In Spite of Slide History, Homes Built In Path of Slope

As more news comes out, it becomes clear that the slope that gave way in Washington was known to be at risk, and yet homes were permitted to be built in risky areas:

It's now five days into the search for survivors of the massive landslide in Oso in Washington's Snohomish County. National Guard Troops are combing the area with emergency extraction teams. The unofficial death toll so far is now 24, and authorities are promising more clarity tomorrow on the list of missing people. Some 176 persons are unaccounted for but the real number is thought to be lower than that.
This area was not new to landslides. They've happened repeatedly on this hill over the decades. And in fact, the slope was once referred to as Slide Hill. Snohomish County Emergency Management Director John Pennington said on Monday the area had been considered very safe. Today he said this.
JOHN PENNINGTON: People knew that this is a landslide-prone area. Sometimes big events just happen, sometimes large events that nobody sees happens.
SIEGEL: So, should the people who live in Oso have known this might happen? And if so, who should have told them?
Well, we're going to ask Ken Armstrong. He's an investigative reporter for The Seattle Times and he's written about the history of this slope. Welcome to the program.
KEN ARMSTRONG: Thank you, Robert. Thanks for having me on.
SIEGEL: And first, give us some more detail on how many times this particular hill has given way and did it destroy homes before?
ARMSTRONG: It has given away so many times that it is referred to as Slide Hill, as you mentioned before. It gave away in 1949, in '51, in '67, in '88, in 2006. There have been reports written over the years from geologists, hydrologists who have said that this hill is constantly moving. And that whatever measures are taken to minimize the risks posed by it, they're likely to fail in the long run.
SIEGEL: Which raises the question, pretty important and obvious one: Why were people building homes on this hill?
ARMSTRONG: It's the same question I suppose that can be posed to why do people build on the Outer Banks of North Carolina, or in areas of Southern California hit by wildfires. I think there is a certain assumption of risk. One of the most jarring images here was provided by a geologist. In 2006, there was a large slide. And even before the debris had been removed, he went out and visited and saw carpenters building new homes.
It's up to the county to decide whether to issue building permits. And here, the county has continued to issue them even after these slides.
SIEGEL: As you say, the county was issuing building permits. People still presumably would need insurance. People who were real estate agents involved in selling properties would have to come clean about the history of the property. I mean other people might have been accountable, don't you think?

Sure, this slide was bigger than the others, but geologists warned people that a slide like this was possible.  While somewhat unexpected, this disaster could have been mitigated to some extent with decent planning and land use restrictions.