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Bulletin of Volcanology

, Volume 59, Issue 5, pp 345–355 | Cite as

Pit crater structure and processes governing persistent activity at Masaya Volcano, Nicaragua

  • Hazel Rymer
  • Benjamin  van Wyk de Vries
  • John Stix
  • Glyn Williams-Jones
ORIGINAL PAPER

Abstract

 Persistent activity at Masaya Volcano, Nicaragua, is characterised by cycles of intense degassing, lava lake development and pit crater formation. It provides a useful site to study the processes which govern such activity, because of its easy accessibility and relatively short cycles (years to decades). An understanding of the present activity is important because Masaya is visited by large numbers of tourists, is located close to major cities and has produced voluminous lavas, plinian eruptions and ignimbrites in the recent past. We provide structural and geophysical data that characterise the "normal" present state of activity. These indicate that the ongoing degassing phase (1993 to present) was not caused by fresh magma intrusion. It was associated with shallow density changes within the active Santiago pit crater. The activity appears to be associated predominantly with shallow changes in the pit crater structure. More hazardous activity will occur only if there are significant departures from the present gravity, deformation and seismic signatures.

Key words Masaya Santiago Pit Structure Microgravity Magma Gas 

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Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • Hazel Rymer
    • 1
  • Benjamin  van Wyk de Vries
    • 1
  • John Stix
    • 2
  • Glyn Williams-Jones
    • 2
  1. 1.Department of Earth Sciences, The Open University, Milton Keynes, MK7 6AA, UK Fax: +44 1908 652558 e-mail: h.rymer@open.ac.ukGB
  2. 2.Department of Geology, Université de Montreal, CP. 6100, Montreal, CanadaCA

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