The sensors detect signals from many different sources that include cars, boats and machinery operating up to several kilometers away. They also pick up the background "hum of the Earth" caused by ocean waves breaking on continental shelves around the world.
Scientists noticed that sensors on Barro Colorado recorded an intriguing wave pattern at an intermediate frequency. They suspected that this pattern could be caused by standing waves in Lake Gatun. Standing waves, also known as "seiches," are common in enclosed bodies of water like lakes and harbors where waves moving in opposite directions interact. By installing a water-level detection meter along the shoreline, researchers confirmed that changes in the water level of the lake correspond to the unusual seismic signal.
This is not the first report of seiches in Lake Gatun. Earlier reports correlated the release of methane gasses in the sediments below the canal to seiches and bottom currents in the lake. The Panama Canal Authority provided data about the depth of the Canal channel and of Lake Gatun that the authors used to model wave patterns in the lake.
Boat traffic and wind speed correlate with the unusual wave pattern, which was more common during the day than it was at night, but more information is needed to confirm what is actually causing the waves.
