The phenomena of ground vibrations may be originated either by natural causes (earthquakes, volcanic eruptions, landslides and meteorite impacts) or by man-made activities (industry, traffic, construction, demolition and rock blasting) and their consequences sometimes represent the most relevant factor for ground and structural damage, as well as for people nuisance.

It is obvious that greater vibration intensities are associated with both the magnitude of released energies and to shorter distances from their sources, thus involving the role of ground attenuation on the propagation of stress waves from their origin to the monitoring points.

Determination of relevant safety criteria for structures affected by ground vibrations has been achieved by many institutions under different approaches, according to the specific events that are occurring. However, an overall analysis of those criteria indicates that it is possible to encompass all such events under an unifying approach based on the energy transmitted to the ground, which may lead to reliable solutions for safety control and protection purposes. Examples of this criterion are provided.

1 Introduction

Ground vibrations are dynamic phenomena that must be adequately understood and quantified by means of appropriate scientific concepts, followed by specialized engineering applications. This knowledge should be dominated by operators and local authorities in order to specify the acceptability of plant or equipment, the permissible working hours (not including emergency operations) and the maximum allowable levels of vibration and noise at the boundaries of the site (Sarsby, 2000). Those problems should be solved before work starts, providing an assessment to the feasibility of most engineering projects,whatever its stage is (initial conception, design, tender, construction, regular activity, etc.).

Besides empirical approaches for such a control, there are means of predicting those effects if quantification of the main influencing variables is performed, in order to establish their specific involvement in the resulting magnitudes of vibration at any site that is to be protected.

An important factor of dealing with vibrations and their effects is the definition of three categories, which are (according to Sarsby, 2000):

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