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Microtremor study in the sediment-filled basin of Zafarraya, Granada (southern Spain) (1991)

J. Morales ; F. Vidal ; J. A. Pena ; [weitere]

In: Bull. Seism. Soc. Am., Edmonton, Conseil de l'Europe, vol. 81, no. 2, pp. 687-693, pp. B10410, (ISSN: 1340-4202)

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Publikationsdatum: 1991

Schlagwort(e): Micro-tremor (seismic noise) ; NOISE ; Site amplification ; Earthquake engineering, engineering seismology ; noksp ; BSSA ; Ibanez

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BIBLIOGRAFIE SEISMOLOGIE

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Separation of scattering and intrinsic attenuation in southern Spain and western Anatolia (Turkey) (1995)

A. Akinci ; E. Del Pezzo ; J. M. Ibáñez

In: Geophys. J. Int., Tokyo, Inst. f. Theoret. Geodäsie, vol. 121, no. B7, pp. 337-353

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Publikationsdatum: 1995

Schlagwort(e): Quality factor ; Seismology ; Attenuation ; Scattering ; Ibanez ; GJI

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BIBLIOGRAFIE SEISMOLOGIE

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Insights into the 2011–2012 submarine eruption off the coast of El Hierro (Canary Islands, Spain) from statistical analyses of earthquake activity (2012)

J. M. Ibáñez, S. De Angelis, A. Díaz-Moreno, P. Hernández, G. Alguacil, A. Posadas, N. Pérez

Oxford University Press

In: Geophysical Journal International

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Publikationsdatum: 2012-08-24

Beschreibung: SUMMARY The purpose of this work is to gain insights into the 2011–2012 eruption of El Hierro (Canary Islands) by mapping the evolution of the seismic b -value. The El Hierro seismic sequence offers a rather unique opportunity to investigate the process of reawakening of an oceanic intraplate volcano after a long period of repose. The 2011–2012 eruption is a submarine volcanic event that took place about 2 km off of the southern coast of El Hierro. The eruption was accompanied by an intense seismic swarm and surface manifestations of activity. The earthquake catalogue during the period of unrest includes over 12 000 events, the largest with magnitude 4.6. The seismic sequence can be grouped into three distinct phases, which correspond to well-separated spatial clusters and distinct earthquake regimes. The estimated b -value is of 1.18 ± 0.03, and a magnitude of completeness of 1.3, for the entire catalogue. B is very close to 1.0, which indicates completeness of the earthquake catalogue with only minor departures from the linearity of Gutenberg–Richter frequency–magnitude distribution. The most straightforward interpretation of this result is that the seismic swarm reached its final stages, and no additional large magnitude events should be anticipated, similarly to what one would expect for non-volcanic earthquake sequences. The results, dividing the activity in different phases, illustrate remarkable differences in the estimate of b -value during the early and late stages of the eruption. The early pre-eruptive activity was characterized by a b -value of 2.25. In contrast, the b -value was 1.25 during the eruptive phase. Based on our analyses, and the results of other studies, we propose a scenario that may account for the observations reported in this work. We infer that the earthquakes that occurred in the first phase reflect magma migration from the upper mantle to crustal depths. The area where magma initially intruded into the crust, because of its transitional nature is characterized by high fracturing, thus favours anomalously high b -values. The larger magnitude earthquakes recorded in the second phase may reflect relaxation around the magma reservoir that had fed the eruption and, thus, lower b -values.

Print ISSN: 0956-540X

Digitale ISSN: 1365-246X

Thema: Geologie und Paläontologie

Publiziert von Oxford University Press im Namen von The Deutsche Geophysikalische Gesellschaft (DGG) and the Royal Astronomical Society (RAS).

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Disk-mediated accretion burst in a high-mass young stellar object (2017)

A. Caratti o Garatti; B. Stecklum; R. Garcia Lopez; J. Eislöffel; T. P. Ray; A. Sanna; R. Cesaroni; C. M. Walmsley; R. D. Oudmaijer; W. J. de Wit; L. Moscadelli; J. Greiner; A. Krabbe; C. Fischer; R. Klein; J. M. Ibañez

Springer Nature

In: Nature Physics

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Publikationsdatum: 2017-03-03

