BOGOTA (Reuters) - Colombia’s top administrative court on Friday began hearings that could be long and contentious about proposals to drill for oil using the technique known as fracking, hailed for sharply boosting supplies but criticized for causing environmental damage.

Demonstrators take part in a protest against the use of fracking, in Bogota, Colombia June 7, 2019. REUTERS/Luisa Gonzalez TPX IMAGES OF THE DAY

The public hearings in the Council of State, which is tasked with ruling on administrative matters, stem from a decision made late last year to temporarily suspend regulations for development of non-conventional oil deposits.

Fracking is not yet in use in Colombia. While there is no law against the practice, the government says regulations are needed before it can be used. Its possible use has sparked vitriolic debate among lawmakers, activists, officials and regular citizens about whether it could cause pollution or other environmental harms.

“We consider this high-impact litigation,” Magistrate Ramiro Pazos told Reuters after the largely procedural hearing. “It’s an issue of extreme importance for the country.”

Six magistrates could rule next month on whether the suspension should continue, Pazos said, while evidence gathering on whether fracking should go ahead will take until the end of the year.

The next hearing, which will include witness testimony, is scheduled for July.

The tribunal’s decision to suspend the regulations came after environmental lawyer Esteban Lagos, with support from the Universidad del Norte college, anti-fracking activists and a leftist lawmaker, filed a suit against the energy ministry to halt potential use of the technique.

Lagos, representing himself, said he was optimistic about the process.

State-run oil company Ecopetrol is acting as a co-defendant and asked the court to lift the suspension measure so a fracking pilot project can proceed.

The company has applied for several fracking licenses and is looking to spend $500 million on exploring unconventional deposits over the next three years.

Hundreds of activists gathered outside the court building to protest fracking - one of 70 marches set to take place around the country on Friday.

Fracking could nearly triple Colombia’s reserves of crude and gas, the government has said.

Hydraulic fracturing breaks up rock formations with pressurized liquid. Its use is credited for booming oil and gas production in the United States, but environmental activists have blamed it for water pollution and earthquakes.

An expert commission convened by the government to study fracking recommended strict monitoring of three pilot projects to determine whether the technique should be widely used.

Three commission members will be able to testify in the case, Pazos ruled. </s> The rise of fracking has reshaped the global energy landscape.

It recently hit a new milestone in the U.S. Fracking now accounts for more than half of all U.S. oil output, according to the Energy Information Administration. It's a stunning feat considering fracking made up less than 2% of American oil production in 2000.

Hydraulic fracturing technology, more commonly known as "fracking," paved the way for drilling into America's enormous shale deposits. It has fueled a dramatic boom in U.S. oil production.

Back in 2000, there were just 23,000 fracking wells pumping about 102,000 barrels of oil a day. Now there are 300,000 fracking wells, churning out 4.3 million barrels per day.

Fracking "has allowed the United States to increase its oil production faster than at any time in its history," the EIA said in recent report.

U.S. output has nearly doubled over the past decade and America only trails Saudi Arabia and Russia globally.

That surge in American crude is one of the main reasons why there is a global glut in oil that keeps getting worse. The excess supply caused oil prices to peak in mid-2014 and crash as much as 75% since then.

"Prices are where they are because shale has been so phenomenally successful. It's changed the whole pricing paradigm," said Tamar Essner, director of Nasdaq's energy team.

So how does fracking work?

Fracking involves shooting a mixture of mostly water and sand under high pressure against a rock formation until it fractures. The sand fills the fracture, forcing crude oil out of the rock formation.

Fracking has been criticized for its potential environmental consequences, including water contamination and earthquakes. These concerns were summed up in a 2010 HBO documentary called "Gasland" that focused on communities impacted by natural gas fracking.

Shale oil is not a new discovery. It's actually been around for 60 years. What's new is that the technology has vastly improved in recent years.

Innovation has made previously-expensive fracking much more efficient. High oil prices before and after the Great Recession lured tons of investment dollars into this space, fueling a technological revolution. Investors were also motivated by extremely low interest rates to borrow cheap and invest in this technology.

