2 Yellowstone and Hawaiian Hotspots Slides 3 and 4 show the path and approximate times of the Yellowstone and Hawaiian hotspot traces a Calculate approximately how fast each of the plates overlying these hotspots are moving in mm year b The Hawaiian hotspot has erupted continuously for hundreds of millions of years According to the map how many calderas have formed from the Yellowstone hotspot the last 17 million years this number is close to the number of eruptions Each yellow circle and age is a different caldera c The Hawaiian hotspot occurs on the Pacific Plate and produces mostly effusive mafic eruptions almost continuously The Yellowstone hotspot occurs on the North American Plate and produces very very very large explosive felsic to intermediate eruptions every few million years The source of the mantle plumes that feed each hotspot is similar both seem to originate at or near the core mantle boundary and will be compositionally the same as it reaches the bottom of the crust Most Hawaiian eruptions are VEI 0 1 Volcanic Explosivity Index the most recent Yellowstone eruptions was VEI 8 The volume of material produced by each hotspot is the same over time but obviously the timing and size of each is very different Talk to your group and come up with a few ideas of why these hotspots produce such different results Hint Think about how their locations are different but also about temperature of magma formation explosive large moderate small on ery large VEI 0 8 Erupted tephra volume 0 0001 km 0 001 km 0 01 km 0 1 km 1 km 10 km 100 km 1 000 km O O Examples Mount St Helens October 1 2004 Mount St Helens December 7 1989 Mount St Helens June 12 1980 Merapi Indonesia 2010 Mount Helens May 18 1980 Pinatubo 1991 Krakatau 1883 Tambora 1815 Mazama 7700 years ago Long Valley Caldera CA 760 000 years ago Yellowstone Caldera 600 000 years ag