All of which have application to the geotechnical engineer and should be seen as another tool in your toolbox.
Please post in this forum if you have any questions about how geophysics can help with your specific problem, or help better approach a problem you often encounter. Post a problem and some information on the project and let the geophysics community see what we can do to provide you a solution that can help.
Seismoelectrics exploits the physical phenomena that stress waves induce electrical currents in the ground. A seismic source is used to generate stress waves and the induced electrical currents are then mapped to determine variations in the layering of ground materials.
It is a method that is primarily used in the exploration for minerals as sulfides and ore bodies generate large electrical currents relative to background, but has been applied to shallower mapping of top of bedrock, although in these cases there are other methods that would probably be better suited to the task of bedrock delineation (true seismic methods, GPR, or electrical resistivity).