Earthquake Hazards on the Cascadia Subduction Zone

Heaton, Thomas H.; Hartzell, Stephen H.

doi:10.1126/science.236.4798.162

Cited by 133 publications

(97 citation statements)

References 20 publications

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“…Its seismicity is mostly located offshore: along the Mendocino Transform Fault (MTF), within the highly deformed Gorda plate, and along the Cascadia Subduction Zone (CSZ) (Figure 1). Paleoseismic evidence of great earthquakes along the CSZ [Atwater, 1987], including radiocarbon dating and several offshore turbidite episodes of deformation in the last 2000 years [Clarke and Carver, 1992], indicate that the CSZ is capable of multiple M8+ earthquakes, as large as M9 [Goldfinger et al, 2008;Satake et al, 1996;Heaton and Hartzell, 1987].…”

Section: Methodsmentioning

confidence: 99%

Rapid detection and characterization of large earthquakes using quasi-finite-source Green's functions in continuous moment tensor inversion

Guilhem

Dreger

2011

Geophys. Res. Lett.

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Large earthquakes along subduction zones have the potential to generate tsunamis along local coasts, as well as traveling far across oceans. By continuously inverting for moment tensors we show that it is possible with a single procedure to automatically detect, locate and determine source parameters of any earthquake, from magnitude 3.5 to larger than 8 located in both the near‐ and far‐field. We find that the detection and characterization of large earthquakes is improved when quasi‐finite‐source Green's functions are used in a point‐source moment tensor approach as they represent to some extent the rupture's finiteness and directivity. Solutions can be obtained within several minutes after the origin time of the earthquake, and could therefore be used as part of a near‐source tsunami early warning system, capable of providing tens of minutes of possible warning depending on the distance of the earthquake rupture from the coast.

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Section: Methodsmentioning

confidence: 99%

Rapid detection and characterization of large earthquakes using quasi-finite-source Green's functions in continuous moment tensor inversion

Guilhem

Dreger

2011

Geophys. Res. Lett.

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“…Although the Cascadia subduction zone has many characteristics of the Chilean-type subduction zone, there are some differences [Spence, 1989], the most important being the absence of historic large earthquakes [Heaton and Hartzell, 1987]. Two possible interpretations of this absence are that subduction is occurring aseismically or that elastic strain is The most common method of estimating long-term uplift rates on a tectonically active coast utilizes accurate elevation measurements and dating of late Pleistocene marine terraces.…”

Section: Introductionmentioning

confidence: 99%

Age estimates and uplift rates for Late Pleistocene marine terraces: Southern Oregon portion of the Cascadia Forearc

Muhs¹,

Kelsey²,

Miller³

et al. 1990

J. Geophys. Res.

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Marine terraces are prominent landforms along the southern Oregon coast, which forms part of the forearc region of the Cascadia subduction zone. Interest in the Cascadia subduction zone has increased because recent investigations have suggested that slip along plates at certain types of convergent margins is characteristically accompanied by large earthquakes. In addition, other investigations have suggested that convergent margins can be broadly classified by the magnitude of their uplift rates. With these hypotheses in mind, we generated new uranium series, amino acid, and stable isotope data for southern Oregon marine terrace fossils. These data, along with terrace elevations and two alternative estimates of sea level at the time of terrace formation, allow us to determine terrace ages and uplift rates. Uranium series analysis of fossil coral yields an age of 83 _ 5 ka for the Whisky Run terrace at Coquille Point in Bandon, Oregon. A combination of amino acid and oxygen isotope data suggest ages of about 80 and 105 ka for the lowest two terraces at Cape Blanco. These ages indicate uplift rates of 0.45-1.05 and 0.81-1.49 m/kyr for Coquille Point and Cape Blanco, respectively. Late Quaternary uplift rates of marine terraces yield information about deformation in the overriding plate, but it is unclear if such data vary systematically with convergent margin type. In order to assess the utility of the southern Oregon uplift rates for predicting the behavior of the Cascadia subduction zone, we compared late Quaternary uplift rates derived from terrace data from subduction zones around the world. On the basis of this comparison the southern Oregon rates of vertical deformation are not unusually high or low. Furthermore, late Quaternary uplift rates show little relationship to the type of convergent margin. These observations suggest that local structures may play a large role in uplift rate variability. In addition, while the type of convergent margin may place an upper limit on possible uplift rate, greater upper limits serve to increase the range of possible uplift rates. In the case of the southern Oregon coast, variability in uplift rate probably reflects local structures in the overriding plate, and the rate of uplift cannot be used as a simple index of the potential for great earthquakes along the southern Cascadia subduction zone.

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“…Evidence has been cited (Heaton et al, 1987) that suggests that the Cascadia subduction zone has characteristics found in other subduction zones that have experienced large shallow earthquakes. Examples are subduction zones in southern Chile, southwestern Japan and Columbia.…”

Section: Historical Earthquakesmentioning

confidence: 99%

Bridge Damage Models for Seismic Risk Assessment of Oregon Highway Network

Dusicka

Roberts²

2011

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Type of Report and Period CoveredFinal Report Sponsoring Agency Code Supplementary Notes AbstractThe highway transportation network of the United States relies on the health and integrity of major infrastructure elements such as bridges. Frequently traveled parts of Oregon are within the seismically active Pacific Northwest and many of the bridges were designed and built to lateral demands that were assumed to be less than the current expectation, a deficiency caused by our growing awareness of seismic hazard and our enhanced understanding of the non-linear response of bridges. This vulnerability to damage from earthquakes can result in not only immediate damage, but also in potentially lingering economic impact caused by the disruption to traffic and freight mobility.Using analytical methods, fragility curves were constructed assuming lognormal capacity and demand distributions. Probability of failure was determined for the four damage state conditions of slight, moderate, extensive, and complete levels of damage. These statistical values were compared to the median and dispersion values proposed by other researchers, in addition to those calculated using guidelines from the HAZUS Technical Manual. Older multiple-span Oregon bridges were found to be significantly more fragile than the HAZUS models.As a result of this modeling and analysis effort, the relative fragility of the modeled typical 3-span and 5-span bridges was determined and quantified. Possible causes of the relatively high fragilities were also considered.17.

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Earthquake Hazards on the Cascadia Subduction Zone

Cited by 133 publications

References 20 publications

Rapid detection and characterization of large earthquakes using quasi-finite-source Green's functions in continuous moment tensor inversion

Rapid detection and characterization of large earthquakes using quasi-finite-source Green's functions in continuous moment tensor inversion

Age estimates and uplift rates for Late Pleistocene marine terraces: Southern Oregon portion of the Cascadia Forearc

Bridge Damage Models for Seismic Risk Assessment of Oregon Highway Network

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