what type of plate boundary caused the 1964 alaska earthquake what type of plate boundary caused the 1964 alaska earthquake

Is earthquake a result of plate tectonics? But this was no ordinary tremor. In Alaska, the flattening caused some of the affected land to drop. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely. Like a jigsaw puzzle, Earths lithosphere is divided into interlocking pieces, called plates. View from the playground of the Government Hill School in Anchorage, showing damage from the 1964 earthquake. What type of fault caused the 1964 Alaska Earthquake? The 1964 M9.2 Great Alaska Earthquake, which is still the second largest earthquake ever recorded worldwide, began under Prince William Sound. 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. On the east, the North American Plate is subducting westward, forming volcanoes of the Lesser Antilles Island Arc. Point Reyes National Seashore and Joshua Tree National Park have granitic magma-chamber rocks of the eroded arc, and Pinnacles National Park preserves volcanic rocks. Plate boundaries from The Plates Project, University of Texas Institute for Geophysics. Systematic horizontal movements of the land relative to bodies of confined or semiconfined water may have caused unexplained short-period wavessome of which were highly destructiveobserved during or immediately after the earthquake at certain coastal localities and in Kenai Lake. Focal-mechanism studies, when considered in conjunction with the pattern of deformation and seismicity, suggest that it was a complex thrust fault (megathrust) dipping at a gentle angle beneath the continental margin from the vicinity of the Aleutian Trench. These tectonic plates move gradually, bumping and grinding against each other. Scientists are still working out many details of plate tectonics. The Virgin Islands are in a broad zone where the landscape is being sheared up as the Carribean Plate slides eastward past the oceanic part of the North American Plate. The 1964 Alaska Earthquake and Tsunami lecture by George Plafker, USGS Geologist Emeritus. They also sought to locate the quakes epicenter. FOIA Railroad tracks warped. . The water drove a long, 2-by-6-inch-wide plank through a trucks 10-ply tire. When oceanic and continental plates meet, the denser oceanic plate moves under the less dense continental plate. Along much of the boundary, the bulk of the motion occurs along the San Andreas Fault. You push and push. Alaskas long southern coastline marks where the Pacific Plate, moving north, dives beneath the North American Plate. April 30May 2, 2014 in Anchorage, Alaska. These cracks generally ran at high angles to the faults and could run a few hundred feet and span 6 inches (15 centimeters). 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 yellow cab of the truck wrapped around the right side of a tree; its wheels around the left side. That raised rock runs from the right foreground to the left background. Anchorage house pulled apart as the ground on which it had been anchored opened up, creating a fissure (or graben). Read more from USGS: The Great Alaska Earthquake and Tsunami of March 27, 1964, Teachers' questions: The quake that shook up geology. If a segment of the San Andreas Fault is locked for a century, then a large earthquake might result in 200 inches (2 inches/year x 100 years) of movement along the fault in less than a minute. A documentary chronicling the first 72 hours after the 1964 Alaska Earthquake and the response to the disaster by the United States Office of Civil Defense, U.S. Military, and local, state, and federal officials. Those instruments also helped identify the shape of the fault responsible for all the shaking. Transform boundaries occur on the north and south sides of the Caribbean Plate. Both plates are capped by oceanic crust. Strong, destructive earthquakes can accompany a rapid, several-meter uplift of bedrock along subduction zones. The 16 feet (about 200 inches, or 5 meters) of offset along the fence line thus carries a powerful message. The only stronger trembling ever recorded was a magnitude-9.5 monster that shook Chile in May 1960. Aftershock distribution suggests movement on a segment of the megathrust, some 550600 miles long and 110180 miles wide, that underlies most of the major zone of uplift and the seaward part of the major zone of subsidence. And it moved parts of the Alaskan coast 15 meters (50 feet) toward the sea. That doesnt seem like much, but over time it adds up. Explains how Yakutat terrane accretion drives mountain building and crustal fault earthquakes like the 2002 M7.9 Denali Earthquake. Still, the fact that it reached those areas at all is testament to the enormity of the quake. Alaskans are familiar with earthquakes. Get a new perspective on earthquakes with this rich collection of multimedia resources. The fastest plate race at 15 centimeters (6 inches) per year The slowest creep along at fewer than 2.5 centimeters a year. No Alaskan who survived would ever forget this day. Ahead of the wave. Science News for Students. The warning system doesnt monitor local tsunamis, however. Its a well-documented certainty. In places, the waves towered as high as a 20-story building. The damage was caused entirely by the shifting of ground along the fracture, USGS concluded. This opinion piece by USGS geologist Peter Haeussler, et