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Sioux Falls Scientists endorse Earthquake! for showing how scientists are
struggling to predict earthquakes. It's not easy and the clues are few.

Earthquake!

Earthquake! (2007) - 56 minutes
Earthquake! at Amazon.com

"Only fools, charlatans and liars predict earthquakes."

So quipped the late Charles Richter, who knew enough about nature's ultimate upheavals to invent the scale by which they are measured.

Nevertheless, prediction is the siren song of earthquake studies - the alluring problem on which reputations can be won or wrecked. Not just careers, but millions of lives and billions of dollars depend on the ability of scientists to say just when and where the earth will move. In fact, much of the entire history of earth science has been a struggle to account for the periodic lurching of solid ground. Follow as Nova takes a look at the high-stakes quest to predict earthquakes.

5-26-17 Nowcasting may help forecast big earthquakes in 53 major cities
Nowcasting may help forecast big earthquakes in 53 major cities
Records of small quakes can help us gauge how close we are to really big ones, using a technique borrowed from economics and finance. The ground can start shaking under your feet with almost no warning. Earthquakes have proven nearly impossible to forecast so far, but a technique borrowed from economics and finance can now help us estimate how high the risk is. Seismic nowcasting, as it is called, assesses the current risk of a major earthquake in a given area based on the smaller tremors the area has experienced in the past. Nowcasting gives a snapshot in time, whereas forecasting looks into the future. It’s akin to metrics that incorporate the latest fluctuating data to evaluate whether there’s a looming downturn in an economy or industry. John Rundle at the University of California, Davis, and colleagues have used the technique on data from the US Geological Survey’s earthquake catalogue to calculate the “earthquake score” of 53 major cities around the world. “If you have a high earthquake score, and then you start seeing more small earthquakes, I’d get worried. You’re accumulating hazard, so to speak,” says Rundle, who presented the team’s results at an earth science conference in Chiba, Japan, on 22 May. Geological fault systems on the margins of tectonic plates can evolve rapidly, and the researchers worked on the assumption that earthquakes occur over irregular cycles. They also assumed that some patterns are regular, though, with an average number of small earthquakes striking a region between the rarer “big ones”, which are tens of thousands of times more earth-shattering. This allows the researchers to figure out what stage in a cycle a given city has reached based on how many small quakes have hit since the last big one. Stresses and strain build up over time with each new small earthquake – a small quake being one between magnitudes 3.0 and 6.5. Eventually the rock cannot tolerate the stress, and an earthquake releases energy while fracturing the rock. If a lot of stress has built up, then the quake could be a big one.

12-14-16 Sentinels map Earth's slow surface warping
Sentinels map Earth's slow surface warping
British researchers are now routinely mapping a great swathe of Earth's surface, looking for the subtle warping that ultimately leads to quakes. The team is processing satellite images to show how rocks in a belt that stretches from Europe's Alps to China are slowly accumulating strain. Movements on the scale of just millimetres per year are being sought. The new maps are being made available to help researchers produce more robust assessments of seismic hazard. The kind of change they are trying to chart is not noticeable in the everyday human sense, but over time will put faults under such pressure that they eventually rupture - often with catastrophic consequences. "We may well discover regions that have very small strain rates that we have not been able to detect before," said Dr Richard Walters "And that may well tell us that earthquakes are more likely in some areas that traditionally have been thought of as being completely stable and not at risk of having earthquakes at all."

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Earthquake!

Sioux Falls Scientists endorse Earthquake! for showing how scientists are
struggling to predict earthquakes. It's not easy and the clues are few.