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Quiescent deformation of the Aniakchak Caldera, Alaska mapped by InSAR

Geology

By:
, , , and
DOI: 10.1130/G22015.1

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Abstract

The 10-km-wide caldera of the historically active Aniakchak volcano, Alaska, subsides ???13 mm/yr, based on data from 19 European Remote Sensing Satellite (ERS-1 and ERS-2) interferometric synthetic aperture radar (InSAR) images from 1992 through 2002. The pattern of subsidence does not reflect the distribution of pyroclastic deposits from the last eruption in 1931 and therefore is not related to compaction of fragmental debris. Weighted least-squares inversion of the deformation maps indicates a relatively constant subsidence rate. Modeling the deformation with a Mogi point source locates the source of subsidence at ???4 km below the central caldera floor, which is consistent with the inferred depth of magma storage before the 1931 eruption. Magmatic CO2 and He have been measured at a warm soda spring within the caldera, and several sub-boiling fumaroles persist elsewhere in the caldera. These observations suggest that recent subsidence can be explained by the cooling or degassing of a shallow magma body (???4 km deep), and/or the reduction of the pore-fluid pressure of a cooling hydrothermal system. Ongoing deformation of the volcano detected by InSAR, in combination with magmatic gas output from at least one warm spring, and infrequent low-level bursts of seismicity below the caldera, indicate that the volcanic system is still active and requires close attention for the timely detection of possible hazards. ?? 2006 Geological Society of America.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Quiescent deformation of the Aniakchak Caldera, Alaska mapped by InSAR
Series title:
Geology
DOI:
10.1130/G22015.1
Volume
34
Issue:
1
Year Published:
2006
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Geology
First page:
5
Last page:
8
Number of Pages:
4