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Ocean Dynamics - With the continued rise in global mean sea level, operational predictions of tidal height and total water levels have become crucial for accurate estimations and understanding of...  相似文献   
2.
The Gulf of Patti and its onshore sector represent one of the most seismically active regions of the Italian Peninsula. Over the period 1984–2014, about 1800 earthquakes with small-to-moderate magnitude and a maximum hypocentral depth of 40 km occurred in this area. Historical catalogues reveal that the same area was affected by several strong earthquakes such as the Mw = 6.1 event in April 1978 and the Mw = 6.2 one in March 1786 which have caused severe damages in the surrounding localities. The main seismotectonic feature affecting this area is represented by a NNW–SSE trending right-lateral strike-slip fault system called “Aeolian–Tindari–Letojanni” (ATLFS) which has been interpreted as a lithospheric transfer zone extending from the Aeolian Islands to the Ionian coast of Sicily. Although the large-scale role of the ATLFS is widely accepted, several issues about its structural architecture (i.e. distribution, attitude and slip of fault segments) and the active deformation pattern are poorly constrained, particularly in the offshore. An integrated analysis of field structural geology with marine geophysical and seismological data has allowed to better understand the structural fabric of the ATLFS which, in the study area, is expressed by two major NW–SE trending, en-echelon arranged fault segments. Minor NNE–SSW oriented extensional structures mainly occur in the overlap region between major faults, forming a dilatational stepover. Most faults display evidence of active deformation and appear to control the main morphobathymetric features. This aspect, together with diffused continental slope instability, must be considered for the revaluation of the seismic and geomorphological hazard of this sector of southern Tyrrhenian Sea.  相似文献   
3.
Cultrera  F.  Barreca  G.  Burrato  P.  Ferranti  L.  Monaco  C.  Passaro  S.  Pepe  F.  Scarf&#;  L. 《Natural Hazards》2016,86(2):253-272

The Gulf of Patti and its onshore sector represent one of the most seismically active regions of the Italian Peninsula. Over the period 1984–2014, about 1800 earthquakes with small-to-moderate magnitude and a maximum hypocentral depth of 40 km occurred in this area. Historical catalogues reveal that the same area was affected by several strong earthquakes such as the Mw = 6.1 event in April 1978 and the Mw = 6.2 one in March 1786 which have caused severe damages in the surrounding localities. The main seismotectonic feature affecting this area is represented by a NNW–SSE trending right-lateral strike-slip fault system called “Aeolian–Tindari–Letojanni” (ATLFS) which has been interpreted as a lithospheric transfer zone extending from the Aeolian Islands to the Ionian coast of Sicily. Although the large-scale role of the ATLFS is widely accepted, several issues about its structural architecture (i.e. distribution, attitude and slip of fault segments) and the active deformation pattern are poorly constrained, particularly in the offshore. An integrated analysis of field structural geology with marine geophysical and seismological data has allowed to better understand the structural fabric of the ATLFS which, in the study area, is expressed by two major NW–SE trending, en-echelon arranged fault segments. Minor NNE–SSW oriented extensional structures mainly occur in the overlap region between major faults, forming a dilatational stepover. Most faults display evidence of active deformation and appear to control the main morphobathymetric features. This aspect, together with diffused continental slope instability, must be considered for the revaluation of the seismic and geomorphological hazard of this sector of southern Tyrrhenian Sea.

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Ocean Dynamics - The sea level observations from satellite altimetry are characterised by a sparse spatial and temporal coverage. For this reason, along-track data are routinely interpolated into...  相似文献   
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High resolution swath bathymetry of shallow water (< 200 m) oceanic seamounts is a relatively rare issue. During the recent Gorringe_2003 cruise over the Gorringe Bank (Eastern Atlantic) we collected multibeam bathymetry on the bank’s two shallow summits, Gettysburg and Ormonde in the –25/–400m depth range at a resolution rarely achieved over an oceanic seamount. We also carried out bottom samplings and ROV dives in the same bathymetric interval. The acquisition parameters and the characteristics of the echosounder employed allowed to generate a Digital Terrain Model (DTM) with metric spatial resolution upto 75–100 m depths. To ensure proper tidal corrections a tide-gauge was deployed at sea-bottom during the survey. DTM reveals for the Gettysburg Seamount an almost perfectly circular summit resulting from the blanket of bioclastic sediments over an igneous ‘core’ consisting of sheared and foliated serpentinites. The core is dissecated by N 10° W trending ridges elevating some tens of metres and filled in between by bioclastic sands. Both foliation and ridge patterns seem related to primary igneous fabric rather than later structural deformation. The overall circular shape confirms the origin of the seamount as a mantle serpentinite diapir in analogy with similar, but subduction-related, circular seamounts observed in the Bonin Trench (western Pacific). In contrast the Ormonde elongated summit follows the regional tectonic trend with a N 60° E active (seismogenic?) fault on its southeastern flank. Its basement morphology corresponds to the outcrops of igneous rocks chiefly consisting of gabbros, volcanic rocks and dyke intrusions. On both seamounts topographic profiles show that the ‘shelf’ area is somewhat convex rather than flat like that of ‘Pacific type’ guyots and is bordered by a depositional, locally erosional shelf break, located between –170 and –130 m. Various terraced surfaces and some geological evidence confirm previous observations and indicate relative sea-level oscillations with partial emersion of the two summits that seem occurred during the last glacial cycle (past 120 ka).  相似文献   
6.
The AltiKa altimeter records the reflection of Ka-band radar pulses from the Earth's surface, with the commonly used waveform product involving the summation of 96 returns to provide average echoes at 40 Hz. Occasionally there are one-second recordings of the complex individual echoes (IEs), which facilitate the evaluation of on-board processing and offer the potential for new processing strategies. Our investigation of these IEs over the ocean confirms the on-board operations, whilst noting that data quantization limits the accuracy in the thermal noise region. By constructing average waveforms from 32 IEs at a time, and applying an innovative subwaveform retracker, we demonstrate that accurate height and wave height information can be retrieved from very short sections of data. Early exploration of the complex echoes reveals structure in the phase information similar to that noted for Envisat's IEs.  相似文献   
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