Saturday's mudslide was the first in years, though Gastineau Avenue has a history of slides and has long been designated a hazardous area by the city.
"Most of the Mount Roberts slope above South Franklin Street and Gastineau Avenue must be considered as highly hazardous in terms of damage and potential loss of life from landslides," says a 1972 city report on geophysical hazards.
The report says 11 "major" landslides were identified and mapped on the slope, three of which were "massive" in size; the other eight were smaller but still destructive. Twenty-one landslide paths were mapped on the Mount Roberts slope above the city, of which 15 were identified with a high hazard level.
The same area that had a mudslide Saturday had a large slide in 1920, and a different spot on Gastineau Avenue experienced a large slide in 1936.
"In both of those, buildings were knocked off their foundations and slid down the hill," said city Engineering Director Rorie Watt. "In the grand scheme of things, this slide is a fairly small one, although it did do some damage."
"Essentially it gets to too much water in the dirt," Watt said. "It's like building sandcastles on the beach. If you just have a little bit of water, it stands up" and if there's too much, there's a slide.
Watt said he suspected this slide was due partially to trees having been blown over in high winds.
Special engineering, such as retention and diverting structures, is required in areas with mudslide and avalanche hazards.
The mudslide in the 1930s killed several people, Watt said. No one was injured in Saturday's slide, though it damaged two apartment complexes and several vehicles.
A man known as "Captain Kirk," reported as possibly missing on Sunday was found unharmed Monday morning, according to Louise Galvan of Polaris House, a nonprofit that helps people with mental illnesses.
Area residents were allowed back into their homes Sunday morning, though city engineers closed Strasbaugh Apartments on Sunday because of suspected structural damage. Up to 80 people were displaced by the slide.
Two of the six apartment units were damaged by mud. AEL&P spokesperson Gayle Wood said electricity had been restored to the buildings in the area.
Contact reporter Mary Catharine Martin at 523-2276 or firstname.lastname@example.org.