California cascadia subduction zone earthquake and tsunami. Great subduction zone earthquakes occur around the world where the tectonic plates that make up the surface of the earth collide. Local, state, and regional officials can use such estimates to plan riskreduction efforts and prepare for emergency response and recovery. Earthquake hazards on the cascadia subduction zone science. A university of washington research project, to be presented oct.
Geological survey and university of washington press 2015. Pieces of mantle found rising under north and south ends of. Great earthquakes of variable magnitude at the cascadia subduction zone. This archived document is maintained by the state library of oregon as part of the oregon documents depository program. A new view into the cascadia subduction zone and volcanic arc. It runs 700 miles underwater along pacific northwest, from canada to california.
Of the other six zones around the pacific where young pdf. Ground motions due to large magnitude subduction zone earthquakes. Implications for earthquake hazards along the washington margin. There are now ongoing efforts led by scientists to improve the resilience of the. When the stored energy is suddenly released by slippage across the fault at irregular intervals, the cascadia subduction zone can create very large earthquakes such as the magnitude 9 cascadia earthquake of 1700. Mar 17, 2018 earthquakes and tsunamis in the cascadia subduction zone pdf sometime in the future, the pacific northwest, including oregon, washington, vancouver island, and northern california, will experience a devastating earthquake as large as magnitude 9the same magnitude as an earthquake in coastal northeast japan in 2011 in which nearly 16,000. Sites offigure 2 with long earthquake histories,and with ages more precisethan those from mostsites, are labeled in bold italics. This subduction zone can produce earthquakes as large as magnitude 9 and corresponding tsunamis. Cascadia subduction zone earthquakes cascadia region. When, not if, the next great cascadia subduction zone earthquake strikes the pacific northwest. Large subduction earthquakes on the cascadia subduction zone pose a potential seismic hazard. Overview a major seismic event will significantly impact the oregon economy immediately after and in the longer run. New cascadia subduction zone earthquake study is worse news. The last major csz earthquake and tsunami occurred in 1700.
We model tsunami runup and inundation along the northern california coast caused by hypothetical earthquakes on the cascadia subduction zone csz. The geologic record shows that the largest cascadia subduction zone earthquakes and accompanying tsunamis occur about every 500 years, plus or minus 200 years. Cascadia subduction zone earthquakes for an excellent brief introduction to the risk of a devastating earthquake in the cascadia region, choose this document. Of these 41, nineteen have produced a full margin rupture, wherein the entire fault opens up. California cascadia subduction zone earthquake and tsunami response plan provides a framework outlining how local, tribal, state, and federal governments and private and nongovernmental organizations ngos will respond and coordinate immediately following a catastrophic earthquake along the northern california coast. An assessment of the megathrust earthquake potential of the. Investigating cascadia subduction zone geodynamics through. Seafloor core evidence indicates that there have been fortyone subduction zone earthquakes on the cascadia subduction zone in the past 10,000 years, suggesting a general average earthquake recurrence interval of only 243 years. If the whole cascadia margin seismogenic zone fails in a single event, empirical fault area versus magnitude relations give earthquakes as large as m w 9. Great earthquakes of variable magnitude at the cascadia subduction zone alan r. Very young oceanic lithosphere 10 million years old is being subducted beneath north america at a rate of approximately 4 centimeters per year. This means that we are in the time window where a destructive cascadia earthquake. Pdf evidence for large earthquakes at the cascadia. Earthquakes on the cascadia subduction zone have struck the northwest offshore for at least 10,000 years.
The last time the cascadia subduction zone burped up a massive, zonewide earthquake was way back in 1700. Known as the cascadia subduction zone, it runs for seven hundred miles off the coast of. Location of coastal sites along the cascadia subduction zone with evidence for great cascadia earthquakes and accompanying tsunamis after atwater and hemphillhaley, 1997, their fig. Scientists estimated the magnitude and timing of each quake by examining soil samples at more than 50 undersea sites between washington, oregon and california.
Subduction zone earthquakes are among the most impactful natural hazards on earth the cascadia subduction zone csz of the u. During an earthquake bottom, the area sea ward of the locked zone is uplifted and the flexural bulge collapses. The most recent big cascadia earthquake occurred on january 26, 1700, dated by accounts from japan of an orphan tsunami generated by a cascadia earthquake and recorded after the wave crossed the pacific ocean. The bend in the margin trend and subducting slab end effects are included. Cascadia subduction zone usgs earthquake hazard program. Learn vocabulary, terms, and more with flashcards, games, and other study tools.
The oceanic lithosphere entering the cascadia subduction zone in all segments is extremely young, less than 10 ma. Hazus was used to estimate the losses that could result from a m9. Stretching off the pacific shore from northern california some 0 kilometers to the tip of vancouver island, the cascadia subduction zone appears capable of its own magnitude 9 earthquake. Dec, 2019 the cascadia subduction zone off the coast of north america spans from northern california to southern british columbia. However, in common with most other subduction zones, the outer margin is slowly being compressed, similar to a giant spring. The cascadia subduction zone csz is a 1,000 km 620 mi long dipping fault that stretches from northern vancouver island to cape mendocino in northern california. Cascadia subduction zone earthquake economic impact. Geological survey, ms 966, po box 25046, denver, co 80225, usa b department of geology, humboldt state university, arcata, ca 95521, usa c oregon department of geology and mineral industries, coastal field. The cascadia subduction zone shares many characteristics with subduction zones in southern chile, southwestern japan, and. Cascadia subduction zone pacific northwest seismic network. Just north of the san andreas, however, lies another fault line. Pdf evidence for large earthquakes at the cascadia subduction. An assessment of the megathrust earthquake potential of.
