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Correspondence: Response of a gravimeter to an instantaneous step in gravity

Heaton, Thomas H. (2017) Correspondence: Response of a gravimeter to an instantaneous step in gravity. Nature Communications, 8 . Art. No. 66. ISSN 2041-1723. PMCID PMC5645468. doi:10.1038/s41467-017-01348-z.

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Montagner et al. presented evidence that a signal observed prior to P-waves on gravimeters operating in Japan during the 2011 Tohoku-Oki earthquake was caused by gravitational field changes propagating at light speed. In this comment, I explore the expected response of gravimeters attached to the Earth’s surface and subjected to an instantaneous acceleration step, g(t)=g_0+ΔgH(t), where H(t) is a Heaviside step function. I argue that at the time of the step, inertial accelerations from the elastic response of the Earth exactly cancel the gravitational step; in order to observe the gravity step using a gravimeter, one must wait until the Earth deforms and begins to re-equilibrate. This conclusion is an application of the principle of equivalence between gravitational and inertial mass. In the case of the signal reported for Tohoku-Oki, I estimate that inclusion of the Earth’s elastic response should significantly decrease the expected acceleration at the time of the P-wave.

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Heaton, Thomas H.0000-0003-3363-2197
Additional Information:© 2017 The Author(s). This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit Received: 17 January 2017; Accepted: 12 September 2017; Published online: 17 October 2017. The authors declare no competing financial interests.
PubMed Central ID:PMC5645468
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ID Code:82457
Deposited By: Tony Diaz
Deposited On:18 Oct 2017 23:12
Last Modified:15 Nov 2021 19:50

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