sampled in this study. Direct comparison with an earlier paleomagnetic study performed on the island indicates that, for the three investigated flows, modern demagnetization techniques yield much better defined paleomagnetic directions. The Matuyama‐Brunhes transition was recorded in a three‐flow section and is dated at 781±18 ka, in good agreement with other recent radiometric age determinations. The mean paleomagnetic pole calculated from the 23 normal polarity flows is indistinguishable from geographic north, which implies that no significant persistent axial quadrupole term can be identified at this site for the last million years. This result contradicts earlier results and has important implications for models of the time‐averaged field (TAF). An Occam algorithm was used to construct a TAF model from the global volcanic database from the last 5 Ma. Substitution of the mean direction calculated from the earlier study for the Lesser Antilles by our new mean value reduces the quadrupole term by more than 30%. This effect, which was produced by changing data from a single site, demonstrates that older paleomagnetic sites may need to be reinvestigated. Furthermore, it also highlights the limitations of TAF models that can be inferred from paleomagnetic databases in their present state.

Database of geomagnetic observatory monthly means seeks contributors

The Department of Geomagnetism of the Institut de Physique du Globe de Paris (IPGP) has compiled a new global database of monthly mean values of geomagnetic elements. This database was originally compiled for a study of “geomagnetic jerks”—apparent sudden step changes in secular acceleration, either side of which the secular variation appears to be approximately linear—for which time series of annual mean values had been the principal source of observational data.Researchers at IPGP encourage geomagnetic observatories throughout the world to submit their monthly mean values for inclusion in the database as soon as possible at the end of each month. The values submitted must be at least provisionally corrected to absolute values at the reference point of the observatory. The preferred method to submit data is by e‐mail in a specified format, but observatories that lack e‐mail facilities may send their results by fax or mail.

Strain constraint on the source of the alleged Varotsos‐Alexopoulos‐Nomicos (VAN) precursor of the 1995 Aigion earthquake (Greece)

We present the data continuously monitored at the Institut de Physique du Globe de Paris/National Technical University of Athens Galaxidi geophysical observatory before the 1995 Aigion earthquake (Greece) and analyze their implications for the source of the alleged Varotsos‐Alexopoulos‐Nomicos (VAN) precursor (seismic electric signals (SES)) of this earthquake. On April 30, 1995, an electrotelluric anomaly of 10 mV km−1 was observed at the VAN station of Volos, located 150 km NE of Aigion. The VAN group attributed it to the preparation for the 1995 Aigion earthquake. The same day, the N‐S tiltmeter of the Galaxidi observatory, located 30 km NE of Aigion, did not detect any tilt above its noise level, 7.5 × 10−8 rad. Assuming all conditions which provide the greatest electric signal at Volos but the smallest local deformation, we model the characteristics of the source that is required to generate the SES observed at Volos with a N‐S tilt at Galaxidi compatible with our observations. We suppose, as is usually done for possible earthquake precursors, that the electrotelluric signal results from streaming potentials induced in response to the pore fluid flow accompanying an aseismic creep event near the hypocenter of the upcoming earthquake. We also suppose that the electrical structure between Aigion and Volos is composed of a favorable two‐dimensional (2‐D) horizontal conductive layer at midcrustal depth, excluding a local amplification at Volos (the SES appeared with comparable ΔV/L values on both the short and long measurement lines), as well as a highly speculative ad hoc 1‐D channel between Aigion and Volos (as proposed by VAN). With these assumptions, we find that a coupling coefficient greater than 500 V MPa−1 would explain the reported anomaly. Typical values of this coefficient measured in the laboratory are of the order of 100 mV MPa−1 The source of the SES of April 30, 1995, is hence very unlikely to have been located in the hypocentral zone of the 1995 Aigion earthquake, whatever its actual link with the earthquake.

Three years of high precision gravity measurements at the gravimetric station of Brasimone - Italy

From August 1995 up to now, at the Enea Research Center of Brasimone, in the Italian Apennines between Bologna and Florence (Italy: 44º07'N, 11º.07'E, 890 m height), the superconducting gravimeter GWR model TT70 number T015 has been continuously recording the variation of the local gravity field, in the frame of the Global Geodynamics Project. The gravimetric laboratory, being a room of the disused nuclear power plant of Brasimone, is a very stable site, free from noise due to human activities. Data blocks of several months of continuous gravity records have been collected over a time span of three years, together with the meteorological data. The gravimeter has been calibrated at relative accuracy better than 0.3% with the aid of a mobile mass system, by imposed perturbations of the local gravity field and recording the gravimeter response. The results of this calibration technique were checked by two comparison experiments with absolute gravimeters performed during this period: the first, in May 1994 with the aid of the symmetrical rise and fall gravimeter of the Institute of Metrology Colonnetti of Turin, and the second in October 1997 involving an FG5 absolute gravimeter of the Institute de Physique du Globe of Strasbourg. The gravimeter signal was analysed to compute a high precision tidal model for Brasimone site. Starting from a set of gravimetric and atmospheric pressure data of high quality, relative to 46 months of observation, we performed the tidal analysis using Eterna 3.2 software to compute amplitudes, gravimetric factors and phases of the main waves of the Tamura catalogue. Finally a comparison experiment between two of the STS-1/VBB broadband seismometers of the MedNet project network and the gravity records relative to the Balleny Islands earthquake (March 25, 1998) were analysed to look for evidence of normal modes due to the free oscillations of the Earth.

