Comparison of polynomial and similarity transformation based datum-shifts for Egypt

Abd-Elmotaal, Hussein A.

doi:10.1007/bf00808290

Cited by 31 publications

(5 citation statements)

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“…For example, the Mw 7.9 earthquake ruptures the southern segment of the fault and causes~4.5 m average slip on the fault, while the Mw 7.5 earthquake ruptures the central segment and induces~4.1 m average slip (Figures 3a, 5b, 5c, 5e, and 5f). Our modeled relationship between coseismic slip and seismic magnitude is also consistent with the empirical slip-magnitude relationship in previous studies (e.g., Wells & Coppersmith, 1994).…”

Section: Coseismic Displacementssupporting

confidence: 90%

Seismicity, Fault Slip Rates, and Fault Interactions in a Fault System

2020

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Seismicity and the partitioning of slip rates in interacting and mechanically coupled fault systems are poorly understood. We developed and used three‐dimensional viscoelastoplastic finite element models to simulate earthquakes, earthquake cycles, and synthetic seismicity in single and bifurcated fault systems and investigate seismicity, fault slip rates, and interactions and mechanical coupling between faults in fault systems. The modeled interseismic velocities and coseismic displacements are consistent with those from analytical and quasi‐analytical solutions. We found that the modeled frequency‐magnitude relation satisfies the Gutenberg‐Richter relation and the b value is inversely related to differential stress. We observed that the seismicity on two parallel faults is often interdependent and complementary: high seismic moment release rates on a fault are usually accompanied by low ones on the other fault and vice versa; the two faults collectively accommodate far‐field tectonic loading and crustal relative motion. Model results showed that when two parallel faults have the same or similar strength, they have similar seismicity and long‐term slip rates, but when one of the two faults has lower strength, it has more active seismicity and a faster slip rate than the other; the sum of their slip rates equals the far‐field crustal relative motion in both cases. The results in this study provide scientific insights into the spatiotemporal migration of seismicity and partitioning of fault slip rates in an interacting and mechanically coupled fault system and help to qualify b values and to evaluate the earthquake hazard and risk on each of the faults in such a system.

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Section: Coseismic Displacementssupporting

confidence: 90%

Seismicity, Fault Slip Rates, and Fault Interactions in a Fault System

2020

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“…Polynomial functions of a predetermined form, usually with a total degree as in (2), have been proposed to model other datum shifts. 6-term functions (with total degree 2) have been used by Abd-Elmotaal (1994), Kutoglu (2009) and Mitsakaki, Agatza-Balodimou and Papazissi (2006). 10-term functions (with total degree 3) have been used by Ayer, Boakye-Yiadom and Smith-Ephraim (2010).…”

Section: Construction Of Mresmentioning

confidence: 99%

“…16-term polynomials with top power 3 have been used by Chen and Hill (2005). In all these examples except Abd-Elmotaal (1994), the equivalence of the polynomials to multiple regression equations is stated or implied, despite the absence of tests for statistical significance. Kutoglu (2009) does provide a rationale for restricting terms to total degree 3, and that is the danger of "erratic behaviours" from polynomials of higher order.…”

Section: Construction Of Mresmentioning

confidence: 99%

Partitions of normalised multiple regression equations for datum transformations

Ruffhead

2022

Bol. Ciênc. Geod.

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Multiple regression equations (MREs) provide an empirical direct method of transforming coordinates between geodetic datums. Since they offer a means of modelling distortions, they are capable of a more accurate fit to datumshift datasets than more basic direct methods. MRE models of datum shifts traditionally consist of polynomials based on relative latitude and longitude. However, the limited availability of low-power terms often leads to high-power terms being included, and these are a potential cause of instability. This paper introduces three variations based on simple partitions and 2 or 4 smoothly conjoined polynomials. The new types are North/South, East/West and Four-Quadrant. They increase the availability of low-order terms, enabling distortions to be modelled with fewer side effects. Case studies in Great Britain, Slovenia and Western Australia provide examples of partitioned MREs that are more accurate than conventional MREs with the same number of terms.

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“…We assumed that the Longxian-Qishan section of the Longxian-Qishan-Mazhao Fault is completely broken. According to the global empirical formula, i.e., Mw 5.16 + 1.12lgL (Wells and Coppersmith, 1994), for the rupture length and magnitude of strike-slip faults, the moment magnitude is Mw 7.35 According to the empirical formula, i.e., M 5.303 + 1.181lgL (Ran, 2011), for the strike-slip fault magnitudefracture parameter in western China, the magnitudes is 7.61.…”

Section: Bc Qishan Earthquake Parametersmentioning

confidence: 99%

Using Google Earth Images to Extract Dense Landslides Induced by Historical Earthquakes at the Southwest of Ordos, China

Qinjian

et al. 2021

Front. Earth Sci.

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As historical earthquake records are simple, determining the source parameters of historical strong earthquakes over an extended period is difficult. There are numerous uncertainties in the study of historical earthquakes based on limited literature records. Co-seismic landslide interpretation combined with historical documents can yield the possibility of reducing these uncertainties. The dense co-seismic landslides can be preserved for hundreds to thousands of years in Loess Plateau, North China; furthermore, there are notable attribute differences between earthquake landslides and rainfall-triggered landslides. Along the southwestern margin of the Ordos Block, only one severe earthquake has been recorded in the past 3,000 years. The records of “Sanchuan exhaustion and Qishan collapse” provide clues for an investigation of the 780 BC Qishan earthquake. In this study, combined with historical documents, current high-resolution Google Earth images were used to extract historical landslides along the southwestern of the Ordos Block. There were 6,876 landslides with a total area of 643 km2. The landslide-intensive areas were mainly distributed along the Longxian–Qishan–Mazhao Fault in the loess valley area on the northeastern side of the fault. Loess tableland and river terraces occur on the southwest side of the fault; dense landslides have not been examined due to the topographical conditions in this area. By analyzing the spatial distribution of historical earthquake damage in this region, comparing the characteristics of rainfall-triggered landslides, and combining existing dating results for bedrock collapse and loess landslides, the interpretation of dense historical landslides can be linked to the Qishan Earthquake. The interpretation results are associated with historical records. Analyses of current earthquake cases show that the distribution of dense landslides triggered by strong earthquakes can indicate the episeismic area of an earthquake. In addition, the non-integrated landslide catalog without small- and medium-scale coseismic landslides can be used to effectively determine the source parameters of historical strong earthquakes and perform quantitative evaluations. This study evaluates the focal parameters of the 780 BC Qishan earthquake based on interpretations of the spatial distribution range of historical landslides as representations of the range of the extreme earthquake zone.

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Comparison of polynomial and similarity transformation based datum-shifts for Egypt

Cited by 31 publications

References 1 publication

Seismicity, Fault Slip Rates, and Fault Interactions in a Fault System

Seismicity, Fault Slip Rates, and Fault Interactions in a Fault System

Partitions of normalised multiple regression equations for datum transformations

Using Google Earth Images to Extract Dense Landslides Induced by Historical Earthquakes at the Southwest of Ordos, China

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