“Buoys have a lot of parts and electricity, so they attract fish. Fish attract fishermen. And the fishermen abuse the buoys,” says Louise Comfort, a professor of international relations at the University of Pittsburgh. By 2016, when another large earthquake struck Sumatra, every single one of the 22 stations had been destroyed, vandalized, or raided for parts. A team of American and Indonesian researchers—led by Comfort—have proposed and tested a lower-cost network of tsunami sensors, but they do not yet have funding to install it.
Even without that network of sophisticated buoys, Indonesian authorities still managed to use a more rudimentary set of GPS sensors and ordinary buoys to predict last Friday’s tsunami ahead of time. But this, too, was for naught. The earthquake that spawned the tsunami also took out the local power and communications grid, muzzling tsunami sirens throughout Palu. As the dreadful wave approached, beachfront alarms did not sound.
In fact, that power outage also broke the rudimentary network of tidal gauges used to predict the tsunami in the first place. Tragically, the Indonesian government took this lack of data as an all-clear: “They canceled the tsunami warning at the exact same time that the tsunami was coming ashore,” McKinnon told me.
Yet it’s not clear whether—even if the buoys did work—they would have saved many lives in Palu. The U.S. government, for instance, runs the world’s most sophisticated tsunami early-warning system. But it’s less miraculous than most people think, says Chris Goldfinger, a professor of geophysics at Oregon State who studies what tsunamis would do to the coast of the Pacific Northwest.
“There’s this idea that the [early-warning] system will provide some useful warning to you, if you’re on the beach, directly adjacent to the fault line, and that’s not really true,” he told me. “In most cases, if you’re on a coastline that has a big subduction zone, the earthquake is the warning.”
Photos from the deadly earthquake and tsunami in Indonesia
Take, for instance, the big subduction fault that happens to be right near an American coast: the Cascadia subduction zone—the subject of that terrifying 2015 New Yorker story. If that subduction zone slips, it will probably loose a devastating earthquake on the Pacific Northwest, originating somewhere near the coast. “It’s just going to go without any preamble or any warning,” Goldfinger said. “And then that starts the stopwatch.”
The stopwatch, that is, for the tsunami. If the Cascadia quake lasts for two minutes, it could spawn a 15-foot tsunami. If it lasts for longer than that—and the ground could shake for up to six minutes—it could unleash a wave “on the order of 90 feet,” Goldfinger told me.
But how would we know this wave is coming? Most of the U.S. early-warning sensors sit relatively offshore. If Cascadia triggered a tsunami, its point of origin would likely sit between the coastline and that array of tsunami sensors. So any wave would have to travel out to sea before it could be detected by a U.S. government sensor. Even once it’s detected, news of the wave must still be transmitted to a satellite, sent back down to Earth, and reviewed by a person in the U.S. tsunami center before, finally, resulting in an official early-warning alert.