Viscosity regimes of homogeneous silicate melts

Other| April 01, 1995 Viscosity regimes of homogeneous silicate melts Yan Bottinga; Yan Bottinga Institut de Physique du Globe, Department des Geomateriaux, Paris, France Search for other works by this author on: GSW Google Scholar Pascal Richet; Pascal Richet Search for other works by this author on: GSW Google Scholar Anne Sipp Anne Sipp Search for other works by this author on: GSW Google Scholar American Mineralogist (1995) 80 (3-4): 305–318. https://doi.org/10.2138/am-1995-3-412 Article history first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Twitter LinkedIn Tools Icon Tools Get Permissions Search Site Citation Yan Bottinga, Pascal Richet, Anne Sipp; Viscosity regimes of homogeneous silicate melts. American Mineralogist 1995;; 80 (3-4): 305–318. doi: https://doi.org/10.2138/am-1995-3-412 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyAmerican Mineralogist Search Advanced Search Abstract Extrapolation of laboratory measurements of the viscosity (η) of silicate melts is frequently needed in order to analyze petrological and volcanological processes. Therefore a general understanding of silicate melt viscosities is required. In this paper we survey the present state of our knowledge and distinguish three flow regimes for homogeneous silicate liquids: (1) a low-viscosity regime (η <1 Pa·s), where the viscosity obeys a temperature-dependence power law in accordance with mode coupling theory (these low viscosities are typical for depolymerized melts); (2) an intermediate regime (1 <η <1012 Pa·s), where silicate melt viscosity is determined by the availability of configurational states (the dependence of the viscosity on the temperature is described aptly by the configurational entropy theory of Adam-Gibbs); and (3) a high-viscosity regime, where the liquid has been transformed into a glass (η >1012 Pa·s) (this regime is not well known, but available measurements indicate an Adam-Gibbs or an Arrhenian temperature dependence of the glass viscosity). Examples are given of igneous rocks whose geneses were affected by these flow regimes. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Outstanding student papers

Two Outstanding Student Paper Awards were given in the Geomagnetism and Paleomagnetism Section at the AGU Fall Meeting, which was held last December in San Francisco.Florence Garnier, who presented “Geomagnetic Field Intensity Over the Last 42,000 Years Obtained From Core SOH‐4, Big Island Hawaii,” received the French equivalent of an M.S. in Geophysics in July 1993 from the University of Paris 7/Institut de Physique du Globe de Paris. In September 1993, she started a Ph.D. program in paleomagnetism at the Centre des Faibles Radioactivit7eacute;s, Laboratoire mixte CEA‐CNRS, located in Gif‐sur‐Yvette, France. Her research focuses on long‐term changes of the geomagnetic field intensity retrieved from lava sequences of Kilauea, Mauna Loa, and Mauna Kea volcanoes. In this research, which is a joint project between her laboratory and the University of Hawaii, she uses mainly paleomagnetic methods, but also uses radiometric datings.

Astronomy in Algeria

Astronomy in Algeria is linked to the Algiers Observatory which is the only place where there is any astronomical activity. The Observatory was built in 1889 and was an important contributor to the famous Carte du del project. After independence, because there were so few Algerian astronomers and the site had deteriorated, the activity of the Observatory slowed down significantly.In 1980, the year of the violent El-Ansam earthquake, a decision was taken, on the initiative of the present director (M. Benhallou, Professor of Seismology) to create an Algerian earthquake-surveillance network. This led to the creation of the research centre CRAAG (Centre de Recherche en Astronomie, Astrophysique et Geophysique) in which I’Observatoire d’Alger and the Institut de Physique du Globe have been merged. Thus, the Algiers Observatory has become more and more devoted to geophysical research. Towards the end of the 1980s, a group of Algerian astronomers, educated in foreign universities, joined CRAAG. The most recent recruit came in 1991. Today, the Department of Astronomy and Astrophysics contains ten members—nearly half the total number of Algerian astronomers.