The earthquake lasted approximately 4.5 minutes and is the most powerful recorded earthquake in U.S. history. The cards slip along their faces, forming a broad zone of shearing between your unaffected hands. Water mains and gas, sewer, telephone and electrical systems were all damaged or destroyed due to the landslides. Transform boundaries where plates slide passed each other. Movement in narrow zones along plate boundaries causes most earthquakes. Shallow earthquakes and little volcanism occur where one plate slides laterally past another. This megathrust fault has been the source of many large earthquakes including the 1964 Alaskan earthquake that registered a magnitude 9.2 and remains the second largest earthquake in . Aftershocks from the quake continued for three weeks. Transform boundaries occur on the north and south sides of the Caribbean Plate. 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. An interplate earthquake is an earthquake that occurs at the boundary between two tectonic plates.Earthquakes of this type account for more than 90 percent of the total seismic energy released around the world. Together, these destructive waves swept Alaskas coastline with devastating speed and power. Transform boundaries - where plates slide passed each other. For more earthquake and tsunami data, images, and educational materials, visit NCEIs Natural Hazards website . Federal government websites often end in .gov or .mil. At spreading zones, molten rock rises, pushing two plates . That doesnt seem like much, but over time it adds up. 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. 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. NCEI is the global data and information service for tsunamis. The 1964 Alaska Earthquake and Tsunami lecture by George Plafker, USGS Geologist Emeritus. Enter your e-mail address above. 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. Get a new perspective on earthquakes with this rich collection of multimedia resources. To the north and northwest of the zone of uplift, subsidence forms a broad asymmetrical downwarp centered over the Kodiak-Kenai-Chugach Mountains that averages 2 feet and attains a measured maximum of 7 feet along the southwest coast of the Kenai Peninsula. 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 . W.R. Hansen/ USGS, 1964 Alaska quake files. The earthquake opened fissures in bedrock next to the Hanning Bay and Patton Bay faults. Divergent boundaries - where two plates are moving apart. Strong ground motion at Seward lasted 3-4 minutes. July 26, 2013. USGS published the results of investigations of the Alaska earthquake of March 27, 1964 in a series of six Professional Papers. Such movement on the faults is generally a response to long-term deformation and the buildup of stress. The fault responsible was the Aleutian Megathrust, a reverse fault caused by a compressional force. Also just like a rug, the land spreads out as it flattens. uplift A upward shift in some section of Earths surface due to tectonic activity along a fault. Remove unwanted regions from map data QGIS. They have been transported about 300 miles (500 kilometers) in a north-northwestward direction along the transform plate boundary. Subduction zones usually have a deep trench along the top. By recording the size, direction and arrival times of the different seismic waves from a quake, seismographs help pinpoint its size and epicenter. April 27, 2012. N Pres = National Preserve. Instead, blocks of crust are torn apart in a broad zone of shearing between the two plates. This causes the crust to crack and form faults where earthquakes occur. As the plates grind together, they get stuck and pressure builds up. When the plates finally give and slip due to the increased pressure, energy is released as seismic waves, causing the ground to shake. As the mid-ocean ridge separating the Farallon and Pacific Plates entered the subduction zone, the Farallon Plate separated into the Juan de Fuca and Cocos Plates. These quakes at transform faults are shallow focus. You can now see under the house to the yard beyond (center right of photo). At still others, known as transform boundaries, plates slide past each other. April 30, 202323:15:06 AKDT (May 1, 202307:15:06 UTC)62.0155N148.8858W Depth 13.6 miles (22 km), This event has not been reviewed by a seismologist, 2156 Koyukuk Drive, PO Box 757320, Fairbanks, AK 99775. Some start and then stop, only to start again much later. For western California, each slipping card face would be a fault surface. Compaction in the Rock Cycle: Understanding the Process Behind Sedimentary Rock Formation, Crystallization in the Water Cycle: A Fundamental Process in Water Distribution and Purification, Understanding Crystallization