1808/1809 mystery eruption

A colossal volcanic eruption in the VEI6 range is believed to have taken place in late 1808 and is suspected of contributing to a period of global cooling that lasted for years.^[1]

Background

Before the 1990s, the deterioration of the weather in the early 1810s was unremarked by climatologists as normal for the Little Ice Age. A study of Greenland and Antarctic ice cores in the 1990s found markers that implied that a massive volcanic eruption had occurred in early 1809. The problem facing climotologists and volcanologists was that there were no recorded eruptions of the order of significance needed in this period.^[2] Further research and Bristlecone pine tree ring data pointed to the eruption being in 1808.^[3]

Location and date

Adding to the mystery was the expectation that any eruptions of that magnitude should have been noticed at the time. Checks of records from the time throughout the world were checked but nothing appeared viable until the summer of 2014, when PhD student Alvaro Guevara-Murua and Dr Caroline Williams of the University of Bristol discovered a description of atmospheric events consistent with such an event by Colombian scientist Francisco José de Caldas. De Caldas served as Director of the Astronomical Observatory of Bogotá between 1805 and 1810 and in 1809 reported a transparent cloud that obstructs the sun's brilliance at Bogotá. The cloud had first been observed by him on 11 December 1808 and visible across Colombia. He also reported that the weather had been unusually cold with frosts. To the south, in Peru similar observations were made by physician José Hipólito Unanue of Lima.^[4] These reports led those involved to suggest the window for date of the eruption was within 14 days of 4 December 1808.^[4]

The area on or near the equator to the west of Colombia and Peru with potential volcano's and the least reporting at that time was the South Western Pacific Ocean between Indonesia and Tonga. This area had no European settlements except for a few missionaries in Tahiti in 1808. Reporting on volcanic activity, such as those in the Rabaul area, which had had VEI6 eruptions, only went back to the mid 1800's.^[5]

Known significant eruptions in 1808

In the year 1808, there were also major eruptions in Urzelina eruption, Azores - May and Taal Volcano, Philippines - March.^[6] Neither of these occurred within the correct time period.

References