When the waves approach land, they will slow down and begin to grow in height. If a quake hits locally, or the quake causes an underwater landslide in Kachemak Bay, you may only have 15 to 20 minutes.

Tsunamis occur most often in the Pacific Ocean and Indonesia because the Pacific Rim bordering the Ocean has a large number of active submarine earthquake zones. However, tsunamis have also occurred recently in the Mediterranean Sea region and are expected in the Caribbean Sea as well.

The vast majority of tsunamis form due to earthquakes — specifically tectonic tsunamis. As an earthquake happens, the ground beneath the water is moved up and/or down abruptly and as this movement happens, a mass of water is displaced and starts moving in all directions. This marks the start of a tsunami.

Tsunamis can be generated when the sea floor abruptly deforms and vertically displaces the overlying water. When large areas of the sea floor elevate or subside, a tsunami can be created. Large vertical movements of the earth’s crust can occur at plate boundaries.

IF YOU ARE UNDER A TSUNAMI WARNING:

1. First, protect yourself from an Earthquake.
2. Get to high ground as far inland as possible.
3. Be alert to signs of a tsunami, such as a sudden rise or draining of ocean waters.
4. Listen to emergency information and alerts.
5. Evacuate: DO NOT wait!
6. If you are in a boat, go out to sea.

The least probable, but still possible, cause is the impact of an asteroid or a meteorite in the sea, while the more frequent causes are underwater disturbances: a volcanic collapse, a landslide or an earthquake. Not all earthquakes generate tsunamis.

Tsunamis can be generated on impact as a rapidly moving landslide mass enters the water or as water displaces behind and ahead of a rapidly moving underwater landslide.