Since the 1950s oceanographers have known that seismographs sometimes pick up ocean waves and sometimes referred to them as Microseismic waves. There was little practical applications until pretty recently.
In the past few years though a few scientist have been looking at the microsiesmic data both and land and in a new series of undersea instruments that survive powerful storms better than buoys or ships.
The new applications of the data are being used to study recent storms and providing a lot of information about frequency and size of storm waves. This should improve both sea state forecast, analysis of the storm itself, and forecast of coastal damage.
In a different application of microsiesmic data to research large storms of the past, particularly before there was a dense network of land stations. The buoy network is also pretty new and ships either avoided such storms after radio become common, didn't survive, or when they did report were largely reporting their dead reckoning position prior to Loran navigation. Ships also tend to follow narrow band of ship routes after reliable engines were invented while sailing ships traversed a wider range of seas.
Anyhow scientist are starting to sort through the seismograph data that goes back the 19th century, digitizing what was recorded on paper, and analyzing that data for P-waves from strong ocean storms hundreds of miles away. This should help identify frequency and intensity of past storms--something of great interest given the warming of the past century.
Like many of the natural sciences this is an example of using data from other fields
in ways never imagined to fill in gaps and seams in the past. I think it's neat.