The c. AD 1305 Kaharoa eruptive episode consisted of a complex sequence of basalt-triggered highsilica rhyolite eruptions from at least seven vents along an 8 km linear zone across Tarawera Volcano. Initial plinian eruptions from a summit vent spread Kaharoa Tephra southeast across the North Island, accompanied by phreatomagmatic explosions and pyroclastic density currents from vents opened on the northern flanks of the volcano. The early plinian phase was ended by extrusion of Crater Dome in the summit vent, with explosive activity migrating to two adjacent vents (Tarawera and Ruawahia) to the southwest and northeast. Renewed plinian eruptions, apparently from the northern vents, produced tephra falls dispersed northeast-northwest from the volcano. Extrusion of the three summit lava domes was accompanied by voluminous block-and-ash flows generated by collapse of the growing Ruawahia and Wahanga Domes, forming large fans to north, southeast, and northwest of the volcano.Calculation of Kaharoa lava volumes and comparisons with the extrusion rates of observed dome-building eruptions suggest a duration of c. 4 yr for the c. 4 km 3 Kaharoa eruptive episode. This estimate, of years rather than days or weeks, is significant for planning an effective response to a future similar rhyolite episode in New Zealand.

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The Islands of Ponza and Gavi (western Pontine Archipelago, Italy) preserve parts of a subaqueously emplaced, high‐silica (75–77% SiO2) rhyolitic lava flow that overlies the margins of three older domes. Exposures of the lava alone cover 24 km2, and with a thickness of 150 m exposed in the cliffs, the preserved volume of the lava flow is 3.6 km3, and the original volume is likely to have exceeded 7 km3. The lava flow consists of coherent obsidian and several hyaloclastite facies, including in situ and clast‐rotated breccias and sandstones, which all exhibit gradational relationships. The coherent obsidian occurs as separate domains and is often flow banded. Although flow folds occur, the banding is generally subhorizontal, dipping gently to the NNE. The hyaloclastite, representing 90% of the lava by volume, has a diffuse layering varying from 0.5 to 2 m in thickness. This layering also dips gently to the NNE and is marked in places by alternation of some coherent horizons, coarse and finely fragmented in situ hyaloclastite, pumiceous hyaloclastite, and clast‐rotated hyaloclastite. The layering is laterally continuous and consistent in orientation over most of the 13 km length of Ponza: the subhorizontal orientation of the flow banding and presence of resedimented deposits in the upper parts of the sequence indicate that the unit is a lava flow. The resedimented deposits comprise both proximal and distal deposits of debris flows and turbidity currents initiated by gravitational instability of the upper and marginal parts of the lava flow and include stratified monomictic obsidian breccias and bedded vitric siltstones and sandstones. The lava flow has been intruded and crosscut by rhyolitic bodies of various ages, including discordant, coherent to internally fractured contemporaneous rhyolite bodies, and late, penecontemporaneous dikes with glassy margins and alteration haloes.

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