PDF The 1964 Great Alaska Earthquake and TsunamisA Modern - USGS This is called subduction. Faults are fractures in Earths crust where movement has occurred. USGS published the results of investigations of the Alaska earthquake of March 27, 1964 in a series of six Professional Papers. In particular, learn about how the earthquake liquefied the ground, generated tsunami waves, and . They also sought to locate the quakes epicenter. Right image Our plate boundary comprises ~2,500 miles of the circum-Pacific "Ring of Fire" where ongoing subduction gives rise to arcs of active volcanoes and the largest earthquakes in the world. The granite rocks in the foreground are similar to those found in Yosemite National Park in the Sierra Nevada Mountains. Uplift that averages 6 feet over broad areas occurred mainly along the coast of the Gulf of Alaska, on the adjacent Continental Shelf, and probably on the continental slope. Through very complete mapping of vertical deformation and faulting and the application of tectonics, he was first to propose in 1965 that the source of the 1964 Alaska earthquake was a low-angle thrust fault. Along with the NOAA Pacific Tsunami Warning Center located at Ford Island, Hawaii, the National Tsunami Warning Center monitors and warns for tsunami threats 24/7 throughout the year. The San Andreas Fault and Queen Charlotte Fault are transform plate boundaries developing where the Pacific Plate moves northward past the North American Plate. Short video (4 min) by Stephen Wessells, USGS relating how the largest quake in U.S. history had profound and lasting impacts on our lives. You can now see under the house to the yard beyond (center right of photo). Tomales Bay. Ned Rozells personal account of his meeting with George Plafker, one of three USGS Geologists who responded to the Alaska quake a few days after event. The tsunamis created by the earthquake reached land within a few minutes of the ground shaking and engulfed some areas as much as 170 feet above sea level. Today, almost 60 years since the Great Alaska Earthquake, the Tsunami Warning Centers issue tsunami warnings in minutes, not hours, after a major earthquake occurs. That movement generated huge and fast-moving waves in the open ocean, called tsunamis. Along much of the boundary, the bulk of the motion occurs along the San Andreas Fault. As the tremors ended, local tsunamis sprung up almost immediately, leaving residents little to no time to flee for higher ground. That is where the plates push into, against or away from each other. Then, as Alaskas shaking ceased, things got worse much worse. Both plates are capped by oceanic crust. USGS concluded that the earthquake did not shake down much of the snowpack. 345 Middlefield Road, MS 977 Plate boundaries. S. Perkins. A map of some dozen major tectonic plates and several minor ones. March 21, 2011. According to the United States Geological Survey, The 1964 earthquake was giant because of the large area of the fault that slipped during the earthquake and the large amount of slip, or relative motion, between opposite sides of the earthquake fault.. the first to be generally understood by earth scientists as having occurred on a subduction zone interface: the slip was along the gently dipping boundary, or "megathrust fault," between the denser downgoing oceanic plate and the lighter overriding continental plate. These plates constantly move. Learn about the Great Alaska Earthquake of 1964 in this video adapted from the Valdez Museum & Historical Archive. Credit: Photo Courtesy of Robert J. Lillie. The lithosphere is relatively rigid and is broken into slowly moving tectonic plates. National Park Service lands contain not only active examples of all types of plate boundaries and hotspots, but also rock layers and landscapes that reveal plate-tectonic activity that occurred in the distant past. Houses pulled apart. Typically, a convergent plate boundarysuch as the one between the Indian Plate and the Eurasian Plateforms towering mountain ranges, like the Himalaya, as Earths crust is crumpled and pushed upward. The powerful tremors lasted for nearly five minutes and were felt over a large area of Alaska and in parts of the western Yukon Territory and British Columbia. The earthquakes that occur along these zones, called spreading centers, are relatively small. If one plate is trying to move past the other, they will be locked until sufficient stress builds up to cause the plates to slip relative to each other. Feb. 13, 2013. Strong, destructive earthquakes can accompany a rapid, several-meter uplift of bedrock along subduction zones. Register to access: Already Registered? This uplift attained a measured maximum on land of 38 feet in a northwest-trending narrow belt less than 10 miles wide that is exposed on Montague Island in southwestern Prince William Sound. Perhaps nowhere on Earth is such a landscape more dramatically displayed than along the San Andreas Fault in western California. Oct. 16, 2012. Due to the long duration of the earthquake, catastrophic ground failures occurred. The collision of tectonic plates can result in earthquakes, volcanoes, the formation of mountains, and other geological events. In bays and inlets, the quake also triggered underwater landslides. Transform boundaries where plates slide passed each other. What causes earthquakes? - British Geological Survey Two types of tsunami were produced as a result of this massive quake. There, in California, that motion causes earthquakes along the infamous San Andreas Fault. Trenchward velocities are found also for some sites in the Anchorage area. The