Ground Failure from the Anchorage, Alaska, Earthquake of 30 November 2018

2019 ◽  
Vol 91 (1) ◽  
pp. 19-32 ◽  
Author(s):  
Randall W. Jibson ◽  
Alex R. R. Grant ◽  
Robert C. Witter ◽  
Kate E. Allstadt ◽  
Eric M. Thompson ◽  
...  
Keyword(s):  
High Frequency ◽  
Ground Deformation ◽  
Earthquake Magnitude ◽  
Rock Falls ◽  
Ground Failure ◽  
Port Facilities ◽  
Significant Damage ◽  
Earth Flows ◽  
1964 Alaska ◽  
Alaska Earthquake

Abstract Investigation of ground failure triggered by the 2018 Mw 7.1 Anchorage earthquake showed that landslides, liquefaction, and ground cracking all occurred and caused significant damage. Shallow rock falls and rock slides were the most abundant types of landslides, but they occurred in smaller numbers than global models that are based on earthquake magnitude predict; this might result from the 2018 earthquake being an intraslab event. Liquefaction was common in alluvial and intertidal areas; ground deformation probably related to liquefaction damaged numerous houses and port facilities in Anchorage. Ground cracking was pervasive near the edges of slopes in hilly areas and caused perhaps the most significant property damage of all types of ground failure. A complex of slump–earth flows was triggered along coastal bluffs in southern Anchorage where slides also occurred in 1964; the 2018 slides involved both mobilization of new landside material and reactivation of parts of the 1964 landslide deposits. Large translational slides that formed during the 1964 Alaska earthquake showed evidence of deformation along pre‐existing failure surfaces but did not reactivate with new net downslope displacement. Modeling suggests that ground motion in 2018 was of insufficient duration and too high frequency to trigger reactivation of the deep landslides.

Landslides Triggered by the 2002 Denali Fault, Alaska, Earthquake and the Inferred Nature of the Strong Shaking

2004 ◽  
Vol 20 (3) ◽  
pp. 669-691 ◽  
Author(s):  
Randall W. Jibson ◽  
Edwin L. Harp ◽  
William Schulz ◽  
David K. Keefer
Keyword(s):  
High Frequency ◽  
Near Field ◽  
Rupture Zone ◽  
Fault Rupture ◽  
Rock Falls ◽  
Ground Shaking ◽  
Denali Fault ◽  
Rock Avalanches ◽  
Landslide Distribution ◽  
Alaska Earthquake

The 2002 M7.9 Denali fault, Alaska, earthquake triggered thousands of landslides, primarily rock falls and rock slides, that ranged in volume from rock falls of a few cubic meters to rock avalanches having volumes as great as 15×106m3. The pattern of landsliding was unusual; the number of slides was less than expected for an earthquake of this magnitude, and the landslides were concentrated in a narrow zone 30-km wide that straddled the fault rupture over its entire 300-km length. The large rock avalanches all clustered along the western third of the rupture zone where acceleration levels and ground-shaking frequencies are thought to have been the highest. Inferences about near-field strong shaking characteristics drawn from the interpretation of the landslide distribution are consistent with results of recent inversion modeling that indicate high-frequency energy generation was greatest in the western part of the fault rupture zone and decreased markedly to the east.

Types and Areal Distribution of Ground Failure Associated with the 2019 Ridgecrest, California, Earthquake Sequence

2020 ◽  
Vol 110 (4) ◽  
pp. 1567-1578 ◽  
Author(s):  
Randall W. Jibson
Keyword(s):  
Epicentral Distance ◽  
Wide Band ◽  
Field Investigation ◽  
Earthquake Sequence ◽  
Lateral Spread ◽  
Fault Rupture ◽  
Rock Falls ◽  
Epicentral Area ◽  
Ground Failure ◽  
Almost All

