COMMENT: Marty, Right here in Alaska, we now have been placed on alert that Mt Spurr might erupt quickly. Your laptop has been exceptional projecting these pattern of rising volcanic exercise right here in 2025 and we’re nonetheless within the first quarter. Do you might have any historic evaluation of Mt. Spurr?
Rob
REPLY: Mount Spurr, a stratovolcano in Alaska’s Aleutian Arc, had no confirmed historic eruptions which were documented in human data previous to its vital 1953 eruption. Nonetheless, geological research reveal prehistoric exercise:
- Holocene Eruptions:
- The newest main eruptive interval occurred roughly 8,000–9,000 years in the past, involving pyroclastic flows and lava dome formation that formed the present construction of the volcano. These eruptions have been recognized by way of tephrochronology and radiocarbon relationship of volcanic deposits.
- Late Pleistocene Exercise:
- Proof suggests earlier eruptions through the late Pleistocene, although exact dates are much less well-constrained. These occasions contributed to the volcano’s formation and progress.
It’s beneath watch proper now for a attainable eruption. Earlier than 1953, Mount Spurr’s eruptions have been prehistoric, with no written data or observations. Mount Spurr’s prehistoric eruptions are primarily studied by way of geology, however their ash layers present invaluable instruments for archaeologists.
The 1953 eruption of Mount Spurr in Alaska was categorized as a VEI 3 (Volcanic Explosivity Index 3) occasion. This eruption on July 9, 1953, produced a major Plinian ash column reaching roughly 21 km (70,000 ft) in peak. Nonetheless, the quantity of erupted materials (tephra) was estimated at round 0.021 km³, putting it throughout the VEI 3 vary (0.01–0.1 km³).
There have been earthquakes in 2004 and particles flows by 2005. That was 51 years from 1953. Since this ought to be fractal, I might suspect there was in all probability a giant one round 5200 years prior. This could possibly be constructing to a giant one above VEI 5 by 2031/2032. It ought to be coming alive right here of the 72-year cycle from 1953 which brings us to 2025. We should still be taking a look at a VEI3 or VEI4 for that would go away the door open for an even bigger one by 2031/2032.
For comparability, Mount Spurr’s 1992 eruption was rated VEI3/VEI 4, with a barely greater tephra quantity (-0.055 km³) and a plume peak of 14 km. The excellence underscores that VEI considers each eruptive quantity and secondary components like plume peak and eruption length. The 1953 occasion, whereas explosive and impactful, didn’t meet the quantity threshold for VEI 4.
Understanding the VEI
Every VEI degree represents a tenfold improve in erupted materials (e.g., VEI 4 is 10x bigger than VEI 3). Larger VEI eruptions produce taller plumes, injecting ash and gases into the stratosphere (VEI 5+ can have an effect on international local weather). Extra vital eruptions (VEI 5+) are much less frequent however extra harmful.
VEI 7: Tambora (1815) ejected 160 km³ of fabric into the environment, thereby lowering international temperatures by -3°C, often called the 12 months and not using a Summer season in 1816.
VEI 6: Pinatubo (1991) launched 10 km³, inflicting international cooling by -0.5°C.
VEI 5: Mount St. Helens (1980) erupted 1 km³, however didn’t alter the local weather but it was devastating 600 km²