Volcanological study of the great Tambora eruption of 1815.

By a conservative estimate, 175km ³ of nepheline-normative trachyandesitic pyroclastic materal (equivalent to approx 50km ³ of dense rock) was erupted in 24h. A 6X7km caldera, approx 1km deep, formed at the end of the pyroclastic flow phase; caldera volume closely matches that of magma ejected. Plinian and co-ignimbrite ash fall > 1cm thick covered > 500 000km ² of the Java Sea and surrounding islands, accounting for >2/3 of the magma volume erupted. This distal tephra is known only from 1815 reports, indicating that some great eruptions, especially those from island volcanoes, may be virtually undetectable in the geologic record without supporting information, such as deep-sea core data. Land-based volume estimates may be insufficient to characterize eruption magnitude in many cases.-from Authors