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Comment on “Earthquake-induced prompt gravity signals identified in dense array data in Japan” by Kimura et al.

Vallée, Martin and Ampuero, Jean Paul and Juhel, Kévin and Bernard, Pascal and Montagner, Jean-Paul and Barsuglia, Matteo (2019) Comment on “Earthquake-induced prompt gravity signals identified in dense array data in Japan” by Kimura et al. Earth, Planets and Space, 71 (1). Art. No. 51. ISSN 1880-5981. https://resolver.caltech.edu/CaltechAUTHORS:20191218-132846311

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Abstract

A recent work by Kimura et al. (Earth Planets Space 71:27, 2019. https://doi.org/10.1186/s40623-019-1006-x) (hereafter referred to as K19) claims to provide the first observational constraints on the prompt elastogravity signals (PEGS) induced by an earthquake. To make their claim, the authors argue that the observations shown in Vallée et al. (Science 358:1164–1168, 2017. https://doi.org/10.1126/science.aao0746) (hereafter referred to as V17) are spurious and their modeling inaccurate. Here we show that K19’s claim is invalid because it is based on flawed data processing. In fact, K19’s analysis involves an incomplete correction of the instrument response of broadband seismic sensors, which essentially dismisses low-frequency components of the data that are critical for the detection of intrinsically low-frequency signals such as PEGS. As a direct consequence, signals are much more difficult to observe than in V17, where the low part of the signal spectrum is carefully taken into account. This deficient data processing also explains why the signal amplitude reported by K19 after stacking data from multiple stations is lower than the individual signals reported by V17. Moreover, failing to take appropriate measures of data quality control, K19 used signals from low-quality sensors to call into question the signals detected by high-quality sensors. Finally, K19 use an inadequate simulation approach to model PEGS, in which the important effect of the ground acceleration induced by gravity changes is ignored. In summary, K19 do not show any viable arguments to question the observations and modeling of PEGS presented in V17.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1186/s40623-019-1030-xDOIArticle
https://doi.org/10.31223/osf.io/zn3ymOrganizationDiscussion Paper
https://doi.org/10.1186/s40623-019-1006-xRelated ItemEarth Planets Space 71:27, 2019
https://doi.org/10.1126/science.aao0746Related ItemScience 358:1164–1168, 2017
ORCID:
AuthorORCID
Vallée, Martin0000-0001-8049-4634
Ampuero, Jean Paul0000-0002-4827-7987
Juhel, Kévin0000-0003-0881-6904
Bernard, Pascal0000-0002-9577-9218
Montagner, Jean-Paul0000-0001-9958-3012
Additional Information:© 2019 The Author(s). This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided 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 SAC (http://ds.iris.edu/ds/nodes/dmc/software/downloads/sac/) free software was used for data processing. Most numerical computations were performed on the S-CAPAD platform, Paris, France. Authors’ contributions: MV designed this comment, with inputs from KJ and JPA. MV performed the data analysis, produced the associated figures and wrote the text with JPA. KJ, JPM, MB, and PB commented the initial versions of the manuscript. All authors read and approved the final manuscript. The authors declare no competing interests. Availability of data and materials: Data from the F-net network are publicly available at the NIED F-net server: http://www.fnet.bosai.go.jp. MAJO station belongs to the GSN network (https://doi.org/10.7914/SN/IU), MDJ station to the NCDSN network (https://doi.org/10.7914/SN/IC), and NE93 to the NECESS/UT network (https://doi.org/10.7914/SN/YP_2009). Data from the GSN, NCDSN and NECESS/UT networks are publicly available at the IRIS data management center (http://ds.iris.edu/ds/nodes/dmc/). Consent for publication: Not applicable. Ethics approval and consent to participate: Not applicable. We acknowledge the financial support from the UnivEarthS Labex program at Sorbonne Paris Cité (ANR-10-LABX-0023 and ANR-11-IDEX-0005-02) and from the Agence Nationale de la Recherche (Grant ANR-14-CE03-0014-01).
Group:Seismological Laboratory
Funders:
Funding AgencyGrant Number
Agence Nationale pour la Recherche (ANR)ANR-10-LABX-0023
Agence Nationale pour la Recherche (ANR)ANR-11-IDEX-0005-02
Agence Nationale pour la Recherche (ANR)ANR-14-CE03-0014-01
Subject Keywords:Prompt elastogravity signals; Tohoku earthquake; Instrument response; Noise levels
Issue or Number:1
Record Number:CaltechAUTHORS:20191218-132846311
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20191218-132846311
Official Citation:Vallée, M., Ampuero, J.P., Juhel, K. et al. Comment on “Earthquake-induced prompt gravity signals identified in dense array data in Japan” by Kimura et al.. Earth Planets Space 71, 51 (2019) doi:10.1186/s40623-019-1030-x
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:100356
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:18 Dec 2019 22:26
Last Modified:09 Mar 2020 13:19

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