The fracking revolution first hit the natural gas space, fueling a wave of production in giant shale fields such as the Barnett and Marcellus spread across Texas, New York, Pennsylvania and Ohio. But a supply glut quickly formed in natural gas, causing prices to crater.

Related: Saudis to take control of largest U.S. refinery

Days of $100 oil gone for now thanks to fracking

Fracking then spread to shale oil fields, led by the Eagle Ford and Permian Basin of Texas and the Bakken formation of North Dakota. This turned out to be a game changer because it brought about a ton of new supply that was cheaper to drill than deepwater projects or even the Canadian oil sands.

"The incremental amount of new supply was really underestimated. I don't think any OPEC member took shale seriously until maybe two years ago," said Essner.

The other game-changing characteristic of fracking shale oil is how fast the entire process is. While deepwater production in places like the Gulf of Mexico require tons of lead time, shale wells can be drilled and start pumping oil relatively quickly.

The "fast-cycle" nature of shale is one of the reasons many believe the days of $100 oil are gone for now.

Lately, shale drillers have dialed down pumping and U.S. oil output has declined a tad in recent months because oil prices fell as low as $25 a barrel.

However, everyone expects some of these oil fields to be easily switched back on the minute oil prices hit levels where they can make money. For some shale oil fields that price can be as low as $40 a barrel.

"It puts a ceiling on how far and how fast prices can go up," Essner said. </s> (CNN) President-elect Donald Trump has selected former Texas Gov. Rick Perry to be his nominee for energy secretary, multiple transition sources told CNN Tuesday, which would make him head of an agency he once sought to eliminate.

Perry, twice an aspirant for the White House and for decades a swaggering figure in the Texas Republican Party, returns to the national limelight after his career in politics withered amid scandal and embarrassment.

If confirmed by the Senate, Perry will inherit a department that has focused on promoting clean energy and reducing dependence on fossil fuels, but has also seen domestic production of oil explode. And his selection is a nod to the traditional GOP emphasis on energy sources like coal and oil.

A hallmark of Obama's Energy Department has been the grants and loans it issues for research. The loan program was expanded to include renewable energy projects as part of Obama's economic stimulus package in 2009, and more than $30 billion in loans have been issued since then.

These loans have also been a source of controversy. In 2011, Obama administration had to defend its loan to Silicon Valley energy startup Solyndra when it filed for bankruptcy and taxpayers had to foot a $535 million bill. For all its support of green energy, the department has also presided over a massive oil boom.

Obama's current energy secretary Ernest Moniz is a longtime supporter of fracking, which he sees as a "bridge" to a low-carbon future. He has lauded increased domestic production of oil and natural gas via the technique. Hydraulic fracturing technology, more commonly known as fracking, now accounts for more than half of all US oil production -- a massive jump considering fracking made up less than 2% of the country's oil output in 2000. The production of American crude has nearly doubled in the past decade, putting U.S. behind only Saudi Arabia and Russia in world rankings.

Trump has made it clear he wants the US to play an even bigger role in the global oil ecosystem.

"I've never understood why, with all of our own reserves, we've allowed this country to be held hostage by OPEC, the cartel of oil-producing countries, some of which are hostile to America," Trump wrote in his book "Crippled America."

Experts say pumping more oil could decrease the country's dependence on foreign crude, but there's also a risk it would send prices crashing again. Oversupply caused oil prices to plummet as much as 75% between 2014 and earlier this year.

Perry's selection culminates a four-year effort to rebuild his political image in the aftermath of his disastrous 2012 run. A late entrant into the presidential primary, Perry was recruited as the sought-after alternative to eventual nominee Mitt Romney, but his policy stumbles failed to install confidence and his career sputtered.

The crystallizing moment -- when Perry on a primary debate stage blanked and painfully could not recall the name of the third federal agency he vowed to eliminate as President -- none other than the Energy Department that he will now lead -- a gaffe that became known primarily for the word with which he ended his live misery: "Oops."

Four years later -- under the threat of prosecution for allegedly promising to strip funding for a county agency if a local official would not leave her post -- Perry's campaign was more modest. He became one of the first candidates to attack Trump, labeling him at one point a "cancer on conservatism," but dropped out in September 2015 amid fundraising troubles. He eventually became an occasional surrogate for Trump during the general election.