earthquake and ensuing tsunamis caused about $311 million in damages in 1964(about$2.3 billiontoday). They washed away everything in their immediate path buildings, docks and people. . M9.2 Alaska Earthquake and Tsunami of March 27, 1964 - USGS An examination of the 1964 Alaska Good Friday Earthquake from a (pre- plate tectonics theory) geological point of view. Fifty years later, it continues to shape Alaska, its people, and the science of earthquakes. All Rights Reserved. It was the first time we had physical proof of plate tectonics, concludes West. They still had many questions to answer. URL: https://pubs.usgs.gov/pp/0543i/ Some had been up to 24 inches (61 centimeters) in diameter and as much as 101 feet (30.8 meters) above sea level. In Mexico, a combinatiion of divergent and transform plate boundary motion is opening the Gulf of California, causing the Baja Peninsula to separate from the rest of Mexico. Where tectonic plates slip horizontally past one another, lithosphere is neither created nor destroyed. The boundary type that produces the most earthquakes is convergent boundaries where two continental plates collide earthquakes are deep and also very powerful. Most plates (like the North American one) span both land and seafloor regions. Aftershocks from the quake continued for three weeks. Tectonics of the March 27, 1964 Alaska Earthquake S. Ornes. Two earthquake faults exposed on Montague Island are subsidiary northwest-dipping reverse faults along which the northwest blocks were relatively displaced a maximum of 26 feet, and both blocks were upthrown relative to sea level. But Plafker saw it first, there in Alaska. There are three types of plate boundaries: spreading zones, transform faults, and subduction zones. Which type of boundaries can produce earthquakes at which produces the largest earthquakes? Convergent boundaries , where two plates are moving toward each other, are of three types, depending on the type of crust present on either side of the boundary oceanic or continental . Types of Plate Boundaries - Geology (U.S. National Park Service) The Pacific Plate slides north-northwestward past the North American Plate along the San Andreas Transform Plate Boundary. In the Turnagain Heights area of Anchorage, soil liquefaction (when the ground behaves like a liquid) triggered a landslide which moved parts of a suburban bluff 2,000 feet into the bay, taking up to 75 homes with it. The delta slump triggered a local tsunami which destroyed almost anything left standing and ruptured the Union Oil Companys oil tanks, igniting a massive fire. Explains how Yakutat terrane accretion drives mountain building and crustal fault earthquakes like the 2002 M7.9 Denali Earthquake. HISTORY reviews and updates its content regularly to ensure it is complete and accurate. The San Andreas Fault is one of the best examples of lateral plate motion. briefly recounts the events of March 27, 1964 and explains the scientific and societal importance of the earthquake. Californias San Andreas fault is a transform boundary. NP = National Park Postseismic Deformation after the 1964 Great Alaskan Earthquake The movement releases stored-up 'elastic strain' energy in the form of seismic waves, which propagate through the Earth and cause the ground surface to shake. In addition to local tsunamis caused by underground landslides, the earthquake triggered an enormous tectonic tidal wave. S. Ornes. Forty million years ago, a large tectonic plate, known as the Farallon Plate, was between the Pacific and North American plates. Meanwhile, land near the coast just above the fault rose when the fault slipped. Volcanic rocks at Pinnacles National Park were displaced about 190 miles (305 kilometers), while granitic rocks of Point Reyes National Seashore have moved about 310 miles (500 kilometers). On This Day: Great Alaska Earthquake and Tsunami, Aftershocks from the quake continued for three weeks, Transoceanic tsunami waves swept across the Pacific and reached as far away as Hawaii and Japan, The earthquake and ensuing tsunamis caused about $311 million in damages in 1964(about$2.3 billiontoday), Tsunami Warning Centers issue tsunami warnings in minutes, not hours, after a major earthquake occurs, National Tsunami Hazard Mitigation Program, Tsunami Forecast Model Animation: 1964 Alaska Earthquake, NCEI Great Alaska Earthquake Image Database, VIDEO: NCEI Ask a Scientist with Nic Arcos: Tsunamis. It effortlessly toppled telephone poles, buckled railroad tracks, split roads in half, uprooted buildings, cars and docks and tore homes apart. Finally, the transform boundary, that the San Andreas . But 50 years ago, that now infamous Alaska quake shook steadily and terrifyingly for almost five solid minutes. Policies and Notices, U.S. Department of the Interior | Plafker had confirmed that the earthquake occurred in a subduction zone. Aug. 16, 2013. Comparable horizontal movements are presumed to have affected those parts of the major zones of uplift and subsidence for which retriangulation data are unavailable. Although the school was destroyed, the nearby water tower was undamaged. July 6, 2011. The violent shaking led to water, sewer and gas line breaks and widespread telephone and electrical failures. They have been transported about 300 miles (500 kilometers) in a north-northwestward direction along the transform plate boundary. Channel Islands National Park, Santa Monica Mountains National Recreation Area and Joshua Tree National Park are within the Transverse Ranges, a block of crust that rotated as a result of the shearing motion. Seafloor topography map source: