Why do some volcanoes erupt in frequent small bursts instead of one huge blast?

Volcanoes with basaltic magma often erupt in smaller, more frequent bursts because the magma is relatively fluid and gas can escape through it more easily. When gas does not get trapped, the system is less likely to build the enormous pressure needed for a single catastrophic explosion. This is one reason volcanoes such as Kilauea in Hawaii often produce lava fountains and flows rather than giant ash plumes. In contrast, thicker, silica-rich magma traps gas more effectively and can erupt far more violently.