The bend in the margin trend and subducting slab end effects are included. However, in common with most other subduction zones, the outer margin is slowly being compressed, similar to a giant spring. Local, state, and regional officials can use such estimates to plan riskreduction efforts and prepare for emergency response and recovery. Openfile report o22, cascadia subduction zone earthquakes. We present data that indicate the periodicity of slow earthquakes in cascadia and the current onset of such an event. When, not if, the next great cascadia subduction zone earthquake strikes the pacific northwest. 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 basin is an ideal place to develop a turbidite paleoseismologic method and to record paleoearthquakes because. The rupture zone of cascadia great earthquakes from. 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. Just north of the san andreas, however, lies another fault line. Earthquakes on the cascadia subduction zone have struck the northwest offshore for at least 10,000 years. Recent subduction zone fault earthquakes around the world underscore the similar challenges we will face when.
Dec, 2019 the cascadia subduction zone off the coast of north america spans from northern california to southern british columbia. The cascadia subduction zone could deliver the worst earthquake in north america. The two largest earthquakes in recent years in oregon, scotts mills magnitude 5. 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. To learn more about the history of the cascadia subduction zone and the science that led. Implications for earthquake hazards along the washington margin. 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. The last such earthquake occurred over 300 years ago. The last major csz earthquake and tsunami occurred in 1700. Very young oceanic lithosphere 10 million years old is being subducted beneath north america at a rate of approximately 4 centimeters per year.
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. It is for informational purposes and may not be suitable for legal purposes. Pdf turbidite event historymethods and implications for. Periodic slow earthquakes from the cascadia subduction zone. Jul 02, 2019, maureen walton, and rob witter 2 july 2019. Great earthquakes of variable magnitude at the cascadia subduction zone. Resources cascadia prepared cascadia subduction zone. New cascadia subduction zone earthquake study is worse news. Addressing cascadia subduction zone great earthquake. Cascadia subduction zone usgs earthquake hazard program. Of the other six zones around the pacific where young earthquakes megathrust events on the subduction interface in historic time. Pdf great earthquakes of variable magnitude at the cascadia. In places along cascadias coast, the tsunami may be as high as 3040 feet 912 m.
Overview a major seismic event will significantly impact the oregon economy immediately after and in the longer run. 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. 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. 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. We model tsunami runup and inundation along the northern california coast caused by hypothetical earthquakes on the cascadia subduction zone csz. 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. Introduction the cascadia subduction zone margin of western north america figure 1 is unusual in having experienced no historical great thrust earthquakes.
Sites offigure 2 with long earthquake histories,and with ages more precisethan those from mostsites, are labeled in bold italics. Jan 29, 2019 the last time the cascadia subduction zone burped up a massive, zone wide earthquake was way back in 1700. Results of this analysis indicate strengthening corridors before a major seismic event will enable the state to avoid a significant amount of economic loss. Cascadia subduction zone earthquakes for an excellent brief introduction to the risk of a devastating earthquake in the cascadia region, choose this document. The last time the cascadia subduction zone burped up a massive, zonewide earthquake was way back in 1700. Local tsunami hazards in the pacific northwest from cascadia subduction zone earthquakes by eric l.
The last known megathrust earthquake in the northwest was in january, 1700, just over 300 years ago. It runs 700 miles underwater along pacific northwest, from canada to california. Cascadia subduction zone earthquake economic impact. 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. Pdf large, historically unprecedented earthquakes at the cascadia subduction zone in western north america have left signs of sudden land. This means that we are in the time window where a destructive cascadia earthquake. Dogami openfile report series oregon department of geology.
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 last cascadia megaquake occurred january 26, 1700 with an estimated moment magnitude of 8. Jun 08, 2016 quote from crew cascadia subduction scenario 20. Investigating cascadia subduction zone geodynamics through. Earthquake hazards on the cascadia subduction zone science. An earthquake will destroy a sizable portion of the coastal northwest. Cascadia subduction zone earthquakes cascadia region.
A new view into the cascadia subduction zone and volcanic arc. Hazus was used to estimate the losses that could result from a m9. Great earthquakes of variable magnitude at the cascadia. A university of washington research project, to be presented oct. This archived document is maintained by the state library of oregon as part of the oregon documents depository program. Great earthquakes of variable magnitude at the cascadia subduction zone alan r. 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. 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. Pdf evidence for large earthquakes at the cascadia. Evidence for large earthquakes at the cascadia subduction zone. 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. Known as the cascadia subduction zone, it runs for seven hundred miles off the coast of. Much depends on the local topographythe lay of the landboth underwater and along the shore. Cascadia is americas own tectonic version of sumatra, where the magnitude 9.
Cascadia subduction zone pacific northwest seismic network. An assessment of the megathrust earthquake potential of the. Dogami openfile report series oregon department of. This subduction zone can produce earthquakes as large as magnitude 9 and corresponding tsunamis. The csz has a history of producing large earthquakes and will produce 8. Pdf evidence for large earthquakes at the cascadia subduction. Cascadia subduction zone worse than san andreas fault cnn. Geological survey and university of washington press 2015. New cascadia subduction zone earthquake study is worse. A cascadia megaquake refers to large, deep thrust earthquakes along the cascadia subduction zone. Large subduction earthquakes on the cascadia subduction zone pose a potential seismic hazard. The geologic record shows that the largest cascadia subduction zone earthquakes and accompanying tsunamis occur about every 500 years, plus or minus 200 years. Feb 11, 2016 the cascadia subduction zone could deliver the worst earthquake in north america.
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. During an earthquake bottom, the area sea ward of the locked zone is uplifted and the flexural bulge collapses. There had been just a handful of detailed simulations of a magnitude9 cascadia earthquake, and it was hard to know. California cascadia subduction zone earthquake and. Oct 23, 2017 a university of washington research project, to be presented oct.
Earthquakes and tsunamis in the cascadia subduction zone. Washington state transportation center trac publication date. Located off the pacific northwest coast, this plate runs from central vancouver island, b. The cascadia subduction zone shares many characteristics with subduction zones in southern chile, southwestern japan, and colombia, where comparably young. Approved by the crew board of directors on september 6, 20. 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. When, not if, the next great cascadia subduction zone earthquake strikes the pacific northwest, oregon will face the greatest challenge in its history. There are now ongoing efforts led by scientists to improve the resilience of the. Of the other six zones around the pacific where young pdf. 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. 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. Pieces of mantle found rising under north and south ends of.
Pdf a new view into the cascadia subduction zone and volcanic. Learn vocabulary, terms, and more with flashcards, games, and other study tools. The height of the wave and how far inland it travels will vary with location. Pacific northwest to megathrust earthquakes and to implement an earthquake early. The cascadia subduction zone shares many characteristics with subduction zones in southern chile, southwestern japan, and. 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. The rupture zone of cascadia great earthquakes from current.
An assessment of the megathrust earthquake potential of. Ground motions due to large magnitude subduction zone earthquakes. California cascadia subduction zone earthquake and tsunami. The cascadia subduction zone off the coast of north america spans from northern california to southern british columbia. The csz forms the boundary between the pacific and north american tectonic plates and extends from. The oceanic lithosphere entering the cascadia subduction zone in all segments is extremely young, less than 10 ma. The next fullmargin rupture of the cascadia subduction zone will spell the worst natural disaster in. Scientists estimated the magnitude and timing of each quake by examining soil samples at more than 50 undersea sites between washington, oregon and california. Of these 41, nineteen have produced a full margin rupture, wherein the entire fault opens up.
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