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Search Results: 1 - 10 of 472039 matches for " Miguel A. Santoyo "
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Possible lateral stress interactions in a sequence of large interplate thrust earthquakes on the subducting Cocos and Rivera plates
Santoyo, Miguel A;Mikumo, Takeshi;Mendoza, Carlos;
Geofísica internacional , 2007,
Abstract: large interplate earthquakes in the mexican subduction zone may cluster in space and time. this clustering could be due to stress interactions between large events. we investigate this possibility by calculating the coseismic coulomb failure stress change due to seven large thrust earthquakes (mw>7.4) that occurred from 1973 to 1985 on the cocos plate, and from 1995 to 2003 on the rivera plate subducting beneath the north america plate. the calculations are based on the slip distribution obtained from previous kinematic waveform inversion for these earthquakes. the calculated stress changes are superposed in a cumulative way as a function of time and space. our results show that these earthquakes could be related to each other. at least part of the relation may possibly be attributed to the coseismic stress increase from the occurrence of previous large events in adjacent zones.
Faulting process and coseismic stress change during the 30 January, 1973, Colima, Mexico interplate earthquake (Mw=7.6)
Santoyo, Miguel A.;Mikumo, Takeshi;Quintanar, Luis;
Geofísica internacional , 2006,
Abstract: a large thrust earthquake (mw=7.6) occurred on january 30, 1973, on the plate interface between the subducting cocos plate and the continental north america plate, near the triple junction between the north america, cocos and rivera plates. this event might be related to two sequences of subsequent large earthquakes that occurred around this region. although several authors have analyzed the focal mechanism and depth of this earthquake, we analyzed its source characteristics and performed a linear kinematic waveform inversion for the slip distribution over the fault plane. we find a shallow thrust mechanism (st=285°, dip=16°, ra=85°) consistent with the tectonic environment, with a depth of 16 km and a total moment release of 2.98x1027 dyn-cm. the results show a slip distribution with two main patches, with a maximum dislocation of 199 cm and 173 cm respectively. we calculated the coseismic stress change on and around the fault plane. this earthquake ruptured two main asperities, one downdip and southwest and the other updip and northwest of the hypocenter, with stress change of -31 and -40 bars respectively the surrounding zone of stress increase could have influenced the subsequent seismicity to a distance of up to 120 km from the hypocenter.
Possible lateral stress interactions in a sequence of large interplate thrust earthquakes on the subducting Cocos and Rivera plates
Miguel A. Santoyo,Takeshi Mikumo,Carlos Mendoza
Geofísica internacional , 2007,
Abstract: Large interplate earthquakes in the Mexican subduction zone may cluster in space and time. This clustering could be due to stress interactions between large events. We investigate this possibility by calculating the coseismic Coulomb failure stress change due to seven large thrust earthquakes (Mw>7.4) that occurred from 1973 to 1985 on the Cocos plate, and from 1995 to 2003 on the Rivera plate subducting beneath the North America plate. The calculations are based on the slip distribution obtained from previous kinematic waveform inversion for these earthquakes. The calculated stress changes are superposed in a cumulative way as a function of time and space. Our results show that these earthquakes could be related to each other. At least part of the relation may possibly be attributed to the coseismic stress increase from the occurrence of previous large events in adjacent zones.
Source process and stress change associated with the 11 January, 1997 (Mw=7.1) Michoacán, Mexico, inslab earthquake
Miguel A. Santoyo,Shri K. Singh,Takeshi Mikumo
Geofísica internacional , 2005,
Abstract: We study the source characteristics and the associated coseismic stress change of the January 11, 1997 Michoacán earthquake, based on teleseismic, regional and near-source recordings. This event was located just beneath the ruptured zone of the 1985 Michoacán thrust event. From the inversion of teleseismic recordings, we obtain a nearly-vertical faulting at 35 km depth, a total source duration of 15 sec, a moment magnitude of Mw=7.1, and a mean rupture velocity of 2.8 km/sec. An analysis of teleseismic and local seismograms shows that the rupture had a strong directivity to the southeast, with a rather complex source-time function with two main subevents and a total duration of 13 sec. The dislocation distribution obtained from 2D kinematic linear inversion, using both local strong motion and broad-band teleseismic data, shows a complex rupture pattern with the main seismic moment release occurring in the southwest portion of the fault. A comparison between the coseismic Coulomb failure stress change during the main shock, and the location and mechanism of the aftershocks, suggests that post-event seismicity may have been triggered by the stress changes due to the main event.
