On Tuesday, Siri Zama’s phone was ablaze with tsunami alarms. The 28-year-old Kapolei, Hawaii, high school instructor ran inland.
Rain was falling, and the skies grew very ominous. It was only mildly terrifying. Everyone from here was stressed, so I was a little concerned,” Zama recounted.
Thousands of miles away, an incident had set off those anxiety-inducing alerts: One of the strongest earthquakes ever recorded, with a magnitude of 8.8, slammed Russia’s Far East early on Wednesday. It sent waves of tsunamis across the Pacific into Hawaii, Japan, and other places.
Waves surged onto the shore in adjacent Japan, and areas along the Kamchatka Peninsula in Russia near the epicenter of the earthquake were inundated as inhabitants hurried to higher ground. People in the capital of Hawaii hurried to get into their automobiles and head inland.
Even though there have been no reports of fatalities or significant damage from the tsunami, as of 7:20 p.m. Eastern time, an advisory remains in effect in some areas of the U.S. West Coast.
Recipe for a tsunami
It turns out that a tsunami can be created with very little.
Possibly the most crucial component is a powerful earthquake.According to Eric Geist, a research geophysicist with the US Geological Survey, the magnitude of an earthquake is a crucial factor. In general, for an earthquake to cause a tsunami, its magnitude must be at least 6.5 to 7.
“You need a large enough earthquake that gives enough motion to generate upwards and downwards motion on the ocean sea floor,” Geist said.
However, not every powerful earthquake results in a tsunami. It also relies on the type of motion the earthquake produces and its location.
According to Geist, a tsunami is less likely to result from an inland earthquake. Rather, earthquakes that occur near the coast or underwater have a higher probability of causing a wave. He went on to say that while the Ring of Fire is the site of around 90% of all earthquakes worldwide, it is also a hot region for tsunamis due to the significant tectonic plate changes caused by these events.
Large waves are produced during an earthquake by vertical movements. “How close the earthquake originates to the Earth’s surface is another important factor,” said Harold Tobin, director of the Pacific Northwest Seismic Network and a professor of seismology and geohazards at the University of Washington.
It is more likely to result in a tsunami if it happens nearer the surface, producing what is referred to as a shallow earthquake.
“That fits the bill,” Tobin said of Tuesday’s earthquake.
“It’s a shallow earthquake, exactly the type that tends to produce large and damaging tsunamis,” he stated. “The reason the tsunami warnings were immediately issued is that they were very much warranted by the type of earthquake that occurred.”
Tsunamis have different durations. According to Geist, tsunamis that start in the Pacific Ocean appear to linger longer; some can produce waves for up to 22 hours.
“They are actually trapped along the coast, but they’re also reflecting back and forth across the ocean basin,” Geist stated.
All three components were present in Tuesday’s earthquake. It happened undersea, had vertical motion, and was powerful enough to cause a tsunami. Geist claims that an earthquake in the same region in 1952 that was “quite similar” resulted in a massive wave that devastated Hawaii.
However, because there are so many variables involved, it is difficult to anticipate tsunamis with any degree of accuracy. According to Tobin, researchers are still attempting to determine why the earthquake did not result in a larger wave.
Tobin remarked, “Every earthquake is kind of unique,” “Earthquakes are like individual snowflakes. The tsunami from this one wasn’t as large as first thought.
The power of a tsunami is another unpredictable aspect. Typically, tsunamis begin as long waves traveling across the deep water at the speed of an airliner. The waves move more quickly the deeper it is.
A person on a ship in the middle of the ocean could not even notice a tsunami moving through these places because the waves are low in height.
A tsunami’s wave speed decreases to around 20 to 30 miles per hour once it hits shallow water, while the water below the wave accelerates. The wave’s height also rises at that time.
Geist stated, “That’s when they become very dangerous,” “It’s likely that you witness images of train locomotives being raised by tsunamis. The amount of water involved is the primary reason they are so powerful.
Predicting a tsunami
Geist stated that the field is at a “turning point” in its ability to more precisely anticipate the height and timing of waves, even though tsunami forecasting is still difficult. Two instruments—deep ocean pressure sensors and tide gauges—help scientists better understand what to anticipate.
Since the 1850s, the former has been used to assist harbor masters in forecasting ocean tides. Early in the new millennium, the latter were introduced.
“[Deep ocean pressure sensors] are critical because you can place them near the seismic reactive areas,” Geist stated. “Putting these instruments out is no easy task. A lot of technology is required.
A tsunami spreads perpendicular to the earthquake’s breach once it has formed. Hawaii received Tuesday’s earthquake’s perpendicular energy. However, due to changes in ocean depth, that energy was refracted in different directions. Secondary waves may result from this, and they may move toward Alaska or Papua New Guinea, among other locations in the ocean.
