Miros Measuring Mini-Tsunami Phenomenon in the Oslofjord

Flaskebekk, a small community on the edge of the Oslofjord, regularly experiences what are being termed as “mini-tsunamis”, ostensibly caused by large ships passing areas of the fjord with pronounced variations in water depth. These waves, which are eroding the foundations of Flaskebekk’s boathouses and docks, can reach 1.5 metres in height, with a period of 30-60 seconds.

Miros is working with the local community to measure the wave height, wavelength and wave period of these “mini-tsunamis” in order to better understand their causes and impacts. To measure these parameters Miros has installed their WaveWeather solution on the shore at Flaskebekk.

WaveWeather consists of a highly accurate radar-based wave measurement sensor, The Miros RangeFinder (SM-140), paired with multiparameter meteorological instrumentation. The solution not only measures real-time wave data and water level, but also provides wind speed, wind direction, temperature and more. Dry mounting ensures that equipment is not impacted by the corrosive saltwater environment, the force of waves, floating objects or biofouling.

“This is a good example of how sophisticated technologies developed for major industrial applications can also be applied to the benefit of local communities,” said Miros CEO Andreas Brekke.

The “Mini-Tsunami” Phenomenon

Unlike normal ocean waves which are generated by wind or tides, tsunamis occur when large volumes of water are displaced. This type of wave is typically generated by earthquakes or rock slides. At Flaskebekk, however, the “mini-tsunamis” seem to be caused by large ships passing areas of the fjord where there are significant variations in sea depth. A long wave entering shallow water will be reduced in length but will grow in height, compounding its impact when meeting the shoreline.

“We hope our contribution will help build a better understanding of these curious ‘mini-tsunamis’,” said Brekke.