On deadly ground

By Huw Thomas

As California braces itself for the next Big One, Huw Thomas assesses the big infrastructure challenges for a state that is always on the move.

“San Francisco, at the present time, is like the crater of a volcano, around which are camped tens of thousands of refugees. At the Presidio alone are at least twenty thousand. All the surrounding cities and towns are jammed with the homeless ones, where they are being cared for by the relief committees. The refugees were carried free by the railroads to any point they wished to go, and it is estimated that over one hundred thousand people have left the peninsula on which San Francisco stood.”  These were the words of writer Jack London in the wake of the earthquake that struck the Californian city in 1906. A little after five in the morning on 18 April, the San Andreas fault sprang into angry life shaking residents from their beds, tearing up roads and rattling buildings to rubble. Though the quake itself only lasted around a minute, its effects would be felt for years to come. The fires that raged through San Francisco’s shattered streets after the ground had become still obliterated much of what the quake did not. A comparable level of destruction would not be wrought on an American city until Hurricane Katrina hit New Orleans nearly 100 years later.

In truth, describing the event as the San Francisco Earthquake is misleading, undercutting its true scale. Between San Juan Bautista and Cape Mendocino, 296 miles of the northern San Andreas Fault ruptured, with the vibrations being felt as far away as Oregon and Los Angeles. Though California residents have become used to dealing with their state’s violent geology in the intervening years, there has yet to be a repeat of the 1906 episode. Rather than this being a cause for celebration, the long period since San Andreas’ last major movement simply means the inevitable arrival of the next ‘Big One’ is creeping ever closer.

The latest scare came on 4 April 2010 when a 7.2 magnitude quake in Baja California, Mexico shook homes in Las Vegas and Los Angeles, reminding even the most sanguine southern Californians of the Sword of Damocles hanging over their heads. Or rather, beneath their feet. “The really big earthquake is absolutely inevitable,” says Dr. Lucile Jones, a seismologist with the US Geological Service and Chief Scientist for the Multi Hazards Demonstration Project in Southern California. “The plate tectonics are not going to stop. The San Andreas Fault is going to be producing earthquakes close to Magnitude 8, maybe over. The big problem is the difference between geologic and human timescales. We know the earthquake is absolutely inevitable, but there’s a significant possibility it might not show up for 100 years, and that doesn’t feel inevitable to most human beings.”

But with every year that passes, the inevitability of another major quake becomes more pressing. “The average time between earthquakes on most parts of the San Andreas Fault is somewhere been 100 and 150 years,” Jones continues. There’s no place that we’ve been able to get recurrence involved that we have greater than 150 years on the San Andreas. The last earthquake on the southern San Andreas Fault was 153 years ago. On some sections of the southern San Andreas Fault it’s been as much as 300 years.”

Thursday 10:00 am, 13 November 2008  (...the quake begins...)
The San Andreas Fault suddenly awakens at Bombay Beach, northeast of the Salton Sea, and the rupture shoots northwest along the fault at two miles per second, sending seismic energy waves out in all directions. In an instant, the ground on the two sides of the fault is offset nearly 44 feet.

The description above is drawn not from real events but from a document entitled The Shakeout Earthquake Scenario – A Story Southern Californians Are Writing. It was put together to accompany a multi-agency exercise designed to prepare for the possible after-effects of a major quake on the southern section of the San Andreas Fault (see The Great ShakeOut) and paints a troubling picture of the hours, days and minutes following a major tremor.

While improving building codes and remedial work on older structures would prevent damage on the scale witnessed in the quake of 1906, the destruction would nonetheless be significant. Emergency services would have difficulty responding and many people would be trapped in collapsed buildings, injured, or both. As with the San Francisco quake, fire would also be a major issue. Ruptured gas mains, snapped power cables and damaged fuel stations could all burst into flame, a danger compounded by the likely disruption to water supplies.

Along with its volatility, the San Andreas Fault is also responsible for other geographic features that make responding to the next Big One a particular challenge. Over millions of years, the violent tectonic action along the coast has pushed up mountains, cutting Southern California off from the rest of mainland USA. This means that major transportation infrastructure has to be routed through only a few corridors, significantly increasing the risk that they will be severed when a quake hits. This creates major knock-on effects even for communities that escape the quake’s immediate attentions. “The ports of Los Angeles and Long Beach we actually don’t think are going to be badly damaged by a San Andreas earthquake because they’re far enough away, but they’re shipping out to the rest of the country.” Says Lucy Jones. “They have 45 percent of the freight, the sea traffic that comes into the United States and goes out to the rest of the country on railway lines, the closest of which crosses the San Andreas Fault in the area of this earthquake.”

