Processing of ambient vibration records for the estimation of the fundamental vibration period of soil deposits

It is presented the processing of ambient vibration records, using a technique proposed by Nakamura in 1989, for the estimation of the fundamental horizontal vibration period of soil deposits. This technique of noninvasive nature allows us, by recording a few minutes of ambient noise, to characterize the dynamic behavior of the soil. A module for the elimination of transients recorded during the measurement was added to the program written to perform the processing of the data in order to preserve the stationary parts of the records. The aim of the fundamental horizontal vibration period estimation is to evaluate local site effects and thus anticipate the damage caused by earthquakes. As a case of study it is presented a seismic micro-zonation work for the city of Mayaguez in Puerto Rico, whose result is an isoperiod soil map for that city.