In the early hours of July 30th, a powerful magnitude 8.8 earthquake struck the Kamchatka Peninsula in Russia’s Far East, triggering tsunami warnings of varying levels for many places along the U.S. West Coast, Alaska, Japan, and other Pacific countries. As the tsunami approached, the U.S. National Weather Service recommended specific actions to be taken.
The National Oceanic and Atmospheric Administration (NOAA) stated that a tsunami is a series of huge waves caused by earthquakes or underwater volcanic eruptions. Seismic activity can result in sudden displacement of seawater, creating powerful sea currents and gigantic waves that increase in height as they near the coast.
Tsunamis consist of multiple waves and can last for a prolonged period. The first wave may not always be the largest, with subsequent waves potentially surging in height. Major tsunamis can persist for several days, as in the case of Japan warning that the tsunami triggered by the Kamchatka Peninsula earthquake could last for more than a day.
According to the U.S. National Weather Service, tsunamis cannot be precisely predicted. Tsunami Warning Centers base their predictions on the magnitude and location of the triggering earthquake and use forecasting models to estimate wave height, affected areas, and arrival times once a tsunami is detected.
NOAA utilizes the Deep-Ocean Assessment and Reporting of Tsunamis system (DART) and collaborates with a broader international network to measure changes in water pressure as tsunami waves pass through, allowing for real-time detection, measurement, and notification of tsunamis occurring in the open ocean.
The U.S. National Weather Service employs a 4-level tsunami warning system, with severity ranked from high to low as follows: Warning, Advisory, Watch, and Information Statement.
People should also be alert to visible natural signs of an incoming tsunami, such as loud noises from the sea, sudden changes in water levels, or water receding rapidly from the shore.
A “tsunami warning” is the highest-level alert, signifying “Take Action, Danger! A tsunami capable of causing widespread flooding is expected or occurring. Dangerous coastal flooding and powerful currents may be present, possibly lasting for hours or days after the initial wave arrives.”
In the event of a tsunami warning, authorities advise immediate evacuation to higher ground and as far inland as possible, at least 30 meters above sea level or 1.6 kilometers away from the coast, following local directives.
While it is recommended to seek higher ground, most tall buildings are not designed to withstand the impact of a tsunami. However, in the absence of other options, upper floors of some sturdy high-rise structures may offer some protection.
Ready.gov, a website by the U.S. Department of Homeland Security, suggests that if a tsunami warning is issued while you are at sea, head to deeper waters that reach a safe depth; if you are in a harbor, leave the vessel and move to a safe inland area.
For international partners in the Pacific and Caribbean regions, the U.S. will only issue tsunami threat notifications, not warnings. According to the National Weather Service, tsunami threat messages outline the potential impact of tsunamis on people, buildings, and ecosystems, allowing each country to decide on the appropriate warning to issue.