The restricted access routes into Southern California means that is not just transportation that is put at risk. Gas, electricity, water and communication lines also have to squeeze through comparatively narrow entry points, greatly increasing their vulnerability. “There are lifeline corridors that cross those mountains,” Jones continues. “There are only something like five places where everything comes in. Where we have this railway line, we also have two gasoline pipelines that go from the refineries of Los Angeles out to Arizona and Nevada, as well as a natural gas pipeline that brings natural gas into southern California. Those three pipelines cross each other basically at the San Andreas Fault, and if they rupture there and they explode into each other, there’s going to be a huge fire.  That’s also then where Interstate 15 and the major railway line are.”

In addition, there is a major electrical connection bringing in power from hydroelectric dams on the Colorado River that crosses the fault near Palm Springs. Were that to be severed the effects would be felt further afield than just Southern California. “Once you break that connection and separate the generation from the load, the system will start to shut down to protect itself,” Jones explains. “About thirty seconds into the earthquake that rupture will break through the line there. In another fifty seconds all of western North America will be dark.”

While those on the western side of the fault will likely have power restored the same day, the same cannot be said for the rest of Southern California. The only source of electricity in the region capable of cold starting the grid is the nuclear power plant at San Onofre, which would have to go through 72 hours of safety checks before it could be fired up. Even then, power would be restored only intermittently, with rolling light-ups supplying electricity to different communities for short two hour periods.


Friday 10:00 am, 14 November 2008  (...24 hours after the quake began...)
Utility companies are working around the clock to restore services, yet most people in the areas of heaviest shaking lack electricity, natural gas, and water. Utility workers, like transportation crews, medical staff, and emergency responders, push themselves to do their crucial jobs despite concerns about their own families.


The issue of water is another major issue in post-quake Southern California. Quite aside from the immediate challenge of combating fires, the long-term implications of a disrupted supply are potentially even more damaging. “What the earthquake could do is rupture pipelines and damage surface reservoirs,” says Ted Johnson, Chief Hydrogeologist at the Water Replenishment District of Southern California. “It could knock out a lot of the surface water infrastructure, and there’s just not a lot of spare parts lying around.  If all those pipelines get damaged they just can’t be replaced within a matter of days. It could take six months to manufacture them because they’re not just lying in stock in a warehouse somewhere.”

It is here that the Water Replacement District comes in. On a day-to-day basis, the organization’s task is to simply top up water supplies piped into the region from much cheaper sources of groundwater. In normal conditions, the mix is about 60 percent surface water to 40 percent groundwater. If a major quake were to hit, that figure could shift to 100 percent groundwater for quite some considerable time. “Could be up to three years is the most we’ve seen,” says Johnson. “Six months would be better. The groundwater basin could certainly last for six months, a year definitely, but the computer modeling shows it could handle the demand for up to three years provided there was better water conservation. People are going to really have to cut back on their water supply use.”

Ensuring that the groundwater basins remain full enough to meet both daily needs and emergency post-quake requirements is a constant struggle in such characteristically arid area. “We’re looking for more supplies of water to refill the basins,” Johnson continues. “Using recycled wastewater is one of the main things that we’re doing more and more of these days. The Orange County water district has a big project that takes treated sewage water and puts it underground.  We’re doing a lot of the same thing to reuse our water instead of just letting it go to waste to the ocean, and it’s that water that is refilling our aquifers. It sits underground for a year or more before it’s pumped out again so it’s further purified down there. We’re also trying to capture more storm water.”

But even if the reserves are there, getting them to where they are needed will be no easy task in an earthquake-ravaged state. “In many cases the water systems are more than 100 years old,” says Lucile Jones. “The oldest one is built out of cast iron, which is extremely brittle material. Then they moved from that to concrete, another very brittle material.” Though the last 20 or 30 years have seen pipe systems built out of more ductile iron, there remains a huge amount of critical infrastructure that is virtually guaranteed to fail in an earthquake.

The Baja California quake in April offers a smaller scale example of what could be expected from a more severe tremor. “The California Water Emergency Network got activated with this Baja earthquake because there was a lot of damage to the water systems in Imperial County in southernmost part of California right at the border,” Jones explains. “The damage is quite extensive to water treatment plants, to the pipe delivery system, to sewage systems. There’s also the problem of cross contamination when you have sewage pipes and water pipes breaking.”

Scale the recent quake up to one that ruptures along 200 miles of the San Andreas Fault and your problems are much bigger. Water systems would be shattered across a huge area of Southern California and putting them back together would be a massive logistical, construction and manufacturing challenge. In many cases repair would not be cost effective and the only option would be to rebuild from the ground up.


