This sidewalk over by 39th and Victor avenues show visible shifting from earthquakes through the decades. Credit: Amir Aziz

Andrew Alden is a geologist and writer who moved to Oakland in 1989 and has been documenting the Town’s topography for over two decades. In 2007, he launched Oakland Geology, a blog where he publishes his discoveries.

His years studying the city’s depths are what fueled his new book, Deep Oakland: How Geology Shaped a City, released by Heyday Books on May 9. Initially, Alden intended to focus his writing on what lies beneath our feet. But the book evolved into something more:  a history of the land and the people who’ve shaped it, from the Ohlones to the Spanish settlers, Mexicans, and “American squatters” of the mid-19th century who helped build the city of Oakland.

The result is a book that acts as a time machine, filled with fascinating details about our area’s past, and illustrates how the land was shaped by its inhabitants: How for centuries, the Ohlone used controlled burning to manipulate the environment and maintain large swaths of grasslands; the political forces that later stripped them from their native home; and how three Americans—Horace Carpentier, Edson Adams, and Andrew Moon—took control of land seized from the Peralta family, setting in motion Oakland’s incorporation in the 1850s. 

Geologist and author Andrew Alden during a recent walking tour of Hayward Fault locations in Oakland. Credit: Amir Aziz

But make no mistake: Alden’s book is chock-filled with science, too. In one section of Deep Oakland, Alden describes what the area that is now downtown Oakland once looked like:

[An] expanse of fine sand, without a pebble to be found in it, that stands between ten and forty feet in elevation and lies up to sixty feet thick. On all sides, the sandy platform slopes gently downward on its edge. 

In other words, downtown Oakland was built on sand dunes. 

The book’s chapters are broken down by geographic landmarks: The Hayward Fault, Lake Merritt, Downtown, Mountain View Cemetery, the Piedmont Block, The Fan, Indian Gulch, the Bay Shore and Flats, Sibley Volcanic Reginal Preserve, Leona Heights and the Southern Oakland Hills, and Ridgeline. Every chapter provides a geology lesson coupled with historical context.

Fault Lines 4
“Fault zone station” markers are small indicators laid out across the fault trace, which are regularly monitored by a team of scientists from San Francisco State University who specialize in tracking seismic movements. Credit: Amir Aziz

The chapter on the Hayward Fault—which runs parallel to the East Bay Hills—explains how the fault has shaped Oakland’s landscape and will continue to shape its future. Oakland is a resilient city, living with our fault and ready to take its earthquakes in stride, reads an excerpt. 

“Nobody knew about the Hayward Fault until maybe 50 years ago when the first papers documenting the creep on the fault were published,” Alden told The Oaklandside in an interview. However, he added, “once it’s in the literature, that doesn’t mean anyone in the city government is going to notice it.”

In 1972, the Alquist-Priolo Earthquake Fault Zoning Act was signed into law, requiring California to conduct geological surveys of all the active faults in the state and generally barring the construction of homes within 50 feet of an active fault line. 

Alden has spent years observing and documenting locations throughout Oakland where signs of the Hayward Fault are visible—sites that explained are noticeable “only with guidance and practice.” He has also documented locations of “fault zone station” markers—small indicators laid out across the fault trace, easily missed by casual passersby, which are regularly monitored by a team of scientists from San Francisco State University who specialize in tracking seismic movements. 

Alden revisits these areas every few years to capture images that show the warping and shifting of sidewalks and deep cracks in the pavement.

The Oaklandside met with Alden at the corner of 39th and Victor avenues in Redwood Heights, one of the fault locations he mentions in the book and on his blog. He pointed out the shifting of the sidewalk caused by seismic activity there and a marker a few feet away on the ground, which scientists have been monitoring since the 1970s. 

“It’s been real steady, three to four millimeters a year. If you add it up, that’s 200 millimeters (over 7 inches). It’s appreciable,” he said of shifting caused by the fault since the ‘70s.

The sidewalk on 39th Avenue as seen when Andrew Alden visited on May 4, 2011. Credit: Andrew Alden
The same sidewalk had significantly shifted when Andrew Alden visited on Dec. 19, 2018. Credit: Andre Alden

“This is an odd place,” he added, pointing to the area where 39th Avenue goes down a steep hill. There’s currently a reservoir running behind 39th Avenue. But old maps from 1895 show there was once a body of water there, with streams running through the areas where there are now paved streets.

Revere Avenue and Marlow Drive in the Sheffield Village neighborhood is another area with visible cracking on the pavement (an area Alden described as “real dramatic). Another was in Berkeley, on Stonewall Road by the Claremont Hotel, he said. But that area has since been repaved.

Cracking at Revere Avenue and Marlow Drive. Credit: Andrew Alden

In Oakland, Alden quipped, the longer it takes the city to repave streets, the more of an opportunity there is to go out and see these areas with the naked eye. 

While there is a legitimate reason to fear the damage that a massive earthquake can cause, Alden suggested there is also much to learn from and appreciate about our local fault. In the book, he writes:

There’s far more to the Hayward fault than the immediate threat it poses. Patiently over millions of years, it has arranged Oakland’s landscape, affecting all of its parts—and the lives of those in them—in ways it takes a geologist to appreciate. 

Alden hopes his work will enable Oakland residents to look at the city in a new way, to see how every rock, every grain of sand, and crack in the asphalt helps to define a city’s landscape.

“I want to inspire people, new geologists, the kids in the flats, to not just look at the hills, but go up and knock around in the woods, study the rocks, look at the views,” he said. “And I want everybody in the hills to look at the flats and think about what they represent and go down to the shore.”

As part of his book tour, Alden will be appearing at various speaking engagements in the Bay Area through the end of June.

Azucena Rasilla is a bilingual journalist from East Oakland reporting in Spanish and in English, and a longtime reporter on Oakland arts, culture and community. As an independent local journalist, she has reported for KQED Arts, The Bold Italic, Zora and The San Francisco Chronicle. She was a writer and social media editor for the East Bay Express, helping readers navigate Oakland’s rich artistic and creative landscapes through a wide range of innovative digital approaches.