Comparison of seismic analysis methods applied to a historical church struck by 2009 L’Aquila earthquake     

Yohei Endo  Luca Pelà  Pere Roca  Francesca da Porto  Claudio Modena 《Bulletin of Earthquake Engineering》2015,13(12):3749-3778

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Closing and continentalization of the South Pyrenean foreland basin (NE Spain): magnetochronological constraints     

Elisenda Costa  Miguel Garcés  Miguel López‐Blanco  Elisabet Beamud  Miriam Gómez‐Paccard  Juan Cruz Larrasoaña 《Basin Research》2010,22(6):904-917

This paper presents new magnetostratigraphic results from a 1100‐m‐thick composite section across the marine to continental sediments of the central part of the SE margin of the Ebro basin (NE Spain). Integration with existing marine and continental biochronological data allows a robust correlation with the geomagnetic polarity time scale. The resulting absolute chronology ranges from 36.3 to 31.1 Ma (Priabonian to Rupelian), and yields an interpolated age of ～36.0 Ma (within chron C16n.2n) for the youngest marine sediments of the eastern Ebro basin. This age is in concordance with a reinterpretation of earlier magnetostratigraphic data from the western South Pyrenean foreland basin, and indicates that continentalization of the basin occurred as a rapid and isochronous event. The basin continentalization, determined by the seaway closure that resulted from the uplift of the western Pyrenees, was probably coincident with a mid‐amplitude eustatic sea level low with a maximum at 36.2 Ma. The base level drop that followed the basin closure and desiccation does not appear associated to a significant sedimentary hiatus along the margins, suggesting a late Eocene shallow marine basin that rapidly refilled and raised its base level after the seaway closing. Rapid basin filling following continentalization predates the phase of rapid exhumation of the Central Pyrenean Axial Zone from 35.0 to 32.0 Ma, determined from the thermochronology data. It is possible then that sediment aggradation at the front of the fold‐and‐thrust belt could have contributed to a decrease in the taper angle, triggering growth of the inner orogenic wedge through break‐back thrusting and underplating. Contrasting sedimentation trends between the western and eastern sectors of the South Pyrenean foreland indicate that basin closing preferentially affected those areas subjected to sediment bypass towards the ocean domain. As a result, sediment ponding after basin closure is responsible for a two‐fold increase of sedimentation rates in the western sector, while changes of sedimentation rates are undetected in the more restricted scenario of the eastern Ebro basin.  相似文献   

Multi-parametric approach to the analysis of soil radon gas for its validation as geoindicator in two sites of the Phlegrean Fields caldera (Italy)     

F. De Cicco  M. Pugliese  M. Quarto  V. Roca  C. Sabbarese  F. Savino  I. Aquino  W. De Cesare 《Environmental Earth Sciences》2017,76(8):317

Radon is considered one of the short- and immediate-term earthquake precursors by International Association of Seismology and Physics of the Earth’s Interior. For this reason, the accurate and reliable measurement of its specific activity in soil gas is mandatory. Since its presence is influenced by many environmental factors, in order to eliminate this influence on the radon activity measurement a multi-parametric and multi-site analysis is necessary. Following this approach, a continuous radon monitoring was carried out in two sites of the Phlegrean Fields caldera (Campania, Italy) using the RaMonA system, which also allows for the measurement of temperature, relative humidity and pressure. In particular, the dependence of measured radon specific activity on the meteorological conditions was studied using the multiple linear regression method. The analysis was implemented also by testing data averages on different timescales. In this paper, the results of a preliminary analysis performed on data collected throughout 2012 are presented; the outcomes obtained allow to emphasize site-specific behavior and to discriminate apparent radon “anomalies” of climatic origin from those tied to the phenomena occurring in the earth’s crust. The method employed showed its usefulness by removing the effects of meteorological conditions and thus to better identify the possible radon anomalies caused by seismo-volcanic activity. The peculiarities of the different sites and some correlations with earthquakes are discussed.  相似文献   

Seismic Zonation of Barcelona Based on Numerical Simulation of Site Effects   总被引：1，自引：0，他引：1  

J. Cid  T. Susagna  X. Goula  L. Chavarria  S. Figueras  J. Fleta  A. Casas  A. Roca 《Pure and Applied Geophysics》2001,158(12):2559-2577

—?Seismic responses of different sites of Barcelona have been investigated through numerical modelling. Geological maps and geotechnical data available from drillings for buildings and infrastructures have been used to determine the dynamical properties of the soils through different correlations between standard geotechnical data and dynamical parameters obtained in other regions. An estimation of the depth of the Palaeozoic basement has been obtained through an inversion of a detailed gravity survey. A 1-D equivalent linear method has been used to compute complete transfer functions and other spectral responses, such as PSA and PSV for various damping values, with the purpose of classifying zones with similar behaviour. Given the uncertainties associated with the input data, a Montecarlo's simulation process has been carried out. Four zones, characterized by their corresponding transfer function and by PGA amplifications, are proposed. The numerical results are compared with those previously obtained through microtremor measurements, showing that predominant periods derived from Nakamura's technique should be taken carefully.  相似文献   