13 May, 2009 (...6 months later...)
Water is back in faucets, sinks, and air conditioning units across the region, but it is too late for many businesses, especially smaller businesses that lacked the resources to wait out the bad times. Businesses forced to close have a domino effect, and as the chances diminish for regaining jobs or finding new ones, more and more people are struggling to rebuild their lives.

Aside from the immediate human cost a major quake along the San Andreas Fault, it is the long-term economic implications of infrastructure damage that is the most worrying. Prior to 1906, San Francisco was the largest city on the west coast, a massive business hub and the main gateway the Pacific and Asia. While the city would be rebuilt, the long period of reconstruction saw Los Angeles emerge as the leading Californian city, a position that it holds to this day.

Though property damage would likely be less severe today because of improved building techniques and codes, the fact remains that businesses unable to secure regular access to power and water in the weeks and months following a quake would have a hard time staying afloat. People and goods would be unable to move freely around, all of which contributes to cascading economic consequences. The very real fear is that by the time basic services were running normally, it would already be too late for countless organizations, families and individuals.

The quake cannot be stopped and Los Angeles isn’t going anywhere, so what can be done? “One of the ways we could make a big difference about it would be to develop an engineering approach to the power and pipe lines that could accommodate thirty feet of motion and still stay up,” says Jones. “When they built the Trans-Alaska Pipeline, they crossed a really big fault called the Denali Fault. They built into it a Teflon slider system with joints that would allow the pipe to stay intact for up to twenty feet of offset. In 2002 we had a bad earthquake with eighteen feet of offset, and the system worked. The pipe did not break.”

However, current economic realities make it a cheaper option for the utilities that own the pipes and power lines to repair something broken than to build something that won’t break in the first place. Continual improvement of building codes and the creation of new techniques to make structure more resilient is also essential.

“The earthquakes are so infrequent,” says Ted Johnson. “They could be ten years apart.  You can instruct and you teach people especially after one has happened, but then you can’t keep it in the forefront every day and people tend to get lazy about their planning, so it is the responsibility of government agencies and teachers to keep the word out.” Efforts like The Great ShakeOut represent perhaps the best approach, bringing together everybody living in the shadow of San Andreas to promote scientific and rational responses to a threat that virtually defies human understanding.

“We need to get people to believe it without paralyzing them to the point that they don’t want to think about it,” says Lucile Jones. California was shaking long before we arrived and it will keep shaking long after we’re gone. We just have to find the best possible way to hang on.

The Great ShakeOut

Now an annual event taking place on the third Thursday in October, The Great California ShakeOut is the largest preparedness drill in America. Involving government agencies, businesses, schools and individual families, it aims to provide the necessary tools to prepare for and react to the inevitable earthquakes that will likely plague the region in perpetuity. The most recent event took place in 2009 and involved more 6.9 million people across the state practicing evacuations and techniques such as ‘drop, cover and hold on’ designed to keep people as safe as possible during a quake. The event also raises awareness of emergency provisions needed for survival in the aftermath and ways in which homes and business can be prepared to minimise damage.

The drill is backed up by a huge amount of research looking at the science of earthquakes, their social and economic impacts and what planners can do to best ready themselves. While earthquakes are far too predictable to ever truly mitigate against, the Great ShakeOut hopes to show that cooperation and education can at least make the best of a bad situation and prevent a disaster becoming a catastrophe.

San Andreas: A history of violence

Fort Tejon, 9 January 1857

Rupture length: 225 miles
Magnitude: 7.9
Maximum displacement: 30 feet
Depth: Less than 6 miles
Fact: As powerful as the quake that ravaged San Francisco in 1906, aftershocks were still being felt at Fort Tejon over a year later 

San Francisco, 18 April 1906

Rupture length: 296 miles
Magnitude: 7.9
Maximum displacement: 28 feet
Depth: 5 miles
Fact: With an estimated 3000 deaths and as many as 300,000 left homeless, the worst natural disaster to ever befall California

Loma Prieta, 17 October 1989

Rupture length: 25 miles (subterranean)
Magnitude 6.9
Maximum displacement: na
Depth: 11 miles
Fact: The quake caused $18 billion in damage to transportation infrastructure and disrupted the Major League Baseball season for 10 days

Parkfield, 28 September 2004

Rupture length: na
Magnitude: 6
Maximum displacement: na
Depth 4.9 miles
Fact: The town of Parkfield sits directly on top of the fault. It experiences a magnitude 6 quake on average every 22 years