Using a calibrated upper living position of marine biota to calculate coseismic uplift: a case study of the 2016 Kaikōura earthquake, New Zealand
<p>The 2016 <span class="inline-formula"><i>M</i><sub>w</sub>=7.8</span> Kaikōura earthquake (South Island, New Zealand) caused widespread complex ground deformation, including significant coastal uplift of rocky shorelines. This coastal deformatio...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-05-01
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| Series: | Earth Surface Dynamics |
| Online Access: | https://www.earth-surf-dynam.net/8/351/2020/esurf-8-351-2020.pdf |
| Summary: | <p>The 2016 <span class="inline-formula"><i>M</i><sub>w</sub>=7.8</span> Kaikōura earthquake (South Island, New Zealand) caused widespread complex ground deformation, including significant coastal uplift of rocky shorelines. This coastal deformation is used here to develop a new methodology, in which the upper living limits of intertidal marine biota have been calibrated against tide-gauge records to quantitatively constrain pre-deformation biota living position relative to sea level. This living position is then applied to measure coseismic uplift at three other locations along the Kaikōura coast. We then assess how coseismic uplift derived using this calibrated biological method compares to that measured using other methods, such as light detection and ranging (lidar) and strong-motion data, as well as non-calibrated biological methods at the same localities. The results show that where biological data are collected by a real-time kinematic (RTK) global navigation satellite system (GNSS) in sheltered locations, this new tide-gauge calibration method estimates tectonic uplift with an accuracy of <span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M2" display="inline" overflow="scroll" dspmath="mathml"><mrow><mo>±</mo><mo>≤</mo><mn mathvariant="normal">0.07</mn></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="44pt" height="11pt" class="svg-formula" dspmath="mathimg" md5hash="e2702525ab1522abba976ab594f19cfe"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="esurf-8-351-2020-ie00001.svg" width="44pt" height="11pt" src="esurf-8-351-2020-ie00001.png"/></svg:svg></span></span> m in the vicinity of the tide gauge and an overall mean accuracy of <span class="inline-formula">±0.10</span> m or 10 % compared to differential lidar methods for all locations. Sites exposed to high wave wash, or data collected by tape measure, are more likely to show higher uplift results. Tectonic uplift estimates derived using predictive tidal charts produce overall higher uplift estimates in comparison to tide-gauge-calibrated and instrumental methods, with mean uplift results 0.21 m or 20 % higher than lidar results. This low-tech methodology can, however, produce uplift results that are broadly consistent with instrumental methodologies and may be applied with confidence in remote locations where lidar or local tide-gauge measurements are not available.</p> |
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| ISSN: | 2196-6311 2196-632X |