Modeling the Holocene slip history of the Wasatch fault (Utah): Coseismic and postseismic Coulomb stress changes and implications for paleoseismicity and seismic hazard

2018 ◽  
Vol 131 (1-2) ◽  
pp. 43-57 ◽  
Author(s):  
Meike Bagge ◽  
Andrea Hampel ◽  
Ryan D. Gold
2018 ◽  
Author(s):  
Andrea Hampel ◽  
◽  
Meike Bagge ◽  
Ryan D. Gold

Author(s):  
A Verdecchia ◽  
S Carena ◽  
B Pace ◽  
C B DuRoss

Summary Static and quasi-static Coulomb stress changes produced by large earthquakes can modify the probability of occurrence of subsequent events on neighboring faults. This approach is based on physical (Coulomb stress changes) and statistical (probability calculations) models, which are influenced by the quality and quantity of data available in the study region. Here, we focus on the Wasatch Fault Zone (WFZ), a well-studied active normal fault system having abundant geologic and paleoseismological data. Paleoseismological trench investigations of the WFZ indicate that at least 24 large, surface-faulting earthquakes have ruptured the fault's five central, 35–59-km long segments since ∼7 ka. Our goal is to determine if the stress changes due to the youngest paleoevents have significantly modified the present-day probability of occurrence of large earthquakes on each of the segments. For each segment, we modeled the cumulative (coseismic + postseismic) Coulomb stress changes (∆CFScum) due to earthquakes younger than the most recent event on the segment in question and applied the resulting values to the time-dependent probability calculations. Results from the Coulomb stress modeling suggest that the Brigham City, Salt Lake City, and Provo segments have accumulated ∆CFScum larger than 10 bars, whereas the Weber segment has experienced a stress decrease of 5 bars, in the scenario of recent rupture of the Great Salt Lake fault to the west. Probability calculations predict high probability of occurrence for the Brigham City and Salt Lake City segments, due to their long elapsed times (> 1–2 ka) when compared to the Weber, Provo, and Nephi segments (< 1 ka). The range of calculated coefficients of variation (CV) has a large influence on the final probabilities, mostly in the case of the Brigham City segment. Finally, when the Coulomb stress and the probability models are combined, our results indicate that the ∆CFScum resulting from earthquakes postdating the youngest events on each of the five segments substantially affects the probability calculations for three of the segments: Brigham City, Salt Lake City, and Provo. The probability of occurrence of a large earthquake in the next 50 years on these three segments may therefore be underestimated if a time-independent approach, or a time-dependent approach that does not consider ∆CFS, is adopted.


Author(s):  
R. Alac Barut ◽  
J. Trinder ◽  
C. Rizos

On August 17&lt;sup&gt;th&lt;/sup&gt; 1999, a M&lt;sub&gt;w&lt;/sub&gt; 7.4 earthquake struck the city of Izmit in the north-west of Turkey. This event was one of the most devastating earthquakes of the twentieth century. The epicentre of the Izmit earthquake was on the North Anatolian Fault (NAF) which is one of the most active right-lateral strike-slip faults on earth. However, this earthquake offers an opportunity to study how strain is accommodated in an inter-segment region of a large strike slip fault. In order to determine the Izmit earthquake post-seismic effects, the authors modelled Coulomb stress changes of the aftershocks, as well as using the deformation measurement techniques of Interferometric Synthetic Aperture Radar (InSAR) and Global Navigation Satellite System (GNSS). The authors have shown that InSAR and GNSS observations over a time period of three months after the earthquake combined with Coulomb Stress Change Modelling can explain the fault zone expansion, as well as the deformation of the northern region of the NAF. It was also found that there is a strong agreement between the InSAR and GNSS results for the post-seismic phases of investigation, with differences less than 2mm, and the standard deviation of the differences is less than 1mm.


2014 ◽  
Vol 971-973 ◽  
pp. 2172-2175
Author(s):  
Dong Ning Lei ◽  
Jian Chao Wu ◽  
Yong Jian Cai

TheCoulomb stress changes are usually adopted to make analysis on faultinteractions and stress triggering. This paper mainly deals with Coulomb stresschange of mainshock and affect on aftershocks. We preliminarily conclude thatthe mainshock produce Coulomb stress change on aftershocks most behavingpositive and triggered them. By calculating it is obvious that more aftershocksfell into stress increasing area and triggering percentage is up to ninety ofmaximum and seventy-one of minimum.


2015 ◽  
Vol 173 (1) ◽  
pp. 49-72 ◽  
Author(s):  
K. M. Leptokaropoulos ◽  
E. E. Papadimitriou ◽  
B. Orlecka–Sikora ◽  
V. G. Karakostas

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