Abstract

Knowledge regarding the characteristics of soils in Bogotá basin has been possible to get through previous microzonation studies. However, there is still insufficient knowledge of the crustal velocity structure of the region. Bogotá is located in a region prone to a significant seismic hazard. Historically, the city has been affected by strong earthquakes, reaching moment magnitudes greater than or equal to 7. Furthermore, the city was built on a lacustrine basin, with soft soils of considerable depth that may strongly amplify the ground motion during an earthquake. In this article, we describe the development of a first crustal structure and material properties model for the region of Bogotá, Colombia, covering an area of about 130 km by 102 km. This effort aims at constructing a realistic 3D seismic velocity model using geological and geotechnical information from several sources. Major geological units have been identified and mapped into the model. The Inverse Distance Weighted (IDW) interpolation was used to create continuous surfaces delimiting the geological units. Seismic-wave properties are assigned to any point in the domain using a location-based approach. We expect this model to be useful for a wide range of applications, including dynamic ground motion simulations and fault system modeling.

Highlights

  • This paper presents the development of a seismic velocity model for the region of Bogotá, Colombia

  • CVM-S, CVM-H, and Wasatch Front Community Velocity Model (WFCVM) are some of the velocity models that have been widely used in the United States for simulating ground motions from past earthquakes as well as estimating basin effects from potential future earthquakes

  • The first version was released in 2003 by Süss and Shaw (2003), and contains a P-wave seismic velocity structure derived from sonic logs and oil exploration reflection data in the Los Angeles basin, Vs is calculated from Vp using the relation “Brocher’s regression line” (Brocher, 2005a)

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Summary

Introduction

This paper presents the development of a seismic velocity model for the region of Bogotá, Colombia. The USGS estimates were used to characterize the shear-wave velocity of shallow sediments as a homogeneous layer of 30 m depth The algorithm selects this dataset when there is no data from other sources (e.g. points located out of the basin or points not covered by well logs). Faust methodology: According to Faust (1951), a relationship between compressional wave velocity, depth and age of the geological units can be established This approach, previously implemented in the velocity model of Los Angeles basin, California, USA (Magistrale, 1996), was used to characterize points at depths between 30 m and 4 km when there was no other available data.

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