al. It extends across the two zones from the chain of active volcanoes in the Aleutian Range and Wrangell Mountains probably to the Aleutian Trench axis. A broad earthquake-monitoring system was created to gather data and help seismologists predict future earthquakes and their potential damage. During the earthquake, its estimated the fault slipped between 30 to 60 feet, an immense shift. , Divergent boundaries where two plates are moving apart. The sequence begins shortly after the last earthquake. The primary fault, or zone of faults, along which the earthquake occurred is not exposed at the surface on land. In 1964, portions of the Pacific Plate along Alaskas long southern coastline moved north, diving beneath the North American Plate. They have been transported about 300 miles (500 kilometers) in a north-northwestward direction along the transform plate boundary. tectonic plates The gigantic slabs some spanning thousands of kilometers (or miles) across that make up Earths outer layer. Massive landslides were triggered by the quake near downtown Anchorage and several residential areas, damaging or destroying about 30 blocks of dwellings and commercial buildings. Learn about the great leaps in research over the past 50 years. Learn more about UAs notice of web accessibility. You'll be happy you did. Contact Information, Menlo Park, Calif. Then suddenly, it pops open. subsidence A downward shift in some section of Earths surface. Experiment: Are fingerprint patterns inherited? The earthquake was accompanied by vertical displacement over an area of about 520,000 square kilometers. Magnitude type: M l 2; Event type: earthquake; Tectonic Setting of Southern Alaska . This post is part of Exploring Earthquakes, a rich collection of resources co-presented by the California Academy of Sciences and KQED. A reverse fault, like the Cascadia subduction zone off the coast of Oregon and Northern California (north of Mendocino California), has relatively deep earthquakeslike the 1964 Alaska earthquake and the 2004 Listing total number of features into an ArcGIS Online feature pop-up, Convergent boundaries: where two plates are colliding. (2) Intermediate depth seismicity (below 20 miles) occurs in the so-called Benioff Zone, where the subducting Pacific Plate descends towards the mantle beneath the North American Plate. 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 motion on the north is not pure transform; there is some convergence that contributes to uplift of the topography. As the plates grind together, they get stuck and pressure builds up. Monday Saturday: 9:30 am 5 pm Alaska's continental shelf and North American plate rose over 9 meters during the earthquake. No safe motoring here anymore. Plafker had confirmed that the earthquake occurred in a subduction zone. At this boundary, the Pacific Plate slides beneath the North American Plate, causing the majority of Alaska's earthquakes, including the 1964 earthquake. Seismic waves caused the earth to "ring like a bell." As bad as the tremors were, the worst was yet to come. Point Reyes National Seashore, California. For example, moving at about 2 inches (5 centimeters) per year, in our lifetime the Pacific Plate moves 10 to 15 feet (3 - 5 meters) past the North American Plate along the San Andreas Fault, a transform plate boundary in California. The 1964 earthquake was a defining moment in a territory that had just achieved statehood. The rocks pulled down under the continent begin to melt. Some start and then stop, only to start again much later. Earthquake history, photos, videos, and more from the Alaska Division of Homeland Security & Emergency Management. The Sierra Nevada are the eroded remnants of the volcanic arc developed when the Farallon Plate subducted beneath the continent. These strike-slip faults and their associated structures are defined by linkage of mid-ocean spreading centers and subduction zones, and are exposed onshore as they traverse the continental crust between mid-ocean ridges and other plate boundary segments (Figure 2). Copalis River, Washington Trees along the Washington coast were killed by salt-water invasion when the land suddenly dropped during the last great Cascadia Subduction Zone earthquake . Learn more about UAs notice of web accessibility. What kind of plate boundary causes mountains to form? 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. As the plates collide, the oceanic plate is forced beneath the continental plate. That movement generated huge and fast-moving waves in the open ocean, called tsunamis. The dynamics of a subduction zone explained why the 1964 earthquake was so massive. Now, a full half-century after Alaskas gigantic quake, geologists are still feeling its effects. Imagine that your left hand is the undeformed Pacific Plate, your right hand the intact North American Plate. It is also the second largest earthquake ever recorded, next to the M9.5 earthquake in Chile in 1960. The San Andreas Fault and Queen Charlotte Fault are transform plate boundaries developing where the Pacific Plate moves northward past the North American Plate. Federal government websites often end in .gov or .mil. Often it is the older and colder plate that is denser and subducts beneath the younger and warmer plate. The San Andreas Fault is just one of many active earthquake faults in a broad zone of shearing along the transform plate boundary in the San Francisco Bay Area. One of many trees damaged by quake impacts. It caused extensive damage to the city, including fires that lasted for several days, and killed an estimated 3,000 people. Most earthquakes at divergent plate boundaries occur at mid-ocean ridges where two pieces of oceanic crust are moving away from each other. This is an earthquake. 