article_snippet: In particualr Scientists monitored the ionosphere, the layer of the Earth's atmosphere which contains a high concentration of ions and free electrons and is able to reflect radio waves.
article_snippet: The study which was co-authored by Professor Friedemann Freund of the SETI Institute and Professor Jean-Pierre Raulin of the Centre of Radio Astronomy and Astrophysics Mackenzie (CRAAM) in Brazil, and is published by the journal Physics and Chemistry of Earth, looked at reasons for this disappearance.
article_snippet: The study which was co-authored by Professor Friedemann Freund of the SETI Institute and Professor Jean-Pierre Raulin of the Centre of Radio Astronomy and Astrophysics Mackenzie (CRAAM) in Brazil, and is published by the journal Physics and Chemistry of the Earth recorded the reflection of very low frequency (VLF) radio waves above the area surrounding the epicentre.
article_snippet: The scientists detected disturbances in the ionosphere - the layer of Earth's atmosphere which contains a high concentration of ions and free electrons and is able to reflect radio waves - which started two weeks before the earthquake.
article_snippet: The results are particularly interesting as we also found evidence of disturbances in the ionosphere in the area where the quake struck.
article_snippet: We believe that both of these anomalies arise from a single cause: seismic activity causing stress build-up in the earth’s crust, leading, among other things, to massive air ionisation.
article_snippet: Professor Friedemann Freund of the Seti Institute, who works at Nasa’s Ames Research Centre in California, added:
article_snippet: If air ionisation occurred, air ionisation is likely that air ionisation was particularly strong along such a ridge.
article_snippet: These changes, that we are now able to measure, express These changes, that we are now able to measure in many different ways at Earth’s surface and above.