A study of convective systems, water vapor and top of the atmosphere cloud radiative forcing over the Indian Ocean using INSAT-1B and ERBE data     

R. Roca  S. Louvet  L. Picon  M. Desbois 《Meteorology and Atmospheric Physics》2005,90(1-2):49-65

Summary The distribution of cloud radiative forcing (CRF) at the top of the atmosphere over the Indian Ocean is investigated using satellite observations. Two key regions are considered: The eastern Indian Ocean and the Bay of Bengal which experience maximum upper-level cloudiness in winter and summer respectively. It is found that longwave CRF in the Bay of Bengal during summer is similar to that over the eastern Indian Ocean during winter. On the other hand shortwave CRF magnitude is larger in the Bay of Bengal. These differences explain the net CRF difference between the two regions. The stronger shortwave forcing seems to be related to the Upper-Level Cloudiness being larger over the Bay than over the eastern Indian Ocean. The reasons for the longwave CRF similarities are analysed in more details. Using the results from a convective system classification method, it is first shown that the longwave radiative properties of the individual systems do not vary much from one region to another. The distribution of the different kind of systems, a proxy for the vertical cloudiness structure, does not either indicate strong difference between the regions. It is then proposed that the substantial precipitable water vapour amount observed over the Bay of Bengal damps the effects of the upper-level cloudiness on radiation compared to the relatively dryer eastern Indian Ocean area; yielding to similar LW CRF in both region despite more Upper-Level Cloudiness over the Bay of Bengal. These observations are supported by idealised radiative transfer computations. The distribution of cloudiness and radiative forcing is then analysed over the whole tropical Indian Ocean for each season. July is characterized by a low longwave CRF regime (relative to January) over the most convectively active part of the Ocean. The non linear damping effect of water vapor on longwave CRF is also shown to contribute to this regime. Overall, this study reaffirms the need for simultaneous documentation of the cloud systems properties together with their moist environment in order to understand the overall net radiative signature of tropical convection at the top of the atmosphere (TOA).  相似文献   

Trojans’ Odyssey: Unveiling the early history of the Solar System     

Philippe Lamy  Pierre Vernazza  Joel Poncy  Vincent Martinot  Emmanuel Hinglais  Elisabet Canalias  Jim Bell  Dale Cruikshank  Olivier Groussin  Joern Helbert  Francesco Marzari  Alessandro Morbidelli  Pascal Rosenblatt  Holger Sierks 《Experimental Astronomy》2012,33(2-3):685-721

In our present understanding of the Solar System, small bodies (asteroids, Jupiter Trojans, comets and TNOs) are the most direct remnants of the original building blocks that formed the planets. Jupiter Trojan and Hilda asteroids are small primitive bodies located beyond the ‘snow line’, around respectively the L₄ and L₅ Lagrange points of Jupiter at ～5.2?AU (Trojans) and in the 2:3 mean-motion resonance with Jupiter near 3.9?AU (Hildas). They are at the crux of several outstanding and still conflicting issues regarding the formation and evolution of the Solar System. They hold the potential to unlock the answers to fundamental questions about planetary migration, the late heavy bombardment, the formation of the Jovian system, the origin and evolution of trans-neptunian objects, and the delivery of water and organics to the inner planets. The proposed Trojans’ Odyssey mission is envisioned as a reconnaissance, multiple flyby mission aimed at visiting several objects, typically five Trojans and one Hilda. It will attempt exploring both large and small objects and sampling those with any known differences in photometric properties. The orbital strategy consists in a direct trajectory to one of the Trojan swarms. By carefully choosing the aphelion of the orbit (typically 5.3?AU), the trajectory will offer a long arc in the swarm thus maximizing the number of flybys. Initial gravity assists from Venus and Earth will help reducing the cruise time as well as the ΔV needed for injection thus offering enough capacity to navigate among Trojans. This solution further opens the unique possibility to flyby a Hilda asteroid when leaving the Trojan swarm. During the cruise phase, a Main Belt Asteroid could be targeted if requiring a modest ΔV. The specific science objectives of the mission will be best achieved with a payload that will perform high-resolution panchromatic and multispectral imaging, thermal-infrared imaging/ radiometry, near- and mid-infrared spectroscopy, and radio science/mass determination. The total mass of the payload amounts to 50?kg (including margins). The spacecraft is in the class of Mars-Express or a down-scaled version of Jupiter Ganymede Orbiter. It will have a dry mass of 1200?kg, a total mass at launch of 3070?kg and a ΔV capability of 700?m/s (after having reached the first Trojan) and can be launched by a Soyuz rocket. The mission operations concept (ground segment) and science operations are typical of a planetary mission as successfully implemented by ESA during, for instance, the recent flybys of Main Belt asteroids Steins and Lutetia.  相似文献