Sally S. – Door County WI
We really appreciate your help & working with you on our dock!
We really appreciate your help & working with you on our dock!
Ice Shove, Ice Heave, Ice Surge, or Ice Tsunami, no matter what you call it, they all refer to the same natural phenomena.
First, you need to understand how a pressure ridge forms so please follow this link to this article: https://wisconsinpws.com/ice-pressure-ridge/
The pressure ridge is the usual predecessor of an ice shove.
Having read the article, we need to talk very briefly about the terminology of a pressure ridge.
From the previous article, you can see the “rubble” forming the “Keel” of the pressure ridge. After the Keel forms the “Sail” forms above the surface of the ice. When the next strong wind comes along the “sail” will begin pushing against the shore ice. Eventually, some of it will begin to climb over the shore ice and form an ice shove.
Ice shoves normally happen during a spell of warmer weather. However, the shove may happen anytime the ice is weakened and then exposed to strong winds.
A shove is more likely to occur the longer the ice is exposed to the winds. The most common time of the year to see this phenomenon is late February and into March although January is not unheard of if a thaw occurs.
The shove occurs when strong winds rapidly push free-floating ice towards or along the shore. Strong winds over time drive areas of ice onshore. As these moving masses of ice travel towards the shoreline, they begin piling up when they encounter resistance from the shoreline or other obstacles. The resulting shove can reach heights of up to 50 feet.
An ice shove has tremendous power and have been known to push houses off their foundations and uproot large trees and crush seawalls.
Shoreline barriers like trees, seawalls and shallow cliffs do not present any challenge to an ice shove. The ice simply piles up until it flows over the object or simply crushes it. The shove could continue on its journey as long as the winds continue. This depends on the force of the wind and the strength of the ice. One or two properties may be affected while the adjoining properties see no movement at all.
There is only one thing that you can do – move your waterfront equipment far enough away that the ice normally will not get to it. In doubt? Watch what your neighbors do in Fall. If they have been there for any length of time they know how far back to go to protect their equipment in a normal year. Our crews remove equipment in Fall and have a good idea where it has to go also.
With little or no shoreline, here’s an example of what PWS does to prevent damage to your equipment. The lift and dock had to be raised to the top of a ledge to avoid damage.
Ice Shoves sometimes affect a small area of shoreline all the way up to vast distances. This ice shove affected just one property while the neighbors had no damage.
For more information check this video to see an actual ice shove in action: https://www.youtube.com/watch?v=Pf5pWz7uRt4
Pier & Waterfront Solutions specializes in ShoreMaster docks, lifts, and accessories both residential and commercial. We service the rest.
PWS is located in the center of Door County at 7325 St Hwy 57. Located 1 mile North of County MM (Hwy 42) and South of Sturgeon Bay at the intersection of Idlewild Road. Our staff is ready to help you anytime.
Want us to address a dock or boat lift topic for you? Feel free to give us a call.
Call Jerry at 920-493-4404 or email him at Jerry@wisconsinpws.com for more information.
A pressure ridge is the result of a change in temperature which causes the ice to crack and form a floating ice sheet. This formation is usually located a few hundred feet off the shoreline. This is the beginning of a pressure ridge.
The ice near the shore is anchored securely to the shoreline. The floating ice on the outer side of the crack separates and then is moved back to the joint by the winds. The resulting pressure builds up and crushes the edges into pieces called rubble.
The rubble forms the “Keel” of a ridge, which as the name implies, is below the water line. The loose rubble accumulates and builds up until it reaches the bottom of the water. After reaching the bottom the remaining crumbed ice at the surface begins to move vertically. This forms the “Sail” portion or upper part of the pressure ridge. The “sail” is the part you actually see on the surface of the ice. It can be a foot high or several feet high.
The pressure ridge can form very rapidly especially when the wind direction shifts. Since the rubble below is exposed to non-freezing temperatures, it can melt away.. This will leave a very weak and fluctuating joint at the surface.
Ice shoves occur during warmer weather also- normally in late February and into March. They require a steady or gusty, strong wind over a period of time.
The ice shove occurs when strong winds rapidly push free floating ice towards the shore. Strong winds from the same direction over, say, a 12 to 24 hour period, are enough to drive huge areas of ice onshore. As these moving masses of ice move towards the shoreline they will begin piling up when they encounter resistance from the shoreline or other obstacles. The resulting ice shove can reach heights of 50 feet.
An ice shove has tremendous power and have been known to push houses off their foundations and uproot large trees. Shoreline barriers like trees, seawalls and shallow cliffs are not a challenge for a ice shove. The ice simply piles up as shown above until it flows over the object or crushes it. It will continue on its journey as long as the wind continues to blow. (See the video at the end of this article for a demonstration of an ice shove)
Ice Shoves can affect a small area of shoreline or vast distances depending on the force of the wind and the strength of the ice. At times, one or two properties are affected while the adjoining properties see no movement at all.
Simple – In the fall move your docks and lifts far enough back that the ice normally will not get to it. In doubt? Watch what your neighbors do. They know how far back to go.
Here’s an example of what PWS has had to do to prevent damage from ice shoves when there is little or no shoreline:
Boat Lift being removed for winter
This lift and accompanying dock had to be raised to the top of a ledge because there was inadequate shoreline available to protect the equipment from any ice movement.
For more information check this video to see an actual ice shove in action: www.youtube.com/watch?v=Pf5pWz7uRt4
Found this article helpful? Call Jerry at 920-493-4404 or Email Jerry@wisconsinpws.com for more information. Also go to “NEWS” on any page of our website for a complete list of articles meant to keep you informed on the latest product information and maintenance issues.