The article presents the study of modal parameter variations of a 9 story, shear wall building during several seismic events, including the Mw=8.8 2010 Chile Earthquake. The building, constructed in 1962, has been instrumented with a continuous monitoring network since March 2009. The network includes 8 accelerometers and 3 soil humidity sensors beneath the foundation. The main purpose of the system is to monitor and correlate the dynamic behavior of the building for different ambient conditions and shaking levels. This study is based on the seismic records obtained during the Mw=8.8 earthquake and 30 of its aftershocks, in addition to the events recorded before the main-shock. A study of the variation in the modal parameters of the building during each seismic event is performed, using a parametric Multiple Input Multiple Output (MIMO) Identification technique. Medium and low level earthquakes caused only transient variations in the modal parameters of the building, which disappear after the strong shaking has ended. Despite the low structural damage detected after the event, the large 2010 Earthquake caused significant and permanent changes in the modal parameters, with modal periods increasing up to 41% during the main-shock. Finally, the correlation between the identified modal periods and the severity of shaking is also determined.