In his first 100 days, Trump says he'll roll back Obama-era regulations on the fossil fuel industry, bringing jobs back to coal country. Many of these regulations fall under the Environmental Protection Agency , but leadership from the Energy Department could play a key role.

Trump has also pledged to expand drilling on federal land, which would require approval from the Interior Department. The Army Corps of Engineers, which reports to the Department of Defense, oversees the permit process for the contentious Dakota Access Pipeline.

Trump picked Oklahoma Attorney General Scott Pruitt to lead the EPA last Thursday. He has not yet announced his choice for Interior secretary. </s> Fracking begins in UK for first time since 2011

LONDON (AP) — Protesters have gathered near a shale gas exploration site in northwestern England, as fracking began in the U.K. for the first time since 2011.

Hydraulic fracturing had been stalled in the country after two earthquakes in the same area led to legal challenges. Environmental campaigners failed last week in Britain's High Court to keep the work in Lancashire from proceeding.

Energy firm Cuadrilla said in a statement Monday that it was "pleased to confirm that it has started hydraulic fracturing operations at our Preston New Road shale gas exploration site."

The company plans to drill at two horizontal exploration wells for about three months. Demonstrators say they'll monitor the site around the clock.

Protester Ginette Evans said Monday: "The fight's just really started." </s> Media playback is unsupported on your device Media caption The BBC's David Shukman explains how fracking works

Fracking for shale gas has begun for the first time in the UK since it was linked with earthquakes in 2011.

Energy firm Cuadrilla confirmed the controversial process had started at its site in Little Plumpton, Lancashire after a legal challenge failed on Friday.

Protester Ginette Evans said there was a "mood of disappointment" but insisted the fight was "not over".

Cuadrilla insisted the process was safe and would be of "enormous" benefit.

The company's chief executive Francis Egan said: "These are the first exploration wells that will be tested... we have high hopes for them but we have to wait and see what comes out."

If successful, he said it would "lead to tens of thousands of jobs and could be a very significant contributor to the exchequer and... could also reduce emissions because it will be better than importing gas from far afield".

The energy firm confirmed in a statement at 13:15 BST that it would spend at least three months fracking two horizontal wells, and then it would test to see if the gas flow was commercially viable.

If it is, up to 20 wells could be built.

Two protesters closed Preston New Road earlier when they cemented their arms together in a tyre and sat down in the middle of the road. They have since been cut free by police.

Another demonstrator climbed on to scaffolding on top of a van at the entrance to Cuadrilla's Little Plumpton site.

They were served with contempt of court notices for breaching the injunction Cuadrilla obtained preventing trespassers from entering land where fracking is taking place.

Image caption Protesters were sitting in the road outside the site, leading to its closure

Campaigner Bob Dennett, who failed to stop the work from beginning in the High Court, said: "They have sacrificed Lancashire to the gods of greed."

"We will do whatever we can to halt [Cuadrilla] in their tracks," he added.

Another campaigner, 87-year-old Anne Power, said she was "so angry" because it would be an environmental "disaster" and said she would continue the fight "as long as she has a voice".

Image copyright PA Image caption Protester Anne Power in Preston New Road site said she was "so angry" fracking has started

Lee Petts, chairman of Lancashire For Shale pro fracking group, said he was "really pleased" that fracking had finally started after a "long journey".

He said the industry had "huge scope" and could be as big a contributor to the Lancashire economy as BAE Systems.

Cat Smith, Labour MP for Lancaster and Fleetwood, tweeted: "Future generations will look back at this and wonder why we didn't heed climate change warnings."

"The Tories have slashed support for small scale renewables, scaled back support for electric vehicles and are being slammed by a leading climate scientist for its pursuit of fracking."

A spokesperson for the Department for Business, Innovation & Skills said: "Shale gas has the potential to be a new domestic energy source, enhancing our energy security and delivering economic benefits, including the creation of well paid, quality jobs.

"We have been clear that any shale developments must be safe and environmentally sound."

