Chronology and eruption dynamics of the historic ~ 1700 CE eruption of Tseax Volcano, British Columbia, Canada.
Back to previous page
| Authors: | Le Moigne, Y; Williams-Jones, G; Vigouroux, N; Russell, JK |
| Year: | 2022 |
| Journal: | Frontiers in Earth Science 10: 910451 PDF Article Link (DOI) |
| Title: | Chronology and eruption dynamics of the historic ~ 1700 CE eruption of Tseax Volcano, British Columbia, Canada. |
| Abstract: | The eruption of Tseax volcano in ~1700 CE, in north-western British Columbia, is the second youngest volcanic event in Canada. It is also one of Canada’s worst natural disasters as it killed up to 2,000 people of the Nisga’a First Nation living there at the time. The eruption also significantly impacted the local environment by diverting the Nass River (the 3rd largest river in British Columbia). Within the Nisga’a culture, Adaawak stories preserve an observational account of the Tseax eruption. In this study, we establish the chronology of the eruption by integrating field observations, petrophysical data and Nisga’a oral and written histories. The Nisga’a stories corroborate the short duration and exceptional intensity of the eruption as recorded in the volcanic products. The eruption was divided in two main periods: (1) Period A and (2) Period B. (1) The eruption started in a typical Hawaiian style with low levels of lava fountaining that built up a spatter rampart. This pyroclastic edifice was breached by voluminous pāhoehoe lava flows erupted at high discharge rates. We estimate that almost half of the erupted flow volume (0.20 km3) erupted in Period A was emplaced at 800-1000 m3/s. The lava reached the Nass Valley, 20 km downstream of the volcano, in “swift currents”, diverted the Nass River and engulfed the former Nisga’a villages in only 1 to 3 days, thus likely being responsible for the reported fatalities. The discharge rates progressively diminished to 10-200 m3/s until the end of this first eruptive period, which lasted a few weeks to a few hundred days. (2) During Period B, two ‘a‘ā flows were erupted with discharge rates < 50 m3/s. This period was also characterised by a more explosive eruption style that built a 70 m high tephra cone overlapping with spatter rampart. In total, Period B lasted approximately 20 days. In total, the eruption produced 0.5 km3 of volcanic materials (mostly in the form of lava flows) on the order of weeks to a few months. The short duration of the eruption was probably inherent to the limited amount of melt produced in the mantle. However, the eruption of Tseax was similar in magnitude to the flank eruption on larger shield volcanoes such as Kīlauea’s Fissure 8 in 2018 or Mauna Loa in 1984. |
Departmental members may update their publication list.