Global sea floor topography from satellite and ship depth soundings, 1997, by W. H. F. Smith and D. T. Sandwell, Science, v. 277, p. 1956-1962. The foreground shows a ditch (or graben) that opened up roughly 12 feet (or around 3.7 meters) deep. To view this site, enable JavaScript by changing your browser options and try again. Farther east, the continent began to rift apart in the Basin and Range Province. This happens because the oceanic plate is denser (heavier) than the continental plate. The earthquake hit at 3:11 pm approximately 100 miles (160 km) off the coast of Chile . Poster: Tsunami Sources 1610 B.C. Underwater landslides along the Seward, Alaska, waterfront triggered the strong waves which hit here, 2 miles (3.2 kilometers) from Seward. Excerpt from the TV show The Big Picture produced by the US Army in 1966 about the Alaska Earthquake and its tragic effects. Porosity increases, probably related to horizontal displacements in the zone of subsidence, were reflected in lowered well-water levels and in losses of surface water. The broad zone of shearing at a transform plate boundary includes masses of rock displaced tens to hundreds of miles, shallow earthquakes, and a landscape consisting of long ridges separated by narrow valleys. Another form of convergent boundary is a collision where two continental plates meet head-on. The devastating 9.2 magnitude earthquake and subsequent tsunamis ravaged coastal communities and took over 139 lives. Letters in ovals are abbreviations for NPS sites listed above. Where plates crash together, one dives (subducts) beneath the other, causing volcanoes (red triangles) to erupt on the overriding plate and earthquakes (black stars) at a variety of depths. One of many trees damaged by quake impacts. Though this hazardous event developed the moniker of the Great Alaska Earthquake, it was actually the ensuing tsunamis that did the greatest damage and took the most lives. As you slide your hands laterally past one another, a broad zone of shearing develops as several card faces slip. These cracks generally ran at high angles to the faults and could run a few hundred feet and span 6 inches (15 centimeters). Earthquakes at divergent plate boundaries occur as new crust is created and other crust is pushed apart. For more information on how you can prepare for a tsunami, visit the National Tsunami Hazard Mitigation Program. The fastest plate race at 15 centimeters (6 inches) per year The slowest creep along at fewer than 2.5 centimeters a year. Regional vertical deformation generated a train of destructive long-period seismic sea waves in the Gulf of Alaska as well as unique atmospheric and ionospheric disturbances that were recorded at points far distant from Alaska. The 1964 earthquake was the first time people understood that there were places called subduction zones that produce these really enormous earthquakes. The theory of plate tectonics is a relatively new scientific concept. At transform boundaries lithosphere is neither created nor destroyed. Photo courtesy of the National Parks Conservation Association. What Caused The Most Deaths In The Great Alaska Earthquake Of 1964? Society for Science & the Public 20002023. The average movement of the Pacific Plate past the North American Plate in California is about 2 inches (5 centimeters) per year. This is known as subduction. These instruments detect and record earthquakes. We interpret the trenchward velocities as being caused by a continuing postseismic transient from the 1964 great Alaska earthquake. Eyewitnesses described hearing a crunching, grinding noise as the earth shook. Most earthquakes rattle the ground for just seconds. The earthquake must be a shallow marine event that displaces the seafloor. The accretionary wedge rocks are found in Channel Islands National Park, Golden Gate and Santa Monica Mountains national recreation areas and Cabrillo National Monument. 1719 N Street, N.W., Washington, D.C. 20036, People and animals sometimes team up to hunt for food, Pokmon evolution looks more like metamorphosis, These beetles drink water using their butts. When oceanic and continental plates meet, the denser oceanic plate moves under the less dense continental plate. Regional uplift and subsidence occurred mainly in two nearly parallel elongate zones, together about 600 miles long and as much as 250 miles wide, that lie along the continental margin. Seismicity of the United States, 1568-1989 (Revised), Produced by Creative Arts Studio in 1964 for the USGS. They occur where plates are subducting, spreading, slipping, or colliding. An animation that describes earthquakes along the Aleutian subduction zone, one of the most seismically active in the world, and the Queen Charlotte Transform Fault. Geologic data indicate that the earthquake-related tectonic movements were but the most recent pulse in an episode of deformation that probably began in late Pleistocene time and has continued intermittently to the present. Eventually the weakest card face (the San Andreas Fault) dominates within the broad transform plate boundary. The 1964 M9.2 Great Alaska Earthquake, which is still the second largest earthquake ever recorded worldwide, began under Prince William Sound. What caused the Alaska earthquake in 1964? Earthquakes can strike any location at any time, but history shows they occur in the same general patterns year after year, principally in three large zones of the earth: The world's greatest earthquake belt, the circum-Pacific seismic belt, is found along the rim of the Pacific Ocean, where about 81 percent of our planet's largest earthquakes .