Quaternary volcanism in the Afar

Depression (Ethiopia and Eritrea)(

Merged Landsat TM and Synthetic Aperture Radar (JERS-1) satellite image of Dubbi volcano, Eritrea, responsible for one of the few recorded explosive eruptions in theAfar region in 1861.

Mt. Ruapehu volcano, New Zealand

-Landsat TM thermal infrared and visible composite image.

-The flanks of the volcano are largely snow/ice covered (blue) but the summit contains a hot crater lake (red).

-A slick of sulphur spherules is seen floating on the lake (yellow).

Mount St Helens, Washington • Situated to the north of the

Columbia River in southern Washington State, Mount St. Helens exploded on 18th May 1980 killing 60 people.

• The images above show Mount St. Helens before the eruption in 1973 and 8 years after the eruption in 1988.

• In the 1988 image, the southern side of the characteristic volcanic cone can be seen ‘intact’, whilst apparent to the north is the collapse which resulted in the devastating flow of mud and rock.

Three Sisters, Oregon • This radar interferogram shows a

pattern of ground uplift centered about 3 miles (5 km) west of South Sister volcano in central Oregon.

• Each full color band from blue to red represents about 2.8 cm (slightly more than 1 inch) of ground movement in the direction of the radar satellite.

• In this case, four concentric color bands show that the surface moved toward the satellite (mostly upward) by as much as 10 cm (about 4 inches) sometime between August 1996 and October 2000.

Earthquake

• In radar interferometry, two or more radar images are combined to give measurements of surface height and surface change, making it useful for the detection of earthquake centre.

• This can be seen on the right image showing 1995 earthquake in Kobe, Japan.

Digital Elevation Data: Landslide Hazard Map

Slope Map: Hawaii Landslide Prediction

Desertification: Niger, Africa

Desertification • Advanced Very High Resolution

Radiometers (AVHRR) on NOAA satellites, show the changes in the extent and area of the Sahara Desert from 1984 to 1990.

• The desert is shown in shades of brown, and full vegetative color is shown in purple. Colors in between brown and purple indicate intermediate amounts of vegetation.

• Between 1980 and 1984 the desert grew steadily larger.

• Data gathered during this four-year period showed the southern boundary of the Sahara creeping southward as much as 240 kilometers.

Deforestation

• Landsat image showing deforestation in the Amazon region, taken from the Brazilian state of Para on 15 July 1986.

• The dark areas are forest, the white is deforested areas, and the grey is re-growth.

• The pattern of deforestation spreading along roads is obvious (lower part of the image).