Why are aftershocks from North Korea’s nuclear tests still happening?

Why North Korea’s nuclear test is still producing aftershocks, BBC, 11 December 2017 “…….

Why are aftershocks still happening?

According to the USGS, last weekend’s tremors were “relaxation events”. They measured a magnitude of 2.9 and 2.4.

“When you have a large nuclear test, it moves the earth’s crust around the area, and it takes a while for it to fully subside. We’ve had a few of them since the sixth nuclear test,” an official told Reuters.

The “movement of the earth’s crust” is akin to the very definition of an earthquake and scientists say it is only to be expected in the weeks and months after an explosion of that magnitude.

“These aftershocks for a 6.3 magnitude nuclear test are not very surprising,” Dr Jascha Polet, seismologist and professor of geophysics at California State Polytechnic University, told the BBC.

After any tremor of that size, aftershocks with declining magnitude are common, as the rock moves around and releases stress.

The area around the quake site “experiences deformation, and this creates areas of increased and decreased stress, which affects the distribution of aftershocks,” Ms Polet said.

“The fact that the source of the earthquake is an explosion doesn’t change how we expect the energy to redistribute,” geophysicist and disaster researcher Mika McKinnon, told the BBC.

But research on explosions of a similar magnitude as the North Korea nuclear test at the Nevada Test Site in the US where over decades nuclear tests were carried out, has found that the aftershocks of these events were fewer in number and lower in magnitude.

So each location is unique.

Can tremors destroy the test site?

One of the speculations after the September test was that it would damage the tunnel system North Korea has dug into the mountains at its test site.

“The more energy you put into an area, the more unstable it’s going to get,” Mika McKinnon explained.

“The more tests are happening, the more energy there is, the more redistribution of stress and the more rocks will be breaking.”

There have been some indications of individual tunnel collapses, she explained. “Seismic signals that look more like rock fall than anything else. That will happen more and more.”

But, she adds, there is no way of really knowing whether the entire tunnel system will collapse as this is an engineering problem far more than a scientific one.

It is unclear whether this process already has rendered the current test site unusable but North Korea has hinted its next nuclear test could be above ground…….http://www.bbc.com/news/world-asia-42305161

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On behalf of the blogger Shaun McGee aka arclight aka Sean Arclight on FB and @Arclight2011 on Twitter, my co-blogger, one of us 3 bloggers of Nuclear news blog (https://wordpress.com/post/nuclear-news.net):

Shaun needs badly to replace his computer, which is kaputt. During the past 8 years he has been unceasingly researching and blogging about worldwide nuclear and about Fukushima, producing quality articles.

Please let’s help him to get a new computer, tip in whatever you can spare him. His paypal connected email is arclight2011@riseup.net for donations.

Advanced thanks, Herve Courtois aka Dun Renard

A good news story: Jay Inslee Is Betting He Can Win the Presidency on Climate Change
The Washington governor believes his focus on the environment will resonate with voters. But can he persuade enough Americans to pay attention to him? EDWARD-ISAAC DOVERE, The Atlantic JAN 2, 2019 “………When you’ve been working on something for over a decade, and now seeing people awakening to that, it’s just really gratifying and heartening,” the Washington governor recently told me, sitting in his private study on the top floor of the governor’s mansion. When it comes to climate change, there now appears to be “an appetite for someone who has credibility and a long track record and, most importantly, a vision statement. It’s changed to show an opening in a Democratic primary, I believe.”…..

As he did in Washington State, Inslee would propose a mix of government investments and incentives to spur other investment, restrictions on power plants and emissions, and programs to promote R&D and job growth. An endless number of jobs can be created in the climate arena, Inslee says. It’s the way to make a real dent in income inequality and have the Democratic Party bring tangible solutions to communities in rural America that have been left behind……… https://www.theatlantic.com/politics/archive/2019/01/washington-governor-jay-inslee-running-president/579217/

Sizewell Hero

Greta & Svante Thunberg – Straight Talk

Longtime Reporter Leaves NBC Saying Media Is “Trump Circus” That Encourages Perpetual War

EVENT

The Bulletin of the Atomic Scientists will host a live international news conference at 10 a.m. EST/1500 GMT on Thursday, January 24, 2019, to announce the 2019 time of the Doomsday Clock. The news conference will take place at the National Press Club in Washington, D.C. Watch the announcement live on our website, on our Facebook page, or on Twitter. more https://nuclear-news.net/2019/01/10/the-doomsday-statement-2019-bulletin-of-the-atomic-scientists/

The Nuclear Resister – Nonviolent Resistance for a Peaceful and Nuclear-Free Future

Accidents Can Happen. Voices of Women from Three Mile Island https://www.accidentscanhappenthefilm.com/

A Good News Story: A Surge of Climate Lawsuits Targets Human Rights, Damage from Fossil Fuels Cities, states and the fishing industry want courts to hold fossil fuel companies accountable for global warming. Others argue government inaction violates rights.BY NICHOLAS KUSNETZ “….The past year saw a surge in new lawsuits filed against fossil fuel companies, and major developments in cases pressing governments for action in the United States and abroad.”

“Lawsuits, even if unsuccessful, can help shape public opinion,”

“Mr. Scopes lost the monkey trial, but it led to a lot more awareness about the issue of teaching evolution.”

In Colombia and the Netherlands, citizens won rulings in 2018 ordering their governments to cut emissions and protect forests. By framing climate change in terms of human rights, those cases and similar ones filed in the U.S. and other countries are transforming how the courts address the issue………. https://insideclimatenews.org/news/04012019/climate-change-lawsuits-2018-year-review-exxon-fossil-fuel-companies-human-rights-children-government

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