We are a commune of inquiring, skeptical, politically centrist, capitalist, anglophile, traditionalist New England Yankee humans, humanoids, and animals with many interests beyond and above politics. Each of us has had a high-school education (or GED), but all had ADD so didn't pay attention very well, especially the dogs. Each one of us does "try my best to be just like I am," and none of us enjoys working for others, including for Maggie, from whom we receive neither a nickel nor a dime. Freedom from nags, cranks, government, do-gooders, control-freaks and idiots is all that we ask for.
Unlike real seamen, I do not trust anchors in bigger water other than daytime lunch hooks. There are too many things that can disrupt an anchor, such as wind shifts, big waves, condition of the bottom, etc. It is not unusual for recreational boaters to dive down and check the bottom situation of their anchor. Commercial fishermen use 2 anchors, but the olde time Cape Cod fishermen would often prefer to run up on a beach than sleep on anchor on a bad night when they could not reach harbor.
For large vessels, there are now global positioning systems which will keep you precisely in place without anchor or mooring.
As the Command Duty Officer of a USN aircraft carrier at anchor in a foreign port, I thought I was going to become the senior officer aboard underway one night--at least for a short time. During a squall it was thought that the anchor was not holding. After several tense minutes, it was concluded through multiple radar fixes that we were not moving from our anchorage at all--just swinging about periodically. At that time we did not have satnav, and inertial was inconclusive.
On another occasion the ship lost its anchor. I was not involved, thankfully. The anchor chain is not secured to the ship on a carrier --and maybe not on other large ships-- because if the brake failed it could not be stopped and would cause severe damage when ripped out. In this case, the anchor was inadvertently let go with weigh on, the brake did not hold, and there it went. Happily, a salvage ship was brought in and its divers secured the bitter end and the little fellow was able to hoist it back to the carrier.
Ol late, at any one time there are as many as 70 ships anchored in the outer LA/Long Beach harbors. Clearly, there are not enough desirable anchorage points for that many ships. Reports today are that a container ship was moving about for some reason with its anchor dragging. That seems like lazy seamanship; but, what do I know? I flew airplanes.
WRT my previous comment. I did not make clear that as better anchorages come available the ships off of LA/Long Beach no doubt move to the better locations as they come available. I fish on the bays in the area, and each time that I go the chess board of ships has changed..
So, the story of a ship moving in the area; and possibly not bothering to bring up its anchor for a short transit does not actually surprise me. It is also possible that they keep skeleton crews on board when anchored for extended periods--that I do not know.
I've been involved with this kind of incident before, but with a high pressure gas pipeline. It was marked on every marine chart, paper or electronic, and still the tanker dropped anchor and backed down, paying out chain, leaving it draped across the line. It took us a few days to mobilize a credentialed master and insurers to resolve the problem without further incident.
Most pipelines aren't buried unless there's a good reason to. Sediments shift a lot more than one might expect, leaving free spans, as well. Normally an ROV is sent down once every couple of years to traverse the entire line, note the free-spans, and work up any necessary corrective work.
If the breach was caused by a vessel's anchor, they'll quickly work out who was responsible - ships are tracked all the time now, and it's illegal to turn off the transponder that identifies the ship.
Incidentally, the area of Marine Law is a fascinating one when it comes to disputes like this one will become. The few times that I've been involved with a maritime legal matter: Good Lord. There is something about the mentality and character of sailors and the merchants who operate the ships - it must be the long voyages, bored out of your skull, and the high levels of risk or something. But when there's a maritime incident, it takes real skill, really hardened, sharp, focused and methodical questioning, to get to the bottom of it. I've never come across more bold, determined, and accomplished liars as the ones I've encountered in maritime disputes.