.c.Galapagos Islands


Titles of Investigations:

I.		The Eruptive Styles of Basaltic Shield Volcanoes from Shuttle Imaging Radar-C (SIR-C) and X-SAR Data

II.		Geology of the Galapagos Test Site

III.		SIR-C Radar Investigations of Volcanism and Tectonism in the Northern Andes and Galapagos

Principal Investigators:

I.		Dr. Peter Mouginis-Mark
		University of Hawaii

II.		Dr. Pasquale Murino
		Istituto U Nobile

III.		Dr. Chuck Wood
		University of North Dakota

Site Description:

	Much remains to be discovered about the volcanoes of the western Galapagos Islands.  There are seven shield volcanoes in this area (Fernandina, Ecuador, Wolf, Darwin, Alcedo, Sierra Negra, and Azul) which collectively have erupted more than sixty times this century.  Unlike Hawaii, these volcanoes are infrequently studied due to their inaccessibility and delicate ecology.  In addition, the rugged terrain, lack of water and field support make these volcanoes difficult to map and study in the field.
	Volcanoes in Galapagos are spaced 10-25 km apart, and the stress fields between volcanoes has not influenced the formation of adjacent volcanoes to the extent seen in Hawaiian volcanoes.  The identification of proto-rift zones may indicate that the inside of the volcano has preferred lines of weakness that permit easy eruption of lava.  These lines of weakness may be influenced by the regional structure of the islands rather than the shape of the individual volcano.  The derived radar maps may help us decide between these two models.
		The northern flanks of Wolf Volcano, and most of the flanks of Alcedo Volcano, are either covered with vegetation (we are told it's approximately 0.5 m high) or ash deposits (<1 m thick).  In Landsat and SPOT data, these areas are bland; however, we see evidence for changes in the location of rift zones on Wolf and, from field work, buried lava flows on Alcedo have been identified and may be visible in radar images.  Identification of rift zone location changes would permit the long-term (1,000s to 10,000s of years) evolution of the volcanoes to be determined for the first time.
	The flanks of all the volcanoes, but particularly Fernandina, Wolf, and Darwin, are in places very steep (approximately 30-50¡).  Many lava flows descend the slopes of these volcanoes and may show wide variations in lava texture.  Such textures are usually used to indicate flow rheology and mass eruption rate (pahoehoe is fluid lava erupted at a low mass eruption rate, a'a is more viscous and has a high mass eruption rate).  The calderas of Fernandina, Wolf, Darwin, and Azul volcanoes experience multiple collapse events and produce deep (approximately 1 km) summit craters.

Objectives:

I.		a)	Study the relative importance of rift zones versus radial fissures in volcano evolution;

		b)	Verify radar-penetration capability; if verified SIR-C/X-SAR data will permit the regional extent of lava flows to be mapped and the temporal change in vent locations to be identified. 

		c)	Mapping the spatial variability of lava flow types with respect to slope differences will generate new insights into the flow characteristics, as well as show where high volume eruptions occurred.

		d)	Radar will permit spatter ramparts, fissures, and faults around the summit to be mapped.  These maps will enable the structure of the summits to be identified and correlated with areas of recent summit collapse.  In turn this will help identify the regional structural characteristics of the volcanoes.

II.		a)	Evaluate the multiple capabilities of spaceborne SAR in geological and oceanological applications in the Galapagos area.

III.		a)	Developing radar models for detecting and mapping active volcanoes.

Field Measurements:

Due to the inaccessibility of the Galapagos Islands, field work is not planned in conjunction with the SIR-C/X-SAR mission.

Crew Observations:

1)	Crew Journal: Describe volcanic activity at the site and locate other areas where volcanic activity is seen from orbit for future possible data takes.  Note variations in albedo when lava flow fields are seen from different angles.  

2)	Cameras: Hercules and Hasselblad will be used to photograph the site and other volcanoes visible from orbit at multiple viewing angles.  A telephoto lens used with the Hasselblad is also requested.  Low sun angle images are needed to see shadows of subtle topographic features on the ground.

Coverage Requirements:

	The minimum coverage requirement for the Galapagos is three (3) passes.

Anticipated Results:

I.		a)	A more complete regional view of the eruptive history will be obtained for seven classic shield volcanoes.  This will enable the role of the tectonic setting and spatial variations in activity to be compared using a uniform data set for landforms physically separated by thousands of kilometers which has never before been possible; 

		b)	Develop radar scattering models that enable us to take local test data and extrapolate these observations to the regional scale  Such methods are deemed to be particularly important as the geologic community prepares not only to study geographically isolated terrestrial landforms using ERS-1, JERS-1, and EOS data sets, but also to analyze planetary volcanic terrains such as those on Venus (imaged by NASA's Magellan spacecraft).

II.		a)	To update structural and hydrogeological maps by regional reconstruction of the structural and volcano-tectonics setting and its correlation with plate-tectonics and earthquakes epicenters.

III.		a)	Greatly improve geologic knowledge of poorly mapped, frequently cloud-covered, volcanically active arc.

		b)	Develop an optimal interpretation of radar data for detection and mapping of pyroclastic/ lahar deposits in tropical environments.

		c)	Improve understanding of distribution and character of poorly mapped deposits at the Galapagos volcanoes.