In 1997, Steve Colman set out with a team to survey the sediments under Bear Lake using acoustic profiling.
This method, commonly used to study marine sediments, is also called seismic-reflection profiling. The equipment generates an underwater noise
and then measures how long it takes for the sound waves to return to the surface after reflecting off the lake floor and off layers of sediment
below the lake. Soft bangs are emitted at regular intervals as the boat towing the equipment travels over the lake surface. The path that the
boat takes as it sends and receives the sound is called a seismic line (see seismic map figure at right). The result is a series of profiles along the seismic lines, which show us sediment layers and densities, the location of faults that may disturb the sediment pattern, and where the deepest sediments occur within the lake basin. Gravity and currents typically move sediment from the shallows to the depths, and Bear Lake is no exception. The west-east profile (see seismic profile figure below) shows sediment layers, highlighted by different colored pens, get thicker toward the deep end of the lake along the eastern side. In this profile, three faults are visible, identified by the downward displacement of some layers relative to those immediately beside them. Lines and arrows have been added to mark the fault borders and show which direction the sediments moved along the faults. Read more about earthquakes in the Bear Lake area. |
![]() |