Reconstructing eruptions from historical accounts: Makaturing c. 1765, Philippines

Jenkins, S.F., Phua, M., Warren, J.F.ORCID: 0000-0003-0055-6730, Biass, S. and de Maisonneuve, C.B. (2020) Reconstructing eruptions from historical accounts: Makaturing c. 1765, Philippines. Journal of Volcanology and Geothermal Research, 404 . Article 107022.

Abstract

For some volcanoes, the only evidence for past eruption is provided by historical accounts. When interpreted carefully, these have the potential to be a rich source of information, and yet they have so far been under-utilised in reconstructing eruption histories. The navigator Thomas Forrest describes a large eruption at Makaturing volcano, southern Philippines, in approximately 1765 that he attributes as the catalyst for the local Iranun population transitioning from an agrarian society to long-distance piracy and slave raiding. The rise of Iranun maritime activities disrupted traditional trade routes as far afield as China and ultimately changed the course of southeast Asia's history. However, there is no record of a c.1765 eruption of Makaturing in the scientific literature or in eruption databases. Here, we reinterpret the account of Forrest from a multi-disciplinary perspective, with a historian and physical volcanologists working together to incorporate the greatly needed local context into identifying credible volcanic processes and impacts associated with the reported activity. A deliberately broad suite of potential eruption scenarios was developed, and their spatial extent simulated using Tephra2 and local wind conditions, to identify those simulated eruptions that could have produced the deposits and impacts reported by Forrest. We find that the most likely eruption was ~VEI 4 occurring sometime between May and October, with plume heights in the range 12 to 16 km, although plume heights as low as 10 km could also recreate the reported impacts. While at least one eruption of this size was required to reproduce the impacts reported in the historical record, it may have formed part of a longer sequence of multiple, repeated eruptions. Such an eruption could have acted as a ‘tipping point’ for a local population already on the verge of socio-political and economic collapse, disproportionately affecting regions on a much larger scale than the physical deposits suggest. There remains a disconnect between the eruption recorded in historical accounts and that reproduced by numerical modelling, for which we propose alternative interpretations of the historical record. Unfortunately, given the minimal details available about the eruption, this disconnect is unlikely to be resolved, even when geological studies are possible. However, a valuable benefit of the probabilistic modelling approach presented here is that it highlights the likely direction of tephra dispersal and deposition during a future eruption of Makaturing, supporting rapid tephra hazard assessment in the event of future unrest.

Item Type:	Journal Article
Murdoch Affiliation(s):	Asia Research Centre
Publisher:	Elsevier
Copyright:	© 2020 The Authors
URI:	http://researchrepository.murdoch.edu.au/id/eprint/57344

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