in the Rock Cycle: A Fundamental Process in Rock Formation, Extracting Lat/Lng from Shapefile using OGR2OGR/GDAL. NOAA Natural Hazards Image Database. The invention of new tools and faster data processing have drastically improved NOAAs ability to warn the public of tsunamis and to forecast their wave heights. The long mountain ridges and narrow bays in the region surrounding U. S. Virgin Islands National Park are a product of compression due to the convergence, in addition to lateral motion due to shearing along the transform plate boundary. Scientists learned that at the point where the North American Plate overrode the Pacific Plate, it descended into a subduction zone. July 6, 2011. Thats where one tectonic plate sinks beneath another. Their thickness ranges from 80 to 200 kilometers (50 to 124 miles). A massive tidal wave crushed the small, coastal village of Chenega four minutes after the tremors subsidedthe town lost a third of its population. 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. Valdez was basically leveled. Doing some quick math, one can appreciate how dramatically plate-tectonic forces can affect the landscape, even in our lifetimes. This resulted in a line of volcanoes stretching all the way from what is now Alaska to Central America. Is earthquake a result of plate tectonics? Strong, destructive earthquakes can accompany a rapid, several-meter uplift of bedrock along subduction zones. An animation about tsunami-generating megathrust earthquakes using examples from Japan (2011), Chile (2010), and Alaska (1964) to describe structures that generate deadly tsunamis including: megathrust plate-boundary displacement, deformation of the overriding plate by splay faulting and/or folding, and earthquake-generated landslides. Underwater landslides along the Seward, Alaska, waterfront triggered the strong waves which hit here, 2 miles (3.2 kilometers) from Seward. About 200 million years ago, a large tectonic plate (called the Farallon Plate) started to subduct beneath the western edge of North America. Magnitude type: M l 2; Event type: earthquake; Tectonic Setting of Southern Alaska . National Park Service sites in the Transverse Ranges include Santa Monica Mountains National Recreation Area and part of Joshua Tree National Park. Subduction causes deep ocean trenches to form, such as the one along the west coast of South America. At transform boundaries lithosphere is neither created nor destroyed. The .gov means its official. 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. Left image Oreo cookies are a fun way to demonstrate the three types of plate boundaries and a hotspot. The 1964 M9.2 Great Alaska Earthquake, which is still the second largest earthquake ever recorded worldwide, began under Prince William Sound. N&SP = National and State Parks On the east, the North American Plate is subducting westward, forming volcanoes of the Lesser Antilles Island Arc. The Alaska Earthquake Alliance coordinates earthquake awareness and preparedness activities throughout Alaska. A divergent boundary occurs when two tectonic plates move away from each other. Naturally, most of the action occurs along the edges of tectonic plate. Oral presentations, poster sessions, exhibits, field trips, business meetings and social gatherings all provide participants the opportunity to meet and share with their peers. Special Earthquakes, Earthquake Sequences, and Fault Zones. Farther east, the continent began to rift apart in the Basin and Range Province. CHISChannel Islands National Park, California [, CABRCabrillo National Monument, California[, GOGAGolden Gate National Recreation Area, California[, PINNPinnacles National Monument, California[, POREPoint Reyes National Seashore, California[, SAMOSanta Monica Mountains National Recreation Area, California[, BUISBuck Island Reef National Monument, U.S. Virgin Islands[, VIISVirgin Islands National Park, U.S. Virgin Islands[. Scientists measured a wave runup of 220 feet in the Valdez Inlet. . S. Perkins. California Academy of Sciences. briefly recounts the events of March 27, 1964 and explains the scientific and societal importance of the earthquake. Point Reyes National Seashore, California. One of many trees damaged by quake impacts. There are three main types of plate boundaries: There are four types of boundaries between tectonic plates that are defined by the movement of the plates: divergent and convergent boundaries, transform fault boundaries, and plate boundary zones. Most of Alaskas mainland felt the magnitude 9.2 earthquake, which wobbled Seattles Space Needle some 1,200 miles away. Learn about the Great Alaska Earthquake of 1964 in this video adapted from the Valdez Museum & Historical Archive. Yet as dusk approached on this Good Friday, just two days before Easter, a major upheaval was in store. The data helped engineers develop earthquake-resistant structures to limit future casualties and property damage. The land that was uplifted and sometimes dropped by the Great Alaskan Quake also fits with the plate-tectonics model. 