Warning levels

Issued to inform emergency management officials and the public that an earthquake has occurred, or that a tsunami watch, advisory, or warning has been issued for another section of the ocean.

It’s often meant to indicate there’s no threat of a destructive tsunami and to prevent unnecessary evacuations as the disturbance may have been felt in coastal areas. It may nonetheless caution about the possibility of destructive local tsunamis in some cases.

Although uncommon, it may also be re-issued with additional information, or upgraded if necessary after analysis and/or updated information becomes available.

Issued to alert emergency management officials and the public of an event which may later impact the concerned area, normally based on seismic information without confirmation that a destructive tsunami is underway.

It may be upgraded to a warning or advisory – or merely cancelled – based on updated information and analysis.

Emergency management officials and the public should prepare to take action.

Issued when a tsunami with the potential to generate strong currents or dangerous waves in or very near the water is imminent, expected, or occurring. The threat may continue for several hours after initial arrival, but significant inundation is not expected.

Normally updated to be extended, to adjust affected areas, to be upgraded to a warning, or to be cancelled.

Local officials must take action, which may include closing beaches, evacuating harbours and marinas, and the repositioning of ships to deep waters when there’s time to safely do so.

Issued when a tsunami with the potential to generate widespread inundation is imminent, expected, or occurring. Dangerous coastal flooding and currents are also possible and may continue for several hours.

To provide the earliest possible alert, it’s often issued based only on seismic information. It may later be updated, adjusted geographically, downgraded, or cancelled.

Emergency management officials must take action for the entire tsunami hazard zone, which may include the evacuation of low-lying coastal areas, and the repositioning of ships to deep waters when there's time to safely do so.

• Not felt even under the most favourable circumstances.
• No effect.
• No damage.

• Felt by few people on board in small vessels. Not observed in the coast.
• No effect.
• No damage.

• Felt by most people on board in small vessels. Observed by few people in the coast.
• No effect.
• No damage.

• Felt by everyone on board in small vessels and by few people on board in large vessels. Observed by most people in the coast.
• Few small vessels move slightly onshore.
• No damage.

• Felt by everyone on board in large vessels and observed by everyone in the coast. Few people are frightened and run to higher ground.
• Many small vessels move strongly onshore, few of them crash into each other or overturn. Traces of sand layer are left behind in grounds of favourable conditions. Limited flooding of cultivated land.
• Limited flooding of outdoor facilities (e.g. gardens) of near-shore structures.

• Many people are frightened and run to higher ground.
• Most small vessels move violently onshore, or crash strongly into each other or overturn.
• Damage and flooding in a few wooden structures. Most masonry buildings withstand. 

• Most people are frightened and try to run to higher ground.
• Many small vessels damaged. Few large vessels oscillate violently. Objects of variable size and stability overturn and drift. Sand layer and accumulations of pebbles are left behind. Few aquaculture rafts washed away.
• Many wooden structures damaged, few are demolished or washed away. Slight damage and flooding in a few masonry buildings.

• All people escape to higher ground, a few are washed away.
• Most small vessels are damaged, many are washed away. Few large vessels are moved ashore or crash into each other. Big objects are drifted away. Erosion and littering in the beach. Extensive flooding. Slight damage in tsunami control forest, stop-drifts. Many aquaculture rafts washed away, few partially damaged.
• Most wooden structures are washed away or demolished. Moderate damage in a few masonry buildings. Most reinforced concrete buildings sustain damage, slight damage and flooding is observed in a few.

• Many people are washed away.
• Most small vessels are destroyed or washed away. Many large vessels are moved violently ashore, few are destroyed. Extensive erosion and littering of the beach. Local ground subsidence. Partial destruction in tsunami control forest, stop-drifts. Most aquaculture rafts washed away, many partially damaged.
• Heavy damage in many masonry buildings, few reinforced concrete buildings suffer moderate damage.

• General panic. Most people are washed away.
• Most large vessels are moved violently ashore, many are destroyed or collide with buildings. Small boulders from the sea bottom are moved inland. Cars overturned and drifted. Oil spills, fires start. Extensive ground subsidence.
• Total damage in many masonry buildings, few reinforced concrete buildings suffer heavy damage. Artificial embankments collapse, port water breaks damaged.

• Lifelines interrupted. Extensive fires. Water backwash drifts cars and other objects into the sea. Big boulders from the sea bottom are moved inland.
• Many masonry buildings are destroyed. Few reinforced concrete buildings suffer total damage, many suffer heavy damage.

• Practically all masonry buildings demolished. Most reinforced concrete buildings suffer at least heavy damage.