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A seismically constrained mass discharge rate for the initiation of the May 18, 1980 Mount St. Helens eruption

Brodsky, Emily E. and Kanamori, Hiroo and Sturtevant, Bradford (1999) A seismically constrained mass discharge rate for the initiation of the May 18, 1980 Mount St. Helens eruption. Journal of Geophysical Research B, 104 (B12). pp. 29387-29400. ISSN 2169-9313. doi:10.1029/1999JB900308. https://resolver.caltech.edu/CaltechAUTHORS:20141031-120101243

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Abstract

We calculate the vertical mass discharge rate from Mount St. Helens for the first few minutes of the May 18, 1980 cataclysmic eruption using a new method based on seismic constraints. The observed seismic waves indicate that the seismic source is a series of single forces. We model these forces as thrusts due to a combination of the momentum flux of the erupted products and the pressure of the eruptive jet. The momentum discharge rate is converted to a mass discharge rate based on estimates of the velocity and jet pressure as constrained by a simple fluid dynamical model. Only two parameters are necessary for the calculation: Mach number and sound velocity. The calculated mass ejected in the first 100 s is 1.6×10^(11) −4.6×10^(11) kg. Since the total blast deposit is ∼3.2×10(^11) − 4.1×10^(11) kg, one possible interpretation is that the directed blast had a significant (>30%) vertical component.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1029/1999JB900308DOIArticle
http://onlinelibrary.wiley.com/doi/10.1029/1999JB900308/abstractPublisherArticle
ORCID:
AuthorORCID
Brodsky, Emily E.0000-0002-6855-6860
Kanamori, Hiroo0000-0001-8219-9428
Additional Information:© 1999 The American Geophysical Union. Paper number 1999JB900308. Received January 5, 1999; Revised July 22, 1999; Accepted September 7, 1999. Correspondence and conversations with S. Kieffer, S. Malone, R. Waitt and R. Hoblitt have been valuable in understanding the geological and observational records. This paper is based on work supported under the National Science Foundation grant EAR-9903085 and is contribution 8678 of the Division of Geological and Planetary Sciences, California Institute of Technology.
Funders:
Funding AgencyGrant Number
NSFEAR-9903085
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Caltech Division of Geological and Planetary Sciences8678
Issue or Number:B12
DOI:10.1029/1999JB900308
Record Number:CaltechAUTHORS:20141031-120101243
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20141031-120101243
Official Citation:Brodsky, E. E., Kanamori, H., & Sturtevant, B. (1999). A seismically constrained mass discharge rate for the initiation of the May 18, 1980 Mount St. Helens eruption. Journal of Geophysical Research: Solid Earth, 104(B12), 29387-29400. doi: 10.1029/1999jb900308
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:51123
Collection:CaltechAUTHORS
Deposited By: Joanne McCole
Deposited On:31 Oct 2014 19:59
Last Modified:10 Nov 2021 19:06

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