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. The damage was caused entirely by the shifting of ground along the fracture, USGS concluded. These occur directly along subduction zones. The 1964 Alaska Earthquake taught coastal citizens to run for higher ground at the first sign of strong tremors. One was figuring out why some parts of Alaska had risen as much as 11.5 meters (38 feet), while the ground at other sites had dropped, or subsided. Here, that 11-foot (3.4 meter) drop or subsidence took a line of parked cars with it. March 21, 2011. Photo courtesy of the National Parks Conservation Association. Accessibility The Pacific Plate slides north-northwestward past the North American Plate along the San Andreas Transform Plate Boundary. The publication, as well as. Question: What type of tectonic plate boundary exists along the edge of the North American plate near the coast of Northern California, Oregon, and Washington? When the earthquake hit, the ground underlying the road shimmied, fissured and then split apart. The site is secure. Houses pulled apart. 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). 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. President Lyndon Johnson declared the entire state of Alaska a major disaster area a day after the earthquake. UAF is an AA/EO employer and educational institution and prohibits illegal discrimination against any individual: If you have difficulty accessing the information on this website due to a disability, please contact the web administrator by email at uaf-aec@alaska.edu or by phone at 907-474-7320. The divergent boundary occurs when two tectonic plates move away from each other. The islands contain sedimentary layers and pillow lavas that formed on the ocean floor. (en Espaol). The warning system doesnt monitor local tsunamis, however. Trenchward velocities are found also for some sites in the Anchorage area. Thursday NightLife (21+): 6 10 pm. The Ring of Fire is the most seismically and volcanically active zone in the world. The earthquake and ensuing tsunamis caused about $311 million in damages in 1964(about$2.3 billiontoday). We strive for accuracy and fairness. In central and southern California, for example, the volcanoes have largely eroded away and massive areas of granite from the cooled magma chambers form portions of the Sierra Nevada Mountains, including Yosemite National Park. They also forecasthow large any resulting tsunami will be as it crosses the ocean. Although the school was destroyed, the nearby water tower was undamaged. NS = National Seashore Ground subsidence due to the earthquake created a huge, deep ditch (a graben) that ran through the yard and under this house in Anchorage. Indeed, like ripples in a pond, a tsunami travels outward in all directions. Deployment of tools like deep ocean pressure sensors (Deep-ocean Assessment and Reporting of Tsunamis or DART) are designed to ensure early detection of tsunamis and acquire data critical to real-time forecasts. All articles are regularly reviewed and updated by the HISTORY.com team. Photo courtesy of Robert J. Lillie. In 1964, portions of the Pacific Plate along Alaskas long southern coastline moved north, diving beneath the North American Plate. U.S. Geological Survey Professional Paper 1527, Produced under a Cooperative Agreement for earth science education between the National Park Service's Geologic Resources Division and the American Geosciences Institute. Prior to the 1964 Alaskan earthquake, scientists had limited knowledge of what happens far beneath the earth. S. Ornes. Find History on Facebook (Opens in a new window), Find History on Twitter (Opens in a new window), Find History on YouTube (Opens in a new window), Find History on Instagram (Opens in a new window), Find History on TikTok (Opens in a new window), Education Images/Universal Images Group/Getty Images, Department of Homeland Security & Emergency Management, https://www.history.com/topics/natural-disasters-and-environment/1964-alaska-earthquake. Movement on the megathrust was accompanied by subsidiary reverse faulting, and perhaps wrench faulting, within the upper plate. Seismic waves caused the earth to ring like a bell.. At 5:36 p.m. on March 27, 1964Good Fridaythe earth trembled just as many Alaskans were sitting down to dinner. NP = National Park Most seismic activity occurs at three types of plate boundariesdivergent, convergent, and transform. Photo courtesy of