排序方式： 共有7条查询结果，搜索用时 15 毫秒
1
1.
Seismicity and seismic gap in the Lesser Antilles arc and earthquake hazard in Guadeloupe 总被引：1，自引：0，他引：1
J. Dorel 《Geophysical Journal International》1981,67(3):679-695
Summary. A seismic study of the Lesser Antilles arc has been carried out, first for the period 1950–1978, for which we can use local seismic networks to draw maps of instrumental seismicity, then for the period 1530–1950, for which we have catalogues of felt earthquakes. The striking feature of the spatial distribution of foci is the cluster of epicentres in the northern half of the arc; all large earthquakes ( M > 7.5) are located north of 14° latitude. Seismicity cross-sections through the arc show a variable dipping subduction zone along the arc; the deep seismic zone is steeper in the centre of the arc than on the extremity.
The time-space diagram for historical seismicity, and the evidence of a seismic gap at the east of Guadeloupe lead us to consider the northern half arc as a likely site for a large earthquake in the near future.
The seismic slip rate calculated from all major earthquakes since 1530 is of much greater value than that obtained from recent plate tectonic models, suggesting that the recurrence rate of earthquakes is more than many hundreds of years with a possible aseismic creep. 相似文献
The time-space diagram for historical seismicity, and the evidence of a seismic gap at the east of Guadeloupe lead us to consider the northern half arc as a likely site for a large earthquake in the near future.
The seismic slip rate calculated from all major earthquakes since 1530 is of much greater value than that obtained from recent plate tectonic models, suggesting that the recurrence rate of earthquakes is more than many hundreds of years with a possible aseismic creep. 相似文献
2.
Sylvain Eschenbrenner Jacques Dorel Jean-Pierre Viode 《Pure and Applied Geophysics》1980,118(2):807-822
Résumé En 1977, deux profils sismiques ont été réalisés en Martinique, un dans la région volcanique de la Montagne Pelée, l'autre dans la partie est de l'île. Le premier couvrait des distances de 3 à 23 km et le second de 2 à 50 km.Les structures superficielles du volcan sont interprétées par un modèle à trois couches. Sur une couche déjà connue, à 6,1 km/s nous trouvons, avec une épaisseur de 0,4 à 2,6 km, une vitesse de 4,3 km/s. En surface et jusqu'à une profondeur de 0,8 à 1,4 km la vitesse est d'environ 2,7 à 2,9 km/s.Dans la partie est de la Martinique, il existe une vitesse élevée-6,5 km/s—à partir d'une profondeur faible, de l'ordre de 3 km.
In 1977, two seismic profiles were carried out in Martinique, one in the area of Montagne Pelée volcano, and the second in the eastern part of the island. The length of the first profile ranges from 3 to 23 km and the second from 2 to 50 km. The interpretation shows that the superficial structures of the volcano may be characterized by a three layer model: in the first layer the compressional velocity is about 2.7 to 2.9 km/s, the thickness varying from 0.8 to 1.4 km. The second layer has a velocity of 4.3 km/s and the thickness goes from 0.4 to 2.6 km. The deeper layer known at Leeward West Indies has a 6.1 km/s velocity.The second profile shows that the eastern part of Martinique is marked by a high velocity of 6.5 km/s, found at a depth of 3 km.相似文献
3.
Geophysical studies in recent volcanic zones of both Martinique and Guadeloupe have permitted either to bring to light or to precise the contribution of certain factors to the activities of these regions: pluviometric influence, presence of high temperature (135°C) in solfataric activities of the Guadeloupe, influence of the physico-chemical composition of the magma on the evolution of surface activities. C14 dating allows the epoque of the last important volcanic activity in the Guadeloupe to be determined. Results concerning the correlation of high seismicity connected with volcanic activities in the Guadeloupe are presented. Earthquake swarms (200 to 300 shocks) occur, on the average, every year. 相似文献
4.
Jacques Dorel Sylvain Eschenbrenner Michel Feuillard 《Pure and Applied Geophysics》1979,117(5):1050-1069
Summary In 1976 and 1977, seismic profiles were carried out in Guadeloupe. Two profiles were established in the area of La Soufriére volcano and one profile through the northern part of Guadeloupe and southern part of Grande Terre. The two first profiles were occupied from 1 to 30 km and the third profile between 5 and 50 km.The interpretation shows that the superficial structures are characterized by a three-layers model: the compressional velocity is about 2.7 to 3.0 km/s down to a depth from 1 to 3 km. Below this, the velocity is between 4.0 and 4.5 km/s in a layer whose thickness varies from 1 to 2.5 km. Under this layer we find a 6.0–6.1 km/s layer which is one of the two known crustal layer under Lesser Antilles. The boundary between the old and new are which form the Lesser Antilles arc, is marked by a thicker layer of sediments on the eastern flank of recent volcanic chain. 相似文献
5.
