排序方式： 共有46条查询结果，搜索用时 390 毫秒
21.
Iolanda Gaudiosi Del Monaco Francesco Milana Giuliano Tallini Marco 《Bulletin of Earthquake Engineering》2014,12(2):697-716
In this paper, we focused our attention on a cross-section of the Aterno River Valley where a good quality geological and geophysical dataset allowed to reconstruct accurately the geometry and the Vs profiles along all the plane of the section. Its trace is deliberately aligned close to the strong motion stations that recorded the Mw 6.3 (April 6th 2009) L’Aquila earthquake. We analysed strong and weak motion data available at these latter stations as well as at one of the temporary stations installed during the Microzonation activities and located on outcropping bedrock, in proximity of the cross-section. We used the H/V technique to select a reliable reference site and once we found it, we applied the SSR technique to compute amplification functions in correspondence of two strong motion stations. In turn, for both sites we performed a site response numerical modelling with two different 2D codes and we compared simulated versus experimental transfer functions. We found that the cross-section is well constrained based on the very reasonable agreement between results of numerical modelling and earthquake data analysis. We pointed out also a strong amplification of the deposit at the centre of the valley due to the constructive interference of S and surface waves, not predictable by means of 1D numerical modelling. We also compared the H/V as well as the SSR obtained from strong motion data with the ones computed from weak motion finding evidences of non-linearity in soil behaviour. 相似文献
22.
Four megabeds (I to IV) were recognized throughout the Cerro Bola inlier, a glacially influenced depositional area of the Carboniferous Paganzo Basin, south‐western La Rioja Province, Argentina. Such anomalous thick beds are associated with the collapse of an unstable basin margin after periods of large meltwater discharge and sediment accumulation. Failure of these previously deposited sediments triggered mass flows and associated turbidity currents into the basin. Megabed I is up to 188 m thick and was deposited during a transgressive stage by re‐sedimentation of ice‐rafted debris. Also part of the transgressive stage, Megabeds II, III and IV are up to 9 m thick and are associated with a dropstone‐free period of flooding. Megabeds were subdivided into three divisions (1 to 3) that represent a spectrum of flow properties and rheologies, indicative of a wide range of grain support mechanisms. These divisions are proposed as an idealized deposit that may or may not be completely present; the Cerro Bola megabeds thus display bipartite or tripartite organization, each division inferred to reflect a rheologically distinct phase of flow. Division 1 is a basal layer that consists of clast‐supported and matrix‐supported, pebble conglomerate, rarely followed by weak normally graded to ungraded, very coarse‐ to coarse‐grained sandstone. This lower interval is interpreted to be the deposit of a concentrated density flow and is absent in bipartite megabeds. Division 2 is represented by a mud‐rich sandstone matrix with dispersed granule to pebble‐size crystalline and mudstone clasts. It also includes fragments of sandstone up to boulder size, as well as rafts of cohesive muddy material and wood fragments. Division 2 is interpreted to be a result of debris‐flow deposition. A debrite‐related topography, resulting from the freezing of high yield strength material, captures and partially confines the succeeding upper division 3, which fills the topographic lows and pinches out against topographic highs. Division 3 is rich in mudstone chips and consists of very coarse‐grained, dirty sandstones grading upward to siltstones and mudstones. It is interpreted to be a deposit of a co‐genetic turbidity current. Spectral gamma ray and petrographic analyses indicate that both debrite and co‐genetic turbidite have high depositional mud content and are of similar composition. One of the megabeds is correlated with an initial slump‐derived debris flow, which suggests that the mass flow becomes partitioned both at the top, generating a co‐genetic turbidity current and, at the base, segregating into a concentrated density flow that seems to behave as a gravelly traction carpet. 相似文献
23.
Marco Massa Francesca Pacor Lucia Luzi Dino Bindi Giuliano Milana Fabio Sabetta Antonella Gorini Sandro Marcucci 《Bulletin of Earthquake Engineering》2010,8(5):1175-1187
The Italian strong-motion database was created during a joint project between Istituto Nazionale di Geofisica e Vulcanologia
(INGV, Italian Institute for Geophysics and Vulcanology) and Dipartimento della Protezione Civile (DPC, Italian Civil Protection). The aim of the project was the collection, homogenization and distribution of strong motion data acquired in Italy in the
period 1972–2004 by different institutions, namely Ente Nazionale per l’Energia Elettrica (ENEL, Italian electricity company), Ente per le Nuove tecnologie, l’Energia e l’Ambiente (ENEA, Italian energy and environment organization) and DPC. Recently the strong-motion data relative to the 23th December 2009, Parma (Mw = 5.4 and Mw = 4.9) and to the April
2009 L’Aquila sequences (13 earthquakes with 4.1 ≤ Mw ≤ 6.3) were included in the Italian Accelerometric Archive (ITACA) database
(beta release). The database contains 7,038 waveforms from analog and digital instruments, generated by 1.019 earthquakes
with magnitude up to 6.9 and can be accessed on-line at the web site . The strong motion data are provided in the unprocessed and processed versions. This article describes the steps followed
to process the acceleration time series recorded by analogue and digital instruments. The procedures implemented involve:
baseline removal, instrumental correction, band pass filtering with acausal filters, integration of the corrected acceleration
in order to obtain velocity and displacement waveforms, computation of acceleration response spectra and strong motion parameters.
