Evidence of directivity during the earthquakes of 8 and 10 May 2014 (Mw 6.5, 6.1) in the Guerrero, Mexico seismic gap and some implications

Singh, S. K.; Plata-Martinez, Raymundo; Pérez‐Campos, Xyoli; Espíndola, Víctor Hugo; Arroyo, Danny; Iglesias, A.

doi:10.1007/s10950-019-09829-y

Cited by 5 publications

(3 citation statements)

References 34 publications

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“…Two of the exceptions are the observed FAS for the Guerrero earthquakes of 08/05/2014 (Mw 6.5) and10/05/2014 (Mw 6.1) which are greater than the predicted FAS. This agrees with the strong directivity towards Mexico City during these two earthquakes documented by Singh et al (2019). Figure 18 also includes the Acapulco earthquake of 08/09/2021 (Mw 7.0), and Michoacán -Colima earthquakes of 19/09/2022 (Mw 7.6) and 22/09/2022 (Mw 6.7) which were not included in the regression analysis.…”

Section: Comparison Of Observations and Predictions From The Proposed...supporting

confidence: 74%

Prediction of Fourier Amplitude Spectrum of Ground Motion in Mexico City from Subduction Thrust Earthquakes

Arroyo,

Ordaz,

Singh

2024

Geofis Int

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Mexico City, one of the largest cities in the world, experiences frequent, devastating interplate earthquakes that originate on the subduction thrust along the Pacific coast of Mexico more than 250 km away. A notorious example is the 19 September 1985 Michoacán earthquake (Mw 8.0) which killed ~ 10,000 persons and caused wide-spread destruction in the city. The main cause of seismic damage in Mexico City is its subsoil that amplifies the ground motion. In view of the seismic hazard faced by the city, a reliable estimation of ground motion during future earthquakes is of vital importance. We present a new ground motion prediction equation (GMPE) for the Fourier amplitude acceleration spectrum (FAS) from subduction thrust earthquakes along the Pacific coast of Mexico at the reference station, CU, located in the firm zone of Mexico City. The GMPE is derived via Bayesian regression analysis and is based on an enlarged set of recordings (1965-2020; 40 earthquakes; 250 ≤ R≤ 500 km; 5 ≤ Mw ≤ 8.0). An important feature of the new GMPE is that it includes a term to model different attenuation along different ray paths. The inclusion of this term leads to a reduction in the aleatory variability of the GMPE, particularly at high frequencies. Since spectral amplification of seismic waves with respect to CU is known at many sites in the city, the FAS at these sites can be computed if it is known at CU. The new GMPE has been incorporated in a fully Fourier-based probabilistic seismic hazard analysis of Mexico City.

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Section: Comparison Of Observations and Predictions From The Proposed...supporting

confidence: 74%

Prediction of Fourier Amplitude Spectrum of Ground Motion in Mexico City from Subduction Thrust Earthquakes

Arroyo,

Ordaz,

Singh

2024

Geofis Int

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“…1A ), has not experienced an earthquake with M > 7 since 1911 8 . The largest seismic events in the NW-GG since then have been two near-trench tsunami earthquakes in 2002 (M w 6.7, M w 5.9) 9 , 10 and two aftershocks of the 2014 M w 7.3 Papanoa event with magnitudes M w 6.5 and M w 6.1 11 , 12 . The Guerrero subduction zone is also prone to slow earthquakes, including some of the largest slow slip events (SSE) in the world, with M w > 7.5, that repeat almost every 4 years 8 , 13 .…”

Section: Introductionmentioning

confidence: 99%

Shallow slow earthquakes to decipher future catastrophic earthquakes in the Guerrero seismic gap

et al. 2021

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The Guerrero seismic gap is presumed to be a major source of seismic and tsunami hazard along the Mexican subduction zone. Until recently, there were limited observations at the shallow portion of the plate interface offshore Guerrero, so we deployed instruments there to better characterize the extent of the seismogenic zone. Here we report the discovery of episodic shallow tremors and potential slow slip events in Guerrero offshore. Their distribution, together with that of repeating earthquakes, seismicity, residual gravity and bathymetry, suggest that a portion of the shallow plate interface in the gap undergoes stable slip. This mechanical condition may not only explain the long return period of large earthquakes inside the gap, but also reveals why the rupture from past M < 8 earthquakes on adjacent megathrust segments did not propagate into the gap to result in much larger events. However, dynamic rupture effects could drive one of these nearby earthquakes to break through the entire Guerrero seismic gap.