Because of their shallower waters, some coastal locations, referred to be “strong wave guides,” are more vulnerable to tsunamis. On Tuesday, tsunami warnings were also issued for portions of the Pacific Northwest, including Crescent City, California.
The ocean usually recedes just before a tsunami strikes, signaling the approach of the main wave.
According to earlier claims, some animals, such as snakes and elephants, may sense an impending earthquake or tsunami. “It’s unclear if it’s just a coincidence,” Geist added.
Because they gather up so much ocean debris, tsunamis can even have a stench. It’s typically difficult to hear the approaching waves unless the tsunami begins to demolish buildings. Geist stated that the wave from Tuesday’s earthquake was most likely not heard or even seen by anyone.
But it’s important to take alerts seriously, he said.
“By the time you realize what’s going on, it’s moving so fast, it’ll just overtake you,” Geist stated.
What to do when a tsunami hits
“If you’re on a beach and you see a tsunami, it’s too late to outrun it,” Geist stated.
Therefore, it’s critical to respond to tsunami warnings right away. Being at 30 feet above sea level is generally acceptable, but 100 feet is the best. Tobin says that’s like going uphill two blocks.
According to Tobin, “thirty feet is not a lot above sea level, but that can really be the difference” between danger and safety.
Additionally, coastal jurisdictions provide tsunami evacuation charts that, depending on the local terrain, can suggest a greater elevation.
“You might be a mile inland, but you might still be in a danger zone,” Geist said. “You really have to look at those maps to understand where the safe zones are for a tsunami.”
Tsunamis are not like ordinary waves, Tobin stressed. Some may span up to 100 miles.
“It’s a hump of water that is tremendously long in its wavelength,” Tobin said. “It can be a few feet high, but it travels at the speed of a jet airliner.”
Significant damage can be caused by tsunamis as small as a few feet in height. Typically, they don’t resemble the tsunamis depicted in movies.
“That’s really not what a tsunami looks like,” Tobin stated. “Even a 2-foot-high tsunami can be really dangerous.”
The debris that tsunamis gather as they rip through the earth also contributes to some of the hazard.
“It’s bringing debris from the sea floor, even stuff that’s already picked up along the way, like pieces of wood and chunks of buildings,” Tobin explained. “You can be in serious danger.”
Even if it appears that the tsunami is over, it is still crucial to heed all tsunami warnings.
There isn’t just one wave. Geist stated, “It lasts for a very long time.” “It’s important just to be patient and wait until the all-clear is given before you go back to the coast.”
After the wave
Even while a tsunami may only last a few hours, its impacts might persist for months or even years.
Devastating flooding can result from a tsunami striking a community. The availability of clean water, food, and medical care may be immediately disrupted by flooding.
Water damage can result in structural damage to homes and the growth of mildew within days following a tsunami. Mold allergies increase the likelihood of house displacement, which can worsen other conditions.
“This can have a significant impact on people who are allergic to mold,” said Dr. Jyothi Tirumalasetty, a Stanford immunologist and allergy. “Their asthma can also get worse, and we know that damp and moldy environments can actually promote respiratory symptoms in people.”
There are other changes that are invisible to the naked eye. Standing water can raise the danger of waterborne illnesses like cholera and vector-borne diseases like malaria.
Flooding has long-term effects on mental health and interferes with access to care for long-term conditions like diabetes. The 2004 tsunami that devastated villages in the Indian Ocean had an effect on Tirumalasetty’s family. She claimed that it had a lasting impact on her uncle’s mental health in India.
“There’s that constant worry about, ‘Is this going to happen again, and how are we going to deal with it?'” “Tirumalasetty said.” “In an area like that where there may not be the same preparedness and ability to assess damage and rebuild as quickly, I think that they were impacted for many, many years.”
The elderly, children, and people with previous medical disorders are among the vulnerable patients who should prepare for tsunamis and have what Tirumalasetty refers to as a “go bag.” That can entail a little bag filled with extra masks and inhalers for some people.
“Having all that ready to go and packed, ready to jump in your car, that’s going to get you away from a disaster safely and really provides peace of mind,” she stated. “It’s also going to take care of you during something like [a tsunami], where you have limited access to medications.”
Some researchers contend that a warming world raises the probability of catastrophic weather events like earthquakes and tsunamis, though it is unclear whether this week’s tsunami was caused by climate change. According to Tirumalasetty, a researcher who examines the impact of climate change on human health, her field is actively adjusting to these developments.
“In the medical community, there’s a growing awareness [of climate change], and we are doing our best to include climate change education for medical students,” she stated. “The younger doctors are taking the lead in this, and they have a strong concern for protecting the environment and our most vulnerable patients from natural disasters. I believe we will have better, long-term answers for patients as we continue to struggle with this and the best ways to manage it.”
This paper was written with assistance from Geoff Brumfiel.
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