The spatial extent of tephra deposition and environmental impacts from the 1912 Novarupta

6 The eruption of Novarupta within the Katmai Volcanic Cluster, south-west Alaska, in June 1912 was the 7 most voluminous eruption of the 20 Century but the distal distribution of tephra deposition is 8 inadequately quantified. We present new syntheses of published tephrostratigraphic studies and a large 9 quantity of previously un-investigated historical records. For the first time we apply a geostatistical 10 technique, indicator kriging, to interpolate and integrate such data. Our results show evidence for 11 tephra deposition across much of Alaska, Yukon, the northern Pacific, western British Columbia and 12 northwestern Washington. The most distal tephra deposition was observed around 2500 km downwind 13 from the volcano. Associated with tephra deposition are many accounts of acid deposition and 14 consequent impacts on vegetation and human health. Kriging offers several advantages as a means to 15 integrate and present such data. Future eruptions of a scale similar to the 1912 event have the potential 16 to cause widespread disruption. Historical records of tephra deposition extend far beyond the limit of 17 deposition constrained by tephrostratigraphic records. The distal portion of tephra fallout deposits is 18 rarely adequately mapped by tephrostratigraphy alone; contemporaneous reports of fallout can 19 provide important constraints on the extent of impacts following large explosive eruptions. 20