Openfile report o22, cascadia subduction zone earthquakes. The last cascadia megaquake occurred january 26, 1700 with an estimated moment magnitude of 8. Results of this analysis indicate strengthening corridors before a major seismic event will enable the state to avoid a significant amount of economic loss. Oct 23, 2017 a university of washington research project, to be presented oct. In places along cascadias coast, the tsunami may be as high as 3040 feet 912 m. An earthquake will destroy a sizable portion of the coastal northwest. Jun 08, 2016 quote from crew cascadia subduction scenario 20. Great earthquakes of variable magnitude at the cascadia. Cascadia subduction zone worse than san andreas fault cnn. It is for informational purposes and may not be suitable for legal purposes. Jul 02, 2019, maureen walton, and rob witter 2 july 2019. The cascadia subduction zone could deliver the worst earthquake in north america. New cascadia subduction zone earthquake study is worse.
Pdf large, historically unprecedented earthquakes at the cascadia subduction zone in western north america have left signs of sudden land. Jan 29, 2019 the last time the cascadia subduction zone burped up a massive, zone wide earthquake was way back in 1700. Evidence for large earthquakes at the cascadia subduction zone. The most common are crustal earthquakes, which occur along faults, or breaks in the earths crust, at shallow depths of 612 miles 1020 km below the surface. A cascadia megaquake refers to large, deep thrust earthquakes along the cascadia subduction zone. Because subduction zones generate the largest earthquakes, seismic hazard assessment relies on understanding the degree to which slow earthquakes reduce the energy released by infrequent large earthquakes. Earthquakes and tsunamis in the cascadia subduction zone.
The cascadia primary seismogenic structure model, as proposed here, has important implications for great earthquake shaking and related damage to major metropolitan centers in vancouver, canada, and seattle, olympia, portland, salem, and eugene, usa, in the event of a future major megathrust rupture in the central cascadia subduction zone. Washington state transportation center trac publication date. Of the other six zones around the pacific where young earthquakes megathrust events on the subduction interface in historic time. Approved by the crew board of directors on september 6, 20. We present data that indicate the periodicity of slow earthquakes in cascadia and the current onset of such an event. The two largest earthquakes in recent years in oregon, scotts mills magnitude 5.
Mar 29, 2002 because subduction zones generate the largest earthquakes, seismic hazard assessment relies on understanding the degree to which slow earthquakes reduce the energy released by infrequent large earthquakes. Cascadia is americas own tectonic version of sumatra, where the magnitude 9. The cascadia subduction zone shares many characteristics with subduction zones in southern chile, southwestern japan, and colombia, where comparably young. Earthquakes in oregon oregon department of geology and. Pdf a new view into the cascadia subduction zone and volcanic. Local tsunami hazards in the pacific northwest from cascadia subduction zone earthquakes by eric l. Dogami openfile report series oregon department of. Furthermore, recent sedimentation studies along the continental shelf also provide evidence that great earthquakes usually rupture most of the cascadia subduction interface goldfinger et al. The csz forms the boundary between the pacific and north american tectonic plates and extends from. To learn more about the history of the cascadia subduction zone and the science that led. The rupture zone of cascadia great earthquakes from. Recent subduction zone fault earthquakes around the world underscore the similar challenges we will face when. D model of the cascadia subduction zone calculates the surface deformation for a locked zone or a rupture zone of variable width along the margin. The cascadia subduction zone off the coast of north america spans from northern california to southern british columbia.
The csz has a history of producing large earthquakes and will produce 8. Pdf turbidite event historymethods and implications for. Jul 25, 2018 with four years of data from 268 seismometers on the ocean floor and several hundred on land, researchers have found anomalies in the upper mantle below both ends of the cascadia subduction zone. Dogami openfile report series oregon department of geology. Much depends on the local topographythe lay of the landboth underwater and along the shore. Geological evidence indicates that such great earthquakes have occurred at least seven times in the last 3,500 years, a return interval of 400 to 600 years. Addressing cascadia subduction zone great earthquake. Located off the pacific northwest coast, this plate runs from central vancouver island, b. The rupture zone of cascadia great earthquakes from current. There had been just a handful of detailed simulations of a magnitude9 cascadia earthquake, and it was hard to know. The cascadia basin is an ideal place to develop a turbidite paleoseismologic method and to record paleoearthquakes because.
Periodic slow earthquakes from the cascadia subduction zone. The last known megathrust earthquake in the northwest was in january, 1700, just over 300 years ago. Pdf great earthquakes of variable magnitude at the cascadia. When, not if, the next great cascadia subduction zone earthquake strikes the pacific northwest, oregon will face the greatest challenge in its history.
Pacific northwest to megathrust earthquakes and to implement an earthquake early. Resources cascadia prepared cascadia subduction zone. Feb 11, 2016 the cascadia subduction zone could deliver the worst earthquake in north america. The last such earthquake occurred over 300 years ago. Geist1 abstract since the mid1980s, there has been accumulating geologic evidence of large local tsunamis generated by earthquakes along the cascadia subduction zone off the pacific northwest. California cascadia subduction zone earthquake and.
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