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“…Directivity has been reported even during small earthquakes (Boatwright, 2007;Calderoni et al, 2013;Seo et al, 2022). Strong directivity was reported during two moderate earthquakes in the Guerrero seismic gap (8 May 2014, M w 6.5; 11 May 2014, M w 6.1) (Singh et al, 2019). The recent Acapulco earthquake of 8 September 2021 (M w 7.0) had a strong NE directivity (Iglesias et al, 2022).…”

Section: Discussionmentioning

confidence: 98%

A Seismological Study of the Michoacán-Colima, Mexico, Earthquake of 19 September 2022 (Mw7.6)

et al. 2023

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El sismo de Michoacán-Colima el 19 de septiembre de 2022 (Ms 7.6, Mw 7.6) rompió el límite NW de la interface entre las placas de Cocos y norteamericana, causando daño severo a muchas poblados y ciudades en los estados de Michoacán y Colima. El daño fue además agravado por una réplica de magnitud importante (Mw 6.7) el 22 de septiembre. El sismo principal inició debajo de la costa a una distancia hipocentral de 22 km de la estación sísmica de Maruata (MMIG) donde las aceleraciones y velocidades máximas registradas, PGA y PGV, fueron de 1g y 28 cm/s, respectivamente. El epicentro de la réplica más grande se localizó a ~30 km al SE del sismo principal. El modelado de falla finita del sismo principal presentado por el Servicio Geológico de los Estados Unidos (USGS), revela una propagación de la ruptura a lo largo del rumbo de la falla hacia la dirección NW con una caída de esfuerzos estáticos Δσs, of 3.7 MPa. Nuestra estimación de energía radiada, ER, es 3.44x1015J, de tal manera que ER /M0 es de 1.27 × 10−5 valor similar al calculado para otros grandes sismos de subducción cuyas área de ruptura no se extienden hacia la trinchera. El área que contiene las réplicas del sismo principal de 2022 se traslapa con el área de réplicas del sismo del 30 de enero de 1973 (Mw7.6). Los sismográmas Galitzin de los dos sismos registrados en la estación DeBilt (DBN) localizada en los Países Bajos son razonablemente similares de tal manera que pueden ser clasificados como eventos quasi-repetidos. Por otro lado, el sismograma DBN del sismo del 15 de abril de 1941 (MS 7.7), cuya localización no se conoce bien del todo, aunque se sabe que ocurre en la misma región, difiere sustancialmente de los sismogramas de 1972 y 2022, sugiriendo que el primero rompió un área diferente de la del sismo de 1941. Un análisis extensivo de registros regionales exhibe el efecto de directividad observada en los datos de movimientos fuertes y en los cocientes de aceleraciones del sismo principal y de las aceleraciones de la réplica mayor. La directividad explica la dependencia azimutal observada en los cocientes de PGA y PGV, los cocientes espectrales, la distribución de PGA y la respuesta espectral a 2s Sa (T = 2 s). Debido a la directividad, los valores de PGA, PGV y Sa (T = 2 s) en el Valle de México durante el sismo principal y la réplica mayor fueron muy similares a pesar de la diferencia en magnitud de 0.9. En CU (el sitio de roca firme de referencia en la Ciudad de México), PGA y PGV durante ambos eventos fueron de ~ 6 cm/s2 and 2 cm/s, respectivamente, valores más bajos que los esperados para el sismo principal y más altos que los esperados para la réplica mayor.

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Evidence of directivity during the earthquakes of 8 and 10 May 2014 (Mw 6.5, 6.1) in the Guerrero, Mexico seismic gap and some implications

Cited by 5 publications

References 34 publications

Prediction of Fourier Amplitude Spectrum of Ground Motion in Mexico City from Subduction Thrust Earthquakes

Prediction of Fourier Amplitude Spectrum of Ground Motion in Mexico City from Subduction Thrust Earthquakes

Shallow slow earthquakes to decipher future catastrophic earthquakes in the Guerrero seismic gap

A Seismological Study of the Michoacán-Colima, Mexico, Earthquake of 19 September 2022 (Mw7.6)

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