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Fresnel zone: A pitfall in seismic imaging of mid‐ocean ridge magma lenses
Author(s) -
PonceCorrêa Gustavo J.,
Mutter John C.,
Carbotte Suzanne
Publication year - 1999
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/1999gl010443
Subject(s) - geology , magma , magma chamber , sill , lens (geology) , ridge , seismology , mid ocean ridge , petrology , volcano , paleontology
We present estimates of the Fresnel zone diameter for the axial magma chamber lens along the southern and northern East Pacific Rise and compare them to the magma lens widths derived from migrated seismic sections. The mean values of that diameter are 996 m and 1052 m and the mean values of the magma lens width are 680 m and 1056 m respectively. Most individual estimates of the magma lens width fall below the Fresnel zone diameter. Similar results are presented for three other mid‐ocean ridges. The registered signal is therefore a mix of responses from the magma sill and the encasing rock and lateral resolution is not achieved. We conclude that data analysis procedures that assume a laterally homogeneous Earth, cannot provide reliable estimates of the magma lens physical properties, including whether it is liquid or not.