Site effects in Mexico City eight years after the September 1985 Michoacan earthquakes

doi:10.1016/0267-7261(94)90028-0

Soil Dynamics and Earthquake Engineering

Volume 13, Issue 4, 1994, Pages 229-247

https://doi.org/10.1016/0267-7261(94)90028-0 Get rights and content

Abstract

The purpose of this paper is to take a comprehensive look at site effects in Mexico City for the 1985 Michoacan earthquake. We examine, successively, 1D and 2D models. For the latter, we consider in detail both large scale and small scale heterogeneities, using extensively the Aki-Larner wave propagation method, in the version given by Bard and Gariel. In particular, we make a critical review of the different explanations proposed for the large duration of strong ground motion in the lake zone. Our purpose is two-sided. We first outline the difference between what is well established and what remains still unexplained regarding the seismic response of Mexico City basin. On the other hand, we wish to make explicit the conditions that the proposed models require to explain strong motion duration. Our results allow us to qualify the models proposed to date and to point out what could be the experiments and the new data required to find a truly satisfactory explanation of strong ground motion at Mexico City.

References (43)

J.G. Anderson
Strong ground motion from the Michoacán, Mexico, earthquake
Science
(1986)
L. Esteva
The Mexico earthquake of September 19, 1985 — Consequences, lessons, and impact on research and practice
Earthquake Spectra
(1988)
S.K. Singh et al.
Some aspects of source characteristics of the 19 September 1985 Michoacán earthquake and ground motion amplification in and near Mexico City from strong motion data
Bull. Seism. Soc. Am.
(1988)
S.K. Singh et al.
Evidence for anomalous body-wave radiation between 0·3 and 0·7 Hz from the 1985 September 19 Michoacán, Mexico earthquake
Geophys. J. Int.
(1990)
M. Ordaz et al.
Source spectra and spectral attenuation of seismic waves from Mexican earthquakes, and evidence of amplification in the hill zone of Mexico City
Bull. Seism. Soc. Am.
(1992)
M. Campillo et al.
Destructive strong ground motion in Mexico City: Source, path, and site effects during the great 1985 Michoacán earthquake
Bull. Seism. Soc. Am.
(1989)
L. Zeevart
Strong ground motions recorded during earthquakes of May the 11th and 19th 1962 in Mexico City
Bull. Seism. Soc. Am.
(1964)
R. Dobry et al.
Dynamic properties and seismic response of soft clay deposits
M.P. Romo et al.
General soil conditions and clay properties in the Valley of Mexico
Earthquake Spectra
(1988)
K. Aki et al.
Surface motion of a layered medium having an irregular interface due to incident plane SH waves
J. Geophys. Res.
(1970)

P.-Y. Bard et al.

The seismic response of two-dimensional sedimentary deposits with large vertical velocity gradients

Bull. Seism. Soc. Am.

(1986)

S.K. Singh et al.

On the Origin of long coda observed in the lake-bed strong-motion record of MMexico City

Bull. Seism. Soc. Am.

(1993)

M. Suárez et al.

Características de los depósitos superficiales del Valle de México

(1987)

H.B. Seed et al.

Relationships between soil conditions and earthquake ground motions

Earthquake Spectra

(1988)

H. Kawase et al.

A study on the response of a soft soil basin for incident S, P, and Rayleigh waves with special reference to the long duration observed in Mexico City

Bull. Seism. Soc. Am.

(1989)

F. Sánchez-Sesma et al.

On the seismic response of the Valley of Mexico

Earthquake Spectra

(1988)

C. Lomnitz

Mexico 1985: The case for gravity waves

Geophys. J. Int.

(1990)

J. Flores et al.

Possible resonance effect in the distribution of earthquake damage in Mexico City

Nature

(1987)

T.H. Seligman et al.

Resonant response models for the Valley of Mexico-I. The elastic inclusion approach

Geophys. J. Int.

(1989)

J.L. Mateos et al.

Resonant response models for the Valley of Mexico-II. The trapping of horizontal P waves

Geophys. J. Int.

(1993)

P.-Y. Bard et al.

