Lava temperatures determine flow composition on Earth and Io.

Post by Robert Wright, and Mary C. Bourke,

Hawaii Institute of Geophysics and Planetology, University of Hawaii at Manoa, US.

Department of Geography, Trinity College, Dublin, Ireland.

Image 1: A Giant plume from Io’s Tvashtar volcano composed of a sequence of five images taken by NASA’s New Horizons probe on March 1st 2007, over the course of eight minutes from 23:50 UT. The plume is 330 km high, though only its uppermost half is visible in this image, as its source lies over the moon’s limb on its far side. Image source from NASA.

The temperature at which active lava is erupted correlates well with the composition of the lava.  Mafic lavas may be up to 200-330 degrees celsius hotter than felsic lavas. The range of temperatures observed on active lava surfaces can also be used to determine the style with which the lava is erupted (i.e. as aa or pahoehoe lava flows, as lava lakes, or as lava domes). This is possible because the ease with which the crust is fractured depends on the volumetric flux of lava and its rheology (Image 2). As a result, lava bodies that fracture their cool crusts more easily (like aa flows) have hotter temperature distributions than those that fracture their upper surfaces less readily (such as viscous lava domes). (more…)

Lava Flows on Mars, Io, and Earth

Post by Dr. Jim Zimbelman

Lava flows are one of the common landforms encountered on various objects throughout the inner solar system, as well as on Jupiter’s volcanically active moon Io. Cameras and other remote sensing instruments on various spacecraft have returned an incredible amount of data about lava flows on planetary surfaces. Here we will highlight a couple of examples, along with recent work on lava flows on Earth that is providing new insight into how we can study lava flows on other planets.

Lava Flow on Ascraeus Mons, Mars

Image 1: The image is a portion of frame S08-02516 taken by the Mars Orbiter Camera, which shows part of a heavily cratered lava flow on the flank of the Ascraeus Mons shield volcano in the Tharsis region. The abundance of impact craters on the flow indicates that it is not very recent.

(more…)

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