Are Ice Quakes the Same as Earthquakes? - A-Z Animals

Earth is a dynamic place with a surface that sometimes shifts dramatically enough to cause shaking. This shaking occurs in many places on the planet including around glaciers and ice sheets. Are ice quakes the same as earthquakes? We’ll take a look now.

Are Ice Quakes the Same as Earthquakes?

No, ice quakes are not the same as earthquakes. While both events create a disturbance that registers on the Moment Magnitude Scale, the reasons behind their occurrences are different.

The shaking caused by an ice quake is much more intense at its epicenter than an earthquake. Earthquakes also radiate much farther from their epicenter and are felt for greater distances. Ice quakes can last up to a minute, while most earthquakes are over in seconds unless they’re catastrophic.

What Causes an Ice Quake?

Ice quakes, also called cryoseisms or frost quakes, occur when stress caused by the melting and freezing of ice suddenly releases into the environment. These events are strong enough to have a seismic reading. The source of ice quakes can come from rock or soil full of ice, from glacial movement, or as a result of shifts in frozen lakes.

Conditions that lead to a non-glacial ice quake are specific. Water must have permeated and saturated the soil right before an Arctic or polar air mass moves into the region. This saturation can occur because of precipitation, flooding, or melted ice.

When temperatures plummet from above freezing into subzero conditions quickly, ice quakes are more likely to occur. They are also more likely to occur when it’s coldest in the middle of the night or before the sun rises.

Glacial Earthquakes

A glacial earthquake is a special kind of ice quake. They happen when a big piece of ice falls off of a moving glacier. They also happen when a glacier suddenly moves.

As ice falls off a glacier, it momentarily pushes against the glacier from which it came. When this happens, the massive mother glacier is pushed back along its trajectory.

Once the piece has finished breaking off, the glacier moves back into its original position. This backward and forward movement causes a glacial earthquake via friction between the ice and the ground.

These events can be relatively large and register over a magnitude of 5 on the Moment Magnitude Scale. These types of seismic events are usually caused by more than 100 billion tons of ice in motion.

What Causes an Earthquake?

Earthquakes are caused by motion in faultlines on the surface of the planet. This sudden motion is caused by the release of energy that forms due to straining. This straining is caused by rocks moving against each other in a way that causes distortion.

When faultlines move, they send energy in the form of seismic waves through the ground. These seismic waves cause shaking that can be mild to violent depending on what kind of movement is taking place.

Earthquakes can trigger ice quakes. For example, a huge earthquake with a magnitude of 8.8 near Chile on February 27, 2010, sent seismic waves to Antarctica that triggered smaller earthquakes and ice quakes. The shaking caused the ice to shift which resulted in shaking from ice displacement.

Where do Ice Quakes Occur?

Ice quakes can happen anywhere, especially during an unprecedented thaw. Recorded ice quakes have occurred in North America. The regions affected are mainly the Great Lakes region in both the United States and Canada, New England, Alberta, Ontario, and Quebec.

Glacial earthquakes are observed in Antarctica, Finland, Alaska, Greenland, and Iceland. The largest of these occurrences happen in Antarctica and Greenland because they’re covered in a massive ice sheet. As this ice sheet moves and cracks, it causes seismic activity.

Why Do People See Flashing Lights Before an Earthquake or Ice Quake?

The appearance of lights during a shakedown of the Earth’s surface has been noted since ancient history. However, nobody is quite sure why it happens.

One theory is that certain rocks experiencing stress during the event cause the lights though this remains unsubstantiated. It may be that impure crystals fracture as the stress leading to the quake reaches its peak creating electricity.

Sometimes these lights flash in different colors while other times they look almost like an aurora. They’ve been observed as orbs floating in the air, or as flame-like apparitions moving along the ground.

These lights interest scientists because they might be usable as an early detection system for impending earthquakes. Most of the captured images of these lights occurred right before or during larger earthquakes of magnitude 5 or above. They’re also sometimes visible over 350 miles from the quake’s epicenter.

These lights also appear before some ice quakes. The same mechanisms causing them in earthquakes are probably to blame.

The photo featured at the top of this post is © National Park Service, Alaska Region, Public domain, via Wikimedia Commons – License / Original