Co-seismic deformation of an estuarine terrace, Constitución, Central Chile

• Main Author: José F. Araya Vergara
• Format: Article
• Language: English
• Published: Universidad de Chile, Departamento de Geografía 2015-06-01
• Series: Investigaciones Geográficas
• Online Access: https://investigacionesgeograficas.uchile.cl/index.php/IG/article/view/36673

In the terrace Te, of Constitución, many fractures and associated deformations of its platform appeared in the street pavements after the earthquake of 02.27.2010. On this basis, this work deals with the co-seismic deformation in this terrace, observed by means of survey of fractures and associated superficial deformations. The principal undulated and irregular surface of the terrace shows no difference between the profiles surveyed before and after the 2010 seism, with exception of those that represent a minor part in the northward sector. In exchange, the flagstones or slabs of pavement show brittle micro-deformations or pop up like array structures associated to micro fractures produced during the seism. There is great dissimilarity of size order between principal irregularities of the terrace surface (undulations) and micro-deformations. The principal irregularities of the terrace Te indicate that its undulated form is inherited and older than the seism of 02.27.2010. Only a minor part represents a 2010 co-seismic deformation with gentle warping of the inherited undulation during the seism. In exchange, the flagstone dislocations or brittle deformations shown as pop ups like array are co-seismic microforms. They appear only as small tectonic deformations in the epidermis of the inherited undulated surface. Their apparent random distribution is possibly the result of a complex interaction between the seismic waves and the inherited topography, producing strain structures.