What volcanic belt is Mt. Meager part of?
The Garibaldi Volcanic Belt (GVB), the Canadian segment of the Cascadia Subduction Zone.
Where is Mt. Meager located?
Approximately 60 km northwest of Pemberton, British Columbia.
What are the two main magmatic groups identified in the Garibaldi Volcanic Belt?
Northern Group and Southern Group.
What distinguishes the Northern Group magmas?
They show slab window influence, small melt fractions of enriched mantle, high temperature (>1200°C), and are less oxidized.
What characterizes the Southern Group magmas?
5–12% partial melting of DMM mixed with ~5 wt% subduction fluids, lower temperature (~1100°C), and more oxidized magmas.
What is the age range of Mt. Meager’s volcanic activity?
From about 2.2–1.9 million years ago to present.
What kind of volcanic features make up Mt. Meager?
Multiple eroded summit lava domes and volcanic necks.
What is the general composition of Mt. Meager lavas?
Basaltic to rhyodacitic compositions.
What is significant about the hydrothermal system at Mt. Meager?
It is a long-lived high-temperature system with geothermal exploration temperatures exceeding 220°C.
When did the most recent large eruption at Mt. Meager occur?
Around 2360 years before present (BP).
What major products were generated by the 2360 BP eruption?
Pyroclastic density currents, widespread pumice fall, and rhyodacitic lava flows.
What geological evidence exists of the 2360 BP eruption?
Thick tephra deposits over 60 m on Mt. Meager and fine ash deposits found up to 530 km east in Alberta.
What natural dam formed during the 2360 BP eruption?
A ~110 m high dam composed of welded block and ash flows, later overtopped and failed.
What was the result of the dam failure following the 2360 BP eruption?
A catastrophic outburst flood and lahar that carved a 2.5 km canyon and flowed >35 km downstream.
What was the volume of the 2010 Mt. Meager landslide?
Approximately 53 million m³ (comparable to Hope Slide at 47 million m³).
What was the estimated velocity of the 2010 landslide?
Between 55–60 m/s (about 216 km/h).
What were the human impacts of the 2010 landslide?
Over 1,500 people were evacuated in Pemberton due to damming of the Lillooet River.
What geomorphic effect did the landslide have?
It dammed the Lillooet River and Meager Creek, forming a temporary lake with significant run-up on opposite valley walls.
How many actively deforming slopes were identified at Mt. Meager?
27 slopes with volumes >0.5 × 10⁶ m³.
What was the measured deformation rate of some slopes?
Up to 36 ±10 mm/month during summer seasons.
What technology was used to detect slope movement?
InSAR (Interferometric Synthetic Aperture Radar) and low-cost time-lapse cameras.
When was the main degassing period observed?
Between 2011 and 2016, with increased activity from 2014–2015.
How many fumaroles are visible at the surface?
2–3 fumaroles.
What gases were detected during 2016–2021 gas surveys?
H₂O, CO₂, SO₂, CO, and H₂S, with max readings of 280 ppm H₂S and 2700 ppm CO₂.
