Getting set for ‘The Big One’
by Ryan McDonald
A magnitude 8.0 earthquake on the southern portion of the San Andreas fault would cause an estimated 1,800 deaths and 53,000 injuries throughout Southern California, seismologist Lucy Jones told an overflow crowd at Manhattan Beach’s Joslyn Center Monday night.
The thrust of Jones’ discussion, however, was not on lives lost or treatment of injuries. Instead, she focused on how the millions of people who survive the quake could deal with the chaos likely to ensue, following the catastrophic effects on urban infrastructure that would follow a massive temblor. Some 300,000 structures would be damaged, repairs would cost upwards of $200 billion. Water, power, and telecommunications would all be compromised following a quake, she said and could take at least six months to restore.
“Every major road, railway, and aqueduct in the region crosses the San Andreas fault. When that earthquake happens, they will all be broken,” Jones said.
But the presentation was not entirely doom-and-gloom. Although a large earthquake in the region is inevitable and would affect most of the area’s 20 million residents, there are steps that can be taken to make recovering from a quake faster and easier, Jones said, including some programs now offered by the city.
“The purpose of this talk is not to scare people, but to inform residents of the risks, and show people what they can do about it,” said Mayor David Lesser.
Jones spent decades as a scientist with the U.S. Geological Survey before stepping down last year. Since leaving USGS, Jones has advocated for enhanced earthquake preparedness up and down the state. She has worked with Los Angeles Mayor Eric Garcetti on a pledge to shore up that city’s structures. Earlier this year, she publicly sparred with President Donald Trump over his administration’s plans to scuttle funding for a West Coast earthquake warning system.
She presented historical data about previous California earthquakes, comparisons with contemporary quakes in other parts of the world, and scientific modeling about how shaking on some of the more than 300 faults that crisscross the region could impact Southern California and the South Bay.
Paleoseismology, the study of natural records of past earthquakes, indicates that over the long term, the southern portion of the San Andreas fault has had a major earthquake, on average, every 150 years, Jones said. She was hesitant to say that the region was “overdue,” but noted that the last major quake on the fault occurred in the 1680s.
Other faults, like Newport-Inglewood, are close to the South Bay, and could conceivably result in powerful shaking. But in an earthquake on the San Andreas, the fault capable of producing the most powerful and sustained shocks, shaking in Manhattan would probably be less severe than areas closer to the fault, to the north and east. The danger, however, would come from other sources.
“The shaking here in Manhattan Beach won’t be as bad as elsewhere. Your downside is liquefaction,” in which the pressure of water underneath the soil becomes equivalent to the weight above it, turning the ground on which much of the South Bay is built into “quicksand,” Jones said.
Those most at risk of injury during an earthquake are those living in concrete structures erected in the 1950s and 1960s, which are both most likely to collapse and most likely to hurt people when they do, Jones said. She urged all homeowners living in houses built before 1997 to get their houses inspected and noted that enhanced earthquake resistance tends to add only a small percentage of construction costs.
But even under current conditions, the vast majority of the region’s residents would be expected to survive even a large earthquake, leading to her focus on post-quake infrastructure.
“Most of us will live through the quake. The question is, how do we make life function afterward?” Jones asked.
She brought up the example of a 2011 earthquake in Christchurch, New Zealand, which measured 6.3 on the Richter scale. (The USGS now use the moment-magnitude scale, which differs slightly from the Richter scale, to measure earthquakes.) The quake killed 185 people, almost of two-thirds of whom died in the collapse of a single concrete building that housed a television station.
But it was Jones’ use of an aerial photo of downtown Christchurch, months after the accident, that drew the most audible gasps. Approximately half of the structures were vacant or collapsed. Her point was that natural disasters, from earthquakes to hurricanes, have the potential to cause lasting economic damage. She noted that, in its long history, the city of Los Angeles has seen annual declines in population only twice: in the fiscal years following the Sylmar Earthquake, 1971-72, and the Northridge Earthquake, 1994-95.
She offered a variety of ways cities and citizens, can minimize these impacts, including storing food and having a comfortable pair of shoes available. The Manhattan Beach Community Emergency Response Team Association, a local nonprofit, offers free training for residents. And Battalion Chief Scott Hafdell of the Manhattan Beach Fire Department, who oversees the city’s disaster preparedness, highlighted the “Map Your Neighborhood” program, in which residents divide up areas of the city, and learn where homes vital infrastructure, like gas and water switch-offs, are located.
“The whole plan is, your neighborhood will be able to work as a team. You won’t be the victim; you’ll be out there helping,” Hafdell said.