Today’s Instructional Lesson: Seiches

A seiche is an oscillation associated with a standing wave that occurs in an enclosed or partially enclosed body of water, resulting from seismic activity or meteorological effects.

graphic of wind-driven seiche
Click to view this University of Wisconsin Sea Grant Institute animation of a wind-driven seiche. Seiches are not uncommon phenomena on the Great Lakes and adjacent bays and rivers.

Seiches have been observed on lakes, reservoirs, ponds, rivers, and even swimming pools. You can create your own seiche in your bathtub, just by rocking back and forth. At the right frequency, you can set up an oscillation–essentially a small-scale seiche–that allows the waves to grow until they overflow the bath.

A similar “sloshing”–in this case a seismic seiche–was observed on Saturday, February 27, on Lake Pontchartrain in Louisiana, caused by an earthquake 4,700 miles away off the coast of Maule, Chile. Lake Pontchartrain sits on the Mississippi Delta, which contains a deep layer of surface sediments. Seismic waves can resonate through this sediment more easily than through more firm surface types, making the Gulf region particularly sensitive to earthquake-induced seiches. The seiche affecting Lake Pontchartrain occurred 11 minutes after the 8.8 magnitude Chilean earthquake and resulted in water levels about 6 inches higher than the predicted tides.

Want the video version? Derek Kevra at WWLTV has a great explanation of the quake and resulting seiche here. And if you want to learn more about seiches in history, check out this page from the USGS Earthquake Hazards program.


One thought on “Today’s Instructional Lesson: Seiches

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s