A theoretical investigation of large- and small-scale amplification effects in the Mexico City valley

Earthquake Spectra

(1988)

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The ensemble of studies attributed the observed amplification to basin-edge effects and reverberation of earthquake waves in the sedimentary deposits. The consensus was not as strong for the observed ground motion duration, and some studies attributed it to 3D effects [16] not accounted for in 2D models. It was recently shown that the long duration could be attributed to longer period waves reverberating in the deeper sediments of the basin not previously accounted for [17].
“Basin effects” refers to trapped and reverberating earthquake waves in soft sedimentary deposits overlying convex depressions of the basement bedrock, which significantly alter frequency content, amplitude, and duration of seismic waves. This has played an important role on shaking duration and intensity in past earthquakes such as the M_w 8.0 1985 Michoa'can, Mexico, M_w 6.9 1995 Kobe, Japan, and M_w 7.8 2015 Gorkha, Nepal. Although the phenomenon has been understood and addressed in the literature, it has not been fully incorporated in seismic hazard analysis, and Ground Motion Prediction Equations (GMPE). In this study, we perform an extensive parametric study on the characteristics of surface ground motion associated with basin effects using finite element simulations. We use an elastic medium subjected to vertically propagating SV plane waves and utilize idealized basin shapes to examine the effects of basin geometry and material properties. We specifically study the effects of four dimensionless parameters, the width-to-depth (aspect) ratio, the rock-to-soil material contrast, a dimensionless frequency that quantifies the depth of the basin relative to the dominant incident wavelength, and a dimensionless distance quantifying distance of the basin edges relative to the dominant wavelength. Our results show that basin effects can be reasonably characterized using at least three independent parameters, each of which can significantly alter the resultant ground motion. To demonstrate the application of dimensional analysis applied here, we investigate the response of the Kathmandu Valley during the 2015 M_w 7.8 Gorkha Earthquake in Nepal using an idealized basin geometry and soil properties. Our results show that a simplified model can capture notable characteristics of the ground motion associated with basin effects which suggests that such studies can provide useful insights, relevant to the parameterization of basin effects in GMPEs and design code provisions.
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It caused the death of 370 people, 6000 were injured, and over 200 buildings were collapsed [27]. Following the devastating 1985 earthquake that struck the capital city of Mexico on September 19, 1985 [21], an earthquake early warning (EEW) system was envisage by the mayor of the city and other organizations [24,25]. It is believed that the SASMEX system was the first in its kind in the world and started its operation in 1991.
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Site effects in Mexico City eight years after the September 1985 Michoacan earthquakes

Abstract

Strong ground motion from the Michoacán, Mexico, earthquake

Science

The Mexico earthquake of September 19, 1985 — Consequences, lessons, and impact on research and practice

Earthquake Spectra

Some aspects of source characteristics of the 19 September 1985 Michoacán earthquake and ground motion amplification in and near Mexico City from strong motion data

Bull. Seism. Soc. Am.

Evidence for anomalous body-wave radiation between 0·3 and 0·7 Hz from the 1985 September 19 Michoacán, Mexico earthquake

Geophys. J. Int.

Source spectra and spectral attenuation of seismic waves from Mexican earthquakes, and evidence of amplification in the hill zone of Mexico City

Bull. Seism. Soc. Am.

Destructive strong ground motion in Mexico City: Source, path, and site effects during the great 1985 Michoacán earthquake

Bull. Seism. Soc. Am.

Strong ground motions recorded during earthquakes of May the 11th and 19th 1962 in Mexico City

Bull. Seism. Soc. Am.

Dynamic properties and seismic response of soft clay deposits

General soil conditions and clay properties in the Valley of Mexico

Earthquake Spectra

Surface motion of a layered medium having an irregular interface due to incident plane SH waves

J. Geophys. Res.

The seismic response of two-dimensional sedimentary deposits with large vertical velocity gradients

Bull. Seism. Soc. Am.

On the Origin of long coda observed in the lake-bed strong-motion record of MMexico City

Bull. Seism. Soc. Am.

Características de los depósitos superficiales del Valle de México

Relationships between soil conditions and earthquake ground motions

Earthquake Spectra

A study on the response of a soft soil basin for incident S, P, and Rayleigh waves with special reference to the long duration observed in Mexico City

Bull. Seism. Soc. Am.

On the seismic response of the Valley of Mexico

Earthquake Spectra

Mexico 1985: The case for gravity waves

Geophys. J. Int.

Possible resonance effect in the distribution of earthquake damage in Mexico City

Nature

Resonant response models for the Valley of Mexico-I. The elastic inclusion approach

Geophys. J. Int.

Resonant response models for the Valley of Mexico-II. The trapping of horizontal P waves

Geophys. J. Int.

A theoretical investigation of large- and small-scale amplification effects in the Mexico City valley

Earthquake Spectra