The coloured bands, or fringes, represent movement towards or away from the spacecraft
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The upheaval wrought by the 22 February earthquake in Christchurch, NZ, is illustrated in new radar imagery.
The Magnitude 6.3 tremor killed more than 160 people and shattered a city already reeling from a previous seismic event in September.
Data from the Japanese Alos spacecraft has been used to map the way the ground deformed during the most recent quake.
It shows clearly that the focus of the tremor was right under the city’s south-eastern suburbs.
The type of image displayed on this page is known as a synthetic aperture radar inteferogram.
“To get an earthquake right under their city will have been a surprise to nearly every single person”
John Elliott Oxford University
It is made by combining a sequence of radar images acquired by an orbiting satellite “before” and “after” a quake.
The technique allows very precise measurements to be made of any ground motion that takes place between the image acquisitions.
The coloured bands, or fringes, represent movement towards or away from the spacecraft.
In this interferogram, the peak ground motion is almost 50cm of motion towards the satellite.
“It’s like a contour map but it’s showing to the south-east of Christchurch that the ground motion is towards Alos. That’s uplift,” explained Dr John Elliott from the Centre for the Observation and Modelling of Earthquakes and Tectonics (Comet) at Oxford University, UK.
“And then right under Christchurch, we see subsidence. That’s partly due to liquefaction but it’s mainly due to the way the Earth deforms when you snap it like an elastic band.”
Liquefaction is a phenomenon that afflicts loose sediments in an earthquake and is akin to a lateral landslide.
It is a major issue for Christchurch because the city is built on an alluvial plain, and this type of ground will amplify any shaking during a tremor.
BBC News reader Gillian Needham took this image of central Christchurch moments after the quake struck New Zealand’s second city on 22 February (local time)
Scientists are using the Alos information to understand better the future seismic hazards in this part of New Zealand.
It has become obvious from recent events that Christchurch sits close to “blind faulting” – faulting that is at risk of rupture, but which betrays little evidence of its existence at the surface, meaning the potential danger it poses is not properly recognised.
“It means much more work needs to be done around Christchurch,” said Dr Elliot.
“People knew they could get earthquakes further into the mountains [in the west of South Island]; that’s how they’ve been built in some ways, through earthquakes and all the faulting.
“But to get an earthquake right under their city will have been a surprise to nearly every single person.”
The interferogram is noticeably incomplete – there are several areas where the fringing is missing. There are a number of reasons for this.
To the east is ocean, and this technique does not work over water.
To the west, the issue is related to the satellite track and the fact that it views the Earth in strips. Hence, you get bands of data.
But the more interesting and more relevant omissions are in Christchurch itself.
Dr Elliot commented: “Here, the patches are the result of de-correlation between the acquisition images, where we just can’t match them – they’re too different.
“There are a few reasons for that. Usually it’s the result of vegetation growth, but here it could be due to more extreme shaking or liquefaction.”
Tuesday’s quake was less energetic but more destructive
Researchers are investigating the relationship between September’s Magnitude 7.1 quake and last month’s 6.3 event.
The latter is very much considered to be an aftershock from the first, even though they were separated by six months.
The former occurred about 40km to the west, rupturing a similar length of fault. The most recent quake ruptured about 15km of fault.
What scientists need to know now is the nature of any “seismic gap” between the two; that is, a segment of fault which was not broken in either tremor but which may have been loaded with additional strain because of both those events.
The Advanced Land Observing Satellite (Alos) was launched in 2006
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This article is from the BBC News website. © British Broadcasting Corporation, The BBC is not responsible for the content of external internet sites.
Sony has said it can identify PS3 users running hacked consoles
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Sony has been given permission to obtain details of people who downloaded files needed to hack the PlayStation 3.
A judge in San Francisco granted the electronics giant a subpoena that would allow it to see a list of IP addresses.
The software, used to crack the PS3’s operating system, was posted on the website of George Hotz, who is also known as Geohot.
Sony is suing Mr Hotz, claiming his hacks breach copyright laws, and could allow users to play pirated games.
Court documents, obtained by Wired magazine, show that the company successfully petitioned to obtain IP addresses from the web-hosting company Bluehost.
The details could be used to trace the real-world geographical locations of users who accessed George Hotz’s website, Geohot.com.
However, it may not be Sony’s intention to take legal action against those found to have downloaded the software crack.
Sources with knowledge of the case said there was unlikely to be the appetite for a prolonged and expensive series of legal challenges.
Rather, the subpoena document suggests that Sony wants to discover the number and location of the downloaders in order to establish jurisdiction in its case against Mr Hotz.
“SCEA [Sony Computer Entertainment America] needs to determine how rampant the access to and use of these circumvention devices has been in California in order to rebut Mr Hotz’s suggestion that his illicit conduct was not aimed at the forum state,” the document reads.
The subpoena also grants Sony the right to access information relating to the case from Twitter, Google Blogspot and YouTube.
The company had previously been granted a restraining order against Mr Hotz, banning him from revealing techniques to manipulate the PlayStation 3’s operating system.
The 21-year-old, along with a number of other individuals, is charged with violating several copyright-related laws, including the Digital Millennium Copyright Act
He is also accused of offences under the United States’ Computer Fraud and Abuse Act.
Mr Hotz denies that he set out to help software pirates, claiming instead that he was championing the ‘home brew’ community – users who write their own software for the PS3.
