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Science news digest – 22 October 2012

In the science news this week, human activity caused Spanish earthquake, UK experiences “weirdest weather”, boys are reaching puberty younger, and finally… elephants use hair to stay cool.

Lorca earthquake caused by human activity

In May 2011, a devastating earthquake that killed nine people and injured dozens more near Lorca in southern Spain, may have been triggered by the extraction of groundwater, a new report suggests.

This is the first time that there has been evidence to suggest that human activity caused a major earthquake – there is already evidence showing that small earthquakes have been triggered by activities, such as fracking.

However, this step could help seismologists to predict future events if they can understand how and why such activities cause quakes.

Pablo Gonzalez and his colleagues at the University of Western Ontario investigated whether the removal of groundwater in the area could have caused the earthquake at Lorca. Since 1960, the water table has dropped by 250m – a dramatic change – causing the land to subside by about 15cm a year, reported New Scientist.

The team used radar to model how much land had slipped during the quake and identified where it had originated from. At just 3 kilometres below the Earth’s surface, the quake occurred at a much shallower depth than would be expected for one of its magnitude.

They also modelled the effect that the reduction on groundwater levels would have on stress patterns in the crust, and found that the stresses lined up almost exactly to the rupture pattern seen during the earthquake, leading them to believe that the extraction of groundwater must have triggered the quake.

González believes that the earthquake would have happened anyway, even if the groundwater hadn’t been extracted. "This portion of the fault was tectonically loaded," he said.

However, it is likely to have happened in a different way. Jean-Philippe Avouac from the California Institute of Technology in Pasadena believes the water extraction made the earthquake occur at a shallower depth than it would have been without human intervention. This ultimately made the quake much more destructive.

“It's not just that you're advancing an earthquake that would have happened anyway. It's that you're creating more or larger earthquakes," he said.

However, if it can be understood how these activities trigger earthquakes then more could be done to improve the forecasting of such events, and possibly lead to a method that can relieve stresses in the ground before a major quake occurs.

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UK has experienced “weirdest” weather

The Environment Agency, Met Office and the Centre for Ecology & Hydrology (CEH) have warned that the UK has had the “weirdest” weather ever recorded over the past few months.

The records show that this year has seen the driest spring for over a century, followed by the wettest recorded April to June. Although they stressed that there was no evidence that the change in weather conditions was caused by climate change, the three bodies warned that the UK should plan for equally extreme weather in the future.

However, there was also some encouraging news – despite the extreme weather, only 4,500 properties were flooded this year, compared to over 55,000 properties in 2007.

Paul Mustow, head of flood management at the Environment Agency, explained to BBC news that over 50,000 would have been flooded this year without the flood defences that have been put in place in recent years.

He said: "We have to get our heads round the possibility now that we're going to have to move very quickly from drought to flood - with river levels very high and very low over a short period of time.

"We used to say we had a traditional flood season in winter - now often it's in summer. This is an integrated problem - there's no one thing that's going to solve it. The situation is changing all the time."

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Boys are reaching puberty younger

A study from the American Academy of Pediatrics has found that boys are showing the signs of puberty six months to two years earlier than previous generations. The study looked at 4000 boys in 41 US states aged six to 16 years, reported the Guardian.

This goes along with the discovery in 2010 that showed that girls were starting puberty as young as seven.

The study has not identified the causes of these changes, but it did refer to the possibility that a change in diet, physical activity and other environmental factors could be involved.

The possibility that weight gain could be involved might explain the earlier development in girls, as body fat is linked to production of the female hormone, oestrogen. However, this does not explain the early development in boys.

It is also unclear whether weight gain is the cause of early development, or simply a consequence of it.

The study has also shown a divide in the age boys reach puberty with regard to race. It found that on average, black American boys were showing signs of puberty earlier than their white and Hispanic counterparts.

"It could be biological, genetic or environmental. It could be something African American kids are being exposed to that white kids aren't. We really don't know," said Richard Wasserman, director of the AAP's Pediatric Research in Office Settings network. "We have raised as many questions as we've answered."

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And finally…

Elephants use hair to keep cool

A new study seems to suggest that elephants buck the trend when it comes to staying cool, opting to grow hair rather than shed it, reported the Telegraph.

According to the study, elephants use the bristly hair to dissipate heat, increasing their heat loss by up to 20 per cent.

It has been well known that elephants have adapted large ears in order to regulate their temperature, as well as bathing in rivers, but this is a new discovery.

Professor Elie Bou-Zeid, from Princeton University who led the research said: “Hair works as an insulator when it covers the skin. We show that sparse hair has the opposite effect.

“Sparse hair increases heat dissipation from the skin of elephants. What was surprising to us was the magnitude we found for this effect.”

In still conditions, sparse hair increased heat loss by five per cent, and up to 23 per cent in a light breeze. They also found that hair switches from being an insulator to a heat dissipater when there are fewer than 300,000 hairs per square metre.

Conor Myhrvold, the lead author on the study, said: “the heat transfer effect of elephant hair challenges the belief that a sparse hair layer would have provided insulation early on in its evolutionary development.

“It could therefore be a first step to resolving the prior paradox of why hair was able to evolve in a world much warmer than our own.”

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