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<front>
<journal-meta>
<journal-id journal-id-type="publisher">ISPRS-Archives</journal-id>
<journal-title-group>
<journal-title>The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences</journal-title>
<abbrev-journal-title abbrev-type="publisher">ISPRS-Archives</abbrev-journal-title>
<abbrev-journal-title abbrev-type="nlm-ta">Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.</abbrev-journal-title>
</journal-title-group>
<issn pub-type="epub">2194-9034</issn>
<publisher><publisher-name>Copernicus Publications</publisher-name>
<publisher-loc>Göttingen, Germany</publisher-loc>
</publisher>
</journal-meta>
<article-meta>
<article-id pub-id-type="doi">10.5194/isprs-archives-XLIX-B4-2026-637-2026</article-id>
<title-group>
<article-title>Mapping Natural Disasters Using Social Media Posts with an Encoder-Decoder Model</article-title>
</title-group>
<contrib-group><contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Ekhtari</surname>
<given-names>Nima</given-names>
</name>
<xref ref-type="aff" rid="aff1">
<sup>1</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Niccolai</surname>
<given-names>Andrew</given-names>
</name>
<xref ref-type="aff" rid="aff2">
<sup>2</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Slocum</surname>
<given-names>Kevin</given-names>
</name>
<xref ref-type="aff" rid="aff3">
<sup>3</sup>
</xref>
</contrib>
<contrib contrib-type="author" xlink:type="simple"><name name-style="western"><surname>Glennie</surname>
<given-names>Craig</given-names>
</name>
<xref ref-type="aff" rid="aff4">
<sup>4</sup>
</xref>
</contrib>
</contrib-group><aff id="aff1">
<label>1</label>
<addr-line>Civil Engineering Faculty, University of Houston, Houston, Texas, USA</addr-line>
</aff>
<aff id="aff2">
<label>2</label>
<addr-line>Associate technical director, Cold Regions Research and Engineering Lab, Hanover, New Hampshire, USA</addr-line>
</aff>
<aff id="aff3">
<label>3</label>
<addr-line>Science, engineering, and technical advisor, Cold Regions Research and Engineering Lab, USA</addr-line>
</aff>
<aff id="aff4">
<label>4</label>
<addr-line>Professor of Civil Engineering, University of Houston, Houston, Texas, USA</addr-line>
</aff>
<pub-date pub-type="epub">
<day>04</day>
<month>08</month>
<year>2026</year>
</pub-date>
<volume>XLIX-B4-2026</volume>
<fpage>637</fpage>
<lpage>642</lpage>
<permissions>
<copyright-statement>Copyright: &#x000a9; 2026 Nima Ekhtari et al.</copyright-statement>
<copyright-year>2026</copyright-year>
<license license-type="open-access">
<license-p>This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit <ext-link ext-link-type="uri"  xlink:href="https://creativecommons.org/licenses/by/4.0/">https://creativecommons.org/licenses/by/4.0/</ext-link></license-p>
</license>
</permissions>
<self-uri xlink:href="https://isprs-archives.copernicus.org/articles/XLIX-B4-2026/637/2026/isprs-archives-XLIX-B4-2026-637-2026.html">This article is available from https://isprs-archives.copernicus.org/articles/XLIX-B4-2026/637/2026/isprs-archives-XLIX-B4-2026-637-2026.html</self-uri>
<self-uri xlink:href="https://isprs-archives.copernicus.org/articles/XLIX-B4-2026/637/2026/isprs-archives-XLIX-B4-2026-637-2026.pdf">The full text article is available as a PDF file from https://isprs-archives.copernicus.org/articles/XLIX-B4-2026/637/2026/isprs-archives-XLIX-B4-2026-637-2026.pdf</self-uri>
<abstract>
<p>Real-time mapping of social media posts from users in the affected areas during a natural disaster can generate actionable intelligence for disaster response teams. Given the complexities of natural language used in such posts, modern approaches rely on Artificial Intelligence (AI) to improve accuracy. Extracting actionable geospatial intelligence from unstructured text requires a robust geoparsing pipeline comprising toponym detection and toponym resolution. While general-purpose Large Language Models (LLMs) can be utilized for toponym detection, their operational utility in high-volume, real-time workflows is constrained by high computational costs and a heavy reliance on intensive prompt engineering. To address these limitations, this study presents a highly efficient alternative utilizing custom encoder-decoder models fine-tuned specifically for toponym detection. Leveraging a dataset of 7,400 curated tweets from the 2024 hurricane Helene and another dataset of 50,000 tweets from the 2017 hurricane Harvey, we fine-tuned Google Research&amp;rsquo;s Flan-T5-base architecture twice. Both finetuned versions of the model demonstrated relatively good robustness, converging to F1 scores of 0.87 and 0.83 for hurricanes Helene and Harvey respectively. For the subsequent toponym resolution stage, we implemented a hybrid pipeline that categorizes extractions into four GIS-aligned classes. Regional-scale entities are matched against authoritative local GIS feature layers using a fuzzy string matching approach to map polygons, while localized features are resolved to point coordinates via GoogleMaps Geocoding API. The results of mapped tweets are examined as dynamic heatmaps that prove to be valuable in generating geospatial intelligence for disaster management.</p>
</abstract>
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