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Great Alaska Earthquake, Prince William Sound, March 28, 1964 |
| The Prince William Sound magnitude 8.4 MS (9.2 MW) earthquake on March 28, 1964 at 03:36 GMT (March 27 at 5:36 pm local time), was one of the largest shocks ever recorded on the North American Continent. The quake was felt over 500,000 square miles. The quake took 131 lives and caused $350-500 million in property damage (122 of the deaths were attributed to the tsunami). The area of the damage zone (50,000 square miles) and the duration of the quake (3 to 4 minutes) were extraordinary. This set of slides shows geologic changes, damage to structures, transportation systems, and utilities and tsunami damage. It features the effects of four major landslides in Anchorage during the 1964 event. |
Uplifted dock, Prince William Sound, Alaska | |
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Uplift And Subsidence The uplifted dock on Hinchinbrook Island, Prince William Sound, shows uplift. Land in this area rose about 8 feet (2.4 m) during the earthquake, and the dock could then be used only at extremely high tides. Tsunami damage also occurred in this area. Photo Credit: U.S. Geological Survey, Menlo Park, CA |
Subsidence at Portage, Alaska | |
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Uplift And Subsidence The village of Portage, at the head of Turnagain Arm of Cook Inlet, is flooded at high tide as a result of 6 feet (1.8 m) of tectonic subsidence during the earthquake. After the quake, the shoreline was as much as 2 miles (3.4 km) inland from the pre-earthquake mean shore line. The town of Portage was inundated and covered with a blanket of silt. Much of the highway to Anchorage was covered by water. Photo Credit: U.S. Geological Survey, Menlo Park, CA |
Hanning Bay Fault Scarp, Alaska | |
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Faults This view is looking southwest along the Hanning Bay fault scarp on southwest Montague Island in Prince William Sound. The Hanning Bay fault was reactivated during the earthquake. Its trace is marked by a 10- to 15-foot high (3.0 m to 4.5 m) bedrock scarp which trends obliquely across the field of view from the right foreground to the left background. The fault trace lies between the uplifted wave-cut surface that is coated white by desiccated calcareous marine organisms and borders the open ocean, and the area of brown sand and silt in the cove. The ground northwest of the fault (right side of photo) was displaced upward as much as 16 feet (4.8 m) with respect to the ground southeast of the fault during the earthquake, but both sides of the fault were uplifted with respect to sea level due to general tectonic uplift of the region. The fault plane dips steeply northwest, or is vertical. Photo Credit: U.S. Geological Survey, Menlo Park, CA |
Underwater Landslides at Seward, Alaska | |
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Landslides This view, taken a few months after the earthquake, is looking north along the waterfront at Seward. Note the "scalloped' shoreline left by the underwater landslides, the severed tracks in the railroad yard which dangle over the landslide scarp, and the heaps of railroad cars and other debris thrown up by the tsunami waves. This massive submarine landslide destroyed a large portion of the Seward waterfront during the quake. Photo Credit: U.S. Geological Survey, Menlo Park, CA |
Government Hill Landslide, Anchorage, Alaska | |
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Landslides The Government Hill Elementary school in Anchorage was torn apart by subsidence of the graben at the head of the Government Hill landslide. The south wing of the school dropped about 30 feet (9 m); the east wind split lengthwise and collapsed. The playground became a chaotic mass of blocks and fissures. Part of this slide became an earthflow that spread 150 feet (45.5 m) across the flats into the Alaska Railroad yards. During the earthquake, the shaking loosened clay beneath Government Hill and the clay began to move toward the flats. On the hill, 400 feet (121.2 m) back from the rim of the bluff, the earth cracked on a front 1,180 feet (357.6 m) wide. Photo Credit: U.S. Geological Survey, Menlo Park, CA |
"L" Street Landslide, Anchorage, Alaska | |
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Landslides A subsidence trough (or graben) formed at the head of the "L" Street landslide in Anchorage during the earthquake. The graben extends from the lower right corner of the picture to the upper left and passes beneath several houses. The slide block, which is the virtually unbroken ground to the left of the graben, moved to the left. The subsidence trough sank 7 to 10 feet (2.1 to 3.0 m) in response to 11 feet (3.3 m) of horizontal movement of the slide block. The volume of the trough is theoretically equal to the volume of the void created at the head of the slide by movement of the slide block. Note also the collapsed Four Seasons apartment building at the top center of the picture and the undamaged three-story reinforced concrete frame building behind it, which are on the stable block beyond the graben. Photo Credit: U.S. Geological Survey, Menlo Park, CA |