Media playback is unsupported on your device Media caption Judith Moritz shows us around one of the UK's first horizontal exploration wells

By Roger Harrabin Environment Analyst

The resumption of fracking falls on the day the government launches Green GB week to highlight technologies that combat climate change.

So how can the government stimulate fracking, while also pursuing zero greenhouse gas emissions?

Well, let's look at the timescales.

The first fossil fuel to be banished from the UK is coal. Next will be oil. Gas is least damaging so it will be last. Experts anticipate the UK will be using dwindling amounts of gas until the middle of the century.

Climate minister Claire Perry asks: "Why would you want to import gas when you could create your own?"

Environmentalists say this argument is flawed. They believe by the time the UK develops a shale gas industry it'll be time to close it down.

Second they point out that coal, oil and gas firms have already discovered enough fossil fuels underground to overheat the planet three times over - and a shale gas industry would only add to the problem.

But the Treasury sniffs potential tax revenues and its arguments have won the day in government. </s> Fracking for shale gas has begun in Lancashire amid protests over the controversial process.

Energy firm Cuadrilla said it had started hydraulic fracturing at Preston New Road in Little Plumpton, on Monday, and it will continue for three months.

It is the first time fracking has taken place in the UK since 2011, when the nascent industry was halted after it caused two small earthquakes in Lancashire.

A spokesman for the company said: “Cuadrilla is pleased to confirm that it has started hydraulic fracturing operations at our Preston New Road shale gas exploration site.

“Hydraulic fracturing of both horizontal exploration wells is expected to last three months after which the flow rate of the gas will be tested.”

Earlier police closed off the site as about 50 protesters gathered ahead of the start of the process and a team had to cut a man and woman out of a set of tyres which they had apparently cemented their arms into.

One activist sat on top of a van outside the site with a banner which read “Stop the Start” while another lay down in front of railings.

Protester Ginette Evans, 60, from Fleetwood, said: “We’ll be monitoring the site 24 hours a day. It is definitely not over, it has just got serious.

She said the there was a mood of disappointment among protesters.

She added: “I’m gutted really. It’s such a dangerous industry and it shouldn’t be here.”

Justin Vanparys, 47, from Blackburn, said: “Fossil fuels should stay in the ground. We have already got global warming.”

He said activists had not been listened to but added: “That just makes you come back even stronger.”

The work had been due to start on Saturday but was delayed by the effects of Storm Callum.

It followed an environmental campaigner failing in a bid to halt the work at the High Court on Friday.

At the hearing in London, Mr Justice Supperstone dismissed Bob Dennett’s application for an injunction preventing the company from fracking the UK’s first horizontal shale gas well pending his proposed legal challenge.

Mr Dennett claimed Lancashire County Council’s emergency response planning and procedures at the site were inadequate, but the judge ruled there was not a “serious issue” to be tried which would justify an interim order.

Fracking for shale gas is taking place for the first time in seven years as the UK Government kicks off the first Green GB Week initiative to highlight the green economy.

It comes after a UN report warned of the urgent need to cut emissions to avoid dangerous climate change, and that carbon from electricity, heating homes, transport, industry and land use must reach net zero by 2050.

Craig Bennett, Friends of the Earth chief executive, said: “The world’s leading climate scientists have published findings that couldn’t be starker: to have a hope of containing global warming we must take action now.

“Yet, ironically, on the same day the government boldly asks how it can reduce carbon emissions to zero, fracking begins.

“It is morally bankrupt to be heralding the start of a whole new fossil fuel industry when climate catastrophe awaits. You can deal with climate change or you can have fracking – you can’t do both.” </s> WASHINGTON -- His nascent administration already under attack, President-elect Donald Trump was considering Monday whether to inject new diversity into the GOP by recommending a woman to lead the Republican Party and an openly gay man to represent the United States at the United Nations, Trump aides said.

Later in the day, a senior Trump official said former New York Mayor Rudy Giuliani is the favorite to be secretary of state. The official spoke on the condition of anonymity because the source isn't authorized to speak on the record. The official said there's no real competition for the job and that it's Giuliani's if he wants it. A second official, however, cautioned that John Bolton, a former U.S. ambassador to the U.N., remained in contention for the job.

