We describe and apply an iterative, time-domain deconvolution approach to receiver-function estimation and illustrate the reliability and advantages of the technique using synthetic- and observation-based examples. The iterative technique is commonly used in earthquake time-function studies and offers several advantages in receiver-function analysis such as intuitively stripping the largest receiver-function arrivals from the observed seismograms first and then the details; long-period stability by a priori constructing the deconvolution as a sum of Gaussian pulses; and easy generalization to allow multiwaveform deconvolution for a single receiver-function estimate.
We present a catalog of subduction zone earthquakes along the Pacifi c coast from central El Salvador to eastern Chiapas, Mexico, from 1526 to 2000. We estimate that the catalog is complete since 1690 for M S ≥ 7.4 thrust events and M ≥ 7.4 normal-faulting events within the upper 60 km of the down-going slab. New intensity maps were constructed for the 27 earthquakes since 1690, using mostly primary data sources. By calibrating with recent events we fi nd that the long axis of the (MM) VII intensity contour for such large earthquakes well approximates the length and location of rupture along the subduction zone and can thus be used to estimate the locations and magnitudes of older events.The section from western El Salvador to Chiapas appears to have ruptured completely in a series of four to fi ve earthquakes during each of the periods 1902-1915, 1743-1776, and possibly 1565-1577. Earthquakes of M W 7.75 ± 0.3 have caused major damage along the 200 km long section from San Salvador to Guatemala City every 71 ± 17 yr, apparently since at least 1575. Although the January 2001 El Salvador earthquake caused damage within part of this zone, no major thrust earthquake has occurred there since at least 1915. We fi nd that much of this section has been relatively quiescent for moderate earthquakes shallower that 50 km since at least 1963. The conditional probability that an earthquake of M W 7.75 ± 0.3 will occur at this location in the next 20 yr is estimated at 50% (±30%).
A partir de registros analógicos en papel ahumado, obtenidos de un estudio de microsismicidad realizado en el Istmo de Tehuantepec en 1986, se determinan los espesores de la corteza terrestre en dicha zona. De la observación de fases Sp (S convertida a P) se infiere la posición de la interface que produjo las conversiones. Asimismo, de las amplitudes de las fases Sp y S, se estima el valor de los coeficientes de calidad Qs y Qp, en la corteza. Se consideran dos posibilidades: Qp = Qs y Qp =2Qs. Se obtuvo una estructura de corteza típicamente continental con un grosor promedio de 36 ± 3.2 km y una discontinuidad intermedia a una profundidad media de 22 ± 23 km. Los coeficientes de calidad del medio para la corteza por debajo de la red sismológica, son: Qs =76 (Qp = Qs) ó Qs =130 (Qp = 2Qs).doi: sin doi
La distribución de velocidades en la estructura cortical del Sur de Guatemala es estimada utilizando los métodos de Velocidad Aparente Minima y Ondas Convertidas, aplicados a datos sísmicos locales. Los resultados son evaluados relocalizando una muestra aleatoria de eventos y por medio de modelado sintético de sismogramas. El modelo de velocidad obtenido posee un gradiente aproximadamente constante en la corteza, que sobrayace una capa intermedia de- 15 km de espesor. Las velocidades del Manto son aproximadamente 8.0 km/sec. Este es un modelo promedio para Guatemala con las limitantes impuestas por la compleja tectónica regional.doi: sin doi
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