Tsunamis and Richmond
Tsunamis 101
The word "tsunami" is from the Japanese words tsu (harbor) and nami (wave). Tsunamis are large wave events caused by a significant displacement of water. The displaced water propagating from the source becomes a tsunami. Tsunami wavelengths are usually very long, sometimes hundreds of kilometres long and can move at speeds similar to trans-Pacific airline flights, up to 1000 kph. The massive December 26, 2004 tsunami traveled at speeds of 480 kph and therefore traveled 600 km in 75 minutes.
The most common cause of tsunamis is underwater earthquakes, however, an underwater landslide, a major oceanic volcanic eruption, and less commonly, a meteorite oceanic landing can also generate these large waves. For a better understanding of earthquakes and the potential impact of an earthquake on Richmond refer to the Earthquakes section of the website.
All waves are made up of a crest (the highest point of the wave) and a trough (the lowest point of the wave). However, there are many differences between a normal wave and tsunami wave, primarily size, speed and source. The chart below shows some of the differences.
| Typical Tsunami Wave vs. Typical Wind-generated Wave | ||
|---|---|---|
| Wave Feature | Wind-generated Wave | Tsunami Wave |
| Wave Speed | 8 -100 kph | 800 - 1,000 kph |
| Wave Period (time required for two waves to pass a single point in space) | 5 to 20 second apart | 10 minutes to 2 hours apart |
| Wave Length (horizontal distance between two waves) | 300 - 600 feet apart (100 - 200 meters apart) | 100 - 500 km apart |
A tsunami moves faster in deeper water and slower in shallower water. So unlike a normal wave, the driving energy of a tsunami moves through the water as opposed to on top of it. As a result, as a tsunami moves through deep water at hundreds of kilometres an hour, it is barely noticeable above the waterline. A tsunami is typically no more than 3 feet (1 meter) high until it gets close to shore. As the ocean floor rises toward land, friction slows the wavefront, causing the rest of the wave to push up behind it. Trailing waves pile into the waves in front of them pushing against the rising frontal wave. This is referred to as “shoaling”. When one wave actually overtakes another, a very steep wall of water, known as a “bore” may be generated. Even though the waves may be slowed considerably, the waves can reach heights exceeding 30 m in shallow water.
It is very important to note that it is not always the wave crest that hits the shore first. Often the wave trough will arrive first, and the first sign of a tsunami is what appears to be an extremely low tide. Tsunamis will alternate coastal flooding and then recession of water, often with several minutes to hours between successive wave periods. The second and third waves are often the largest and the tsunami wave series can last up to 24 hours. When a tsunami warning has been issued, it is important to remain away from coastal areas until emergency officials advise that the situation is safe.
History of Tsunamis
On December 26, 2004 a massive earthquake off the coast of Sumatra generated tsunami waves that inflicted massive damage on the coastlines in 10 countries, killing more than 150,000 people. This disaster overshadowed the devastation of any other tsunami ever seen in recent history.
176 tsunamis were recorded in the Pacific Ocean between 1900 and 1970. Of these, the most damaging tsunami to occur on the British Columbia coast was caused by a magnitude 9.2 earthquake which struck Alaska on March 27, 1964. Waves over six metres high reached the Queen Charlotte Islands and swept along the west coast of Vancouver Island. British Columbian communities including Hot Springs Cove and Port Alberni were deeply impacted. There were no casualties because the first wave served as a warning, alerting emergency services in order to prevent loss of life. The second wave arrived 90 minutes later and was very damaging. This tsunami receded 18 hours later, causing direct losses of approximately $10 million in damage.
Impact on Richmond
While Richmond is an island community, we are not at significant risk of a tsunami. Vancouver Island lies as a kind of breakwater between the open ocean and Richmond providing us with a natural protective barrier. If a tsunami did occur on the open ocean, Vancouver Island would absorb the major impact of a tsunami. The tsunami waves would dissipate to one metre or less as they moved through the Juan de Fuca Straight and Gulf Islands.
In the event of an underwater earthquake occurring just off Richmond’s shores, our tidal flats are expected to absorb much of the water impacts. The City also has a program that ensures the regular inspection and upgrades to our dykes are conducted to ensure maximum structural integrity. Specific studies are done at key dyke locations to ensure they will remain stable during an earthquake.
Tsunamis are in fact not the biggest hazard associated with earthquakes. The shaking of an earthquake can cause more injuries by turning non-structural items into projectiles, damage to infrastructure and unprotected buildings. To learn how to protect yourself during an earthquake and other hazards, visit During an Emergency.
With a grant fromUBCM we were able to have Dr. John Clague and Dr. Ian Hutchinson from Simon Fraser University conduct a study on Tsunamis and the impact on Richmond. Their finding was that Richmond is at low risk for a Tsunami. For a summary of their report, please seeTsunami Study.
Public Warning
British Columbia is part of the Pacific Tsunami Warning System. As part of this network, the Provincial Emergency Program would receive notification of an impending tsunami and would disseminate this information to local municipalities that may be affected. In turn, the City would disseminate this information and local instructions to the public through the media.
As part of your emergency plans & supplies, you should have a battery operated radio to listen for these instructions. It is recommended that in the event of a major earthquake that you tune into CBC 690 AM or any local station that may remain operational. Visit Emergency Supplies for a list of other recommended supplies.
The Emergency Management Office has also undertaken a Public Warning System Feasibility Study. The study is designed to determine the benefits, attributes and costs associated with various different types of public warning systems. We anticipate receiving the results of the study and determining our next steps in the first quarter of 2005.
Evacuation
If the incident does require the evacuation of the community, the routes used will be determined on an assessment of the damage anticipated at the time of the emergency.
Disaster Response Routes have been designated throughout Richmond and the Lower Mainland as routes to enhance the effectiveness of first responders. Fire, police, ambulance and public works crews will require quick access to emergency 
sites to help rescue victims, fight fires and secure the emergency scene, distribute supplies and critical resources and transport the injured to the hospitals. If required, these routes may be used as evacuation routes. Residents are asked to stay off these routes when activated unless directed otherwise by emergency personnel.
Evacuation instructions would be broadcast over the radio, so we recommend that you include a battery operated radio as part of your emergency supplies.
How You Can Prepare
As demonstrated by the tsunami disaster in the South East Asia region, a major disaster can affect daily life for days, weeks, even years. Due to the demands of a major emergency, first responders, City infrastructure and typical resources that we depend on daily may not be readily available. For this reason, individuals, families, and businesses need to be prepared to survive on their own for a minimum of 72 hours.
To help you prepare, the Emergency Preparedness section of the City’s website offers tips on what emergency supplies you should have, how to develop a family emergency plan and how to protect yourself during earthquakes and other natural hazards.
Reception Centres
During an emergency, the City may establish a reception centre to assist evacuees in areas affected by the emergency. A reception centre is any safe gathering place, such as a community centre, church, or hotel conference room where individuals may obtain information and receive assistance. Services such as family reunification, food, clothing, emergency first aid and lodging arrangements are typically performed at Reception Centres by City of Richmond staff and volunteers. For more information please refer to the Reception Centres section of the website.