Beschreibung: Nature Physics 13, 276 (2017). doi:10.1038/nphys3942 Authors: A. Caratti o Garatti, B. Stecklum, R. Garcia Lopez, J. Eislöffel, T. P. Ray, A. Sanna, R. Cesaroni, C. M. Walmsley, R. D. Oudmaijer, W. J. de Wit, L. Moscadelli, J. Greiner, A. Krabbe, C. Fischer, R. Klein & J. M. Ibañez Solar-mass stars form via disk-mediated accretion. Recent findings indicate that this process is probably episodic in the form of accretion bursts, possibly caused by disk fragmentation. Although it cannot be ruled out that high-mass young stellar objects arise from the coalescence of their low-mass brethren, the latest results suggest that they more likely form via disks. It follows that disk-mediated accretion bursts should occur. Here we report on the discovery of the first disk-mediated accretion burst from a roughly twenty-solar-mass high-mass young stellar object. Our near-infrared images show the brightening of the central source and its outflow cavities. Near-infrared spectroscopy reveals emission lines typical for accretion bursts in low-mass protostars, but orders of magnitude more luminous. Moreover, the released energy and the inferred mass-accretion rate are also orders of magnitude larger. Our results identify disk-accretion as the common mechanism of star formation across the entire stellar mass spectrum.

Print ISSN: 1745-2473

Digitale ISSN: 1745-2481

Thema: Physik

Publiziert von Springer Nature

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2D seismic attenuation images of Stromboli Island using active data (2015)

J. Prudencio, E. Del Pezzo, J. M. Ibáñez, E. Giampiccolo, D. Patané

Wiley

In: Geophysical Research Letters

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Publikationsdatum: 2015-03-05

Beschreibung: In this work we present intrinsic and scattering seismic attenuation 2D images of Stromboli volcano. We used 21953 waveforms from air-gun shots fired by an oceanographic vessel and recorded at 33 inland and 10 OBS seismic stations. Coda wave envelopes of the filtered seismic traces were fitted to the Energy Transport Equation in the diffusion approximation, obtaining a couple of separate Qi and Qs in 6 frequency bands. Using numerically estimated sensitivity kernels for coda waves, separate images of each quality factor were produced. Results appear stable and robust. They show that scattering- prevails over intrinsic-attenuation. The scattering pattern shows a strong concordance with the tectonic lineaments in the area, while an area of high total attenuation coincides with the zone where most of the volcanic activity occurs. Our results provide evidence that the most important attenuation effects in volcanic areas are associated with the presence of geological heterogeneities.

Print ISSN: 0094-8276

Digitale ISSN: 1944-8007

Thema: Geologie und Paläontologie , Physik

Publiziert von Wiley im Namen von American Geophysical Union (AGU).

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1–18 Hz Lg attenuation in the Granada Basin (southern Spain) (1992)

Miguel, F. ; Ibáñez, J. M. ; Alguacil, G. ; [weitere]

Oxford, UK : Blackwell Publishing Ltd

Geophysical journal international 111 (1992), S. 0

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ISSN: 1365-246X

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Geologie und Paläontologie

Notizen: The attenuation of the Lg waves for the Granada Basin has been analysed. This study has been done in the frequency domain, eliminating the influences of the source, the instrumental response and the local site response, using the Reverse Two-Station Method (RTSM). The average QLg value for the whole region, obtained for all the paths is: QLg= (105 ± 25)∞(0.93±0.14).The average values of QLg determined for this region are lower than those corresponding to other areas of Spain, and are similar to those of coda-Q obtained using local coda and single scattering methods, for some determined focal depth and for some lapse times (50 and 70 s). Small differences of the attenuation are observed between paths that cross the central part and the edges of the basin. A detailed analysis showed that the E-W and the N-S directions have differences between attenuation values; in the E-W direction Q0Lg (the QLg value at 1 Hz of frequency) is 131 ± 7 and in the N-S one Q0Lg is 88 ± 21. The frequency dependence is similar to the average QLg value. These values may indicate that the attenuation of the Lg waves, at least for this region, may not be affected by only the anelastic dissipation, but also by scattering process. The N-S direction is normal to the dominating fault systems and seems to provide a greater scattering effect than the E-W direction.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1365-246X.1992.tb00576.x

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Separation of scattering and intrinsic attenuation in southern Spain and western Anatolia (Turkey) (1995)

Akinci, A. ; Pezzo, E. ; Ibáñez, J. M.