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. The Alaska Earthquake Alliance coordinates earthquake awareness and preparedness activities throughout Alaska. The belt of seismic activity and major zones of tectonic deformation associated with the 1964 earthquake, to a large extent, lie between and parallel to the Aleutian Volcanic Arc and the Aleutian Trench, and are probably genetically related to the arc. Which type of boundaries can produce earthquakes? Along other, divergent boundaries, plates move away from each other. But if you see something that doesn't look right, click here to contact us! Meanwhile, land near the coast just above the fault rose when the fault slipped. Indeed, the state averages some 60 each day about 22,000 a year. Thats a type of convergent plate boundary where one plate dives beneath another. . The 1964 Alaska earthquake resulted from rupture along the thrust fault boundary bet- ween the downgoing Pacific Plate and the overriding North American Plate, causing widespread shaking and tectonic defor- mation. Earthquakes and tsunamis can happen along any coastline, at any time of the year, but Alaska is particularly prone to them because it sits on the convergence of two tectonic platesthe Pacific Plate and the North American Plate. Like modern subduction zones, the region had an accretionary wedge (Coast Range), a forearc basin (Great Valley), and a volcanic arc (Sierra Nevada). 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. About 80% of earthquakes occur where plates are pushed together, called convergent boundaries. Other plates include continents, and some plates include both continents and ocean. They recalled seeing asphalt roads rise and fall like waves and the ground opening and closing before them, water shooting up through the ensuing cracks. The aftermath of the Great Alaska Earthquake and Tsunami led to the creation of the NOAANational Tsunami Warning Centerin Palmer, Alaska. The seismographs recorded these aftershocks as well. The San Andreas Fault that runs through much of California is an enormous transform plate boundary. March 27, 1964, was a quiet day in Alaska. 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 1964 Alaska earthquake, the strongest earthquake ever recorded in North America, struck Alaskas Prince William Sound, about 74 miles southeast of Anchorage. The Earthquake Trail at Point Reyes weaves back and forth across the fault line. by Carl W. Stover and Jerry L. Coffman, The San Andreas Fault is the transform plate boundary where a thin sliver of western California, as part of the Pacific Plate, slides north-northwestward past the rest of North America. This pattern has since been seen at other subduction zones. In the Caribbean Sea, the U. S. Virgin Islands lie along a transform plate boundary where the small Caribbean Plate moves eastward past the oceanic part of the North American Plate. Transform plate boundaries produce enormous and deadly earthquakes. These films were shot by amateur and professional cameramen in the hours and days following the earthquake at locations such as Anchorage, Kodiak, Seward, Valdez, Chenega, Afognak. Another form of convergent boundary is a collision where two continental plates meet head-on. Due to the long duration of the earthquake, catastrophic ground failures occurred. Rocks have been disrupted by shearing and other forces associated with the transform plate motion and, in some instances, transported northward a long distance from where they originally formed. USGS.The 1964 Great Alaska Earthquake. Out of great catastrophe arises innovation and a new hope for the future of disaster preparedness. The transform plate boundary is a broad zone forming as the Pacific Plate slides northwestward past the North American Plate. At an ocean-ocean convergent boundary, one of the plates (oceanic crust and lithospheric mantle) is pushed, or subducted, under the other (Figure 4.6. When the plates finally give and slip due to the increased pressure, energy is released as seismic waves, causing the ground to shake. Abridged from The lower portion (right center) is white from the dried out remains of shellfish that had lived on this rock when it was still part of the seafloor. Sometimes the extraction of groundwater leaves a hole that cannot support the ground above. The movements of the plates help shape the geological features of our planet. Special Earthquakes, Earthquake Sequences, and Fault Zones. Document ID 19990116704 Document Type Other In that one quake, it was the first time you could actually see plate motion in action. Heres evidence of the impacts of those waves that surged into the deep-water port of Whittier after the earthquake. Divergent boundaries - where two plates are moving apart. Coastal forests plunged below sea level and were destroyed by salt water. The convergent boundary happens when two plates slide toward each other to form a subduction zone or a continental collision. It