The Guide to Earthquakes & Tsunamis in American Samoa

American Samoa is situated within the Pacific Ring of Fire and lies just northwest of the Tonga Trench, making it vulnerable to seismic activity. According to ThinkHazard.org, there is a moderate risk, with about a 10% chance of a potentially damaging earthquake occurring in the next 50 years.

Most earthquakes that affect American Samoa happen offshore, beneath the ocean floor. Because of this, tsunamis pose a greater threat to the islands than ground shaking alone.

Tsunamis are the most serious natural hazard in American Samoa, typically triggered by offshore earthquakes, though undersea landslides and volcanic activity can also cause them.

Since the 1800s, American Samoa has experienced multiple tsunamis, but the most devastating occurred on 29 September 2009. A magnitude 8.0 earthquake struck at 6:48 am, about 193 km (120 mi) southwest of Pago Pago.

Just minutes later, waves reaching up to 15 m (50 ft) hit parts of Tutuila and the Manu'a Islands, resulting in 32 deaths in American Samoa and causing widespread destruction. The 2009 tsunami remains the most catastrophic in the territory's history.

How to Prepare for a Tsunami in American Samoa

American Samoa has an established tsunami warning system, including coastal sirens, radio broadcasts and alerts from the American Samoa Department of Homeland Security. Still, travellers should take extra steps:

• Sign up for alerts from NOAA or the Pacific Tsunami Warning Center
• Be aware of tsunami evacuation maps for where you’re staying and take note of tsunami evacuation signs
• Listen out for tsunami warnings emitted through radio, TV, online on news websites.

What to Do if a Tsunami Warning is Issued

Tsunami warnings can be issued through news media in the South Pacific. Other signs of a tsunami could be a strong earthquake, seeing the ocean recede and/or hearing unusual roaring sounds from the ocean. If any of these signs occur, follow the steps:

• If you see signs of a tsunami before a tsunami warning is issued, act immediately
• If you’re on the coast, move inland and to higher ground immediately
• Head to areas as advised on tsunami evacuation maps and or follow tsunami evacuation signage, if available.

After a tsunami, continue listening to the media for announcements. Only move back into the affected areas when authorities have said it is safe to do so.

Now that you know about natural disasters in American Samoa, here are the answers to the internet's frequently asked questions about earthquakes, tsunamis and natural disasters in American Samoa!

Has American Samoa ever been hit by a tsunami?

Yes, American Samoa was devastated by a major tsunami on 29th September 2009, which was triggered by an 8.0 magnitude earthquake. The tsunami caused significant damage and loss of life across the islands.

What natural disasters are common in American Samoa?

The most common natural disasters in American Samoa include earthquakes, tsunamis, tropical cyclones and flash flooding. The territory's location in the Pacific makes it vulnerable to these weather-related and geological events.

Is there a tsunami warning system in American Samoa?

Yes, American Samoa has a comprehensive tsunami warning system that includes sirens, emergency broadcasts and mobile alerts. The Pacific Tsunami Warning Centre monitors seismic activity and issues warnings when necessary.

When is cyclone season in American Samoa?

Cyclone season in American Samoa typically runs from November to April, with peak activity occurring between December and March. During this period, the island is at higher risk of tropical storms and cyclones. For more information, check out American Samoa Weather, Seasons & Climate + Weather by Month.

What should I do if there's an earthquake in American Samoa?

If you experience an earthquake in American Samoa, immediately drop to your hands and knees, take cover under a sturdy desk or table, and hold on until the shaking stops. If you're near the coast, move to higher ground immediately after the shaking ends due to tsunami risk.