Finite Fault Analysis and Near Field Dynamic Strains and Rotations due to the 11/05/2011 (Mw5.2) Lorca Earthquake, South-Eastern Spain
Miguel Angel Santoyo
Physics , 2012, DOI: 10.1007/s10518-013-9492-x
Abstract: The 11/5/2011 Lorca, Spain earthquake (Mw5.2) and related seismicity produced extensive damage in the town of Lorca and vicinity. During these earthquakes, evidence of rotations and permanent deformations in structures were observed. To analyze these aspects and study the source properties from the near field, the displacement time histories were obtained including the static component at Lorca station. Displacement time histories were computed by an appropriate double time integration procedure of accelerograms. Using these data, the foreshock and mainshock slip distributions were calculated by means of a complete waveform kinematic inversion. To study the dynamic deformations, the 3D tensor of displacement gradients at Lorca station was first estimated by a single station method. Using the finite fault inversion results and by means of a first order finite difference approach, the dynamic deformations tensor at surface was calculated at the recording site. In order to estimate the distribution of the peak dynamic deformations, the calculation was extended to the close neighboring area of the town. The possible influence of the near-field deformations on the surface structures was analyzed.
Surface Dynamic Deformation Estimates From Seismicity Near the Itoiz Reservoir, Northern Spain
Miguel A. Santoyo,Patricia Martínez-Garzón,Antonio García-Jerez,Francisco Luzón
Physics , 2014,
Abstract: We analyzed the ground motion time histories due to the local seismicity near the Itoiz reservoir, in order to estimate the surface 3D displacement-gradients and dynamic deformations. The seismic data were obtained by a semi-permanent broadband and accelerometric network installed by the University of Almeria during 2008 and 2009. Seismic sensors were located on surface and at underground sites in the vicinity of the dam. The dynamic deformation field was calculated by two different methods. On one hand, by the Seismo-Geodetic method using the data from a three-station micro-array. On the other hand, by Single-Station estimates of displacement gradients, assuming the incidence of body wave fields propagating through the recording site. The dynamic deformations obtained from both methods were compared and analyzed in the context of the local effects near the dam. The shallow 1D velocity structure was estimated from seismic data by modeling the body-wave travel times. After the comparison of the dynamic displacement gradients, the time histories result quite similar within the time-window of body-wave arrivals. The strain misfits between methods vary from 3.9% to 11.6% and rotational misfits vary from 1.5% to 22.7%. Amplitudes of displacement gradients vary in the range of 10-8 to 10-7 strains. From the analysis, these low amplitudes appear directly related with the low-magnitudes of earthquakes analyzed. The misfits between the two methods studied here are small and within the same values with respect to direct measurements. While both methods studied here have shown to be adequate for dynamic deformation evaluations, the Single-Station method has proved to be a good option for the analysis of local seismicity, where few three-component stations are available. The results obtained here would help to extend the applicability of these methodologies to other sites of engineering interest.
Karyotype description of Pomacea patula catemacensis (Caenogastropoda, Ampullariidae), with an assessment of the taxonomic status of Pomacea patula
Diupotex-Chong,María Esther; Cazzaniga,Néstor J.; Hernández-Santoyo,Alejandra; Betancourt-Rule,José Miguel;
Biocell , 2004,
Abstract: mitotic chromosomes of the freshwater snail pomacea patula catemacensis (baker 1922) were analyzed on gill tissue of specimens from the type locality (lake catemaco, mexico). the diploid number of chromosomes is 2n = 26, including nine metacentric and four submetacentric pairs; therefore, the fundamental number is fn = 52. no sex chromosomes could be identified. the same chromosome number and morphology were already reported for p. flagellata, i.e., the other species of the genus living in mexico. the basic haploid number for family ampullariidae was reported to be n = 14 in the literature; so, its reduction to n = 13 is probably an apomorphy of the mexican pomacea snails. lanistes bolteni, from egypt, also shows n = 13, but its karyotype is much more asymmetrical, and seems to have evolved independently from p. flagellata and p. patula catemacensis. the nominotypical subspecies, p. patula patula (reeve 1856), is a poorly known taxon, whose original locality is unknown. a taxonomical account is presented here, and a mexican origin postulated as the most parsimonious hypothesis.
