In situ ground deformation measurements from the summit of axial volcano during the 1998 volcanic episode

Authors
Citation
Cg. Fox, In situ ground deformation measurements from the summit of axial volcano during the 1998 volcanic episode, GEOPHYS R L, 26(23), 1999, pp. 3437-3440
Citations number
11
Categorie Soggetti
Earth Sciences
Journal title
GEOPHYSICAL RESEARCH LETTERS
ISSN journal
00948276 → ACNP
Volume
26
Issue
23
Year of publication
1999
Pages
3437 - 3440
Database
ISI
SICI code
0094-8276(199912)26:23<3437:ISGDMF>2.0.ZU;2-C
Abstract
Since September 1987, seafloor instrumentation monitoring ground deformatio n has been maintained on the summit of Axial Volcano on the central Juan de Fuca Ridge. During a January 1998 volcanic episode, pressure records from the central caldera showed a significant increase in pressure, indicating c aldera subsidence of over 3 m. This observed subsidence is interpreted to r epresent volcanic deflation as magma is erupted and/or injected into the vo lcanic flanks. Temperature anomalies of nearly 0.45 degrees C were also obs erved. A comparison of the subsidence record with hydroacoustic recordings indicates a continuous volcanic tremor signal coincident with the subsidenc e event. The time-coincidence of subsidence of the summit caldera with migr ation of epicenters into the volcanic rift zones confirms that during the 1 998 episode, the volcanic flanks were supplied by lateral dike injection fr om a central magma body, rather than locally derived magma sources.