Surface Rupture of the 2002 Denali Fault, Alaska, Earthquake and Comparison with Other Strike-Slip Ruptures

2004 ◽  
Vol 20 (3) ◽  
pp. 565-578 ◽  
Author(s):  
Peter J. Haeussler ◽  
David P. Schwartz ◽  
Timothy E. Dawson ◽  
Heidi D. Stenner ◽  
James J. Lienkaemper ◽  
...  

On 3 November 2002, an M7.9 earthquake produced 340 km of surface rupture on the Denali and two related faults in Alaska. The rupture proceeded from west to east and began with a 40-km-long break on a previously unknown thrust fault. Estimates of surface slip on this thrust are 3–6 m. Next came the principal surface break along ∼218 km of the Denali fault. Right-lateral offsets averaged around 5 m and increased eastward to a maximum of nearly 9 m. The fault also ruptured beneath the trans-Alaska oil pipeline, which withstood almost 6 m of lateral offset. Finally, slip turned southeastward onto the Totschunda fault. Right-lateral offsets are up to 3 m, and the surface rupture is about 76 km long. This three-part rupture ranks among the longest strike-slip events of the past two centuries. The earthquake is typical when compared to other large earthquakes on major intracontinental strike-slip faults.

1988 ◽  
Vol 59 (4) ◽  
pp. 315-315
Author(s):  
Robert McCaffrey ◽  
Joanne Fredrich

Abstract We have examined the largest earthquakes in the Australian continent over the past 20 years by modeling their teleseismic long-period P and SH and short-period P waveforms. Eight earthquakes beneath the continent show thrust faulting at depths shallower than 10 km. Three (1, 2, 4 below) produced surface faulting and their waveforms indicate centroid depths of 3 km or less. The P-axes in the southwestern half of the continent have easterly trends. Preliminary examination of the 3 large earthquakes near Tennant Creek on 22 January, 1988, (7–9) indicate thrusting at less than 10 km depth, but with N-trending P-axes. The largest event (9), at 12:06 GMT, had a seismic moment of roughly 1019 Nm, which makes it comparable in size to the 1968 Meckering event (1). One event (6) beneath the continental margin indicates strike-slip at 26 km depth.


2004 ◽  
Vol 20 (3) ◽  
pp. 555-563 ◽  
Author(s):  
Roger A. Hansen ◽  
Natalia A. Ratchkovski

The M7.9 Denali fault earthquake occurred on 3 November 2002 with an epicenter located 135 km south of Fairbanks and 283 km north of Anchorage. This epicenter is 22–25 km east of the M6.7 Nenana Mountain earthquake that occurred eleven days earlier, October 23, awakening some inhabitants of central Alaska at about 3:30 that morning. Like most earthquakes of its size, the M7.9 earthquake was a complex event. The rupture began with vertical slip along a 40-km segment of the previously unrecognized Susitna Glacier thrust fault, which is connected to the Denali fault. The rupture continued with right-lateral horizontal slip along the main trace of the Denali fault. It eventually split off the Denali fault onto the more southeast-trending Totschunda fault. The total rupture length was 330–340 kilometers, with at least three areas of high slip, or high energy release.


2021 ◽  
Vol 13 (4) ◽  
pp. 685
Author(s):  
Marco Polcari ◽  
Mimmo Palano ◽  
Marco Moro

We evaluated the performances of different SAR-based techniques by analyzing the surface coseismic displacement related to the 2019 Ridgecrest seismic sequence (an Mw 6.4 foreshock on July 4th and an Mw 7.1 mainshock on July 6th) in the tectonic framework of the eastern California shear zone (Southern California, USA). To this end, we compared and validated the retrieved SAR-based coseismic displacement with the one estimated by a dense GNSS network, extensively covering the study area. All the SAR-based techniques constrained the surface fault rupture well; however, in comparison with the GNSS-based coseismic displacement, some significant differences were observed. InSAR data showed better performance than MAI and POT data by factors of about two and three, respectively, therefore confirming that InSAR is the most consolidated technique to map surface coseismic displacements. However, MAI and POT data made it possible to better constrain the azimuth displacement and to retrieve the surface rupture trace. Therefore, for cases of strike-slip earthquakes, all the techniques should be exploited to achieve a full synoptic view of the coseismic displacement field.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yang Gao ◽  
HuRong Duan ◽  
YongZhi Zhang ◽  
JiaYing Chen ◽  
HeTing Jian ◽  
...  

AbstractThe 2019 Ridgecrest, California seismic sequence, including an Mw6.4 foreshock and Mw7.1 mainshock, represent the largest regional seismic events within the past 20 years. To obtain accurate coseismic fault-slip distribution, we used precise positioning data of small earthquakes from January 2019 to October 2020 to determine the dip parameters of the eight fault geometry, and used the Interferometric Synthetic Aperture Radar (InSAR) data processed by Xu et al. (Seismol Res Lett 91(4):1979–1985, 2020) at UCSD to constrain inversion of the fault-slip distribution of both earthquakes. The results showed that all faults were sinistral strike-slips with minor dip-slip components, exception for dextral strike-slip fault F2. Fault-slip mainly occurred at depths of 0–12 km, with a maximum slip of 3.0 m. The F1 fault contained two slip peaks located at 2 km of fault S4 and 6 km of fault S5 depth, the latter being located directly above the Mw7.1hypocenter. Two slip peaks with maximum slip of 1.5 m located 8 and 20 km from the SW endpoint of the F2 fault were also identified, and the latter corresponds to the Mw6.4 earthquake. We also analyzed the influence of different inversion parameters on the fault slip distribution, and found that the slip momentum smoothing condition was more suitable for the inversion of the earthquakes slip distribution than the stress-drop smoothing condition.


