Earthquake Engineering in Areas Away from Tectonic Plate Boundaries

Author(s):  
Nelson Lam
2018 ◽  
Vol 156 (2) ◽  
pp. 208-241 ◽  
Author(s):  
CHRISTIAN VÉRARD

AbstractSince the 1970s, numerous global plate tectonic models have been proposed to reconstruct the Earth's evolution through deep time. The reconstructions have proven immensely useful for the scientific community. However, we are now at a time when plate tectonic models must take a new step forward. There are two types of reconstructions: those using a ‘single control’ approach and those with a ‘dual control’ approach. Models using the ‘single control’ approach compile quantitative and/or semi-quantitative data from the present-day world and transfer them to the chosen time slices back in time. The reconstructions focus therefore on the position of tectonic elements but may ignore (partially or entirely) tectonic plates and in particular closed tectonic plate boundaries. For the readers, continents seem to float on the Earth's surface. Hence, the resulting maps look closer to what Alfred Wegener did in the early twentieth century and confuse many people, particularly the general public. With the ‘dual control’ approach, not only are data from the present-day world transferred back to the chosen time slices, but closed plate tectonic boundaries are defined iteratively from one reconstruction to the next. Thus, reconstructions benefit from the wealth of the plate tectonic theory. They are physically coherent and are suited to the new frontier of global reconstruction: the coupling of plate tectonic models with other global models. A joint effort of the whole community of geosciences will surely be necessary to develop the next generation of plate tectonic models.


2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Sean M. Langemeyer ◽  
Julian P. Lowman ◽  
Paul J. Tackley

AbstractThe presence of offsets, appearing at intervals ranging from 10s to 100s of kilometres, is a distinct characteristic of constructive tectonic plate margins. By comparison, boundaries associated with subduction exhibit uninterrupted continuity. Here, we present global mantle convection calculations that result in a mobile lithosphere featuring dynamically derived plate boundaries exhibiting a contrasting superficial structure which distinguishes convergence and divergence. Implementing a yield-stress that governs the viscosity in the lithosphere, spreading boundaries at the top of a vigorously convecting mantle form as divergent linear segments regularly offset by similar length zones that correlate with a large degree of shear but comparatively minimal divergence. Analogous offset segments do not emerge in the boundaries associated with surface convergence. Comparing the similarity in the morphologies of the model plate margins to the Earth’s plate boundaries demonstrates that transform-like offsets are a result of stress induced weakness in the lithosphere owing to passive rupturing.


1982 ◽  
Vol 31 ◽  
pp. 11-27

Data on earthquakes in Greenland from the international and Canadian seismological bulletins have been checked against the seismograms of the seismological stations in Greenland. A few new earthquakes have also been located based on seismograms from Greenland and Canada. A total of 103 reliable earthquakes have been confirmed, located and relocated. The earthquakes occur mainly along the coasts of eastern, northern and western Greenland. The largest earthquakes in Greenland have magnitudes around 5. There is no tectonic plate boundary in Greenland. The intraplate earthquake zones in north-eastern and in northern Greenland are situated as linear continuations of the plate boundaries near the bend of the mid ocean ridge close to Station Nord, between Spitzbergen and Greenland. Under the ice cap only a few earthquakes have occurred. In eastern and in northern Greenland a few swarms of earthquakes have been found. In western Greenland a sequence of seismic signals is noticed at a distance of 17 5 km from Godhavn. Its origin may be small earthquakes. The time sequence of the earthquakes in Greenland shows two time intervals of increased earthquake activity after the two largest earthquakes. This indicates that stress adjustments in the largest earthquakes give rise to stress adjust­ments in the smaller earthquakes more than 1000 km away, in other parts of Greenland. There is only limited correlation between earthquake activity and surface geology. It can not be determined whether the main cause of the intraplate earthquakes in Greenland is isostatic uplift following the latest ice age or tectonic plate motion in connection with sea floor spreading in the Norwegian-Greenland Sea and in the Arctic Ocean.


Sensors ◽  
2021 ◽  
Vol 21 (10) ◽  
pp. 3519
Author(s):  
Yanbing Bai ◽  
Ning Ma ◽  
Shengwang Meng

The largest possible earthquake magnitude based on geographical characteristics for a selected return period is required in earthquake engineering, disaster management, and insurance. Ground-based observations combined with statistical analyses may offer new insights into earthquake prediction. In this study, to investigate the seismic characteristics of different geographical regions in detail, clustering was used to provide earthquake zoning for Mainland China based on the geographical features of earthquake events. In combination with geospatial methods, statistical extreme value models and the right-truncated Gutenberg–Richter model were used to analyze the earthquake magnitudes of Mainland China under both clustering and non-clustering. The results demonstrate that the right-truncated peaks-over-threshold model is the relatively optimal statistical model compared with classical extreme value theory models, the estimated return level of which is very close to that of the geographical-based right-truncated Gutenberg–Richter model. Such statistical models can provide a quantitative analysis of the probability of future earthquake risks in China, and geographical information can be integrated to locate the earthquake risk accurately.


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