Volume 17, Number 3 (1990)

Patterns of Volcanism in the Cascade Arc During the Past 15,000 Years

William E. Scott
David A Johnston Cascades Volcano, Observatory, United States Geological Survey, Vancouver, Washington.
Published September 9, 1990
How to Cite
Scott, W. E. (1990). Patterns of Volcanism in the Cascade Arc During the Past 15,000 Years. Geoscience Canada, 17(3). Retrieved from https://journals.lib.unb.ca/index.php/GC/article/view/3675


About 110 well-dated and 70 poorly dated eruptive periods less than 15,000 years old at individual volcanoes in the Cascade arc constitute a data set for identifying spatial and temporal patterns of eruptive activity. Key features of the record include: (1) the mean frequency of eruptive periods during the past 4,000 years is approximately two per century, however, the variance about the mean may be large; (2) at most major centres, episodes of activity lasting several thousand years are defined by groups of eruptive periods separated by apparent dormant intervals of roughly similar duration, (3) arc-wide clustering of eruptive activity may exist at 0-4 ka, 6-8 ka, and 10-14 ka. Such clustering would be remarkable in light of significant along-arc changes in crustal structure, stress field, and subduction-zone geometry.