If the Yellowstone Hot Spot is now so far away, why have the eruptions continued?


Recent seismic data suggests that in the wake of the Yellowstone Hot Spot a 10-mile thick slab of basalt has been left behind in a mid-crustal position and some of it may contain partial melt. This region is experiencing basin and range type faulting, which is stretching or pulling apart the crust. The Lost River Range above Arco, Idaho, is a good example that these forces (tension) are still acting. In 1983 these forces caused a magnitude 7.3 earthquake, during which Mount Borah went up about 1-ft. and the Lost River Valley in that area dropped about 13-ft. On the Eastern Snake River Plain instead of producing mountain ranges, the tensional forces have allowed decompression melting resulting in dike emplacement and periodic eruption of molten rock onto the surface. As long as these forces continue to act, more eruptions will eventually occur.