Astypalaea Linea

Press Release

The San Andreas fault and a Strike-slip Fault on Europa are shown at similar scales. The Europan fault is similar in size to the California portion of the San Andreas fault. Galileo images of this fault are broadening models and may help build understanding of earth movements on our own planet.

Broad areal coverage of Europa obtained by Voyager 2 in 1979 (left image) offered the first view of this intriguing fault called Astypalaea Linea. Here on Earth, unlike Europa, large strike-slip faults like the San Andreas are set in motion by plate tectonic forces. On Europa, tides generated by Jupiter's gravitational tug on Europa, may be the force that caused the fault to open and the blocks on either side of it move lengthwise in one direction. The area on either side of the fault is displaced. In the right picture, segments on either side of the fault are shifted back by the amounts shown with the white separations. The shift is similar to going back in time and reconstructing the area.

The box delimits the area of the Voyager coverage which was targetted for higher resolution investigations by the Galileo spacecraft. These Galileo images show a portion of the fault as long as the California portion of the San Andreas fault which runs from the Mexico border to San Francisco.

Rotated structures like the "S" shaped cracks and ridges in this zoomed in section of the Galileo data are typical of a process known as "simple shear," and characterize many large strike-slip faults on Earth. Comparisons between these structures related to faults on Europa and those on Earth may generate ideas useful in the study of terrestrial faulting. This zoomed in section of the Galileo data shows what appears to be the central crack where the fault originally opened. Successive layers, like tree rings, form as material (warmer, softer ice from below Europa's brittle ice shell surface, or frozen water from a possible subsurface ocean) enters the gap periodically from below and hardens.

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The San Andreas fault and a Strike-slip Fault on Europa are shown at similar scales. The Europan fault is similar in size to the California portion of the San Andreas fault. Galileo images of this fault are broadening models and may help build understanding of earth movements on our own planet.


Broad areal coverage of Europa obtained by Voyager 2 in 1979 (left image) offered the first view of this intriguing fault called Astypalaea Linea. Here on Earth, unlike Europa, large strike-slip faults like the San Andreas are set in motion by plate tectonic forces. On Europa, tides generated by Jupiter's gravitational tug on Europa, may be the force that caused the fault to open and the blocks on either side of it move lengthwise in one direction. The area on either side of the fault is displaced. In the right picture, segments on either side of the fault are shifted back by the amounts shown with the white separations. The shift is similar to going back in time and reconstructing the area.


The box delimits the area of the Voyager coverage which was targetted for higher resolution investigations by the Galileo spacecraft.	These Galileo images show a portion of the fault as long as the California portion of the San Andreas fault which runs from the Mexico border to San Francisco.


Rotated structures like the "S" shaped cracks and ridges in this zoomed in section of the Galileo data are typical of a process known as "simple shear," and characterize many large strike-slip faults on Earth. Comparisons between these structures related to faults on Europa and those on Earth may generate ideas useful in the study of terrestrial faulting.	This zoomed in section of the Galileo data shows what appears to be the central crack where the fault originally opened. Successive layers, like tree rings, form as material (warmer, softer ice from below Europa's brittle ice shell surface, or frozen water from a possible subsurface ocean) enters the gap periodically from below and hardens.