Mantle-Crust Volcanics and Geodynamics of the Yellowstone Hotspot from Seismic and GPS Imaging and Earthquake Swarm Magmatic Interaction

Abstract:

The Yellowstone hotspot is the product of plume-plate interaction that has produced a large and active silicic volcanic field within the N. American Plate. Our newest research on Yellowstone includes: 1) A recent discovery by seismic imaging that the Yellowstone volcanic system extends as a connected magmatic system from at least 1000 km deep in the mantle with melt ascending upward in a WNW tilted plume to a newly discovered lower-crustal magma body at 20-45 km depth and 4x larger than the shallow crustal reservoir 5-15 km deep. Moreover the shallow 70 km NE-SW crustal magma body unexpectedly extends 15 km NE well beyond Yellowstone’s volcanic field a distance that N. American Plate would advance in 640,000 years, i.e., the time of the last Yellowstone super eruption and hence reflecting plate motion over the Yellowstone mantle plume; 2) Yellowstone’s giant mantle-crust connected magma system represents ~48,000 km³ with ~1800 km³ of melt that fuels Yellowstone’s extraordinarily high heat flux of up to ~ 3 Watts/meter² that in turn drives Yellowstone’s world renown hydrothermal system; and 3) How migration of magma vertically into and laterally out of the crustal magma reservoir, measured by GPS and earthquake correlation, reveals the mechanics of Yellowstone’s “natural volcano pressure relief valve” that retards volcanic eruptions for thousands of years, but that occasionally breach the brittle-ductile transition in volcanic eruptions. We will also discuss the most recent and largest earthquake in Yellowstone in over 30 years, a magnitude 4.8 event, on March 30, 2014 near Norris Geyser Basin. This earthquake was part of a larger sequence of swarm activity in the Norris area that began in September 2013 and continued into June 2014. GPS derived deformation at Norris revealed unusually high uplift rates at ~15 cm/yr. attaining 60 mm of uplift at the time of the M_W4.8 event and that dramatically reversed to subsidence at rates of ~17 cm/yr. Notably, however the much larger Yellowstone volcanic caldera began a new episode of pronounced uplift in late 2013 a few months prior to the Norris event suggesting caldera-wide magmatic migration at the NE caldera area that drove the Norris event. These data indeed confirm that the Yellowstone hotspot is a “living, breathing, shaking, baking” feature of global significance.