Updated

WASHINGTON (AP) — The impatient nation isn't getting answers fast enough in the Gulf of Mexico oil spill disaster.

What exactly went wrong? Who messed up? How much oil is pouring into the Gulf? Can the oil get to Florida and even up the Atlantic coast? What will the environmental and economic consequences be? Will the chemicals used to disperse the oil leave their own destructive legacy?

As the oil spreads, people on the Gulf Coast, in Washington and elsewhere want answers in a New York minute. But these mysteries of the deep are not yielding easily.

Over three weeks, more than a dozen congressional hearings and scores of hours of witness testimony did not get to the rupture's cause or its full effects. Many more inquiries are ahead. But then such hearings, especially in an election year, are often designed more to give lawmakers a stage to rant against a politically safe target than to find facts.

Vital clues, such as the burned-out behemoth of a rig and a safety device that was supposed to prevent such a blowout, rest under a mile of water accessible only by remote-controlled vessels. Some of the crewmen who manned the rig at the moment of crisis, including two responsible for shutting the oil flow, are dead.

The murkiness isn't just as the ocean bottom. It's now acknowledged by the government that federal regulators were too close to the oil industry and, as a consequence, probably too lax in enforcing safety rules. But did that cronyism somehow contribute to the spill?

President Barack Obama raised the possibility Thursday that the project might never have been approved if his administration had acted more aggressively to overhaul the Interior Department agency that oversees offshore drilling.

If the changes taking place now "had been happening fast enough," he said, "this might have been caught. Now, it's possible that it might not have been caught."

A look at some knowns and unknowns as BP PLC, the well's owner, carries out its risky "top kill" operation to seal the gaping wound a mile down:

FALSE CONFIDENCE:

BP and regulators widely believed that because there had never been such a catastrophic blowout in the Gulf, it would not happen — and that whatever accident occurred could be contained even in a mile of water. That bravado is reminiscent of another environmental crisis three decades ago, when the nuclear industry said a reactor meltdown could not happen. Then it did, Three Mile Island in Pennsylvania.

In another age, they also said the Titanic was unsinkable.

METHANE RUSH:

Human error and mechanical failure probably both played a part in the accident.

The crisis began late on the night of April 20 with an unexpectedly powerful rush of methane gas up the well pipe to the sea surface. The rush was so powerful that it shot heavy material — designed to keep downward pressure inside the pipe — to a nearby supply vessel. The state-of-the-art Deepwater Horizon drilling rig was consumed with such speed that, as Steve Newman, president of rig owner Transocean told senators, "the drill crew had very little, if any, time to react."

Eleven crew members died and 115 barely escaped.

EARLY WARNING?

The House Energy and Commerce Committee collected 100,000 pages of documents from BP, Transocean and others, and produced evidence that the crew had hints of a developing problem on the day of the explosion: worrisome pressure readings in the pipe, which was being sealed for future oil production. This could have been a tip-off to an intrusion of methane gas.

But why? That's still an unknown.

Could the cement injected into the pipes have been deficient? Was it a mistake to replace some of the "mud" used to apply downward pressure in the pipes with lighter seawater before a final cement cap was applied?

The seawater theory appeared to gain more credence this past week at a hearing in New Orleans. According to witness statements, senior managers worried BP was "taking shortcuts" by replacing heavy drilling fluid with saltwater in the well.

Statements from oil rig workers and a congressional memo about a BP internal investigation of the blast indicated warning signs were ignored. Tests less than an hour before the blowout found a buildup of pressure indicating "a very large abnormality," BP's investigator said, according to the congressional memo.

Still, the rig team was "satisfied" that another test was successful and resumed adding the sea water, said the memo by Reps. Henry Waxman, D-Calif., and Bart Stupak, D-Mich. Waxman is chairman of the Energy and Commerce Committee; Stupak heads the subcommittee on oversight and investigations.

Also at the New Orleans hearing, Douglas Brown, the rig's chief mechanic, testified about what he described as a "skirmish" between the "company man" — a BP official — and three rig employees during a meeting the day of the explosion. BP owns the well; Transocean was doing the drilling.

"The driller outlined what would be taking place, but the company man stood up and said 'We'll be having some changes to that,'" Brown testified. He said the three other workers initially disagreed but "the company man said 'This is how it's going to be.'"

FAIL-SAFE FAILURE?

Mysteries persist about the blowout preventer, the now-crippled five-story structure sitting atop the well. It was supposed to seal the well pipe at the sea bottom in an eruption. While it didn't close — or may have closed partially — hearings have produced no clear picture of why it didn't plug the well.

Documents emerged showing that a part of the device had a hydraulic leak, which would have reduced its effectiveness, and that a passive "deadman" trigger had a low, perhaps even dead, battery.

Newman repeatedly told lawmakers there was no evidence that the device itself failed and suggested debris might have been forced into the device by the explosive force of the surging gas.

HOW MUCH OIL?

Not even the amount of oil gushing from the well has been pinpointed.

On Thursday, officials upped their estimate, saying the well has been gushing between 504,000 and more than 1 million gallons a day into the Gulf. BP and the Coast Guard estimated soon after the explosion that about 210,000 gallons a day were leaking.

WHERE WILL IT GO?

There's almost as much uncertainty about what is happening to the oil already in the water. Lawmakers got little explanation about what appears to be a large plume of oil moving beneath the water surface. Was it oil or a mixture of oil and chemicals? "Unknown," said Jane Lubchenco, one of the government's top marine scientists.

How much oil will reach the ecologically precious coastal marshes is still uncertain. If oil gets into a fast-moving Gulf "loop'" current it could hit the coral reefs of the Florida Keys and even move around up the Atlantic Coast. Marine scientists say it's not clear how much damage it will cause because the oil might by then may be significantly degraded.

Even one of the bedrock tools for fighting the oil spill — chemicals that break up the oil so it degrades more easily — has raised more questions than answers. The chemicals are being used in amounts and at water depths never envisioned.

"The long term-effects (of the dispersant chemicals) on aquatic life are still unknown," said the head of the Environmental Protection Agency, Lisa Jackson.

And this from Interior Secretary Ken Salazar: "There are many facts which are still unknown. I know enough to know there were a lot of problems here."

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Online:

Live video of oil spill: http://tinyurl.com/2c8y3rj