Superficial volcanic manifestations occurred at Soufriere de Guadeloupe in 1976–1977. Superficial phenomena started on July 8, and had been preceded the previous year by a seismovolcanic crisis of exceptional amplitude for the Caribbean region. The essentially phreatic manifestations were accompanied by an extraordinarily high number of recorded quiakes: 16,467 earthquakes in 21 months, 153 of which classified as clearly perceived. The epicentral area covered about 30 km2, and the seismic energy released reached a total of 1018 erg. Thirty-six volcanic tremors accompanied violent superficial manifestations, and 26 strong phreatic eruptions have been observed. The important role played by seismology as a crisis detector for this type of volcanoes has been clearly shown. 相似文献
6.
Massif Central (France): new constraints on the geodynamical evolution from teleseismic tomography 总被引：2，自引：0，他引：2
M. Granet G. Stoll J. Dorel U. Achauer G. Poupinet K. Fuchs 《Geophysical Journal International》1995,121(1):33-48
The Massif Central, the most significant geomorphological unit of the Hercynian belt in France, is characterized by graben structures which are part of the European Cenozoic Rift System (ECRIS) and also by distinct volcanic episodes, the most recent dated at 20 Ma to 4000 years BP. In order to study the lithosphere-asthenosphere system beneath this volcanic area, we performed a teleseismic field experiment.
During a six-month period, a joint French-German team operated a network of 79 mobile short-period seismic stations in addition to the 14 permanent stations. Inversion of P -wave traveltime residuals of teleseismic events recorded by this dense array yielded a detailed image of the 3-D velocity structure beneath the Massif Central down to 180 km depth. The upper 60 km of the lithosphere displays strong lateral heterogeneities and shows a remarkable correlation between the volcanic provinces and the negative velocity perturbations. The 3-D model reveals two channels of low velocities, interpreted as the remaining thermal signature of magma ascent following large lithospheric fractures inherited from Hercynian time and reactivated during Oligocene times. The teleseismic inversion model yields no indication of a low-velocity zone in the mantle associated with the graben structures proper. The observation of smaller velocity perturbations and a change in the shape of the velocity pattern in the 60–100 km depth range indicates a smooth transition from the lithosphere to the asthenosphere, thus giving an idea of the lithosphere thickness. A broad volume of low velocities having a diameter of about 200 km from 100 km depth to the bottom of the model is present beneath the Massif Central. This body is likely to be the source responsible for the volcanism. It could be interpreted as the top of a plume-type structure which is now in its cooling phase. 相似文献
During a six-month period, a joint French-German team operated a network of 79 mobile short-period seismic stations in addition to the 14 permanent stations. Inversion of P -wave traveltime residuals of teleseismic events recorded by this dense array yielded a detailed image of the 3-D velocity structure beneath the Massif Central down to 180 km depth. The upper 60 km of the lithosphere displays strong lateral heterogeneities and shows a remarkable correlation between the volcanic provinces and the negative velocity perturbations. The 3-D model reveals two channels of low velocities, interpreted as the remaining thermal signature of magma ascent following large lithospheric fractures inherited from Hercynian time and reactivated during Oligocene times. The teleseismic inversion model yields no indication of a low-velocity zone in the mantle associated with the graben structures proper. The observation of smaller velocity perturbations and a change in the shape of the velocity pattern in the 60–100 km depth range indicates a smooth transition from the lithosphere to the asthenosphere, thus giving an idea of the lithosphere thickness. A broad volume of low velocities having a diameter of about 200 km from 100 km depth to the bottom of the model is present beneath the Massif Central. This body is likely to be the source responsible for the volcanism. It could be interpreted as the top of a plume-type structure which is now in its cooling phase. 相似文献
7.
Horia Mitrofan Constantin Marin Dorel Zugr&#x;vescu Alin Tudorache Lucian Beu?iu Mihaela Radu 《地学学报》2008,20(2):87-94
The Na, K, Mg and Ca contents of certain deep‐origin groundwater discharges have been used by Giggenbach (1988) to define a series of ‘geoindicators’, which may provide hints on the up‐flow depth of origin, on the duration of the fluid ascent to the ground surface and on the associated CO2 flux. On occurrence of a Mw = 6.0 Vrancea earthquake, significant fluctuations of Giggenbach’s geoindicators have been recorded in a saline spring, some 50 km away from the epicentre. A pre‐seismic overall anomaly was monitored for 1 year and a half, the sharpest variations occurring about 3 months before the earthquake. Processes controlling the geoindicator fluctuations assumedly took place at 7–8 km depth, while the earthquake hypocenter depth was about 100 km. This could be an evidence for a mechanical coupling still existing between the seismogenic body in the lithosphere and the overlying crust. 相似文献
1