The moves, among dozens under consideration from his transition team, follow an intense and ongoing backlash from Trump's decision Sunday to appoint Stephen Bannon, a man celebrated by the white nationalist movement, to serve as his chief strategist and senior adviser.

"After winning the presidency but losing the popular vote, President-elect Trump must try to bring Americans together -- not continue to fan the flames of division and bigotry," said House Democratic leader Nancy Pelosi of California. She called Bannon's appointment "an alarming signal" that Trump "remains committed to the hateful and divisive vision that defined his campaign."

[TRUMP: Timeline of president-elect's career + list of appointments so far]

His inauguration just 66 days away, however, Trump focused on building his team and speaking to foreign leaders. He remained sequestered in Trump Tower in New York.

The incoming president spoke to Russian President Vladimir Putin on the phone. His transition office said in a readout that "he is very much looking forward to having a strong and enduring relationship with Russia and the people of Russia." Trump has spoken in recent days with the leaders of China, Mexico, South Korea and Canada.

At the same time, Trump was considering tapping Richard Grenell as U.S. ambassador to the U.N., according to people with direct knowledge of Trump's plans. He would be the first openly gay person to fill a Cabinet-level foreign policy post. Grenell, known in part for aggressively responding to critics on Twitter, previously served as U.S. spokesman at the U.N. under President George W. Bush.

Trump was also weighing whether to select Michigan GOP Chairman Ronna Romney McDaniel, a niece of chief Trump critic and 2012 presidential nominee Mitt Romney, the people said. She would be the second woman ever to lead the Republican National Committee, and the first in four decades.

"I'll be interested in whatever Mr. Trump wants," McDaniel said Monday, adding that she was planning to seek the Michigan GOP chairmanship again.

The people who confirmed the personnel moves under consideration were not authorized to publicly disclose private discussions. They stressed that the decisions were not final.

Giuliani, 72, as a former mayor, federal prosecutor and top Trump adviser, lacks extensive experience in foreign policy, which is central to the secretary of state position. Known for his hard-line, law-and-order views and brusque manner, he would set a different tone than recent holders of the job, including Trump's ex-rival Hillary Clinton, Colin Powell and Condoleezza Rice.

Bolton has years of federal government experience, but he has also raised eyebrows with some of his stances, including a 2015 op-ed in The New York Times in which he advocated bombing Iran to halt the country's development of nuclear weapons.

A spokesman for Giuliani did not immediately respond to a request for comment about his interest in the job. But the former mayor said Monday night at a gathering of executives sponsored by the Wall Street Journal that he "won't be attorney general" in Trump's administration -- a job for which he'd long been seen as a top contender.

Asked about the secretary of state speculation, Giuliani said Bolton "would be a very good choice." But asked if there was anyone better, he replied with a smile: "Maybe me, I don't know."

Also on Monday, Mary Jo White, the head of the Securities and Exchange Commission, announced that she would step down two years before the end of her term, clearing the way for Trump to reshape the way Wall Street is regulated.

The resignation gives Trump a chance early in his term to make changes to investor protections and other regulations, part of what is widely expected to be a broad effort by the new administration to scale back what Republicans consider cumbersome federal rules that slow economic growth.

Trump was also said to be considering an oil billionaire and a North Dakota lawmaker for top posts as he moves to roll back President Barack Obama's environmental and energy policies and to allow the unfettered production of oil, coal and natural gas.

Trump has vowed to rescind "all job-destroying Obama executive actions" and pledged to sharply increase oil and gas drilling on federal lands while opening up offshore drilling in the Atlantic Ocean and other areas where it is blocked.

Topping Trump's to-do list is repealing the Clean Power Plan, Obama's signature effort to limit carbon pollution from coal-fired power plants. The plan -- the linchpin of Obama's strategy to fight climate change -- is currently on hold awaiting a court ruling.

Trump is also targeting recent Obama administration efforts to reduce air and water pollution that have been opposed by Republicans and industries that profit from the extraction and burning of fossil fuels, including a rule to protect small streams and wetlands and ozone regulations designed to cut down on smog.

