Skip to main content

Surface deformation caused by shallow magmatic activity at Okmok volcano, Alaska, detected by GPS campaigns 2000–2002


Annual GPS campaigns were carried out at Okmok volcano in the Aleutian Islands, Alaska, between 2000 and 2002. Surface deformation detected by these measurements reveals that Okmok volcano has been inflating over these 3 years at a variable inflation rate. The horizontal displacements show a radial outward pattern, and there has been significant uplift of the caldera center. The uplift of the caldera center relative to the caldera rim was 2.1 cm during 2000–2001, and 6.7 cm during 2001–2002. The latter rate is quite consistent with that deduced from InSAR measurements spanning 1997–2000, but the deformation rate during 2000–2001 was much slower than during the preceding and succeeding periods. Shallow pressure source was inferred at a depth of 3.1 km beneath the approximate center of the caldera. The location of the source, 5 km laterally from the active vent, is consistent with that inferred from InSAR data during 1997–1998. The total increase in volume during 2000–2002 of the inferred source is 0.44 × 107m3, which is 3–8% of the amount of volume erupted in 1997. The GPS and InSAR data show that magma accumulation beneath Okmok was steady in rate and location during 1997–2002, except for a pause at some time between 2000 and 2001.


  • Dean, K., M. Servilla, A. Roach, B. Foster, and K. Engle, Satellite monitoring of remote volcanoes improves study efforts in Alaska, Eos. Trans. AGU, 79(35), 413, 422–423, 1998.

    Article  Google Scholar 

  • Delaney, P. T. and D. F. McTigue, Volume of magma accumulation or withdrawal estimated from surface uplift or subsidence, with application to the 1960 collapse of Kilauea volcano, Bull. Volcanol., 56, 417–424, 1994.

    Article  Google Scholar 

  • Lu, Z. and T. Masterlark, Magma supply dynamics of Okmok volcano inferred from interferometric SAR, Eos Trans. AGU, 84(46), Fall Meet. Suppl., F1631, 2003.

    Google Scholar 

  • Lu, Z., D. Mann, J. T. Freymueller, and D. J. Meyer, Synthetic aperture radar interferometry of Okmok volcano, Alaska: Radar observation, J. Geophys. Res., 105, 10791–10806, 2000.

    Article  Google Scholar 

  • Lu, Z., E. Fielding, M. R. Patrick, and C. M. Trautwein, Estimating lava volume by precision combination of multiple baseline spaceborne and airborne interferometric synthetic aperture radar: The 1997 eruption of Okmok volcano, Alaska, IEEE Trans. Geoscience and Remote Sensing, 41, 1428–1436, 2003.

    Article  Google Scholar 

  • Mann, D., Deformation of Alaskan Volcanoes, Measured Using SAR Inter-ferometry and GPS, Ph.D. Thesis, University of Alaska Fairbanks, 122 pp., 2002.

  • Mann, D., J. Freymueller, and Z. Lu, Deformation associated with the 1997 eruption of Okmok volcano, Alaska, J. Geophys. Res., 2001JB000163, 2002.

  • Miller, T. P., R. G. McGimsey, D. H. Richter, J. R. Riehle, C. J. Nye, M. E. Yount, and J. A. Dumoulin, Catalog of the historically active volcanoes of Alaska, U.S. Geol. Surv. Open File Rep., 98–582, 1998.

    Google Scholar 

  • Mogi, K., Relations between the eruptions of various volcanoes and the deformations of the ground surface around them, Bull. Earthquake Res. Inst. Univ. Tokyo, 36, 99–134, 1958.

    Google Scholar 

Download references

Author information



Corresponding author

Correspondence to Yousuke Miyagi.

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Miyagi, Y., Freymueller, J.T., Kimata, F. et al. Surface deformation caused by shallow magmatic activity at Okmok volcano, Alaska, detected by GPS campaigns 2000–2002. Earth Planet Sp 56, 29–32 (2004).

Download citation

  • Received:

  • Revised:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

Key words

  • Okmok
  • GPS campaign
  • significant inflation
  • shallow magmatic activity