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Deep History Along the Newport-Inglewood Fault

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We like to think that the past touches us only lightly in L.A., that history can be brushed off -- better yet, domesticated -- by a little more gentrification or the whitewash of nostalgia. What's buried by forgetfulness mostly stays buried in L.A.

Our history may lie deep but never that easily.

Despite the tectonic hyperbole of Dwayne "The Rock" Johnson's "San Andreas," popular fixation on the state's best-known earthquake fault obscures the less cinematic Newport-Inglewood Fault that angles north and west through Los Angeles County from Long Beach to Lakewood, Compton, Gardena, and Inglewood, and then under the Cheviot Hills. New research suggests that the Newport-Inglewood Fault is older than originally thought and far deeper than anyone imagined.

What makes L.A. is 20 miles below our feet and tens of millions of years in the past.

Rubble: Long Beach, 1933
Rubble: Long Beach, 1933  | Photo courtesy L.A. Public Library

Samples taken by UC Santa Barbara researchers from oil wells along a 30-mile section of the fault show unusually high levels of helium-3, an isotope of the gas that fills kids' balloons. He-3 is rare but it averages at higher concentrations the deeper you go. Down there, where the crust transitions to the earth's mantle, is He-3 from the world's beginning, 4.5 billion years ago.

Because ancient He-3 is present in the deepest wells, the Newport-Inglewood Fault, which drivers on the 405 Freeway experience as a line of low hills, seems to have "direct or indirect" connection to the lumpy topography of the crust/mantle interface 20 to 30 miles below. As below, so above. It's as if you could see with X-Ray specs into the planet just by looking at the Baldwin Hills.

The fault isn't only deep; it's old. Analysis of the geology at the bottom of sampling wells indicates that the line of hills we see at the surface marks a 30-million-year-old boundary where an edge of the Pacific plate began sliding under the North American plate. Today, the plate boundary is some 40 miles east, along the San Andreas Fault.

How that leap happened is unclear. That it did happen has lingering effects on L.A. today.

The complicated geology at the old boundary trapped the petroleum deposits of Huntington Beach, Long Beach, Signal Hill, and the Baldwin Hills, fueling L.A.'s car culture from 1922 on. The Newport-Inglewood Fault also forms the boundary between the two water basins on which much of the county depends.

Fallen Tower: Compton, 1933
Fallen Tower: Compton, 1933  | Photo courtesy LA Public Library

Because of over-drafting between 1900 and 1960, the basin west of the fault is subject to saltwater intrusion from the Pacific. Millions of gallons of fresh water must be pumped into wells at the seaward edge of the West Basin to keep brackish water from contaminating the much larger Central Basin to the east of the fault.

Deep and old, the Newport-Inglewood Fault nevertheless does not sleep. At the rate of one to five millimeters a year, the land west of the fault slides past the North American plate. The movement is slightly faster at the fault's southern end.

That movement creates earthquakes. Although the San Andreas Fault has the potential for a truly massive quake, it was the Newport-Inglewood Fault that delivered the most deadly earthquake in Los Angeles history. Its aftermath changed the way we live today.

At 5:55 p.m. on March 10, 1933, a magnitude 6.25 earthquake savaged the towns along the Newport-Inglewood Fault. The worst of the effects were felt in a 15-mile-long corridor through Long Beach, Compton, and Huntington Park.

Ground shaking, which was only moderately strong, lasted less than 20 seconds. It was enough.

The earthquake destroyed property worth almost a billion dollars today. One hundred and twenty people died. Most of the dead were killed when they rushed out of buildings only to be crushed by falling cornices and the collapse of unreinforced masonry façades.

Made Homeless: Long Beach, 1933
Photo courtesy LA Public Library

Many of the buildings that failed were schools. Many of them were poorly designed and even more poorly constructed. Fancy entrance towers fell into heaps of bricks, wood, and broken glass. Had the quake occurred three hours earlier, as school sessions ended that Friday afternoon, hundreds more youngsters -- perhaps thousands -- might have died.

Wood-frame, single-story homes survived, with damage mostly confined to chimneys and porches. Reinforced concrete buildings were untouched.

The Aftermath of 1933

The Long Beach Earthquake changed state law. More than 200 school buildings were either destroyed or judged unsafe to reoccupy. In response, the Field Act, adopted just a month after the quake, empowered the state's Division of Architecture to review plans for new and remodeled schools and authorized on-site construction inspection. No longer would school boards and contractors collude to build unsafe classrooms.

The earthquake shaped the look of communities. Unreinforced masonry buildings fell out of fashion. Schools and other public buildings, with the help of federal funding, would be built of concrete in a stripped-down style or spread out in a rambling, single story campus. Building height limits, already in place, gained additional support. Wood frame houses, low to the ground, had been a local preference before the quake. After, homeowners had another reason for their preference.

1933 changed the way we think about earthquakes. The Long Beach Earthquake was the first to be studied comprehensively, leading to a better understanding of what happens during a quake. Government agencies and insurance carriers developed standards for construction we still use, based on analysis of building failures. Southern Californians were taught the deadly risk of running outside during a quake.

Angeleños began to imagine "The Big One" after years of expert opinion had said that strong earthquakes in L.A. are rare.

News about the age and depth of the Newport-Inglewood Fault won't change laws or building design. The discovery of primordial helium doesn't mean a greater quake risk. But what we now know should add to our impression of the unsafe place we call our home. We should remember to duck, cover, and hold during a quake. We should remember that the low-rise vista of our communities was, at least in part, a hunkering down on our uneasy landscape.

As L.A. neighborhoods become more dense and taller, we shouldn't allow political and developer pressures to bury the risks of building near faults whose depth and age and history we hardly yet know.

Our past hasn't been laid to rest. It's still in the landscape and under our feet.

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