|Duration of observation:||1993 - 2010|
|Inferred cause of deformation:||Magmatic|
|Characteristics of deformation:|
InSAR measurements at Spurr cover two seismic swarms. The first swarm took place in 1996 – 1998 at Strandline Lake, 30 km northeast of Spurr. Initial InSAR observations showed no evidence of strong surface deformation, ruling out magma intrusion at depths <10 km (Kilgore et al., 2011). Later observations by Lu and Dzurisin (2014) identify broad inflation associated with this event, and find that best-fitting models agree with a deep source (12-16 km). InSAR measurements covering a second earthquake swarm in 2004 – 2005 beneath the summit of Spurr also show broad inflation at 10 – 14 km depth. Modelled volume changes associated with both events are similar (0.04 – 0.06 km³), and are interpreted to be caused by episodic intrusion of magma into the crust. InSAR measurements outside of these periods show no evidence of deformation.
|Reference:||Kilgore, W.W., Roman, D.C., Biggs, Juliet, and Hansen, Roger, 2011, Seismic and geodetic investigation of the 1996-1998 earthquake swarm at Strandline Lake, Alaska: Geophysical Journal International, v. 186, n. 3, p. 1365-1379, doi:10.1111/j.1365-246X.2011.05115.x.|
|Reference:||Lu, Z., and Dzurisin, D., 2014, InSAR imaging of Aleutian volcanoes: Chichester, UK, Springer-Praxis, 390 p.|
|Reference:||U.S. Geological Survey Alaska Volcano Observatory (AVO) website|
Spurr summit viewed from the N. Source: C. Kern, U.S. Geological Survey AVO website