This procedure is applied to each accelerogram and it is realised to preserve the low frequency content of the records. 相似文献
24.
Site response study in Abruzzo (Central Italy): underground array versus surface stations 总被引：1，自引：1，他引：0
G. De Luca E. Del Pezzo F. Di Luccio L. Margheriti G. Milana R. Scarpa 《Journal of Seismology》1998,2(3):223-236
In this site response study we examined local earthquakes recorded at surface stations of a local seismic network and at a temporary underground seismic array installed in a tunnel underneath the Gran Sasso Massif in Abruzzo (central Italy). This allowed us to compare the seismic site response beneath the mountain and on the surface in similar geological environment (soft rock sites). We applied spectral ratios method on different segments of the seismograms and used different reference spectra in the 1–20 Hz frequency band. We found little or no amplification effects at most of the surface stations whereas site transfer functions evaluated with respect to underground sites show an amplification factor up to 6 in the 1–8 Hz frequency range. Coda spectral ratios estimated at soft rock sites are confirmed as good estimates of shear wave transfer function. 相似文献
25.
Rural diversification in Croatia is well advanced because many rural families have been able to find work in secondary and
tertiary activities without the need to migrate to the towns. Many rural settlements have now attained an urban character
although there are regional variations, including a contrast between the continental zone with a relatively high level of
commitment to agriculture and the coastal areas, with pronounced ‘deagrarisation’ where the ports and tourist resorts are
well developed and the natural resource conditions for agriculture are poor. These variations are examined at the municipality
level with reference to two key indicators: the share of nonagricultural population and the share of workers in the total
active population. Four categories of socio-economic transformation are recognised: more urbanised, urbanised, less urbanised
and rural. The main regional differences between the continental and coastal areas are confirmed with the latter showing a
relatively high level of socio-economic transformation through the prominence of more highly urbanised municipalities.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
26.
G. Milana R. M. Azzara E. Bertrand P. Bordoni F. Cara R. Cogliano G. Cultrera G. Di Giulio A.M. Duval A. Fodarella S. Marcucci S. Pucillo J. R��gnier G. Riccio 《Bulletin of Earthquake Engineering》2011,9(3):741-759
After the 2009 April 6th Mw 6.3 L??Aquila earthquake (Central Italy) the Italian Civil Defense Department promoted the microzoning study in the ten zones in the epicentral area that suffered major damage. In this paper we present the activities and the results concerning a temporary seismic network installed in the historical L??Aquila city center indicated as ??macroarea 1?? in the microzoning project. Seismic data were collected to investigate the amplification effects in the city and to support the microzoning activities in verifying both geological profiles and 1D numerical modeling of the seismic response of the city. The conventional spectral approaches using both microtremor and earthquake data allowed to determine the fundamental resonance frequencies and the amplification factors within the city respectively. The spatial variability of these quantities can be related to the geological and geomorphologic characteristics of the investigated area. A comparison between the network data and the data recorded by the two strong motion instruments installed in the city was also made. This allows verifying the relative response of the accelerometric stations that recorded in the city the major events of the sequence. 相似文献
27.
Abstract Along the Periadriatic Lineament in the Alps and the Sava-Vardar Zone of the Dinarides and Hellenides, Paleogene magmatic associations form a continuous belt, about 1700 km long. The following magmatic associations occur: (1) Eocene granitoids; (2) Oligocene granitoids including tonalites; (3) Oligocene shoshonite and calc-alkaline volcanics with lamprophyres; (4) Egerian-Eggenburgian (Chattian) calc-alkaline volcanics and granitoids. All of these magmatic associations are constrained by radiometric ages, which indicate that the magmatic activity was mainly restricted to the time span between 55 and 29 Ma. These igneous rocks form, both at surface and in the subsurface, the distinct linear Periadriatic-Sava-Vardar magmatic belt, with three strikes that are controlled by the indentation of Apulia and Moesia and accompanying strike-slip faulting. The geology, seismicity, seismic tomography and magnetic anomalies within this belt suggest that it has been generated in the African-Eurasian suture zone. Based on published analytical data, the petrology, major and trace element contents and Sr, Nd and O isotopie composition of each magmatic association are briefly defined. These data show that Eocene and Oligocene magmatic associations of the Late Paleogene Periadriatic-Sava-Vardar magmatic belt originated along a consuming plate margin. Based on isotopie systems, two main rock groups can be distinguished: (1) 87Sr/86Sr = 0.7036–0.7080 and δ18O = 5.9–7.2‰, indicating basaltic partial melts derived from a continental mantle-lithosphere, and (2) 87Sr/86Sr = 0.7090–72131 and δ18O = 7.3–11.5‰, indicating crustal assimilation and melting. The mantle sources for the primary basalt melts are metasomatized garnet peridotites and/or spinel lherzolites and phlogopite lherzolites of upper mantle wedge origin. The geodynamic evolution of the plutonic and volcanic associations of the Periadriatic-Sava-Vardar magmatic belt was related to the Africa-Eurasia suture zone that was dominated by break-off of the subducted lithospheric slab of Mesozoic oceanic crust, at depths of 90–100 km. This is indicated by their contemporaneity along the 1700 km long belt. © 2002 Éditions scientifiques et médicales Elsevier SAS. All rights reserved. 相似文献
28.