ABSTRACT The July 2019 Ridgecrest, California, earthquake sequence included the largest earthquake (M 7.1) to strike the conterminous United States in the past 20 yr. To characterize the types, numbers, and areal distributions of different types of ground failure (landslides, liquefaction, and ground cracking), I conducted a field investigation of ground failure triggered by the sequence around the periphery of the epicentral area (which had limited access). The earthquake sequence triggered sparse and widely scattered landslides over an area of ∼22,000  km2 and at a maximum epicentral distance of 114 km; these metrics are within the upper bounds as compared with global averages for earthquakes of similar size. Some rock falls blocked primary and secondary roads, but no other landslide damage was reported. Almost all of the landslides in the peripheral area were small rock falls (∼1–10  m3), but a few larger (∼100  m3) rock slides also occurred. Though there are only informal reports about ground failure in the immediate epicentral area and we lack a detailed survey there, the small number (hundreds) and size of the landslides still seems to be far below global averages for M 7.1. This could be a result of the arid landscape and lack of a deeply weathered zone of soil and regolith. Liquefaction occurred along part of the western margin of Searles Valley. One large (∼0.4  km2) lateral spread caused by liquefaction severely damaged parts of Trona. Minor liquefaction also occurred in a ∼100-m-wide band along the fault-rupture zone in some places.

Rapid resetting of an estuarine recorder of the 1964 Alaska earthquake

2001 ◽  
Vol 113 (9) ◽  
pp. 1193-1204 ◽  
Author(s):  
Brian F. Atwater ◽  
David K. Yamaguchi ◽  
Stein Bondevik ◽  
Walter A. Barnhardt ◽  
Lorin J. Amidon ◽  
...  
Keyword(s):  
1964 Alaska ◽  
Alaska Earthquake

Shallow P+-N Junction Fabrication by Plasma Immersion Ion Implantation

1991 ◽  
Vol 223 ◽  
Author(s):  
C. A. Pico ◽  
X. Y. Qian ◽  
E. Jones ◽  
M. A. Lieberman ◽  
N. W. Cheung
Keyword(s):  
Ion Implantation ◽  
Ideality Factor ◽  
High Frequency ◽  
Cyclotron Resonance ◽  
High Field ◽  
Electron Cyclotron Resonance ◽  
Forward Bias ◽  
Electron Cyclotron ◽  
Significant Damage ◽  
Plasma Immersion Ion Implantation

ABSTRACTPlasma immersion ion implantation (PIII) has been applied to fabricate shallow p-n junction diodes and MOS test structures. BF3 ions created by an electron cyclotron resonance source were implanted into n-type Si(100) at an accelerating voltage of −2 kv. The implant doses ranged from 4 × 1014/cm2 to 4 × 1015/cm2. In some cases, the top layers of the Si(100) substrates were preamorphized by a 3 × 1015/cm2 to 1016/cm2 implant of SiF4 by PIII at −7.2 kV prior to the BF3 implant. The ideality factor exhibited in both non- and preamorphized samples during forward bias is 1.02 to 1.05. Reverse leakages were measured at 30 nA/cm2 at −5V. High frequency capacitance and high field breakdown measurements of the oxide test structures showed no significant damage to the oxide.

scholarly journals The northern Thessaly strong earthquakes of March 3 and 4, 2021, and their neotectonic setting

2021 ◽  
Vol 58 ◽  
pp. 222
Author(s):  
Alexandros Chatzipetros ◽  
Spyros Pavlides ◽  
Michael Foumelis ◽  
Sotiris Sboras ◽  
Dimitris Galanakis ◽  
...  
Keyword(s):  
Ground Deformation ◽  
Seismic Hazard Assessment ◽  
Shear Zones ◽  
Normal Faults ◽  
Seismogenic Fault ◽  
Rock Falls ◽  
Tectonic Structures ◽  
Northern Greece ◽  
Stress Changes ◽  
Active Tectonic