was the largest U.S. earthquake ever recorded, and a turning point in earth science. A sudden unlocking could produce an earthquake every bit as big as the one that occurred in Alaska in 1964, when a similar subduction zone boundary snap occurred. Alaskan tectonics are dominated by the Pacific-North American plates. The epicenter is that X-marks-the-spot site where the tremors commenced. All rights reserved. Parks in the Sierra Nevada, including Yosemite, Kings Canyon, and Sequoia national parks, contain granite-type rocks that cooled within magma chambers beneath ancient subduction zone volcanoes. The Transverse Ranges north and east of Los Angeles are so named because they trend in an east-west direction, contrary to the northwest-southeast orientation typical of other ranges along the San Andreas transform plate boundary. 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. Map showing plate boundaries that were active during the 1964 Great Quake. That is where the plates push into, against or away from each other. These occur directly along subduction zones. In Anchorage, roads buckled and sank. Photo courtesy of Robert J. Lillie. There are three types of tectonic plate boundaries: Another large-scale feature is a hotspot, where a plate rides over a rising plume of hot mantle, creating a line of volcanoes on top of the plate. Californias sheared-up landscape and earthquake hazards reflect the movement of the Pacific Plate past the edge of North America along a transform plate boundary that extends from the Mexican border to north of San Francisco. As the ground fractured, the trunk experienced extreme tension and eventually split. United States Government Printing Office, Washington: 1993. Pillow basalt, formed as lava poured out on the ocean floor, was later scraped off the top of the subducting plate and thrust onto the edge of the continent. Sign up for the Academys monthly newsletter and get a promo code for 10% off at our online retail store. Since neither plate is stronger than the other, they crumple and are pushed up. The land that was uplifted and sometimes dropped by the Great Alaskan Quake also fits with the plate-tectonics model. Part of the of the Million Dollar Bridge at Copper River also crumpled. Download the latest version of Adobe Reader, free of charge. When the earthquake struck, seismic waves caused soil liquefaction and a portion of the delta slumped into Port Valdez, taking much of the ports resources, living and otherwise, with it. And it has forever changed what scientists understand about the constant remodeling of Earths surface. Founded in 2003, Science News Explores is a free, award-winning online publication dedicated to providing age-appropriate science news to learners, parents and educators. Transform boundaries - where plates slide passed each other. When two tectonic plates slide past each other, the place where they meet is a transform or lateral fault. The data helped engineers develop earthquake-resistant structures to limit future casualties and property damage. SSAs 2014 Annual Meeting will provide a stimulating exchange of research on a wide range of topics with colleagues from all over the world. Farther east, the continent began to rift apart in the Basin and Range Province. Then, as Alaskas shaking ceased, things got worse much worse. The sedimentary and metamorphic rocks across the fault line are similar to those found in Redwood National and State Parks on the North Coast of California. Learn about the Great Alaska Earthquake of 1964 in this video adapted from the Valdez Museum & Historical Archive. Most earthquakes rattle the ground for just seconds. The site is secure. The publication, as well as Science News magazine, are published by the Society for Science, a nonprofit 501(c)(3) membership organization dedicated to public engagement in scientific research and education. Look at your fingernails and watch them grow. The large white star represents the zone where plates lock together for centuries then suddenly let go, causing the largest earthquakes. (en Espaol). The Great Alaskan Earthquake was a magnitude-9.2 event. The divergent boundary occurs when two tectonic plates move away from each other. The California Academy of Sciences is a 501(c)(3) nonprofit organization. Oral presentations, poster sessions, exhibits, field trips, business meetings and social gatherings all provide participants the opportunity to meet and share with their peers. Also just like a rug, the land spreads out as it flattens. President Lyndon Johnson declared the entire state of Alaska a major disaster area a day after the earthquake. This photo shows a small snow slip in the center foreground. Oreo cookies are a fun way to demonstrate the three types of plate boundaries and a hotspot. You'll learn why earthquakes happen, how they've shaped the Bay Area, and what you can do to prepare for the next one. The largest tsunami wave of the 1964 Alaska Earthquake measured over 200 feet in height and was recorded at Shoup Bay near the Valdez inlet. In particular, We were looking for evidence of surface faulting, he recalled at a press briefing earlier this week. Maybe even for a half or full minute. Movement on the megathrust was accompanied by subsidiary reverse faulting, and perhaps wrench faulting, within the upper plate. in that one quake, it was the first time that you could actually see plate motion in action. The demolished towns of Valdez and Chenega were rebuilt on higher ground, but not everyone was prudent about rebuilding on earthquake-prone land. In 1964, plate tectonics still was just an emerging if unproven concept. 