Damaged Four Seasons Apartments Anchorage, Alaska | |
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Landslides The Four Seasons Apartments in Anchorage was a six-story lift-slab reinforced concrete building which crashed to the ground during the earthquake. The building was structurally complete but unoccupied at the time of the earthquake. The main shear-resistant structural elements of the building, a poured-in-place reinforced-concrete stairwell and a combined elevator core and stairwell, fractured at the first floor and toppled over, and came to rest on top of the rubble of all six floors and the roof. The concrete stairwell is in the center of the picture. Photo Credit: U.S. Geological Survey, Menlo Park, CA |
Scarp in "L" Street Slide, Anchorage, Alaska | |
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Landslides A close-up of one of the scarps bounding the graben on the "L" Street landslide, showing a house which was undercut by subsidence of the graben. The "L" Street slide began to move near the end of the tremor. It was a horizontal translatory slide and probably failed in sand layers or in soft sensitive clay in the area from Anchorage's Fifth Avenue South. Photo Credit: U.S. Geological Survey, Menlo Park, CA |
Damage to Fourth Avenue, Anchorage, Alaska | |
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Landslides This view of damage to Fourth Avenue buildings in downtown Anchorage shows the damage resulting from the slide in this area. Before the earthquake, the sidewalk in front of the stores on the left, which are in the graben, was at the level of the street on the right, which was not involved in the subsidence. The graben subsided 11 feet (3.3 m) in response to 14 feet (4.2 m) of horizontal movement of the slide block during the earthquake. Lateral spreading produced a fan-shaped slide 1,800 feet (545.5 m) across that covered about 36 acres (14.6 hectares) and moved a maximum of 17 feet (5.1 m). Movement on the landslide began after about 1 to 2 minutes of ground shaking and stopped when the shaking stopped. Photo Credit: NOAA/NGDC |
Fourth Avenue Landslide Scarp, Anchorage, Alaska | |
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Landslides The scarp of the Fourth Avenue landslide in downtown Anchorage where two and one half blocks of shops, bars, and stores slowly settled until their entrances were below street level. The Fourth Avenue area showed evidence of earthquake-induced sliding before the 1964 earthquake. About 30 blocks of dwellings and commercial buildings were destroyed or severely damaged in downtown Anchorage. Damage in the City of Anchorage was approximately one-half of the total earthquake damage for the State of Alaska. Photo Credit: U.S. Geological Survey, Menlo Park, CA |
Turnagain Heights Landslide, Anchorage, Alaska | |
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Landslides This shows the Turnagain Heights landslide in Anchorage. Seventy-five homes twisted, slumped, or collapsed when liquefaction of subsoils caused parts of the suburban bluff to move as much as 2,000 feet (606 m) downward toward the bay, forming a complex system of ridges and depressions. The slide developed because of a loss in strength of the soils, particularly of lenses of sand, that underlay the slide. The motion involved the subsidence of large blocks of soil, the lateral displacement of clay in a 25 feet (7.6 m) thick zone, and the simultaneous lateral translation of the slide debris on liquefied sands and silts. Photo Credit: NOAA/NGDC |
Damage to J.C. Penny Building, Anchorage | |
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Other Building Damage This shows the five-story J.C. Penney Building at 5th Ave. and Downing Street in Anchorage where two died and one was injured. Concrete facing fell on automobiles in front of the building. Although the building was approximately square, the arrangement of effective shear-resisting elements was quite asymmetrical consisting principally of the south and west walls that were constructed of poured concrete for the full building height. The north and east sides of the building faced the street. The north side of the building had no shear wall but was covered by a facade composed of 4-inch (10.2 cm) thick precast nonstructural reinforced concrete panels. The east wall, also covered with the precast panels, had poured-concrete shear walls between columns in the two northerly bays and in the bottom three stories of the two southerly bays. The rotational displacement induced by the earthquake apparently caused failure of this east-wall shear-resistant element, the building became more susceptible to rotational distortion, and the south and west shear walls failed. Photo Credit: NOAA/NGDC |