Karyotype description of Pomacea patula catemacensis (Caenogastropoda, Ampullariidae), with an assessment of the taxonomic status of Pomacea patula
María Esther Diupotex-Chong,Néstor J. Cazzaniga,Alejandra Hernández-Santoyo,José Miguel Betancourt-Rule
Biocell , 2004,
Abstract: Mitotic chromosomes of the freshwater snail Pomacea patula catemacensis (Baker 1922) were analyzed on gill tissue of specimens from the type locality (Lake Catemaco, Mexico). The diploid number of chromosomes is 2n = 26, including nine metacentric and four submetacentric pairs; therefore, the fundamental number is FN = 52. No sex chromosomes could be identified. The same chromosome number and morphology were already reported for P. flagellata, i.e., the other species of the genus living in Mexico. The basic haploid number for family Ampullariidae was reported to be n = 14 in the literature; so, its reduction to n = 13 is probably an apomorphy of the Mexican Pomacea snails. Lanistes bolteni, from Egypt, also shows n = 13, but its karyotype is much more asymmetrical, and seems to have evolved independently from P. flagellata and P. patula catemacensis. The nominotypical subspecies, P. patula patula (Reeve 1856), is a poorly known taxon, whose original locality is unknown. A taxonomical account is presented here, and a Mexican origin postulated as the most parsimonious hypothesis.
Carcinoma suprarrenal: supervivenvia a 7 a?os libre de enfermedades tras resección completa del tumor primario y resecciones repetidas de recidivas locorregional y a distancia: Revisión a raíz de un caso con una pobre esperanza de vida inicial
Ramírez Plaza,César P.; Santoyo Santoyo,Julio; Domínguez López,Marta E.; Eloy- García Carrasco,Carmen; Cobo Dols,Manuel; Suárez Mu?oz,Miguel A.; Fernández Aguilar,José L.; la Fuente Perucho,Agustín de;
Archivos Espa?oles de Urología (Ed. impresa) , 2005, DOI: 10.4321/S0004-06142005000200004
Abstract: objectives: we report the case of a female patient with adrenal carcinoma who had undergone surgery and presented with local-regional and distant recurrences, emphasizing the importance of the aggressive surgical treatment to achieve long-term survival which is unexpected sometimes. currently, it represents the gold standard and all cases should be reported to stimulate other groups to work in this line. methods/results: we report the case of a 29-yearold female patient who consulted for left flank pain, being diagnosed of an adrenal tumor by radiological tests; she underwent surgical excision of a left adrenal carcinoma (stage ii). later on she presented with localregional recurrences (2 times) and distant metastases (liver) undergoing excision in three procedures. currently, the patient is alive and free of disease 7 years after diagnosis. conclusions: adrenal cancer recurrences have been considered lethal in the short-term. nevertheless, an aggressive surgical approach of local recurrences and metastasic disease may significantly prolong patient’s survival and, sometimes, leave the patient disease free several years after the diagnosis of the primary tumor.
Faulting process and coseismic stress change during the 30 January, 1973, Colima, Mexico interplate earthquake (Mw=7.6)
M. A. Santoyo,T. Mikumo,L. Quintanar
Geofísica internacional , 2006,
Abstract: A large thrust earthquake (Mw=7.6) occurred on January 30, 1973, on the plate interface between the subducting Cocos plate and the continental North America plate, near the triple junction between the North America, Cocos and Rivera Plates. This event might be related to two sequences of subsequent large earthquakes that occurred around this region. Although several authors have analyzed the focal mechanism and depth of this earthquake, we analyzed its source characteristics and performed a linear kinematic waveform inversion for the slip distribution over the fault plane. We find a shallow thrust mechanism (St=285°, Dip=16°, Ra=85°) consistent with the tectonic environment, with a depth of 16 km and a total moment release of 2.98x1027 dyn-cm. The results show a slip distribution with two main patches, with a maximum dislocation of 199 cm and 173 cm respectively. We calculated the coseismic stress change on and around the fault plane. This earthquake ruptured two main asperities, one downdip and southwest and the other updip and northwest of the hypocenter, with stress change of –31 and -40 bars respectively The surrounding zone of stress increase could have influenced the subsequent seismicity to a distance of up to 120 km from the hypocenter.
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