WHOSE FAULT IS IT?

It’s the town of Sonoma’s fault, or more precisely, the fault of that little crossroads known as Schellville, just south of Sonoma. But that’s getting ahead of the story.

This is the story of the search for Rodgers Creek. It began as I was writing the previous item, which described a 1909 prank that took place in the “hollow back of Rural Cemetery” and “the little valley back of the graveyard.” As someone who’s tramped around the Santa Rosa Rural Cemetery for a quarter century, I knew well the eastern border ended in a “hollow” with a stream, and recalled being told ages ago by a Knowledgeable Person that the stream marked the Rodgers Creek earthquake fault, which someday would lay waste to most of Sonoma County. In years since I’ve also overheard others describe it as the infamous Rodgers Creek and I’ve said so myself, demonstrating I had membership in the League of Knowledgeable Persons. But it struck me as curious that the newspaper story didn’t mention the creek by name, so I decided to do a little research just to verify it. This should be a zippy, two-minute Google, right? Six long days later…

The first thing I discovered was there’s lots of information about the Rodgers Creek Fault, as well as the Rogers Creek Fault. It’s also sometimes called both “Rodger’s” and “Roger’s”, and I often found mixed spellings within the same government documents and academic papers. Case in point is the official USGS report which used “Rodgers” – except once when it didn’t – but click on the link for the fault map and it’s now “Rogers Creek fault.” (UPDATE 2019: Those USGS links no longer are valid – see instead this recent report with maps.) Many other USGS publications also wobble between Rogers/Rodgers, yet a search of their earthquake fault database for “Rogers Creek” returns zip. And worst of all for me, not a single document mentions where the heck Ro?ger?s Creek can be found.

I thought the goal was at hand when I found an obscure 1896 Santa Rosa map that showed members of the Rogers family owned three parcels near the cemetery, and the creek likely flowed through at least one of these properties. (Rogers Way, next to the Fourth street Safeway, was developed from one of these family holdings.) Alas, this was a crazy-making coincidence. But another old map and another reading of the weighty Santa Rosa Creek Master Plan answered the question of what is behind the graveyard: It’s Poppy Creek, to which a drainage ditch extends along the southeastern cemetery border. And yes, as it turns out, the creek happens to overlay the earthquake fault.

(RIGHT: Section of map from Santa Rosa Creek Master Plan, pg. 200. CLICK or TAP to enlarge)

Once I stopped hunting for the celebrated lost creek of Santa Rosa, the real Rodgers Creek was easy to find: It’s a small stream about two miles south of Sonoma that runs between highway 116 (Arnold Drive) and 12 (Broadway). It was chosen as the name for the earthquake fault in 1949 not because of great geological significance, but because it’s so damn interesting. According to a 1921 survey, you can easily see that the creek was formed when a quake diverted the water flow from streams now gone dry, as well as other features that date the significant earthquake to about 200 years earlier (that’s two centuries from 1921, not today).

As years have since gone by, views of the Rodgers Creek Fault have evolved. It’s now orthodoxy that it’s part of the Hayward Fault Zone and stretches all the way to Healdsburg. Locally, it runs parallel to Petaluma Hill Road and east of Taylor Mountain, then cuts through the middle of Bennett Valley and Rincon Valley. It’s also believed that our “Santa Rosa pull-apart basin” (yes, it’s exactly as horrific as it sounds) is a few decades overdue for The Big One, which  could mean a slippage of over six feet in a quake of 7.0 magnitude or greater, which is what happened when Rodgers Creek was created. The current odds are estimated at a 31.7% chance of rupturing in a 6.7 magnitude earthquake or greater before 2045, the highest in the Bay Area (updated 2019). It would be a disaster of catastrophic proportion; right now would be a great time to download the PDF on Santa Rosa earthquake preparedness.

Rodgers Creek Fault Zone in yellow (California Geological Survey)
Rodgers Creek Fault Zone in yellow (California Geological Survey)

Obl. believe-it-or-not footnote: The pursuit of Rodgers Creek began as an attempt to clarify a story about a snipe hunt, an irony that was not lost on me as time passed with little to show for it. Most of my research was spent wandering down yet another “Rogers” blind alley: That Santa Rosa’s forgotten “Rogers Creek” surely was named in honor of seismologist F. J. Rogers of Stanford University, a member of the California State Earthquake Investigation Commission after the 1906 quake who performed the groundbreaking shake table simulations on seismic vibrations through soil. Famous newly-discovered earthquake fault, famous earthquake scientist with the same name – that couldn’t be a coincidence, right? But I was fooled again and tripped up by a different misspelling. In the commission report his full name was only mentioned once, and his initials were reversed into “J. F. Rogers.” There was much puzzlement as I wondered why Mr. J. F., a businessman well known nationally for selling small electrical industrial machinery – not unlike shake tables – had a secret identity as a renowned scientist. But had the commission made the further mistake of naming him “J. F. Rodgers,” I think my head might have exploded. One of the few men so named in that era was a prominent “roadmaster” (a railroad foreman in charge of track integrity). In Santa Rosa, the roadmaster  at the same time was William C. Rogers, who owned the land adjacent to the Rural Cemetery through which the mystery creek flowed.

As a result of these experiences, I’m calling upon Webster’s to add two new words to the unabridged dictionary: “roger,” meaning a small everyday coincidence, and “rodger,” meaning a coincidence that’s completely improbable. Both words will be pronounced the same, of course, so there may be some confusion.

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