Robert J. Lillie. Earth definitely moved with a start during the 1964 quake. Photo courtesy of Robert J. Lillie. IRIS video directed by Robert F. Butler explaining the science behind the earthquake. We interpret the trenchward velocities as being caused by a continuing postseismic transient from the 1964 great Alaska earthquake. to A.D. 2022, U.S. Drought: Weekly Report for April 25, 2023, U.S. Drought: Weekly Report for April 18, 2023, U.S. Drought: Weekly Report for April 11, 2023. What are the three types of convergent boundaries? Out of great catastrophe arises innovation and a new hope for the future of disaster preparedness. Plafker named this event a megathrust earthquake. This was a great leap forward in resolving key mechanisms of the developing theory of plate tectonics. Free educator resources are available for this article. Part of the of the Million Dollar Bridge at Copper River also crumpled. 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. Exhibits along the trail include the reconstruction of a fence that was offset 16 feet (5 meters) during the 1906 earthquake. Letters in ovals are abbreviations for NPS sites listed above. Tectonic setting. These data are incompatible with a significant locked region in this segment of the plate boundary. They were lifted out of the ocean as part of the accretionary wedge of an ancient subduction zone. This was the Big One. United States Government Printing Office, Washington: 1993. Fracking wastes and quakes. Science News for Students. Like many of the rocks that are caught up in the zone of transform motion between the Pacific and North American plates, the rocks at Channel Islands National Park were deformed as part of the accretionary wedge during earlier subduction of the Farallon Plate. It includes many lesser faults in addition to the San Andreas Fault. This is known as subduction. Listing total number of features into an ArcGIS Online feature pop-up, Convergent boundaries: where two plates are colliding. Due to the long duration of the earthquake, catastrophic ground failures occurred. This post is part of Exploring Earthquakes, a rich collection of resources co-presented by the California Academy of Sciences and KQED. The San Andreas Fault that runs through much of California is an enormous transform plate boundary. divergent boundaries The edges of two neighboring tectonic plates that are spreading away from each other. The 1964 M9.2 Great Alaska Earthquake, which is still the second largest earthquake ever recorded worldwide, began under Prince William Sound. For more information on how you can prepare for a tsunami, visit the National Tsunami Hazard Mitigation Program. It explains how the continents and oceans have been shaped, and why there are earthquakes, mountains, volcanoes and tsunamis. Right image Ground failures are an effect of seismic activity in which the ground becomes very soft and acts like liquid, causing landslides, spreading, and settling. The landscapes of our national parks, as well as geologic hazards such as earthquakes and volcanic eruptions, are due to the movement of the large plates of Earths outer shell. http://earthquake.usgs.gov/. This pattern has since been seen at other subduction zones. The magnitude 7.8 San Francisco Earthquake struck the morning of April 18, 1906. The types are ocean-ocean, ocean-continent, and continent-continent. Plates beneath the oceans are much thinner than those under continents. Eyewitnesses described hearing a crunching, grinding noise as the earth shook. When two plates are moving away from each other, we call this a divergent plate boundary. These cracks generally ran at high angles to the faults and could run a few hundred feet and span 6 inches (15 centimeters). Find out what you can do right now to protect yourself in the event of an earthquake. 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. Alaskas continental shelf and North American plate rose over 9 meters during the earthquake. National Park Service sites along the transform plate boundary in California contain rocks formed during the earlier subduction that occurred in western North America. This opinion piece by USGS geologist Peter Haeussler, et al. The San Andreas Fault is responsible for most of the movement in western California, causing a sliver of the state to slide past the rest of the continent. The major area of uplift trended northeast from southern Kodiak Island to Price William Sound and trended east-west to . Along other, divergent boundaries, plates move away from each other. When a continental plate meets an oceanic plate, the thinner, denser, and more flexible oceanic plate sinks beneath the thicker, more rigid continental plate. Geological surveys taken immediately afterward showed