Wave-ing Goodbye To Our Coastline?

It’s time for California to take tsunamis seriously.

In a time of seemingly constant earthquakes, the concern over Tsunamis have been virtually non-existent. This was until January’s volcano eruption in Tonga reminded us that there could be another threat other than quakes for the first time in recent memory. While the tsunami only caused minor flooding in parts of Northern California, it showed how vulnerable we could potentially be to a larger tidal wave.

Similar to Earthquakes, tsunamis occur often, but on a typically small scale.

Tsunami readiness is, however, practiced largely by a small batch of hardcore beach residents who are the most prone to its effects. Marshall Coben is a longtime resident of Malibu and an avid surfer whose family has lived on the coast for four generations. Living on the West Coast, he has found the tsunamis “small and not harmful,” but still takes them “seriously to a degree.”

“The only preparation you can really have is to head to high ground, so knowing where my closest high ground is, is about as prepared as I can be,” Coben said. This approach to preparation is echoed by government officials, more specifically the National Weather Service whose official guidance is to “Protect yourself from the effects of a tsunami by moving from the shore to safe, high grounds outside tsunami hazard areas.” Largely absent from both Coben and officials’ tsunami protocols is reliance on man-made infrastructure that has been put in place to mitigate coastal safety concerns.

The infrastructure typically relies on concrete sea-wall barriers that bounce the waves back into the ocean, though even these have their limits. Depending on the size of the Tsunami they can be overpowered by the tsunami elevating over the wall. An example of this occurred during one of Japan’s 2011 earthquakes, when a tsunami washed over Kamaishi city’s 18-foot sea wall, the tallest built at the time. Even though California is not currently as prone to tsunamis as Japan, there is still a formidable risk.

A report from the California Tsunami Policy Working Group details the potential residents at risk. According to the report, “Within California’s 20 coastal counties…267,347 people (or 117,380 households) permanently reside in potential tsunami inundation areas identified by the State of California.” The number of residents at risk can fluctuate as well, depending on the season. Especially in summertime, the Working Group estimates the population residing in hazardous zones could rise to roughly three million residents.

Ryan Kittel, a forecaster for the National Weather Service, explains “Tsunamis have a long history of affecting California. Most of the tsunamis come from large earthquakes thousands of miles away.”

These types of long-distance tsunamis give anyone in vulnerable areas ample time to evacuate and assess the severity of the wave. However, not all tsunamis are caused by faraway quakes or eruptions, but are instead caused by more local environmental impacts.

“For tsunamis from closer earthquakes, we have a natural warning source, the earthquake itself. If you feel an earthquake, assume a tsunami is coming and stay away from the affected areas,” Kittle said.

The number of California residents who live in tsunami inundation zones fluctuates from hundreds of thousands to millions over the summer.

While for many this advice may seem obvious, sometimes the focus is so fixated on the earthquake that it can be easy to forget the additional impact on the surrounding environment. It is this layered awareness that is crucial in a situation like a tsunami.

Despite the Tonga eruption being considered underwhelming compared to many people’s impressions of a Tsunami, the activity displayed some of the minor symptoms that an event like it can produce. Many coastal residents are acutely aware of the effects that rising sea levels have on infrastructure and environmental formations such as coastal bluffs. That sea-level rise can be observed along California’s Central Coast, where numerous ocean-front houses have been forced into demolition due to their foundation being compromised.

In comparison to a devastating rise in sea levels, tsunamis often take a back seat in natural disaster discussions. This more climate change focused outlook, however, could prove wrong if California were to face a sizable tsunami. “Damaging tsunamis cause water level rise on the order of several feet, while climate change sea level rise is expected to be on the order of inches in the next few decades… the power of tsunamis on their own greatly dwarfs any near-term enhancement from climate change,” Kittle said.

Similar to earthquakes and wildfires, tsunamis should be something that every beach-dwelling Californian is informed about. Even if they do not have the commonality of other environmental hazards, that does not mean we should take them any less seriously.