Those under consideration for energy secretary include Harold Hamm, an Oklahoma oil tycoon and leading proponent of fracking, a technique that uses high-pressure mixtures of water, sand or gravel, and chemicals to extract oil and gas from rock, and Rep. Kevin Cramer of North Dakota, an early Trump supporter from a major oil-drilling state, according to transition planning documents obtained by The Associated Press.

Venture capitalist Robert Grady, who worked in President George H.W. Bush's administration, is listed as a contender to lead both the Energy and Interior departments.

Trump also is likely to move quickly to approve the Keystone XL oil pipeline from Canada, which Obama rejected last year. Trump highlighted the project at a campaign stop in Florida last month and listed it among his top priorities for the first 100 days of his administration.

Environmental groups said they don't plan to make Trump's job easy.

"We intend to fight like mad, both in the courts and in the streets, to resist any rollbacks by the Trump administration," said Michael Brune, executive director of the Sierra Club.

Groups opposing the construction of an oil pipeline through the Midwest are planning more than 200 protest actions across the country today.

Internal deliberations about staffing occurred a day after Trump made overtures to warring Republican circles by appointing Bannon and Republican National Committee Chairman Reince Priebus as his White House chief of staff.

The former media executive led a website that appealed to the so-called alt-right -- a movement often associated with efforts on the far right to preserve "white identity," oppose multiculturalism and defend "Western values."

Priebus on Monday defended the media mogul, saying the two made an effective pair as they steered Trump past Democrat Hillary Clinton and toward the presidency. He sought to distance Bannon from the headlines on his website, saying they were written by unspecified others.

Priebus, who lashed the RNC to Trump this summer despite some intraparty objections, is a GOP operative with deep expertise on the Washington establishment that Trump has vowed to shake up. He has close ties to House Speaker Paul Ryan, a fellow Wisconsinite.

Bannon, meanwhile, helped transform the Breitbart News site into the leading mouthpiece of the party's anti-establishment wing, which helped fuel Trump's political rise. Ryan has been one of the site's most frequent targets.

The Council on American-Islamic Relations said Bannon's selection "sends the disturbing message that anti-Muslim conspiracy theories and white nationalist ideology will be welcome in the White House."

That view was echoed by the Southern Poverty Law Center, which tracks hate groups. It insisted that "Trump should rescind this hire."

Mike Huckabee, a former governor of Arkansas and presidential candidate, accused Bannon's critics of sour grapes. On Twitter, he wrote that Bannon should embrace the criticism from the Council on American-Islamic Relations.

"Critics of Steve Bannon know he's smarter and tougher than they are," Huckabee wrote. "When CAIR doesn't like you, that is a good thing."

Republicans who had long opposed Trump's candidacy also took to Twitter on Sunday night and Monday morning to warn that his choice to rely on the advice of Bannon is an indication of the way that he will govern.

"The racist, fascist extreme right is represented footsteps from the Oval Office," said John Weaver, a Republican strategist who ran the presidential campaign of Ohio Gov. John Kasich and previously advised Sen. John McCain of Arizona. "Be very vigilant, America."

Obama avoided any direct criticism of Trump's personnel moves during an afternoon news conference, suggesting that the new president deserves "room to staff up."

"It's important for us to let him make his decisions," Obama said. "The American people will judge over the course of the next couple of years whether they like what they see."

Information for this article was contributed by Steve Peoples, Julie Pace, Thomas Beaumont, Ken Thomas, Donna Cassata and Bill Barrow of The Associated Press; by Ylan Q. Mui and Renae Merle of The Washington Post; and by Michael D. Shear of The New York Times. </s> Fracking has begun in Britain for the first time since drilling caused earthquakes seven years ago.

Shale gas operator Cuadrilla confirmed the move at its Preston New Road site in a statement. “Hydraulic fracturing of both horizontal exploration wells is expected to last three months after which the flow rate of the gas will be tested,” it read.

The company’s operations outside Blackpool were given the final nod from government in September.

