Desagregación Del Peligro Sísmico Para Algunos Sitios Seleccionados De México

Abstract

Describimos la desagregación del peligro sísmico con base en un modelo aplicable a una región de la costa del Pacífico Mexicano, tomando en cuenta las zonas de fuentes sísmicas, el modelo de recurrencia, y relaciones de atenuación. También desarrollamos relaciones de atenuación aplicables a la ciudad de México (i.e., la estación de registro de CU) y las integramos en el modelo de peligro sísmico adoptado. Proveemos mapas de peligro sísmico para la región de la costa del Pacífico, y espectros de peligro uniforme para algunos sitios seleccionados, incluyendo la estación CU; notamos que las ordenadas del espectro de diseño para la Ciudad de México son mayores a los valores del espectro de peligro uniforme para un periodo de retorno de 125 años. Los escenarios sísmicos identificados muestran que, en ocasiones, la contribución al peligro sísmico para un periodo de retorno de 125 o 475 años es dominada por un solo evento y en otros casos el peligro sísmico es debido a diferentes escenarios sísmicos y tipo de temblores; en particular, para la estación CU, se observa que para un periodo de vibrar menor que aproximadamente 0.7 (s) el peligro sísmico es dominado por sismos intraslab y que los sismos interplaca dominan el peligro sísmico para periodos de vibrar mayores que éste. Para la costa del Pacífico, el peligro sísmico es dominado por sismos interplaca, y por sismos intraslab e interplaca para zonas alejadas de la costa.Palabras clave: desagregación sísmica; espectros de peligro uniforme; sismos interplaca; sismos intraslab

Seismic design and importance factor: Benefit/cost for overall service time versus per unit service time

“…This is in agreement with the consideration made in [4]. [29] Interplate Earthquakes for CU station Eq. (6) (adopted from [33]) Notes: (1) e in the regression equations is a zero mean normal variate with standard deviation r for a random orientation.…”

“…The UHS shown in Fig. 2 for the CU station has two peaks, one for T n near 0.25 s and the other near 1.75 s. The first one is due to inslab earthquakes and the second one is caused by interplate earthquakes [29]. Moreover, the seismic hazard analysis results indicate that the seismic design level suggested in the current Mexico Federal District Code [39] for T n = 1.0 (s) which equals 0.16 g corresponds approximately to the 1520-year return period value.…”

“…1 and Table 1 [25][26][27][28][29], where the source zones are classified into three groups, depending on the earthquake type and earthquake magnitude. The source zones for the first and second groups are located near the Mexican Pacific coastal region and are for interplate earthquakes.…”

“…The coefficients of the GMPEs considered in this study are those estimated based on the geometric mean of the ground motion measures along two orthogonal horizontal directions [35]. The regression coefficients for the GMPEs applicable to the CU station are given in [29]; they are estimated by considering records from 18 interplate earthquakes and records from 12 inslab earthquakes recorded at the CU station. For a few selected T n values, the coefficients are included in Table 2.…”

Ground Motions from the 7 and 19 September 2017 Tehuantepec and Puebla‐Morelos, Mexico, Earthquakes

“…Although a large component of seismic hazard in this region is driven by megathrust events (Zúñiga et al, 1997;Pozos-Estrada et al, 2014;Comisión Federal de Elctricidad [CFE], 2015), the 7 September 2017 M 8.2 Tehuantepec and 19 September 2017 M 7.1 Puebla-Morelos normal-faulting, inslab earthquakes are a stark reminder that other mechanisms contribute to the hazard. In fact, disaggregating the hazard at rock sites shows that at distances < 200 km (i.e., the Puebla-Morelos earthquake to Mexico City) and frequencies larger than 1 Hz, inslab events dominate in many of the largest population centers such as Mexico City.…”