Source, age, and eruptive mechanisms of Rotorua Ash

Rotorua Ash is a widespread (>10 000km 2 ) pyroclastic fall deposit erupted during extrusion of a rhyolite lava complex sited adjacent to the Lake Tikitapu basin, 10 km south‐east of Rotorua City, North Island, New Zealand. The eruption was plinian in character, with maximum rate of emission occurring early in the eruption sequence to produce a high ( c. 20 km) eruption column. Later explosions accompanied extrusion of lavas. Local, near‐vent, pyroclastic flow and surge deposits may have resulted from periods of column collapse. Extrusion of a lava flow from the main pyroclastic vent appears to have terminated the eruption. A 14 C age of 13 800 ± 250 years B.P. (new T 1/2) has been obtained for Rotorua Ash close to the source.