《航空制造工程手册》发动机装配与试车.pdf

Ground deformation at Soufrie `re Hills Volcano, Montserrat during 1998–2000 measured by radar interferometry and GPS G. Wadge a, *, . Mattioli b, . Herd c , 1 aEnvironmental Systems Science Centre, University of Reading, UK bDepartment of Geosciences, University of Arkansas, USA cMontserrat Volcano Observatory, Montserrat, West Indies Received 11 January 2005; received in revised form 9 September 2005; accepted 3 November 2005 Available online 4 January 2006 Abstract We examine the motion of the ground surface on the Soufrie `re Hills Volcano, Montserrat between 1998 and 2000 using radar interferometry (InSAR). To minimise the effects of variable atmospheric water vapour on the InSAR measurements we use independently-derived measurements of the radar path delay from six continuous GPS receivers. The surfaces providing a measurable interferometric signal are those on pyroclastic flow deposits, mainly emplaced in 1997. Three types of surface motion can be discriminated. Firstly, the surfaces of thick, valley-filling deposits subsided at rates of 150–120 mm/year in the year after emplacement to 50–30 mm/year two years later. This must be due to contraction and settling effects during cooling. The second type is the near-field motion localised within about one kilometre of the dome. Both subsidence and uplift events are seen and though the former could be due to surface gravitational effects, the latter may reflect shallow ( b1 km) pressurisation effects within the conduit/dome. Far-field motions of the surface away from the deeply buried valleys are interpreted as crustal strains. Because the flux of magma to the surface stopped from March 1998 to November 1999 and then resumed from November 1999 through 2000, we use InSAR data from these two periods to test the crustal strain behaviour of three models of magma supply: open, depleting and unbalanced. The InSAR observations of strain gradients of 75–80 mm/year/km uplift during the period of quiescence on the we