Cascadia's Fault - Jerry Thompson [143]
“In general, high-rise buildings behave very differently from low-rise buildings,” Heaton said. “They’re primarily designed to be flexible. And in sharp, rapid shaking—during a moderate-size earthquake—highrise buildings perform extremely well.” But a magnitude 9 was quite obviously a different story. Yang told another reporter that there were approximately nine hundred high-rise towers within striking distance of Cascadia and half of those were built prior to 1994, when the new building code imposed tougher standards.
Reading between the lines, it was obvious to me that the number of tall buildings in danger would depend on how far “down-dip” Cascadia’s fault slips when the Big One hits. If the locked part of the subduction zone—the part that will generate the shockwaves—extends farther inland than initially estimated, the impact on high-rise structures in big cities will be even more severe.
CHAPTER 24
Cascadia’s Fault: Day of Reckoning
On a foggy spring morning just before sunrise, twenty-seven miles (43 km) northwest of Cape Mendocino, California, a pimple of rock roughly a dozen miles (19 km) below the ocean floor finally reaches its breaking point. On the same thrust fracture that rattled the towns of Petrolia, Ferndale, Eureka, and Arcata, two slabs of the earth’s crust begin to slip and shudder and snap apart as Cascadia’s fault finishes what it started back in 1992. That day could be only ten years away. Or two hundred years from now. Or it could happen tonight. And this is how I’ve imagined it will unfold.
The first jolt of stress coming out of the rocks sends a shockwave hurtling into northern California and southern Oregon like a thunderbolt—same as last time, only bigger. Ten times the magnitude and thirty-two times more energy. For a few stunned drivers on the back roads in the predawn gloom, the pulse of energy that tears through the ground looks dimly like a twenty-mile (30 km) wrinkle moving through a carpet of pastures and into thick stands of redwoods.
Telephone poles whip back and forth as if caught in a hurricane. Powerlines rip loose in a shower of blue and yellow sparks, falling to the ground where they writhe like snakes, snapping and biting. Lights go out and the telephone system goes down.
Cornices fall, brick walls crack, plate glass shatters. Pavement buckles, cars and trucks veer into the ditch and into each other. A bridge across the Eel River is jerked off its foundations, collapsing into turbulent eddies below, taking a busload of farm workers with it. A gasoline tank truck swerves to miss a car that’s made a panic stop in the middle of Main Street. The tanker bounces over a curb, taking down a lamppost, crashing sideways into a corner store. Seconds later the wreckage explodes. The fire will be difficult to fight because water pipes under the street are broken. People are awake now and screaming, running dazed and wounded into the streets.
Seeing fragments of this happen through drifting shrouds of fog makes it hard for survivors to know how much is real, how much is their worst nightmare. With computers crashing and cell towers dropping offline, all of Humboldt and Del Norte Counties in California are instantly cut off from the outside world, so nobody beyond the immediate area knows how bad it is here or how widespread the damage. Same for southern Oregon. Despite the rising sun everything suddenly seems dark again. People living in the necklace of towns and villages along the coast are now officially on their own. No help will be coming any time soon.
On a spit of sand running down the western edge of Humboldt Bay, an air raid siren wails as residents in the former sawmill town of Samoa, barely a dozen feet (3.6 m) above sea level, bang through their doors—those that will still open, that are not twisted out of true by the violent shaking of their homes—and run, walk, or stumble as best