Long-runout pyroclastic density currents: Analysis and implications
چکیده
Abstract Pyroclastic density currents are hazardous, ground-hugging, hot mixtures of gas and solid particles produced by volcanoes. Currents generated the largest explosive eruptions have traveled distances on order 100 km, their devastating impact has repeatedly marked Earth's geologic history. We show that pyroclastic from super-eruptions during Oligocene in Great Basin United States had exceptional runout may exceeded 300 km. present a quantitative analysis data these consider, particular, areal extent deposits (ignimbrites) as well relationship between eruption mass discharge rate. The ignimbrites elliptical distributions characterized axis length ratios ~2–6, contrast to common subcircular ignimbrites, while maximum runouts versus rates clearly outside prediction intervals defined other data. argue long resulted channeling concentrated regional paleovalleys whose gentle slope worked lengthen travel distance. Our study demonstrates additional factors should be considered assessing hazards posed future super-eruptions.