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Abstract

The January 15 eruption of Hunga volcano in Tonga has provided an unprecedented volume of data on global air-pressure waves and volcanic tsunami. In order to apply the knowledge from these data to the only other example, the eruption of Krakatau (Indonesia) on August 27, 1883, I am assembling an openly accessible digital dataset of both the the air waves and the tsunami from this nineteenth-century example, the first for which any instrumental records (barograms and marigrams) were produced. Its narrow focus and range of sources makes this an unusual data rescue project. The 1888 report produced by the Royal Society of London does not show the air waves in a useful way; the report does contain reproductions of marigrams, though without describing their sources. In a few cases original records survive, but usually what is available is a journal article about some observations, with a foldout plate showing a photolithograph of the original or of a drawing of it. About half of the barograms listed in the 1888 report can be found in some form, and I have found a few new records both of air pressure and sea level; most pressure records come from a wide range of mercury barographs. Images of all records will be used to produce digital time series, relying on custom software. Two results already evident are that many barograms show similar waveforms, which differ from those of the 2022 eruption; and that tsunami were observed across the entire North Pacific ocean.