A last-ditch attempt to prevent it was launched by local resident Robert Dennett, who won an interim injunction against Lancashire County Council on the grounds that its emergency planning was inadequate. But on Friday, the High Court rejected the injunction.

More than 40 activists from campaign group Reclaim the Power also attempted to stop drilling by blockading the site with a van during the early hours of the morning. The erected a scaffold structure on top with a banner reading, “Stop The Start. Don’t Frack the Climate”.

Charlie Edwards, from Reclaim the Power said: “Today the government launched its ‘Green Great Britain’ week – a tokenistic attempt to hide a series of climate wrecking decisions such as expanding Heathrow airport and forcing fracking on the local communities.”

The government was heavily criticised by Greenpeace, Friends of the Earth and the Green Party for maintaining its support for the industry, despite warnings from climate scientists last week that time was running to keep global temperature rises within 1.5C.

It was also hypocritical in the light of energy minister Claire Perry’s request to its climate change advisers for advice on reducing the UK’s greenhouse gas emissions to net-zero, they said.

Catherine Early is a freelance environmental journalist and chief reporter for The Ecologist. She was formerly the deputy editor of the Environmentalist. She can be found tweeting at @Cat_Early76. </s> When an earthquake struck Oklahoma on Saturday, one of the first steps state officials took was to shut down 37 of the state's 3,200 active disposal wells -- a move that drew national attention to the link between oil and gas drilling and earthquakes.

No one was seriously injured in the Oklahoma quake, and investigations and cleanup has begun. Here's what you need to know.

Disposal wells are used by oil and gas producers to get rid of wastewater from the drilling process. The wells push the wastewater deep underground, even deeper than where oil and gas are found.

The wastewater mostly consists of a substance called brine -- a mix of water and chemicals that comes to the surface with oil and gas when they are pumped from the Earth.

A small portion is also the water that's pumped underground in the modern hydraulic fracturing process, a drilling technique often referred to as fracking.

The EPA says there are about 40,000 disposal wells nationwide.

Did the disposal wells cause the earthquake?

That is the concern. Oklahoma didn't have much of a history of earthquakes. But a big one struck in November 2011, causing injuries and leveling houses, and officials said in 2014 that earthquakes in the state have increased 5,000%.

Scientists began looking into the role pumping liquid underground can play in seismic activity decades ago. And while much remains unknown, government scientists said in March that disposal wells have caused an increased risk for "induced" earthquakes in large areas of the country.

That includes the area where Saturday's earthquake occurred.

What's being done to stop it?

Oklahoma regulators have been monitoring the wells for years. In January, the state began forcing 27 disposal wells to reduce their activity. That's also when Oklahoma dedicated $1.4 million to fund "research and response" efforts.

Saturday's order that 37 wells shut down over the next 10 days marks the strongest action against disposal wells yet.

Why are disposal wells used?

The Oklahoma Oil & Gas Association said in April that producers would take "significant measures" to combat the earthquakes and promised to explore alternative disposal methods.

But OKOGA president Chad Warmington said "underground wastewater disposal is currently the safest and most cost-effective way to dispose of produced water."

Drillers also argue that recycling is more expensive, in part because they must pay to transport the wastewater to recycling facilities.

Some drillers do recycle. For example, about 90% of wastewater in Pennsylvania is recycled. In Texas, drought has spurred an increase in recycling.

But recycling has been slow to catch on in Oklahoma, and regulators have been criticized for not taking more aggressive action against disposal wells.

What happens next?

That's not clear. The state of Oklahoma has declared a state of emergency in the wake of Saturday's quake.

Halting or slowing the use of disposal wells won't necessarily resolve the seismic issues. Scientists studying the issue told PBS in March that even if Oklahoma shuttered all its disposal wells, the wastewater that has already been pumped can continue to cause problems.

And the ground is sensitive to sudden changes in disposal well pumping. In fact, Oklahoma regulators ordered the 37 wells offline over the course of 10 days for fear "that a large scale, sudden shutdown could cause an earthquake," according to authorities.
Colombia’s top administrative court begins hearings on proposals to drill for oil using the technique known as fracking.