Electrical Resistivity Tomography (ERT) datasets from the Otemma glacier forefield and outwash plain

<strong>Electrical Resistivity Tomography (ERT) datasets collected in the Otemma forefield (Switzerland) from 2019 to 2021.</strong><br> Data were collected by the research teams of Bettina Schaefli^1,2, Stuart N. Lane¹ and James Irving³. ¹ Institute of Earth Surface Dynamics (IDYST), University of Lausanne, 1015 Lausanne, Switzerland ² Institute of Geography (GIUB), University of Bern, 3012 Bern, Switzerland ³ Institute of Earth Sciences (ISTE), University of Lausanne, 1015 Lausanne, Switzerland For further information, please contact: [e-mail] <strong>This dataset is first referenced and discussed in the research paper by Müller et al., 2022.</strong> ------------------------------------------------------------------------------------------------------------------------------------------------------------------------ <strong>Data Description</strong> Electrical Resistivity Tomography (ERT) profiles were collected around the outwash plain of the Otemma glacier forefield (WGS84 : 45.93434 / 7.41209). All data were collected with a Syscal Pro Switch 48 from Iris Instruments, using an array of maximum 48 electrodes with a spacing between 1 and 10 meters. For each line, measurements were performed using a Dipole-Dipole (dd) and a Wenner-Schlumberger (ws) electrode configuration. All ERT lines locations can be visualized in <em><strong>ERT_map_lines_2019-2021.jpg</strong>.</em> A result overview can be vizualized in <em><strong>ERT_allResults_3Doverview.png</strong>.</em> <strong>Data Structure</strong> Two Juypter Notebook files are provided and can be used to reproduce all inversion analyses. <em><strong>1_createInput_prosys_to_pygimli.ipynb</strong></em> : Transforms the raw data from Syscal Pro (exported with ProsysII software as .csv) to a processed .dat file formated for inversion using the pyGIMLi library. <em><strong>2_ERT_inversion.ipynb</strong></em> : Reads the processed .dat file and performs a 2D robust inversion for a set of regularization parameters for the selected line. In <strong>ERT_data.zip</strong>, 3 folders with similar structure contain all data for year 2019, 2020 and 2021. Each folder contains : <strong>GPS </strong>: folder with electrodes coordinates for each ERT line <strong>inputGiMLi</strong> <strong>prosys_csv</strong>: contains the raw field measurements (downloaded from the Syscal device using ProsysII) <strong>input_ERT </strong>: stores the processed .dat file. (created from notebook 1) <strong>results_lambda</strong> : contains a .png image with the inversion results using different values of the regularization parameter lambda used to assess the sensitivity of the inversion results (over/underfitting). Analysis is performed for each line and each electrode configuration (dd or ws). (created from notebook 2) <strong>results_final</strong> : contains a .png image with the final inversion results for each line and electrode configuration (dd or ws) using the optimal lambda parameter only (all arrays are shown from East to West). (created from notebook 2) <strong>vtk</strong> : contains a .vtk file for each final results for 3D vizualization in the Paraview software. <strong><em>ERT_line_description_yyyy.csv</em> </strong>: a file describing the ERT arrays characteristics (read in notebook 1 and 2) The <strong>results </strong>folder contains : <strong>ERT_3Dview_paraview</strong> folder : contains Paraview state files (.pvsm) for 3D vizualization of all results, as well