Atmosphere ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 83
Author(s):  
Yongming Zhang ◽  
Xin Liu ◽  
Jinyun Guo ◽  
Kunpeng Shi ◽  
Maosheng Zhou ◽  
...  

The Mw7.9 Alaska earthquake at 09:31:40 UTC on 23 January 2018 occurred as the result of strike slip faulting within the shallow lithosphere of the Pacific plate. Global positioning system (GPS) data were used to calculate the slant total electron contents above the epicenter. The singular spectrum analysis (SSA) method was used to extract detailed ionospheric disturbance information, and to monitor the co-seismic ionospheric disturbances (CIDs) of the Alaska earthquake. The results show that the near-field CIDs were detected 8–12 min after the main shock, and the typical compression-rarefaction wave (N-shaped wave) appeared. The ionospheric disturbances propagate to the southwest at a horizontal velocity of 2.61 km/s within 500 km from the epicenter. The maximum amplitude of CIDs appears about 0.16 TECU (1TECU = 1016 el m−2) near the epicenter, and gradually decreases with the location of sub-ionospheric points (SIPs) far away from the epicenter. The attenuation rate of amplitude slows down as the distance between the SIPs and the epicenter increases. The direction of the CIDs caused by strike-slip faults may be affected by the horizontal direction of fault slip. The propagation characteristics of the ionospheric disturbance in the Alaska earthquake may be related to the complex conditions of focal mechanisms and fault location.


2011 ◽  
Vol 44 (3) ◽  
pp. 283-291 ◽  
Author(s):  
D.J.A. Barrell ◽  
N.J. Litchfield ◽  
D.B. Townsend ◽  
M. Quigley ◽  
R.J. Van Dissen ◽  
...  

Tectonics ◽  
2014 ◽  
Vol 33 (8) ◽  
pp. 1519-1533 ◽  
Author(s):  
Paul G. Fitzgerald ◽  
Sarah M. Roeske ◽  
Jeffery A. Benowitz ◽  
Steven J. Riccio ◽  
Stephanie E. Perry ◽  
...  

Author(s):  
W. G. Tonkins ◽  
U. J. Baskurt ◽  
James D. Hart

During the summer of 1996, the TransAlaska Pipeline System (TAPS) experienced pipe vibrations near Thompson Pass, which is located 25 miles north of the Valdez Marine Terminal (VMT). The VMT is the southern terminus of the 48-inch oil pipeline transporting Alaska North Slope Crude for further shipment to market via marine tankers. The pipeline is designed to operate in a slackline mode as it flows over the 2,810 ft. elevation of Thompson Pass. As a result of the slackline experience gained at Thompson Pass, Alyeska evaluated other areas along TAPS where continuous slackline operation either existed in the past or could exist in the future with declining pipeline throughputs. A study determined that other locations along the pipeline could operate in a continuous slackline mode and should be investigated for potential slackline operating problems. This paper describes the slackline testing and evaluation and methods developed by Alyeska to control problems caused by slackline operation. General evaluations and observations of the slackline dynamics phenomena that can cause pipe vibrations along with guidelines and recommendations for the control or elimination of slackline vibration problems are presented.


Solid Earth ◽  
2014 ◽  
Vol 5 (2) ◽  
pp. 837-849 ◽  
Author(s):  
D. Díaz ◽  
A. Maksymowicz ◽  
G. Vargas ◽  
E. Vera ◽  
E. Contreras-Reyes ◽  
...  

Abstract. The crustal-scale west-vergent San Ramón thrust fault system, which lies at the foot of the main Andean Cordillera in central Chile, is a geologically active structure with manifestations of late Quaternary complex surface rupture on fault segments along the eastern border of the city of Santiago. From the comparison of geophysical and geological observations, we assessed the subsurface structural pattern that affects the sedimentary cover and rock-substratum topography across fault scarps, which is critical for evaluating structural models and associated seismic hazard along the related faults. We performed seismic profiles with an average length of 250 m, using an array of 24 geophones (Geode), with 25 shots per profile, to produce high-resolution seismic tomography to aid in interpreting impedance changes associated with the deformed sedimentary cover. The recorded travel-time refractions and reflections were jointly inverted by using a 2-D tomographic approach, which resulted in variations across the scarp axis in both the velocities and the reflections that are interpreted as the sedimentary cover-rock substratum topography. Seismic anisotropy observed from tomographic profiles is consistent with sediment deformation triggered by west-vergent thrust tectonics along the fault. Electrical soundings crossing two fault scarps were used to construct subsurface resistivity tomographic profiles, which reveal systematic differences between lower resistivity values in the hanging wall with respect to the footwall of the geological structure, and clearly show well-defined east-dipping resistivity boundaries. These boundaries can be interpreted in terms of structurally driven fluid content change between the hanging wall and the footwall of the San Ramón fault. The overall results are consistent with a west-vergent thrust structure dipping ~55° E in the subsurface beneath the piedmont sediments, with local complexities likely associated with variations in fault surface rupture propagation, fault splays and fault segment transfer zones.


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