Oxford, UK : Blackwell Publishing Ltd

Geophysical journal international 121 (1995), S. 0

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ISSN: 1365-246X

Quelle: Blackwell Publishing Journal Backfiles 1879-2005

Thema: Geologie und Paläontologie

Notizen: We have obtained a separation of intrinsic and scattering attenuation in two tectonically active areas of the Mediterranean Basin, southern Spain and western Anatolia, using the Multiple-Lapse Time Window Method. In southern Spain, Qs is predominant over Qi for frequencies lower than 4 Hz: between 4 and 8 Hz, results show similar scattering and intrinsic attenuation. For frequencies higher than 8 Hz, intrinsic attenuation is clearly dominant over scattering. Le−1 does not change uniformly with frequency: it increases until 8 Hz and decreases at frequencies greater than 8 Hz. The integrated energy curves of western Anatolia do not show regular change with distance. For the first energy window (0–15 s), there is a clear increase of the energy with distances between 0 and 80 km, and then a decrease after 80 km. The fit of the experimental data in the full hypocentral distance range is not good. We divided the experimental energy curves into two different segments, 0–80 and 80–170 km. In 0–80 km, Bo is close to 1 and the Le−1 values are low (0.004–0.013). In the second distance range (80–170 km) intrinsic attenuation is predominant over scattering. Qs−1 is more frequency-dependent than Qi−1: f−l.47 against f−l.29. We observed that coda Q−1 is equal to the observed Qi−1 for intermediate frequencies, in both regions. However, Qc−1 is really similar to Qs−1 for short distances and is between Qi and Qs for long distances in southern Spain at low frequencies. Qc is similar to the observed Qt in both regions at high frequencies. The poor fit of the simulated curves with experimental data can be explained by introducing geometrical spreading values different to those used here. It is necessary to improve the model used by taking into account phenomena like non-isotropic scattering, variation of attenuation with depth, the presence of surface waves or a geometrical spreading value different to the theoretical one used.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1111/j.1365-246X.1995.tb05715.x

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The pathogenic fungi of the spittlebug in Mexico. III. Innocuity ofErynia neoaphidis andConidiobolus major in experimental animals (1986)

Toriello, C. ; Hernandez-Ibanez, J. M. ; Lopez-Martinez, R. ; [weitere]

Springer

BioControl 31 (1986), S. 371-376

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ISSN: 1573-8248

Schlagwort(e): Erynia neoaphidis ; Conidiobolus major ; innocuity ; experimental animals ; biological control agents

Quelle: Springer Online Journal Archives 1860-2000

Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft

Beschreibung / Inhaltsverzeichnis: Résumé L'utilisation des Entomophthorales dans la lutte biologique contre les insectes n'est possible qu'après avoir vérifié leur innocuité vis-à-vis des vertébrés. Dans ce but, des injections sous-cutanées et intrapéritonéales ont été réalisées chez 274 animaux (cobayes et souris) à l'aide de mycélium et spores deErynia neoaphidis etConidiobolus major pathogènes de la “mosca pinta”. Les seules lésions tissulaires observées sont des nodules, des abcès et des adhérences au niveau de la rate, du foie, des reins et du péritoine. Les champignons n'ont jamais pu être réisolés à partir des divers organes. Les observations histopathologiques ne montrent aucune altération pathologique importante; seuls des filaments lysés entourés de polymorphonucléaires ont pu être retrouvés. Ces résultats indiquent l'innocuité deE. neoaphidis etC. major vis-à-vis des souris et des cobayes.

Notizen: Abstract Previous research concerning theEntomophthorales has demonstrated their capabilities as biological control agents. To use them widely and at industrial levels, studies to demonstrate their innocuity in animals must be made. The present study concerns the intraperitoneal and subcutaneous inoculation of 274 animals (mice and guinea pigs) withErynia neoaphidis Remaudière & Hennebert andConidiobolus major (Thaxter) Remaudière & Keller, fungi pathogenic for the spittlebug [Aeneolamia postica (Walk) andProsapia simulans (Walk)] in Mexico. The alterations found were macroscopic tissue lesions consisting of nodules, abscesses and adhesions in the liver, spleen, kidneys and intraperitoneal cavity. No fungi could be recovered from organs at any time and only lysed filaments surrounded by polymorphonuclear cells could be seen at day 8 post-inoculation. The histopathological findings showed no important pathological alterations. These results suggest the innocuity ofErynia neoaphidis Remaudière & Hennebert andConidiobolus mamor (Thaxter) Remaudière & Keller in mice and guinea pigs.

Materialart: Digitale Medien

URL: http://dx.doi.org/10.1007/BF02373153

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