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| **Section 1** | **Section 1** | ||
| - | **Persistent Scatterers Study of Deformation Leading up to the 2004 Eruption of Mount St Helens** | + | ====== Persistent Scatterers Study of Deformation Leading up to the 2004 Eruption of Mount St Helens ====== |
| **Mt St Helens Eruption Background** | **Mt St Helens Eruption Background** | ||
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| {{:mark:poland_and_lu.jpg}} | {{:mark:poland_and_lu.jpg}} | ||
| - | Because of the wide spatial and temporal spacing, and to a lesser extent, the levels of noise, in data collected by trilateration and GPS, no conclusions could be made about any potential surface deformation that may have occurred locally on the edifice or within the crater of Helens. The ability to produce spatially continuous maps of surface displacements gives InSAR the ability to resolve the question of whether localized deformation may have occurred at Mt St Helens prior to its 2004 eruption. A study conducted by Poland and Lu in 2008 attempted to image both pre and post eruptive deformation at Mount St Helens using interferogram stacking. Because of decorrelation caused by the presence of snow and dense vegetation, even stacks of interferograms were unable to obtain signal within the crater or on the edifice prior to the eruption (Fig ##). While the results prior to the 2004 eruption were inconclusive, post eruptive results successfully imaged subsidence around and on parts of the edifice. | + | **Figure 1.** A stack of interferograms made by Poland and Lu (2008) reveals no apparent deformation.\\ Coherence on the edifice and within the crater is limited due to the presence and disturbance caused by snow. |
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| + | Because of the wide spatial and temporal spacing, and to a lesser extent, the levels of noise, in data collected by trilateration and GPS, no conclusions could be made about any potential surface deformation that may have occurred locally on the edifice or within the crater of Helens. The ability to produce spatially continuous maps of surface displacements gives InSAR the ability to resolve the question of whether localized deformation may have occurred at Mt St Helens prior to its 2004 eruption. A study conducted by Poland and Lu in 2008 attempted to image both pre and post eruptive deformation at Mount St Helens using interferogram stacking. Because of decorrelation caused by the presence of snow and dense vegetation, even stacks of interferograms were unable to obtain signal within the crater or on the edifice prior to the eruption (Fig 1). While the results prior to the 2004 eruption were inconclusive, post eruptive results successfully imaged subsidence around and on parts of the edifice. | ||
| **Motivation** | **Motivation** | ||
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| This effect can be clearly seen in an example of APS (Figure ##), where differences in delay of up to 12cm can exist across a scene, arising from differential changes in the water vapor content of the air. Figure ## shows the map of average apparent velocities that would result from the application of a StaMPS-like algorithm to a series of 12 APS made from 13 maps of atmospheric delay. Differences in velocity on the order of 2 cm/yr are seen over short length scales (~5km), smaller than the StaMPS scene over St Helens (Pictured). | This effect can be clearly seen in an example of APS (Figure ##), where differences in delay of up to 12cm can exist across a scene, arising from differential changes in the water vapor content of the air. Figure ## shows the map of average apparent velocities that would result from the application of a StaMPS-like algorithm to a series of 12 APS made from 13 maps of atmospheric delay. Differences in velocity on the order of 2 cm/yr are seen over short length scales (~5km), smaller than the StaMPS scene over St Helens (Pictured). | ||
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| + | {{:mark:av_vel.jpg}} | ||
| **Discussion and Conclusions** | **Discussion and Conclusions** | ||
