Image reveals secrets of Chile earthquake
[SANTIAGO] The first detailed and complete satellite image of the dramatic changes to the Earth's surface caused by the powerful earthquake that hit Chile in February has been released.
The ground deformations revealed by the satellite data will have major implications for the understanding of earthquakes everywhere, scientists say.
The image, which covers the full 600 kilometres of the earthquake, was issued by Japan's National Research Institute for Earth Sciences and Disaster Prevention (NIED) last week (6 April) and consists of pictures captured by the Japanese Advanced Land Observing Satellite (ALOS) or 'DAICHI'.
It compares the shape of the ground before and after the February earthquake from pictures taken on 10 April 2008 and on 1 March 2010 — two days after the earthquake, which measured 8.8 on the Richter scale.
The image reveals that the displacement across the 600 kilometre fault line where the earthquake occurred was not uniform, which explains why the impact was greater in some areas than in others and why the tsunami triggered by the earthquake had varying heights, forces and directions.
"By examining data gathered before and after this major earthquake, seismologists will have a better sense of what can be expected from an event of this magnitude, what should be measured, and what may happen to the fault line in the north of Chile that is expected to trigger a new earthquake," said Andrés Pavez, a geologist and geophysicist at the University of Chile.
The image will become the "reference figure" for the earthquake, added Sergio Barrientos, scientific director of seismological services at the University of Chile.
It was captured by a sensor on ALOS that penetrates vegetation and takes clear pictures during the day and night in any weather conditions. Images taken before and after the event were combined using a method called interferometry, which reveals deformities in the Earth's terrain with precision.
Scientists at the University of Chile's geophysics department are using about 100 permanent and temporary Global Positioning System (GPS) stations to 'ground-truth' the image (calibrate data sensed remotely) and develop models.
"Since we cannot access the Nazca and South America [tectonic] plates that cause earthquakes in Chile, we need models to measure deformations in the Earth's crust," said Barrientos.
Link to full satellite analysis image of earthquake