California's San Andreas fault has been quiet for far too long and is overdue for a major earthquake, a leading geoscientist has announced. In a conference this week, the state was warned to prepare for a potential earthquake as strong as magnitude 8.0. 
 
 "The springs on the San Andreas system have been wound very, very tight. And the southern San Andreas fault, in particular, looks like it’s locked, loaded and ready to go," said Thomas Jordan, director of the Southern California Earthquake Centre. 
 
 Jordan gave his warning in the keynote talk of the annual National Earthquake Conference in Long Beach, the Los Angeles Times reports. 
 
 Here's why he's so worried: research has shown that the Pacific plate is moving northwest relative to the North American plate at a rate of around 5 metres (16 feet) every 100 years - and that's building up a whole lot of tension along the San Andreas fault line that needs to be relieved regularly. 
 
 But the last time southern California experienced a major shake-up was in 1857, when a magnitude 7.9 quake rupture almost 300 km (185 miles) between Monterey County and the San Gabriel Mountains. 
 
 Further south, areas of the fault line have been quiet even longer, with San Bernardino county not moving substantially since 1812, and the region near the Salton Sea remaining still since the late 1600s. 
 
 All of this means that there's a lot of tension underneath California right now. Last year, Jordan's team found there's a 7 percent chance the state will experience a magnitude 8.0 quake in the next three decades. 
 
 And that's a big problem. Back in 2008, a US Geological Survey report found that a magnitude 7.8 earthquake on the southern San Andreas fault could cause more than 1,800 deaths, 50,000 injuries, US$200 billion in damage, and long-lasting infrastructure disruptions - such as six months of compromised sewer systems and ongoing wildfires. 
 
 Even though Los Angeles isn't on the San Andreas fault line, simulations by the Southern California Earthquake Centre show that the shaking would quickly spread there: 
 
 According to their modelling, that size earthquake could cause shaking for nearly 2 minutes, said Jordan, with the strongest activity in the Coachella Valley, Inland Empire and Antelope Valley. 
 
 The reason Los Angeles is at so much risk is because it's built over a sedimentary basin, and the seismic waves spread and get trapped there to cause more extreme and longer-lasting shaking. As you can see in the magnitude 8.0 simulation: 
 
 While Jordan praised recent initiatives to earthquake retrofit buildings in LA, he warned that the rest of the state needs to get ready for the next big one, by making residents more aware of ways to stay safe during an earthquake and when and how to evacuate. 
 
 "We are fortunate that seismic activity in California has been relatively low over the past century," Jordan explained last year. "But we know that tectonic forces are continually tightening the springs of the San Andreas fault system, making big quakes inevitable." ||||| The quake was so powerful that the soil liquefied, causing trees as far away as Stockton to sink. Trees were also uprooted west of Fort Tejon. The shaking lasted 1 to 3 minutes. 
 
 Even though the San Andreas fault does not go directly into Los Angeles — it is 30 miles away from downtown — the city is expected to be heavily shaken by a large earthquake on that fault. For instance, simulations of a possible magnitude 7.8 quake on the San Andreas fault that begins at the Salton Sea and spreads west toward the San Gabriel mountains show seismic shaking waves "bent into the Los Angeles area," Jordan said. One video shows strong ground-shaking stretching from northern San Diego County to Barstow. 
 
 Using the world's largest supercomputer at the time, the Southern California Earthquake Center in 2010 unveiled a simulated magnitude 8 earthquake that begins in Monterey County, like in 1857, but travels even farther south, heading toward the Mexican border. The L.A. Basin and the San Fernando Valley would be hit hard because the shaking would be trapped by soft soils in the valley and basin. 
 
 "You can see that this area of influence by the shaking has now expanded out to huge proportions," Jordan said. "You see that big directivity pulse out in front, as that energy is being shoved down that fault, that directivity pulse leads energy into seismic waves that excite the sedimentary basins, like the San Fernando Valley and the Los Angeles Basin," and through San Bernardino, Jordan said. 
 
 "You'll notice large shaking in the Los Angeles region persisting for long periods of time," he said.
– Here's an unfortunate hypothetical: An earthquake strikes along the San Andreas fault, damaging three aqueducts that cross it some 32 times. Those aqueducts supply Los Angeles with all but 12% of its water—meaning a serious quake could ultimately leave 22 million people without water. (There would be about six month's worth of water stored on the LA side of the fault, but fixing busted aqueducts could take more than twice that long.) Officials have been aware of the potential for a single quake to hit all three aqueducts since 2008, but as the Los Angeles Times reports, they're now moving to do something about it for the first time. But any solution is pretty far off, in terms of time and money—in terms of the latter, the LAT uses the word "billions." None of the aqueducts has yet had to deal with the scenario; the last huge quake (magnitude 7.9) along the fault was in 1857. The Los Angeles aqueduct travels across the fault under a mountain, by way of the five-mile-long concrete Elizabeth Tunnel. Building a brand new tunnel is the priciest option; sending water over the mountains via an electric pumping mechanism is another idea. In the case of the Colorado River Aqueduct, a quake could raise a section of the pipe by 13 feet, and there aren't any pumps in place to ferry the water to LA. The mayor last week requested that proposals on the issue be submitted by July. Meanwhile, the San Diego Union-Tribune reports that there may be another fault to fear: It points to new research that shows the San Jacinto fault could generate an earthquake as powerful as what the San Andreas fault is capable of.