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Gravity Anomalies in the Galapagos Islands Area

Watts, A. B. and Cochran, J. R. and Case, J. E. and Ryland, S. L. and Simkin, T. and Howard, K. A. (1974) Gravity Anomalies in the Galapagos Islands Area. Science, 184 (4138). pp. 808-809. ISSN 0036-8075. doi:10.1126/science.184.4138.808.

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In a recent report Case et al. (1) presented a free-air gravity anomaly map of the Galapagos Islands based on 32 gravity stations on the islands. On the basis of their data they stated that the Galapagos Islands are associated with an east-west trending "residual negative anomaly" which is superimposed on a "broader positive anomaly of unknown amplitude and extent." They concluded that "the gravity data can be most readily interpreted in terms of a low-density region related to a hot spot or plume" beneath the islands. We believe, however, that the data of Case et al. in no way support this interpretation. Their observations can, in fact, be explained simply if the Galapagos Islands are in some form of isostatic equilibrium. Any form of isostatic compensation will result in an "edge effect" in the free-air anomaly at the location of a large change in relief. For a relatively narrow feature, the edge effect anomalies over the two "edges" merge, resulting in a large positive anomaly. For a wider feature, the two edge effects become separated, resulting in an area of less positive anomalies over the center of the feature.

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Additional Information:© 1973 American Association for the Advancement of Science. Received 21 December 1973. Lamont-Doherty Geological Observatory Contribution No. 2045. Supported by NSF grant GA-27281 and ONR contract N00014-67-A-0108-004. The manuscript was critically reviewed by M. Talwani and E. Herron.
Funding AgencyGrant Number
Office of Naval Research (ONR)N00014-67-A-0108-004
Issue or Number:4138
Record Number:CaltechAUTHORS:20150729-090310857
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Official Citation:Gravity Anomalies in the Galapagos Islands Area A. B. Watts, J. R. Cochran, J. E. Case, S. L. Ryland, Tom Simkin, and K. A. Howard Science 17 May 1974: 184 (4138), 808-809. [DOI:10.1126/science.184.4138.808]
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:59050
Deposited By: Tony Diaz
Deposited On:29 Jul 2015 16:28
Last Modified:10 Nov 2021 22:14

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