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. Such movement on the faults is generally a response to long-term deformation and the buildup of stress. This type of knowledge helps us better design and site infrastructure, and develop disaster preparedness plans so that our families and communities are less at risk when earthquakes do strike. Uplift and subsidence relative to sea level caused profound modifications in shoreline morphology with attendant catastrophic effects on the nearshore biota and costly damage to coasta1 installations. An examination of the 1964 Alaska Good Friday Earthquake from a (pre- plate tectonics theory) geological point of view. Relatively few earthquakes occur in intraplate environments; most occur on faults near plate margins. It was so large that it caused the entire Earth to ring like a bell, observes seismologist Tom Brocher and his colleagues from the U.S. Geological Survey (USGS) in a recent publication. Plates beneath the oceans are much thinner than those under continents. ), rupture processes, elastic rebound, and resulting tsunami. Natasha Ruppert at the Alaska Earthquake Center in Fairbanks is another seismologist. Feature labels. Along convergent boundaries, neighboring plates either collide head-on or a denser ocean plate dives beneath a lighter continental plate. seismograph (also known as aseismometer) An instrument that detects and measures tremors (known as seismic waves) as they pass through Earth. We interpret the trenchward velocities as being caused by a continuing postseismic transient from the 1964 great Alaska earthquake. July 6, 2011. Geologists call plate tectonics a unifying theory. Thats because it explains practically everything about Earths crust. By midnight, 131 people were dead. Much to the dismay of some earthquake experts, luxury homes were rebuilt on areas most likely to experience earthquake damage, including on top of the ruins in Turnagain Heights. Plate boundaries. The second-largest earthquake in the U.S. was a magnitude-9.0 in 1700, which occurred at the Cascadia Subduction Zone, site of the leak. 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 . The April 1933 M6.9 earthquake, which caused considerable damage in Anchorage, appears to have occurred on such . NP = National Park It was the first time we had physical proof of plate tectonics, concludes West. The valleys are commonly due to erosion along individual fault lines. tsunami One or many long, high sea waves caused by an earthquake, submarine landslide or other disturbance. They were scouting for patterns. The San Andreas Fault is just one of several faults that accommodate the transform motion between the Pacific and North American plates. Water mains and gas, sewer, telephone and electrical systems were all damaged or destroyed due to the landslides. This is an earthquake. Perhaps nowhere on Earth is such a landscape more dramatically displayed than along the San Andreas Fault in western California. Beginning about 30 million years ago, so much of the Farallon Plate was consumed by subduction that the Pacific and North American plates were in contact, forming the San Andreas transform plate boundary in western California. The purpose of the group is to bring together both institutions and individuals who have an interest in reducing earthquake hazards in Alaska. Virgin Islands National Park in the U. S. Virgin Islands is located on another transform plate boundary, where the Caribbean Plate is sliding past the oceanic part of the North American Plate. Plate Tectonics and Our National Parks (2020), Text and Illustrations by Robert J. Lillie, Emeritus Professor of Geosciences, Oregon State University [E-mail]. What caused the Alaska earthquake in 1964? Feb. 13, 2013. Convergent (Colliding): This occurs when plates move towards each other and collide. USGS concluded that the earthquake did not shake down much of the snowpack. By definition, intraplate earthquakes do not occur near plate boundaries, but along faults in the normally stable interior of plates. Articles with the HISTORY.com Editors byline have been written or edited by the HISTORY.com editors, including Amanda Onion, Missy Sullivan and Matt Mullen. Another form of convergent boundary is a collision where two continental plates meet head-on. Magnitude type: M l 2; Event type: earthquake; Tectonic Setting of Southern Alaska . The .gov means its official. Thats where one tectonic plate sinks beneath another. Most earthquakes occur at the boundaries where the plates meet. divergent boundaries The edges of two neighboring tectonic plates that are spreading away from each other. Subduction zones occur when one or both of the tectonic plates are composed of oceanic crust. S. Ornes. Many transform boundaries are found on the sea floor, where they connect segments of diverging mid-ocean ridges. Tsunamis caused loss of life, extensive flooding, and damaged harbors along the North American Pacific Northwest coast. epicenter The underground location along a fault where an earthquake starts. 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.