Andrew N. O’Brien Miroslav D. Filipović Evan J. Crawford Nicholas F. H. Tothill Jordan D. Collier Ain Y. De Horta Graeme F. Wong Danica Drašković Jeff L. Payne Thomas G. Pannuti Jared P. Napier Stephen A. Griffith Wayne D. Staggs Srdjan Kotuš 《Astrophysics and Space Science》2013,347(1):159-168
A series of new radio-continuum (λ=20, 13, 6 and 3 cm) mosaic images focused on the NGC 55 galactic system were produced using archived observational data from the Australia Telescope Compact Array. These new images are both very sensitive (down to rms=33 μJy) and feature high angular resolution (down to <4″). Using these newly created images, 66 previously unidentified discrete sources are identified. Of these sources, 46 were classified as background sources, 11 as H?ii regions and 6 as supernova remnant candidates. This relatively low number of SNR candidates detected coupled with the low number of large H?ii regions is consistent with the estimated low star formation rate of the galaxy at 0.06 M ⊙?year?1. Our spectral index map shows that the core of galaxy appears to have a shallow spectral index between α=?0.2 and ?0.4. This indicates that the core of the galaxy is a region of high thermal radiation output. 相似文献
29.
Cheinway Hwang Tzu-Pang Tseng Ting-Jung Lin Dražen Švehla Urs Hugentobler Benjamin Fong Chao 《GPS Solutions》2010,14(1):121-131
The precise orbit determination antennas of F3/C and GRACE-A satellites are from the same manufacturer, but are installed
in different configurations. The current orbit accuracy of F3/C is 3 cm at arcs with good GPS data, compared to 1 cm of GRACE,
which has a larger ratio of usable GPS data. This paper compares the qualities of GPS observables from F3/C and GRACE. Using
selected satellites and time spans, the following average values for the satellite F3/C and satellite A of GRACE are obtained:
multipath effect on the pseudorange P1, 0.78 and 0.38 m; multipath effect on the pseudorange P2, 1.03 and 0.69 m; occurrence
frequency of cycle slip, 1/29 and 1/84; standard error of unit weight, 4 and 1 cm; dynamic–kinematic orbit difference, 10
and 2 cm. For gravity determination using F3/C GPS data, a careful selection of GPS data is critical. With six satellites
in orbit, F3/C’s large amount of GPS data will make up the deficiency in data quality. 相似文献
30.
Sara Amoroso Iolanda Gaudiosi Marco Tallini Giuseppe Di Giulio Giuliano Milana 《Bulletin of Earthquake Engineering》2018,16(10):4443-4466
The Santa Maria di Collemaggio Basilica is an important cultural heritage site and exemplifies Romanesque-Gothic art in the Abruzzo region (central Italy). Erected in the second half of the XII century, the Basilica was severely damaged during the April 6, 2009 L’Aquila earthquake (MW 6.1). In particular, the area of the transept collapsed causing the dome to fall. A refined two-dimensional (2D) geotechnical model was built representing a section that includes the Basilica, in order to better understand the soil response of the Basilica site. The subsoil model was constrained using the geophysical and geotechnical data collected from the seismic microzonation studies, the reconstruction of private damaged buildings and other technical and scientific studies realized in the L’Aquila basin and in the area of the Basilica before and after L’Aquila earthquake. 2D site response analyses were performed to verify the presence of local site effects by comparing simulated versus experimental transfer functions. Moreover, a frequency–wavenumber (f–k) analysis was executed with the aim of evaluating the occurrence of surface waves generated within the basin. 2D seismic effects involve significant amplification in the period range of engineering interest, therein providing an appropriate elastic response spectrum for the restoration of the Basilica. 相似文献