Updated absolute gravity rate of change associated with glacial isostatic adjustment in Southeast Alaska and its utilization for rheological parameter estimation

• Material Type: 記事
• Title: Updated absolute gravity rate of change associated with glacial isostatic adjustment in Southeast Alaska and its utilization for rheological parameter estimation
• Author/Editor: Kazuhiro Naganawa; Takahito Kazama; Yoichi Fukuda
• Publication, Distribution, etc.: 日本 : The Society of Geomagnetism and Earth, Planetary and Space Sciences
• Publication Date: 2022-07-25
• Publication Date (W3CDTF): 2022-07-25
• Periodical title: EPS : Earth, Planets and Space
• No. or year of volume/issue: 74(116)
• Volume: 74(116)
• ISSN (Periodical Title): 1880-5981
• ISSN-L (Periodical Title): 1343-8832
• Text Language Code: eng
• DOI: 10.1186/s40623-022-01666-7; https://doi.org/10.1186/s40623-022-01666-7
• Persistent ID (NDL): info:ndljp/pid/12685403; https://dl.ndl.go.jp/pid/12685403
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• Acquisition Basis: オンライン資料収集制度
• Date Accepted (W3CDTF): 2023-03-07T16:17:01+09:00
• Date Captured (W3CDTF): 2023-03-07
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• Periodical Title (Persistent ID (NDL)): info:ndljp/pid/12287068; https://dl.ndl.go.jp/pid/12287068
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• Summary, etc.: In Southeast Alaska (SE-AK), rapid ground uplift of up to 3 cm/yr has been observed associated with post-Little Ice Age glacial isostatic adjustment (GIA). Geodetic techniques such as global navigation satellite system (GNSS) and absolute gravimetry have been applied to monitor GIA since the last 1990s. Rheological parameters for SE-AK were determined from dense GNSS array data in earlier studies. However, the absolute gravity rate of change observed in SE-AK was inconsistent with the ground uplift rate, mainly because few gravity measurements from 2006 to 2008 resulted in imprecise gravity variation rates. Therefore, we collected absolute gravity data at six gravity points in SE-AK every June in 2012, 2013, and 2015, and updated the gravity variation rate by reprocessing the absolute gravity data collected from 2006 to 2015. We found that the updated gravity variation rate at the six gravity points ranged from −2.05 to −4.40 μGal/yr, and its standard deviation was smaller than that reported in the earlier study by up to 88 %. We also estimated the rheological parameters under the assumption of the incompressible Earth to explain the updated gravity variation rate, and their optimal values were determined to be 55 km and 1.2×10¹⁹ Pa s for lithospheric thickness and upper mantle viscosity, respectively. These optimal values are consistent with those independently obtained from GNSS observations, and this fact indicates that absolute gravimetry can be one of the most effective methods in determining sub-surface structural parameters associated with GIA accurately. Moreover, we utilized the gravity variation rates for estimating the ratio of gravity variation to vertical ground deformation at the six gravity points in SE-AK. The viscous ratio values were obtained as −0.168 and −0.171 μGal/mm from the observed data and the calculated result, respectively. These ratios are greater (in absolute) than those for other GIA regions (−0.15 to −0.16 μGal/mm in Antarctica and Fennoscandia), because glaciers in SE-AK have melted more recently than in other regions.
• DOI: 10.1186/s40623-022-01666-7; https://doi.org/10.1186/s40623-022-01666-7; 10.21203/rs.3.rs-1158163/v1; https://doi.org/10.21203/rs.3.rs-1158163/v1
• Access Restrictions: インターネット公開
• Rights (production): © The Author(s) 2022.; 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 licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence 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.
• Related Material (URI): http://hdl.handle.net/2433/277737; http://id.ndl.go.jp/digimeta/12685403; https://dl.ndl.go.jp/pid/12685403
• References: ETOPO1 1 Arc-Minute Global Relief Model; https://cir.nii.ac.jp/crid/1880020692598189184
• Data Provider (Database): 国立情報学研究所 : CiNii Research; https://cir.nii.ac.jp/
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• Bibliographic ID (NDL): 12685403; http://id.ndl.go.jp/bib/12685403