We present a series of physical experiments that examine with detail the evolution of subsidence in a volcanic maar crater, located in central Mexico. The crater is thought to be connected to the adjacent aquifer, which has been extensively exploited during the last 35 years. Subsidence in the sediments filling the crater show deformation manifested as ring faults and fractures. The results may be relevant to understand the evolution of subsidence in similar volcanic settings elsewhere.

An analysis of the deformation conditions of lacustrine materials deposited in the volcanic valley of the Mexico City is presented. Currently geotechnical studies assume that compressibility of granular materials decreases in depth due to the lithostatic load. Our results show that Cc for fine grain materials (lacustrine) can be vertically variable, particularly when soils and sediments are the product of different volcanic materials. These variations need to be considered when modelling LS.

In the eastern sector of Mexico City the sub soil consists of high contrasting sequences (lacustrine and volcanic inter bedded deposits) that favor the development of erratic fracturing in the surface. The results of applying the GPR, MASW and SR methods simultaneously show the persistence of the clayey lacustrine material with variable thickness encased by volcanic materials. The contrasting mechanical properties between the two types of material may cause slippage over lithological contacts.

Sinkholes in any areas may result deadly or costly. A sinkhole happen to be in a highly trafficked area in Quito, Ecuador. Besides the problems and additional costs of repair, we have found out during our study, that the costs of the people who had to pass this area had to pay much more than the "simple" reconstruction costs. A critical look on historic sinkholes in the central part of the city of Quito, allowed us to identify even huger problems to come in important areas of Quito.