A curb that sits directly atop one section of the Hayward Fault in the East Bay, well known to earthquake science nerds and the local geological community since the 1970's but apparently not so well known to the Hayward City Council, was dug up recently, much to the dismay of all those who'd been photographing it over the years. The curb, at the intersection of Rose and Prospect Streets, served to clearly illustrate how the fault had moved over time, as the city periodically filled in a gap in the concrete between the sidewalk and semi-circular curb.
Geology writer Andrew Alden says he was one of the first to document the curb's movement, a time-lapse of which you can see going back to 1971 on GeologyFieldTrips.com. And he spoke with Canada's National Post, which called the site, "one of the most visited curbs in the United States."
Below, his tweet of a photo upon discovering the curb had been torn up. As the LA Times reports, not knowing that the curb was in any way significant, the assistant city manager of Hayward said "the curb was replaced to install a wheelchair-accessible ramp at that intersection, one of about 150 to 170 such ramps that are installed every year at a cost of $3,000 each."
Bad news: the Rose/Prospect curb is gone after 45 years of recording Hayward fault creep pic.twitter.com/O4GwiURrHB— Andrew Alden (@aboutgeology) June 24, 2016
And it wasn't just a novelty. As retired UC Berkeley professor Doris Sloan tells the National Post, "That’s been, for decades, a site where geologists can go to measure the rate of curb offset," saying she'd been going there since 1971.
The Hayward Fault last erupted with a major earthquake in 1868. Though another big one on the fault could still be decades away, it has had a pattern of major ruptures every 160 years, with a margin of error of about 80 years, meaning it's now due. It's the fault that most concerns earthquake scientists in the Bay Area because it runs under densely populated areas in Fremont, Hayward, Oakland, and Berkeley, and a major earthquake could cause many hundreds of more casualties than the Loma Prieta quake in 1989, whose epicenter was in a far more remote area in Aptos.
As discussed last year, there is currently a 76 percent chance of a 7.0 or greater magnitude quake on the Hayward Fault, and a 95 percent chance of one more Loma Prieta sized, 6.9M or less. The 1868 earthquake is believed to have been a 6.8M. Also, making matters worse, the fault has two spots of possible co-rupture with other nearby faults: the Rodgers Creek Fault in Napa to the north, and the Calavares Fault to the south.
And speaking of the Hayward Fault creeping apart and causing things to move above ground: Hayward's city government has already had to abandon two buildings because movement on the fault has made them unsafe and uninhabitable. The historic, Art Deco City Hall built in 1930 on Alex Giuliani Plaza had been pulled apart enough by fault creep that it was abandoned and closed to the public in 1969; and the highrise City Center building that served as city hall from 1969 to 1998 now stands boarded up and abandoned, awaiting likely demolition.
Let this just serve as one more reminder to get your earthquake kit together.