Maar Volcano Location and Shape (MaarVLS) database v 2.0

By Alison Graettinger1, Alexander Bearden1

1. University of Missouri Kansas City

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The MaarVLS: Maar Volcano Location and Shape (pronounced marvelous) database establishes universal traits of Quaternary maar craters including typical sizes, shapes, and occurrence of these craters in different volcanic field types. The original version released in 2018 had 240 features. Version 2.0 released in 2021 includes 430 Quaternary maars with intact crater rims and literature to support the identification. In version two any modifications related to improved imagery to the original database are noted. 

The MaarVLS database includes manually digitized maar crater outlines, size, and shape parameters with preliminary additional information on tectonic setting, volcanic field characteristics, composition, elevation, and age. MaarVLS currently contains 430 maar craters identified in published literature as Quaternary, between -60 to 70 degrees latitude, from >70 different volcanic fields. To be included in the database a crater must have been previously recognized as a maar and have a complete, or nearly complete crater rim lacking significant incision or human modification. 

MaarVLS is currently a spreadsheet containing 31 categories.  All craters have name and variants, Global Volcanism Program number, latitude, longitude, country, area, perimeter, major axis, minor axis, average diameter, aspect ratio, elongation, isoperimetric circularity, volcanic field name, elevation, and references. Other categories are as complete as current literature allows and include age, composition, depth, population at 5 and 100 km distances, and whether there is evidence of multiple co-located eruptions. Accompanying the database is a Google Earth KMZ file that contains location pins, outlines of the crater rim, and major and minor axis measurement lines for each feature. 

A second spreadsheet of more eroded or modified maars and tuff cones is included called Documented not Measured). This collection is less complete, and features have a note indicating why they are not included in the main database, which could be the result of incomplete rims, low resolution imagery, modification by erosion or human activity, or morphologic characteristics of multiple landform types (tuff cone, maar scoria cone overlap) etc. 

The database is managed by Alison Graettinger at the University of Missouri Kansas City. Additional craters for inclusion are being collected and any contributions, suggestions, or corrections are encouraged. Contact Alison graettingera (at) 

Analysis of hte initial database Graettinger, A.H. 2018 The shape and distribution of Maar craters using the MaarVLS database. Journal of Volcanology and Geothermal Research. Doi: 10.1016/j.jvolgeores.2018.04.002. (Preprint link: 

Additional related research includes: Graettinger and Bearden 2021 Lateral migration of explosive hazards during maar eruptions constrained from crater shape. Journal of Applied Volcanology. DOI: 10.1186/s13617-021-00103-w

Nichols and Graettinger accepted The influence of regional stress and structural control on the shape of maar craters. Volcanica. 

The database has been developed in large part by undergraduate research students at the University of Missouri Kansas City and in the past from University at Buffalo. In particular version 2.0 has benefited from two years of effort by Alexander T. Bearden. 

Cite this work

Researchers should cite this work as follows:

  • Alison Graettinger; Alexander Bearden (2018), "Maar Volcano Location and Shape (MaarVLS) database v 2.0,"

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