Virtual Earthquakes, Virtual Sensors, and the Extraordinary Theory of Interferometry

Scientific Seminar

Dr. Andrew Curtis
University of Edinburgh, UK

Time:      Thursday, September 4,  2008, 11 am
Room:    Building H, VR2

 

Abstract:

Virtual Earthquakes, Virtual Sensors, and the Extraordinary Theory of Interferometry

The new theory of wavefield interferometry, applicable in (an)elastic, electromagnetic and diffusive regimes, is revolutionising seismological Earth observation. For example, recordings of noise from between earthquake occurrences used to be ignored but can now be converted into earthquake-like seismograms from 'virtual' (imagined) earthquake or energy sources. Such seismograms are used to image the real Earth's subsurface.

Using similar theory we have now shown that any well-recorded real energy source such as an earthquake or explosion can itself be converted into a 'virtual' receiver (seismometer). In turn such receivers can be used to record seismograms from other earthquakes or explosions even if they occurred before the original energy source. Such virtual receivers are strain sensors and may be located non-invasively within the Earth's interior.

In exploration seismology seismic interferometry provides new ways to image the top few kilometres of the Earth, and to remove common forms of noise (ground roll and all near surface effects) from seismic records.

This talk will explain the principles behind these extraordinary developments. It will also show how this new theory can in some ways be thought of as a generalisation of standard receiver function analysis, and how it allows the roles of sources and receivers to be thought of as almost synonymous.

More information at: http://www.geolsoc.org.uk/page3182_en.html