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Multiple Dendrochronological Signals Indicate The Eruption Of Parícutin Volcano, Michoacán, MexicoSheppard, Paul R.; Ort, Michael H.; Anderson, Kirk C.; Elson, Mark D.; Vázquez-Selem, Lorenzo; Clemens, Angelika W.; Little, Nicole C.; Speakman, Robert J.; Laboratory of Tree-Ring Research, University of Arizona; Departments of Environmental Sciences and Geology, Northern Arizona University; et al. (Tree-Ring Society, 2008-12)The eruption of Parícutin (1943–1952), a cinder cone volcano in Michoacán, Mexico, caused dendrochronological and dendrochemical responses that might be useful as general dating tools for eruptions. For the eruption period, pines near Parícutin have slightly suppressed ring widths plus high inter-annual variability of width. Wood anatomy changes include traumatic resin ducts and thin bands of false latewood. Dendrochemistry of tree rings shows little temporal variation in most elements, but beginning in 1943 sulfur content increased in rings of four trees and phosphorus content increased in rings of two trees. Hypotheses for increased S and P include new availability of pre-existing soil S and P and/or new input of S and P from the tephra itself. Pines at Parícutin also show suppressed ring widths for five years beginning in 1970, and had the eruption date not been known, the most likely conclusion from ring-width data alone would have been an eruption from 1970 to 1974. However, the 1970s suppression was in response to defoliation by a pine sawfly outbreak, not an eruption. For dendrochronological dating of cinder-cone eruptions, a combination of multiple characteristics (width, chemistry, and anatomy) would be more reliable than depending on any one characteristic alone.