Mt. Vesuvius has experienced a period of semipersistent volcanic activity over the last three centuries, producing mainly lava effusions and some mixed effusive-explosive eruptions of higher magnitude. We present a systematic study on major and volatile elements of melt inclusions trapped in olivine crystals peculiar to lapilli fallout emplaced during the more intense episodes of explosive activity. Based on these data, we propose that the deep feeding system active during this period was formed by a vertically extended volume of crust containing interconnected cracks filled by magma, at pressures >200 MPa. The rise of deep CO2-H2O-rich magma blobs from this system triggered the high Volcanic Explosivity Index (VEI 2--3) eruptions, provoking the emission of intense lava effusions of degassed magmas and abrupt transition to intense lava fountains and sustained columns.