Explosive lava-water interactions II: Self-organization processes among volcanic rootless eruption sites in the 1783-1784 Laki lava flow, Iceland

Christopher W. Hamilton, Sarah A. Fagents, Thorvaldur Thordarson

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34 Citations (Scopus)


We have applied quantitative geospatial analyses to rootless eruption sites in the Hnúta and Hrossatungur groups of the 1783-1784 Laki lava flow to establish how patterns of spatial distribution can be used to obtain information about rootless cone emplacement processes and paleo-environments. This study utilizes sample-size-dependent nearest neighbor (NN) statistics and Voronoi tessellations to quantify the spatial distribution of rootless eruption sites and validate the use of statistical NN analysis as a remote sensing tool. Our results show that rootless eruption sites cluster in environments with abundant lava and water resources, but competition for limited groundwater in these clusters can cause rootless eruption sites to develop repelled distributions. This pattern of self-organization can be interpreted within the context of resource availability and depletion. Topography tends to concentrate lava (fuel) and water (coolant) within topographic lows, thereby promoting explosive lava-water interactions in these regions. Given an excess supply of lava within broad sheet lobes, rootless eruption sites withdraw groundwater from their surroundings until there is insufficient water to maintain analogs to explosive molten fuel-coolant interactions. Rootless eruption sites may be modeled as a network of water extraction wells that draw down the water table in their vicinity. Rootless eruptions at locations with insufficient groundwater may either fail to initiate or terminate before explosive activity has ceased at nearby locations with a greater supply of water, thus imparting a repelled distribution to observed rootless eruption sites.

Original languageEnglish
Pages (from-to)469-485
Number of pages17
JournalBulletin of Volcanology
Issue number4
Publication statusPublished - May 2010

Bibliographical note

Funding Information:
Acknowledgments We thank Karen Pascal for her assistance in the field; Samuel Hulme and Ciarán Beggan for their assistance with GMT and MATLAB, respectively; Steve Baloga and Barbara Bruno for discussions relating to NN analysis; Benjamin Brooks and the Pacific GPS facility for providing DGPS survey equipment and postprocessing resources; Bruce Houghton and Scott Rowland for their comments and suggestions during the preparation of this manuscript; Laszlo Keszthelyi and Lori Glaze for their thoughtful and thorough reviews; and financial support from the National Aeronautics and Space Administration (NASA) Mars Fundamental Research Program (MFRP) grant NNG05GM08G, NASA Mars Data Analysis Program (MDAP) grant NNG05GQ39G, Geological Society of America (GSA), and Icelandic Centre for Research (RANNÍS). SOEST publication number 1800. HIGP publication number 7806.

Other keywords

  • Explosive lava-water interactions
  • Iceland
  • Laki
  • Mars
  • Phreatomagmatic
  • Pseudocraters
  • Volcanic rootless cones


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