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San Andreas Fault line and Golden Bears Stadium

The cracks in the ground are caused by stresses within a single tectonic plate. But when two tectonic plates meet they cause a different kind of crack. They create a huge splits in the ground called faults. And some faults can be very bad news indeed.

At 12:51 on 22nd of February this year. The cathedral spire in Christchurch, New Zealand falls as an earthquake leaves 182 dead. Less than a month later on 11th of March an even bigger earthquake struck Japan. It produced a tsunami with waves of up to 98 feet high, killing perhaps 25,000 people. And on the other side of the pacific just a year earlier, 562 people died in powerful quake in Chile. The Pacific Rim is an area of intense earthquake activity. In fact, over the last 50 years there have been dozens of major earthquakes along the coast of North and South America.

The fact is tectonic plates do move all the time. And the evidence is in a stadium just across the bay from San Francisco. The Golden Bears are the American football team of the University of California, Berkeley. Their home ground the Memorial Stadium is one of the oldest and most iconic football grounds in the US. But the way things are going, the stadium may not be here for much longer. Stands are crumbling, Walls are fracturing. Something strange is going on there. Geologist Roland Burgmann says that its all down to a fault called the Hayward Fault, which runs right underneath the city of Berkely. The fault goes straight through the middle of the stadium. It is literally splitting in the middle. The western half of the stadium is being dragged north west of four millimeters a year.

Since it was built nearly 90 years ago, the two halves of the stadium have been pulled apart 14 inches. Yet the real worry for the Golden Bears is that the fault line is moving too slowly. Its moving by four millimeters a year but that’s not enough. It should be slipping by ten millimeters per year. Its not doing the full amount of slip which is called slip deficit. What that means is, it has to catchup at some point. And we know the way the catchup will happen in a big earthquake. Its been 140 years since last earthquake and we are due one now.

The Hayward Fault that runs through the stadium is of the much larger San Andreas fault system. All the hills and valleys have been created by the constant movement of the land. A view from the air and seeing the fault round woodlands and round hills, one just gets a sense of how massive it is.

Millions of years ago, when the San Andreas fault tore apart the land, a lake was formed. It filled with water, was extended and is now used a reservoir for the whole Bay Area. When the San Andreas fault shifts just a few feet it can cause a quake. But the land is always on the move and over millions of years, the distance it travels is quite extraordinary. Rocks found in northern California started life hundreds of miles away in southern California. This is part of this sort of 20 odd million years trek, that whole slab of land has made, inching its way along as it creeps. And that means the changes to the landscape will be dramatic.

San Francisco and Los Angeles sit on two separate tectonic plates, either side of the San Andreas Fault. Over 9 Million Years LA will move 350 miles north, so you won’t need to drive between the two cities because they will be side by side. There is one thing though that might not be here after the next big quake hits. The symbol of San Francisco, the Golden Gate bridge. There’s a big debate among engineers if its built safe enough for a big earthquake. But its a bit late now, as its been built.

The Golden gate bridge may not survive a major quake. But on the other side of the bay, the Golden Bears have taken dramatic steps to protect their stadium. They’re cutting it in half. When the work is finished, the stadium will rest on separate free-floating blocks of concrete, so if a quake hits, the whole stadium will roll with the punches. One side of the stadium is going to be a completely separate structure from other, and the two sides can move independently, even in a large earthquake. The two sides of the stadium are just going to move their separate paths, thereby there will be much less destruction. The job is going to take two years to complete. It’ll cost the Bears a cool $320 million to carry out.

So when the big one hits there’s one place in the Bay Area that Roland thinks will be more than ready. According to him, the work that’s been done on the stadium right now, it is going to be one of the safest places to be in the next large earthquake.

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