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JET PROPULSION LABORATORY
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PHOTO CAPTION                           P-48282 
                                        February 6, 1997
Manam Volcano
Papua New Guinea

This three-dimensional perspective view of the volcanic island of 
Manam, Papua New Guinea was obtained by a NASA imaging radar 
system onboard a DC-8 aircraft in November 1996.  The volcano, 
one of  the most active in the Pacific "Ring of Fire," was in the 
midst of its largest eruption since 1992 when this image was 
acquired.  The island, approximately 10 kilometers (6 miles) 
across and 1800 meters (5900 feet) high, is actually the top of a 
much larger volcano that rests on the sea floor.  Lava flows and 
hot clouds of rock, ash and gas known as pyrocalstic flows are 
emitted from craters at the summit of the volcano and race down 
the valleys.  Two of  the valleys are visible as dark patches 
near the summit.  Deposits from earlier flows appear orange and 
blue; forested slopes of the volcano appear pink.  Two weeks 
after this image was acquired, the eruption intensified, killing 
several people and forcing the evacuation of thousands of others.  
The topographic information in this image was obtained using the 
technique of radar interferometry, in which the reflected radar 
signals are recorded simultaneously by two antennas mounted on 
separate areas of the aircraft.   This image was acquired by 
NASA's Airborne Synthetic Aperture Radar operated in its 
topographic TOPSAR mode on November 16, 1996.  The image is 
centered at 4.1 degrees South latitude and 145.06 degrees East 
longitude; the image shows the eastern side of the volcano.  No 
vertical exaggeration has been applied. The colors are assigned 
to different radar frequencies and polarizations of 
the radar as follows:  red is P-band (68 cm), horizontally 
transmitted and vertically received; green is P-band, vertically 
transmitted  and received; and blue is C-band
(6 cm), vertically transmitted and received.