Fissured Highway Embankment, Alaska | |
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Damage To Highways And Railroads This highway embankment fissured, spread and slumped on underlying alluvium. The road was built on thick deposits of alluvium and tidal estuary mud along Turnagain Arm of Cook Inlet near Portage, Alaska. These weakened deposits spread laterally away from the road center toward the edge of the embankment. This is the east approach to Twentymile River highway bridge at Portage. Photo Credit: U.S. Geological Survey, Menlo Park, CA |
Bridge Damage, Twentymile River, Alaska | |
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Damage To Highways And Railroads This reinforced concrete-deck highway bridge across Twentymile River near Turnagain Arm of Cook Inlet fell into the river during the earthquake; the adjacent steel railroad bridge survived with only minor damage. Both bridges were founded on thick deposits of soft alluvium and tidal flat mud, and were subjected to severe seismic vibration. During the earthquake some of the concrete deck sections hit the underlying wood piling with sufficient force to drive the bare ends of the wood piles through the concrete deck. Photo Credit: U.S. Geological Survey, Menlo Park, CA |
Bridge Damage on the Cooper River, Alaska | |
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Damage To Highways And Railroads One span of the "Million Dollar" truss bridge of the former Copper River and Northwestern Railroad was dropped into the Copper River by the earthquake, and the other truss spans were shifted on their piers. The bridge construction consisted of concrete piers on concrete caissons 35 to 50 feet (10.6-15.1 m) below the stream bed. The superstructure consisted of steel trusses. Photo Credit: U.S. Geological Survey, Menlo Park, CA |
Damage to Rails at Seward Port, Alaska | |
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Damage To Highways And Railroads Damage to the railroad facilities at Seward Port. Rails were stripped from the railroad ties by the tsunami. Most of the Alaska Railroad dock was washed away by the waves. The railroad also lost two cranes and its waterfront trackage. Note also the damaged oil storage tanks due to fire. The first fire erupted almost immediately after the earthquake began when a tank collapsed at the Standard Oil tank farm. The Texaco installation burned for several days. Photo Credit: NOAA/NGDC |
Tank Farm Fire, Valdez, Alaska | |
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Damage To Highways And Railroads Fire at Valdez, Alaska. The tank fire was triggered by failure of oil storage tanks at the Union Oil tank farm. By 10:30 p.m. about 5 hours after the quake, the whole waterfront was burning furiously. Some buildings along Front Street and Standard Oil's pumping control station also caught fire. The Union Oil tank farm continued to burn for two weeks. Photo Credit: EERI, Slides on Learning from Earthquakes, Set IV |
Tsunami Damage to Spruce Trees, Port Valdez, Alaska | |
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Tsunami Damage Living spruce trees up to 24 inches (60.9 cm) in diameter and between 88 and 101 feet (26.7-30.6 m) above sea level were broken and splintered near Shoup Bay by the surge-wave generated by an underwater landslide in Port Valdez, Prince William Sound. Photo Credit: U.S. Geological Survey, Menlo Park, CA |
Tsunami Damage near Seward, Alaska | |
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Tsunami Damage Tsunami damage to the north end of Resurrection Bay near Seward. The first wave arose after a waterfront and submarine slump developed within minutes of the beginning of the earthquake. A large mound of water rose in the fiord. This wave and other waves washed into the town of Seward destroying buildings, docks, railroad facilities, and small boats. About twenty minutes later the first wave from the major tsunami arrived. The maximum runup was between 30 and 38 feet (9.1 -11.5 m) above mean low water. Waves continued for more than eight hours after the quake. Photo Credit: U.S. Dept. of the Interior |
Tsunami Damage near Resurrection Bay, Alaska | |
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Tsunami Damage This photo was taken at Seward at the north end of Resurrection Bay showing overturned ship, demolished Texaco chemical truck, and torn-up dock strewn with logs and scrap metal after the tsunamis. The waves left a shambles of houses and boats in the lagoon area, some still looking relatively undamaged and some almost completely battered. The total damage to port and harbor facilities at Seward was estimated at more than $14,000,000. Most of this damage was the result of the tsunamis. Twelve persons lost their lives due to the sea waves at Seward. Photo Credit: U.S. Dept. of the Interior |