parts of the Alaskan coast sank up to eight feet, other parts rose up to 38 feet and much of the coast moved 50 feet towards the ocean. The mantle is semi-solid and generally divided into the upper mantle and the lower mantle. The earthquake must be a shallow marine event that displaces the seafloor. There are three types of tectonic plate boundaries: Plates rip apart at a divergent plate boundary, causing volcanic activity and shallow earthquakes; At a convergent plate boundary, one plate dives ("subducts") beneath the other, resulting in a variety of earthquakes and a line of volcanoes on the overriding plate; And it moved parts of the Alaskan coast 15 meters (50 feet) toward the sea. Often it is the older and colder plate that is denser and subducts beneath the younger and warmer plate. Alaskas long southern coastline marks where the Pacific Plate, moving north, dives beneath the North American Plate. SSAs 2014 Annual Meeting will provide a stimulating exchange of research on a wide range of topics with colleagues from all over the world. How do earthquakes occur at convergent plate boundaries? The April 1933 M6.9 earthquake, which caused considerable damage in Anchorage, appears to have occurred on such . When a fault actually slips, the motion is both sudden and exaggerated. 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. Privacy Learn more about UAs notice of web accessibility. S. Ornes. 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. Plafker spent most of the summer in Alaska researching and documenting the earthquake. Along convergent boundaries, neighboring plates either collide head-on or a denser ocean plate dives beneath a lighter continental plate. The three main types of plate movements include: Divergent (Spreading):This is where two plates move away from each other. Local tsunamis also caused destruction in Kodiak, Whittier and Seward. You'll be happy you did. These forces also create a sheared-up landscape that includes spectacularly beautiful coastlines and economically important harbors. The primary fault, or zone of faults, along which the earthquake occurred is not exposed at the surface on land. The epicenter is that X-marks-the-spot site where the tremors commenced. This Story map combines an interactive map with historic photos of the earthquake. And as the Pacific Plate dives, it slopes downward. The San Andreas Fault is just one of several faults that accommodate the transform motion between the Pacific and North American plates. 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. Quake leaves destruction, fear. Science News for Students. This is an earthquake. 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. 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. Which of the following measures an earthquake's intensity based on the observed effects on people and structures? 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. 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. No Alaskan who survived would ever forget this day. Parks in western California contain blocks of crust that have moved great distances north-northwestward along the San Andreas Fault. But this was no ordinary tremor. Sunday: 11 am 5 pm See whats revealedevery Thursday at NightLife. About 80% of earthquakes occur where plates are pushed together, called convergent boundaries. 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. , Divergent boundaries where two plates are moving apart. (For example, the 2011 magnitude-9.0 earthquake off the eastern coast of Japan that unleashed a huge tsunami also was a megathrust earthquake.) The water drove a long, 2-by-6-inch-wide plank through a trucks 10-ply tire. tsunami One or many long, high sea waves caused by an earthquake, submarine landslide or other disturbance. From the earthquake epicenter in northern Prince William Sound, the deformation extends eastward 190 miles almost to long 142 and southwestward slightly more than 400 miles to about long 155. The plates move towards one another and this movement can cause earthquakes. Excerpt from the TV show The Big Picture produced by the US Army in 1966 about the Alaska Earthquake and its tragic effects. Photo by Robert J. Lillie. On March 27, 1964 at 5:36pm local time (March 28 at 3:36 UTC) an earthquake of magnitude 9.2 occurred in the Prince William Sound region of Alaska. Ahead of the wave. Science News for Students. Along convergent boundaries, neighboring plates either collide head-on or a denser ocean plate dives beneath a lighter continental plate. When the ground dropped 3 feet, the trees shallow roots ended up in the tidal zone. Read more from USGS: The Great Alaska Earthquake and Tsunami of March 27, 1964, Teachers' questions: The quake that shook up geology.
