Conventional crosswell surveys are expensive because a source must be placed downhole, which means that the hole must be prepped and placed off-line for a number of days. We suggest an interesting but unproven alternative: place a source on the surface, drop a simple obstruction-like device downhole that scatters tube wave arrivals from the surface source, and use the scattered tube waves energ...

to increase the safety of structures against strong ground motions and their life due to environmental issues on the earth and saving in terms of materials, it is necessary to expand and upgrade seismic resistant systems. however, more cost-effective systems which have sufficient influence on the seismic performance of structures and also more compatibility with the regional conditions, will be...

Recently developed numerical simulation technique can simulate the coupled seismic and electromagnetic signals for a double couple point source or a finite fault planar source. Besides the source effect, the simulation results showed that both medium structure and medium property could affect the coupled seismic and electromagnetic signals. The waveform of coupled signals for a layered structur...

Real-time location of earthquakes can be achieved by using direct imaging of the recorded wave field based on a Kirchhoff reconstruction method similar to that used in the migration of seismic reflection data. The standard method of event location requires the wave arrival at each sensor to be picked and associated with an event. By using direct imaging, the event is identified once in the imag...

S U M M A R Y Converted phase (CP) elastic seismic signals are comparable in amplitude to the primary signals recorded at large offsets and have the potential to be used in seismic imaging and velocity analysis. We present an approach for CP elastic wave equation velocity analysis that does not use source information and is applicable to surface-seismic, microseismic, teleseismic and vertical s...