A sequence of earthquakes occurred on March 3rd and 4th in Northern Thessaly, northern Greece, associated with previously unknown, blind normal faults within the crystalline Palaeozoic basement of the Pelagonian geotectonic zone. Surficial ground deformation, such as liquefaction phenomena in fluvial plains, as well as soil fissures and rock falls, have been mapped. Geological indications of the unmapped seismic fault, i.e., reactivated shear zones, open cracks, etc., have been identified within the bedrock. Based on geological indications, the main fault projection to the surface could be considered a 15 km NW-SE trending structure and average dip of 45o to the NE. The seismic source of the main shock was modelled, and the Coulomb static stress changes calculated for receiver faults similar to the source. The determination of the active tectonic regime of the region by geodetic data and the well-known faults of NE Thessaly plain are also presented, as well as the revised historical and instrumental seismicity. This earthquake raises new concerns and challenges, revising some established views, such as the status of main stress orientations, the orientation of active tectonic structures, the occurrence of a seismogenic fault in a mountainous massif of crystalline rocks without typical geomorphological expression and the role of blind faults in Seismic Hazard Assessment.

Integrated shrub management in semi-arid woodlands of eastern Australia: effects of chemical defoliants applied after an initial disturbance

2001 ◽  
Vol 23 (2) ◽  
pp. 224 ◽  
Author(s):  
James C. Noble ◽  
Anthony C. Grice ◽  
Melissa J. Dobbie ◽  
Warren J. Müller ◽  
Jeff T. Wood
Keyword(s):  
High Frequency ◽  
Application Rate ◽  
Preliminary Screening ◽  
Low Concentration ◽  
Screening Experiments ◽  
Significant Damage ◽  
Eastern Australia ◽  
One Year ◽  
Secondary Chemical ◽  
Semi Arid

Previous fire experiments using artificial fuel have shown that annual fires, especially those applied in the autumn, can effectively control coppicing understorey shrubs in semi-arid woodlands. Such frequent fire is impossible to apply under natural conditions given the limited time available for sufficient herbage fuel to accumulate. Preliminary screening studies were therefore undertaken to test the hypothesis that chemical sprays applied at concentrations less than those normally recommended could be used to mimic high-frequency experimental fires. The effectiveness of 11 chemicals (7 arboricides and 4 dessicants) applied at a range of concentrations was assessed on one site by spot-spraying 5-year-old coppice regeneration of Eremophila mitchellii (budda or false sandalwood) and E. sturtii (turpentine). Chemical activity was assessed by regularly monitoring leaf effect, i.e. by rating the degree of leaf discolouration, scorching, blackening and ultimately leaf fall, over the ensuing 12 months following treatment. Arsenal� and Roundup CT� induced the highest shrub mortalities across all size classes while mortality rates were consistently higher for E. mitchellii than for E. sturtii. A second experiment involved 5 chemicals (4 arboricides and 1 dessicant) applied in a similar manner to 7-year-old seedlings of Cassia nemophila (syn. Senna nemophila) (punty bush). Significant damage to foliage (> 80% leaf effect) of all 3 shrub species was recorded 2 months after treatment with either Roundup CT� or Roundup� (i.e. either 450 or 360 g/L glyphosate respectively), as well as with Arsenal� (250 g/L imazapur + 60 g/L isopropylamine) but only at the highest concentration (i.e. 100% of the 'recommended' rate). In some lower concentration treatments, leaf effect was still increasing 6 months after treatment. In a second series of screening experiments involving 1- and 2-year-old coppices sprayed in autumn and spring, significant interaction occurred between coppice age and season of spraying when averaged over both Eremophila species. At lower concentrations (i.e. 12.5 and 25% of maximum recommended rate), autumn application of Roundup CT� was more effective than spring application, especially once regeneration was 2 years old. Gramoxone� was also most effective at all rates above 12.5% of the maximum when applied in the autumn to two-year-old coppice. However, Garlon� (600 g/L triclopyr) and Tordon 50-DA(r) (50 g/L picloram + 200 g/L 2,4-D) were more effective when applied to 1-year-old coppice in the spring. Overall, the most effective low-concentration treatment was Roundup CT� applied in the autumn to two-year-old coppice. Low-concentration treatment of one-year-old coppice with Roundup CT� and Arsenal� was also consistently more effective when carried out in the autumn (80–90% leaf effect). The probability of shrub mortality was inversely related to coppice biomass with smaller coppices clearly more vulnerable to the added pressure imposed by secondary chemical treatment, independent of application rate.

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