as image files. <em><strong>ERT_results_all.pdf</strong></em> : A summary of all final results for all years (similar content as <em>ERT/inputGiMLi</em><strong>/</strong><em>results_final</em> folders) <em><strong>ERT_results_bedrock.pdf</strong></em> : Contains the vizualization of specific ERT profiles in the outwash plain and their field location . The separation between a surface layer of water-saturated sediments (resistivity &lt;2500 Ωm) and the underlying bedrock is delimited. The likely presence of buried ice blocks (isolated blocks with resistivity &gt;5000-10000 Ωm) is also highlighted. <em><strong>ERT_timelapse_salt_tracer.gif</strong></em> : results of a time-lapse ERT measurement performed on 9 August 2019 to track the movement of a salt plume injected at 06 am, 9.38 meters upslope (see paper by<em> Müller et al., 2022</em> for detailed analysis). The tracer starts to appear at 12:45 at a distance of 30m on the array. Minimum resistivity is reached at between 16:45 and 17:45.<strong>电阻率层析成像（Electrical Resistivity Tomography，简称ERT）数据集，采自瑞士奥泰马前陆，采集时间为2019至2021年。</strong><br> 本数据集由Bettina Schaefli^1,2、Stuart N. Lane¹与James Irving³的研究团队采集完成。¹ 洛桑大学地表动力研究所（Institute of Earth Surface Dynamics，缩写IDYST），瑞士洛桑1015 ² 伯尔尼大学地理研究所（Institute of Geography，缩写GIUB），瑞士伯尔尼3012 ³ 洛桑大学地球科学研究所（Institute of Earth Sciences，缩写ISTE），瑞士洛桑1015 如需进一步咨询，请联系：[e-mail] <strong>本数据集首次在Müller等人2022年的研究论文中被引用并探讨。</strong><br>------------------------------------------------------------------------------------------------------------------------------------------------------------------------<br><strong>数据说明</strong><br>电阻率层析成像（ERT）剖面采集于奥泰马冰川前陆的冰水平原周边（WGS84坐标系：45.93434 / 7.41209）。所有数据均采用Iris Instruments公司的Syscal Pro Switch 48设备采集，电极阵列最大包含48个电极，电极间距介于1米至10米之间。每条测线均采用偶极-偶极（Dipole-Dipole，简称dd）与温纳-斯伦贝谢（Wenner-Schlumberger，简称ws）两种电极排列方式开展测量。所有ERT测线的位置可在<em><strong>ERT_map_lines_2019-2021.jpg</strong></em>中查看，反演成果概览可通过<em><strong>ERT_allResults_3Doverview.png</strong></em>可视化展示。<br><strong>数据结构</strong><br>提供两份Jupyter Notebook文件，可用于复现全部反演分析流程。<em><strong>1_createInput_prosys_to_pygimli.ipynb</strong></em>：将Syscal Pro采集的原始数据（通过ProsysII软件导出为.csv格式）转换为适配pyGIMLi库反演的格式化处理后.dat文件。<em><strong>2_ERT_inversion.ipynb</strong></em>：读取处理后的.dat文件，并针对选定测线，基于多组正则化参数执行二维稳健反演。<br>在<em><strong>ERT_data.zip</strong></em>压缩包中，包含3个结构完全一致的文件夹，分别对应2019、2020及2021年的全部数据。每个文件夹包含以下内容：<br><strong>GPS</strong>：存储各ERT测线的电极坐标文件<br><strong>inputGiMLi</strong><br><strong>prosys_csv</strong>：包含原始野外测量数据（通过ProsysII软件从Syscal设备导出）<br><strong>input_ERT</strong>：存储处理后的.dat文件（由Notebook 1生成）<br><strong>results_lambda</strong>：包含不同正则化参数λ取值下的反演结果.png图像，用于评估反演结果的敏感性（过拟合/欠拟合情况）。针对每条测线与每种电极排列方式（dd或ws）均完成该分析（由Notebook 2生成）。<br><strong>results_final</strong>：包含仅使用最优λ参数得到的各测线与电极排列方式（dd或ws）的最终反演结果.png图像（所有阵列均按自东向西方向展示）（由Notebook 2生成）。<br><strong>vtk</strong>：包含各最终反演结果的.vtk格式文件，用于在Paraview软件中进行三维可视化。<br><em><strong>ERT_line_description_yyyy.csv</strong></em>：描述ERT阵列特征的元数据文件（可在Notebook 1与2中读取调用）。<br><strong>results</strong>文件夹包含以下内容：<br><strong>ERT_3Dview_paraview</strong>文件夹：包含用于所有成果三维可视化的Paraview状态文件（.pvsm）及配套图像文件。<br><em><strong>ERT_results_all.pdf</strong></em>：所有年份全部最终成果的汇总文档（内容与<em>ERT/inputGiMLi</em><strong>/</strong><em>results_final</em>文件夹一致）。<br><em><strong>ERT_results_bedrock.pdf</strong></em>：展示冰水平原内特定ERT剖面及其野外位置的可视化文档。该文档划定了饱水沉积物表层（电阻率<2500 Ω·m）与下伏基岩的分界面，同时突出显示了可能存在的埋藏冰块（电阻率>5000~10000 Ω·m的孤立块体）。<br><em><strong>ERT_timelapse_salt_tracer.gif</strong></em>：2019年8月9日开展的延时ERT测量成果，用于追踪于当日6时在坡上9.38米处注入的盐羽流运移过程（详细分析参见Müller等人2022年的论文）。该示踪剂于12:45在阵列30米距离处首次出现，在16:45至17:45之间达到电阻率最小值。