Africa's ups and downs

Aug 08, 2013

The East African Rift is an area where two tectonic plates are moving apart, making it a region of high geological activity, home to a number of volcanoes.

This animation shows how satellite radars – like the one flown on Envisat – can detect surface displacement with centimetre accuracy from an altitude of about 800 km.

Interferometric Synthetic Aperture Radar – or InSAR – is a remote sensing technique where two or more over the same area are combined to detect slight surface changes between them.

Tiny changes on the ground cause changes in the radar signal and lead to rainbow-coloured in the combined image, known as a 'SAR interferogram'. These interferograms can then show how land is uplifting or subsiding.

For example, Envisat found that the dormant Mount Longonot in Kenya rose by 9 cm from 2004 to 2006. Tectonic activity such as the movement of magma underground may have caused this deformation of the surface above.

Radars can also identify fault lines – such as the radar on the Japanese ALOS satellite. Ground displacement following a series of earthquakes around Karonga, Malawi, was detected in the interferogram, revealing details of a fault line. The visualisations are based on results by Juliet Biggs from the University of Bristol in the UK.

This video is not supported by your browser at this time.
Animation of geological activity of the East African Rift as observed by radars on the Envisat and ALOS satellites. This animation is based on a study by Juliet Biggs from the University of Bristol, UK, as part of ESA’s STSE Changing Earth Science Network Initiative. Credit: Planetary Visions/NERC-COMET/JAXA/ESA

Measurements like those seen in this animation are helping scientists to understand plate tectonics. They provide insights into patterns and consequences of activity that can help to get a clearer picture of a volcano's behaviour.

Explore further: Image: Dronning Maud Land in Antarctica, as seen by ESA's Proba-1

Related Stories

Keeping an eye on volcanoes, from the sky

Mar 29, 2012

The importance of global and frequent data coverage of volcanoes was highlighted in a recent article published in Science. Satellites are finding that volcanoes previously thought to be dormant are showin ...

Image: Volcanic uplift

Jul 02, 2010

(PhysOrg.com) -- This Envisat Advanced Synthetic Aperture Radar interferogram over the Kenyan section of the Great Rift Valley shows small surface displacements that are not visible to the naked eye of the ...

Satellites show how Earth moved during Italy quake

Apr 15, 2009

(PhysOrg.com) -- Studying satellite radar data from ESA's Envisat and the Italian Space Agency's COSMO-SkyMed, scientists have begun analysing the movement of Earth during and after the 6.3 earthquake that ...

Taking the 'pulse' of volcanoes using satellite images

Nov 05, 2012

A new study by scientists at the University of Miami (UM) Rosenstiel School of Marine & Atmospheric Science uses Interferometric Synthetic Aperture Radar (InSAR) data to investigate deformation prior to the eruption of active ...

Recommended for you

Can lightning strike an indoor pool?

8 hours ago

Two swimming pool weather policies have surprised me in recent years. One was when I showed up to swim laps at an outdoor pool as it was beginning to drizzle. "Come on in," I was told; as long as there was no lightning, the ...

Image: Eruption of Wolf Volcano, Galapagos Islands

10 hours ago

In late May 2015, the highest volcano in the Galapagos Islands erupted for the first time in 33 years. The explosive eruption at Wolf volcano on Isabela Island sent volcanic gases and ash roughly 15 kilometers ...

NASA sees new depression forms near Solomon Islands

Jun 30, 2015

The Southern Pacific Ocean Tropical Cyclone Season just got an extension with the birth of a new tropical depression near the Solomon Islands. NASA's Aqua satellite passed over the new depression and saw ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.