In order to identify the generation mechanisms of low-latitude Pc3--4 geomagnetic pulsations, data were obtained from a meridional chain of induction magnetometers spanning L values from 1.4 to 2.7 (-30¿ to -52¿ geomagnetic latitude). The spatial structure of Pc3--4 signal parameters was examined by means of spectral, polarization and interstation phase analysis. This paper describes three typical individual events whose spectral, polarization and phase characteristics indicate the existence of field line resonances at low latitudes within the plasmasphere. The spatial phase structure shows a local minimum and indicates phase motion toward the resonance region. Resonance region widhts of ΔL=0.2 to ΔL=0.8, corresponding to north-south ionospheric scale lengths of 250 and 1500 km or more, respectively, are seen. The coupling of field line resonances to global compressional modes is considered to be a likely generation mechanism of these pulsations. ¿ American Geophysical Union 1993