Sony has said it is now able to remotely identify users who are running hacked PlayStation 3 consoles and that it will ban persistent offenders from using its online services.
This article is from the BBC News website. © British Broadcasting Corporation, The BBC is not responsible for the content of external internet sites.
Modern parents are under pressure with long working hours, childcare dilemmas and family break-ups. But what is the impact on children and what can be done about it?
I’ve got three young children and a full-on job. I’d always thought that these early years were the hardest and now would be the time when I should be around the most.
But in fact I’m quickly learning that the older kids get the more they need you.
My children who are six, five and three want me to take them to school and collect them afterwards. They want me to listen to them reading, help with their drawings, go on school trips and turn up at their plays.
In short they want my time and attention, something that the childcare expert, Penelope Leach, says will continue all the way through the teenage years.
“Would you be surprised to hear that children left on their own regularly until parents get home from work do less homework, are more likely to drink alcohol and tend to get themselves into inappropriate sexual situations? It’s not rocket science,” says Leach.
For millions of families trying to make ends meet, being around a lot can be difficult. Stay-at-home mothers are now in a minority because up to 70% of women with children under the age of one go back to work. When both parents work, you need childcare and that is rarely simple to sort out.
When I had my first child nearly seven years ago, I couldn’t bear the idea of leaving her when my maternity leave was over. When I was pregnant, I’d planned to send my baby to a local daycare centre, but once Ella was born, I couldn’t do it. I wanted her to be in her own home.
So like thousands of other working mothers, I relied on my parents and in laws until I stumbled across a nursery school teacher who has worked as our nanny ever since. But I know I am very lucky – that kind of childcare is expensive.
Many parents do not realise that the demands for quality time never decrease
For a lot of working parents, childminders and daycare are the cheapest and only option. But some academics have been sounding warnings about the downside of nursery care.
Philippa Brewer-Dalziel went back to work full-time when her first child, Keane, turned two. Her hours were long and it meant Keane was at nursery from 7.30am until 6pm five days a week. She noticed a big change in her son’s behaviour.
“He didn’t want to start coming home with me. I think it was just because he wasn’t spending enough time with me. Even though I was his mum, I almost became a stranger to him,” she says.
In the end Philippa became so concerned that she reduced the number of hours she was working. Keane’s now five and is at school. But she’s still worried about his behaviour and thinks that the amount time he spent in daycare may have had a role to play.
“Nothing winds me up more than when someone tells me how to raise my own kids”
Shannon Sommarsby Parent
“Keane became quite aggressive and quite angry towards myself and my partner Darrell. And it flowed over into school and it came to a point where the school were concerned.”
Keane’s behaviour is getting better now. It’s been suggested for some time that spending too much time in nursery care can make children more aggressive and badly behaved. But now experts are worried about what happens when these daycare kids start school.
The child development specialist, Prof Jay Belsky, says that bad behaviour can spread through the classroom ‘like a virus’.
“What you see is a kind of contagion effect. So that the more kids there are in the room with more childcare experience, the more aggressive and disobedient all the children in the room are.”
Other experts disagree. Professor Edward Melhuish, a psychologist from the University of London, believes daycare can be a positive experience but what’s key is the quality of the care. He says children sent to good nurseries can be up to six months ahead of other kids when they reach school age.
“High quality pre-school education does all children a lot of good and the consequences for disadvantaged children are particularly important,” Prof Melhuish says.
There are many distractions for the modern parents
Shannon Sommarsby and Alastair Swaffer believe daycare has been nothing but a positive experience for their two-year-old twins.
Charlotte and Fraser have been going to nursery from eight in the morning until five in the afternoon since they were four months old. But Shannon says they love it, they get to meet other children, they learn to interact.
“Nothing winds me up more than when someone tells me how to raise my own kids because no-one knows our kids apart from us,” Shannon says.
The problem is that no-one seems to be able to tell you conclusively if daycare is good or bad for our children. There seem to be so many ifs and buts. In the end you do just have to make your own choice.
Even at home, spending quality time with your children can be quite difficult. With long working hours, mobile phones, computers, television and so much else going on, it’s easy for parents to be distracted.
Some schools are becoming increasingly aware of this problem, and the effect it has on some pupils’ behaviour. Fairlight School in Brighton is one of 40 around the country taking part in a new American scheme called Fast – families and schools together.
Electronic distractions
It’s about parents learning to enjoy proper time with their children. Once a week they spend a few hours in school, when lessons are over, cooking tea for the kids and chatting as families.
One of the tasks during the session requires parents to spend 15 minutes focusing all their attention on the child as they play and letting them lead the way – they can’t tell their child what to do, tell them off or criticise.
I gave it a go the next day at home with one of my kids at the kitchen table. My computer kept flashing in the background, my mobile beeped in my bag with texts and emails. My other two children wanted my attention. Suddenly 15 minutes without moving seemed like rather a long time.
The headmaster at Fairlight School, Damien Jordan, says parents, despite their best intentions, often don’t give their children enough proper time.
“If you ask children what they want, it’s time with their parents. They don’t have to be taken off on all these fantastic trips and go to places that cost money. They actually want to spend time enjoying themselves, laughing with their parents, cooking with their parents, things that don’t cost a fortune.”
My trip to Fairlight school did make me think. When I got back I banished my laptop from the kitchen and I do now try to put my phone away when I’m playing with the kids. These are small gestures, but I can see how they can make a difference.
Ultimately it’s not lots of toys, trips and techniques that my children want, it’s me.
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