Case Histories of Maine Landslides
Westbrook - 1868
On November 22, 1868, a massive slide in Westbrook caused an estimated 20 acres of land to collapse and flow into the Presumpscot River. The slide blocked the 200 ft wide river channel for a distance of half a mile, raising the upstream water level at least 15 feet and causing serious flooding.
Rockland - 1973
During the early morning of January 25, 1973, a landslide covering about three acres occurred within tens of feet of two homes on Waldo Avenue in Rockland. There are no known technical reports describing the landslide at the time of the event. However, newspaper accounts and the general descriptions and photographs of the event by geologists who visited the site indicate the slide was similar in size and displacement to the 1996 slide. The Portland Press Herald (February 7, 1973) reported that weather conditions at the time of the 1973 slide were warm temperatures (January "thaw"), and that drainage was "excessive," and that in the opinion of geologists who visited the site, the slide was due in part to these conditions. Photographs of the 1973 slide show that it had the classic features of a retrogressive (headward) landslide, with a steep headscarp and slumped blocks rotated toward the headscarp. Toward the slide toe, the surface of the slumped material appears to have flowed, as though it had bulldozed across the land surface.
Gorham - 1983
On September 28, 1983, a landslide occurred in a bluff of marine sediments at the confluence of the Stroudwater River and Indian Camp Brook in Gorham. Seven acres (3 hectares) of land slid to the south and southwest into the river and the brook, taking with it a house and garage, several vehicles, a tank truck, and a well drilling rig. The total area affected by the slide was about 12 acres (5 hectares). This slide is classified as a complex type, having components of translational slide (blocks move out or down along a planar surface without rotation), a rotational slump (blocks which rotate about an axis parallel to the slope and along a concave-up slip surface), and an earth flow (a fluidized failure lacking distinct blocks). The slide failure plane was calculated to be at a depth of about 42 feet (13 m), within a thick section of Presumpscot clay.
Rockland - 1996
Early in the morning of April 16, 1996, a clay bluff failed on the north shore of Rockland Harbor. This landslide formed a new scarp about 200 feet landward of the original top of the bluff in just a few hours and destroyed two homes. The slide occurred along a steep bluff adjacent to Samoset Road. The bluff top was about 50 feet (15 m) above sea level and the base of the bluff slope ended at the high water mark. Slumping of the bluff occurred progressively in a series of discrete landslide events. When it was over, the slide had moved horizontally over 400 feet (120 m) onto the mudflats of the intertidal zone and had disturbed a total area of 3.5 acres (1.4 hectares). For a month following the major slide event, smaller blocks continued to fall from the steep landward slopes. These continued slope failures resulted in enlargement of the affected area by landward progression of the vertical scarp. By landward retreat, the main scarp moved to within 15 feet (5 m) of a sewer main on the seaward side of Samoset Road. The total cost in terms of lost property value and cost to the city for emergency activities, evaluation of the two homes destroyed and loss of land, clean up, and engineered stabilization was approximately $710,000 and is expected to exceed that when work is completed.
Brunswick - 1997
In late March of 1997, a landslide occurred at the edge of the coastal bluffs of glacial marine deposits in the coastal area in Brunswick, Maine, known as Bunganuc. Following the slide in March, the owner's home measured approximately 100 feet from the edge of the landslide head scarp. The slide is interesting because of how far1from the bluff face some of the blocks slid. "Outrunner" blocks (PDF, 1.7Mb) from the slide traveled 183 feet from the base of the bluff.
Wells - 2005
In May of 2005 a landslide occurred in Wells along the banks of the Merriland River. The slide destroyed a portion of a walking trail in the Rachel Carson National Wildlife Refuge and removed the backyard of a nearby house. Parts of the house's foundation were left exposed and the house was declared unsafe to inhabit.
Cumberland - 2006
A large rotational slide occurred in the spring of 2006 along Hobbs Brook in Cumberland, Maine in an area of high relief and steeply sloped stream bank. The slide occurred after a heavy sustained rainfall.
Sanford - 2006
In May of 2006, a large earth flow caused by improper drainage due to recent road construction occurred in Sanford, Maine. The drainage focused heavy runoff towards this property, which then undercut the overlying sand, causing a large earth flow into Branch Brook.
Greenbush - 2006
A landslide occurred along the Penobscot River in the town of Greenbush on June 30, 2006. The slide undercut Route 2 and caused this section of roadway to be closed until the river bank stabilized, and the roadway section was rebuilt. This slide was a rotational landslide caused by multiple factors: 1) location on the outbank of a meander of the Penobscot River, an area of higher stream velocity and erosion; 2) high relief (elevation) in the area of the slide producing increased weight on the slope; 3) steep slope which is the major cause of landslides where the slope reaches a point of steepness that triggers failure of the underlying strata; 4) heavy rainfall over-saturated the underlying marine deposits which increased the overburden weight and reduced the shear strength of the marine deposits, leading to failure; and 5) the underlying geology of the area of the slide is a marine clay that becomes unstable upon saturation.
Brunswick - 2007
On April 16, 2007, a landslide and adjacent slope subsidence occurred along the east shore of Buttermilk Cove in Brunswick, Maine. The slide occurred along a steep bluff adjacent to Route 24 (Gurnet Road). Two distinct areas of slope failures were observed. One, a large rotational landslide, occurred 90 feet north of the house in an area where runoff from both a cross-road culvert and the leach field drainage were focused. This rotational slide produced a distinct 30-foot long concave scarp with a tree-covered toe at the base. The landslide toe extended into the intertidal zone of Buttermilk Cove. The second area of slope movement extended from the southern edge of the main scarp, southward for approximately 90 feet. This is in the same area as the previous subsidence and slope failure on the west side of the house described above. This slope movement and subsidence consisted of fresh tension cracks and minor parallel scarps in the lawn. This movement caused the ground behind the house to slope more steeply toward the top of the bluff and water.
Norridgewock - 2009
On July 9, 2009 a landslide occurred along the Sandy River in Norridgewock, Maine. The slide occurred along a sharp bend on an unpaved section of the Sandy River Road, where the road encroaches upon the Sandy River. The Sandy River at this site appears to have been eroding and undercutting the river bank, causing oversteepening of the slope. This oversteepening of the slope, along with the high precipitation which "lubricated" the underlying marine clay, caused the slope failure. It appears that when the larger slide began, it activated a smaller adjacent slide. The large slide is approximately 40 feet across with a relief (height) of over 20 feet. The smaller slide is approximately 15 feet across with a relief of only 10 feet.
Last updated on November 2, 2010