From many points of view, fiber optic sensors are the ideal transducers for civil structural monitoring. Being durable, stable and insensitive to external perturbations, they are particularly interesting for the long-term health assessment of civil structures. Long-gauge interferometric SOFO sensors have been in use for the last 10 yeas for the monitoring of civil, geotechnical, oil & gas and other structures. The sensors are based on an all-fiber Michelson interferometer with one arm mechanically coupled to the structure and
one used as reference. The original demodulation system is based on low-coherence interferometry and features excellent long-term stability and precision, but is not suitable for dynamic measurements. In order to allow the use of the same sensors for the measurement of dynamic events, a new demodulator was developed. It is based on the coherent demodulation of a coherence-collapsed laser source and is able to demodulate 8 SOFO sensors at frequencies of up to 1 kHz with resolutions of 0.01 microns. This system is particularly adapted for the analysis of dynamic structural deformations produced traffic, wind, seismic and impacts. The use of long-gauge sensors allows a direct measurement of the dynamic strains and the calculation of modal strains and curvatures. This contribution presents the main features of the SOFO static and dynamic system and selected applications examples.