News from the HayWired fault

The ruins of Morse & Heslop’s mill, Haywards, after the 1868 earthquake (Bancroft Library image)

This week the media will mark San Francisco Earthquake Day, 18 April, as they always do but with an extra message for 2018 — this year will be the 150th anniversary of the original “Big One” in the Bay area, the Hayward earthquake of 21 October 1868. The U.S. Geological Survey and a host of partner agencies and organizations will roll out the next piece of a master plan that will guide the response to future large East Bay earthquake on our very own Hayward fault, usually called “a ticking seismic time bomb” by the intrepid researchers who get in front of cameras and audiences.

That first piece, Volume 1 of a planned series, is a scenario called HayWired: a description of a typical magnitude-7 earthquake, modeled after the 1868 quake, presented in as complete detail as we know how, with a special focus on its probable effects today in our highly electronic state. It’s online now at the USGS site.

I wrote about this project here last July, so you can read that post for more background. After that you may enjoy the USGS’s “geonarrative” about HayWired. It’s awesome, but only on a touchscreen device.

Today, though, I wanted to provide some details from the original quake. In 1868 a committee was convened to create a report on the event, but it never finished a report, so whatever work they did was lost. We only know as much as we do because after the San Francisco earthquake of 1906, the commission set up under UC Berkeley’s Andrew Lawson to investigate it decided to add a chapter on previous earthquakes. There were enough survivors of 1868 at the time to record quite a bit of detail. So here are some tidbits from the famous Lawson Report of 1908 about the Hayward quake of 1868.

The great shock happened about 7:50 a.m. on 21 October 1868, and ground ruptures were recorded, with 3 feet of offset in some places, from Mills College down to Warm Springs. North of San Leandro, though, “The county was then unsettled, and the information consisted of reports of cow-boys riding the range.” From Oakland we have these details:

  • “A house near old Blair Park, in the present Piedmont district of Oakland, was badly damaged.”
  • “Pans of milk and tubs of water emptied out almost in a moment, trees whipt about like straws; many houses twisted 5 or 6 inches out of square, particularly those on brick foundations.”
  • “In Brooklyn, as in Oakland, many chimneys were broken off at the roofs.”
  • “The bed of San Leandro Creek, which had been dry for several months, became filled with a stream of water 6 feet wide and a foot deep.”

At Haywards (the name of Hayward at the time) and neighboring towns, “nearly every house was thrown off its foundations.” Dozens of aftershocks were recorded in Haywards during the first 12 hours.

R.C. Vose of Roberts’ Landing wrote, “Our house broke in three pieces, each part falling outward. A boiler of hot water was on the stove, and with the first deafening jolt, the hot water came my way, giving me a bath I have never forgotten.”

In Fremont, Tyson’s Lagoon, the body of water next to the BART station, drained dry and remained dry for three years.

In San Jose, situated as it is in a large sedimentary basin, damage to brick buildings was universal.

12 aftershocks felt in San Francisco during the first day. Damage was most severe in the “made land” (artificial fill) in the former Yerba Buena Cove. Out at the Cliff House “the shock, however, did no damage, not even upsetting the glassware in the bar.” Ships at sea felt strong vibrations, like running aground or the anchor chains running out.

The earthquake was felt in Chico and many Sierra foothill towns, even in Carson, Nevada. Damaging shocks were reported throughout Sonoma County, as well as in Stockton and Sacramento.

All of this will happen again the next time a major quake strikes the Hayward fault. However, today there are hundreds of times as many people living in the affected areas. Back then, about 30 people died. Do the math and pay attention this week.

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