A new index for microzonation of earthquake prone settlement area by considering liquefaction potential and fault avoidance zone: an example case from Edremit (Balikesir, Turkey)
01 Nov 2021-Arabian Journal of Geosciences (Springer Science and Business Media LLC)-Vol. 14, Iss: 21, pp 1-21
TL;DR: In this article, an approach is suggested for the settlement area where there is liquefaction and surface fault rupture hazard at the same time, which allows the assessment of land damage in case an earthquake occurred.
Abstract: In the present study, an approach is suggested for the settlement area where there is liquefaction and surface fault rupture hazard at the same time, which allows the assessment of land damage in case an earthquake occurred. Edremit (Balikesir NW Turkey), mainly under the influence the Edremit Fault Zone in the southern branch of the North Anatolian Fault Zone, was chosen as the study area. According to paleo-seismological findings from the Narli trench, at least three similar earthquakes occurred on the same rupture of Edremit Fault Zone passing in the studied area. In addition, generally the groundwater level in the liquefiable alluvial soil varies between 0.5 and 6 m, and also the ratio of areas of liquefiable soil varies between 56 and 78% at different depths in the area. The buffer zone for the Edremit Fault Zone ruptures was defined based on the distance from the surface fault rupture in the study area, and it was seen that 15% of the study area is within the first-degree fault avoidance zone, while 43.5% is located within free zone. The safety factor against liquefaction for the soil layers was determined by using simple procedure based on SPT-N values, and then, the spatial distribution of the liquefaction potential index was obtained. It is found that 43% of the study area has high or very high liquefaction potential while the rate of the area where liquefaction is not expected is 27.8%. The liquefaction potential and the map showing the fault avoidance zones are important and successful in terms of individual hazard related to earthquake. However, the said maps do not allow to assess, simultaneously and completely, the realistic extent of the possible land damage in case an earthquake occurs. So, using the liquefaction potential index and the distance from the surface fault rupture, a new index, namely land damage index, was defined to create the microzonation of the seismic hazard for liquefaction and surface fault rupture-induced land damage. According to the zonation of land damage index, 29.7% of the study area is consists of Land Damage Zone I where settlement is not allowed. The main goal of the preparation of the said microzonation for the study area is to recognize the hazard from active faults, with respect to liquefaction and surface fault rupture, and to provide guidance to planners on how to mitigate the risk for different types of buildings.
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TL;DR: In this article, a series of empirical relationships among moment magnitude (M ), surface rupture length, subsurface rupture length and downdip rupture width, and average surface displacement per event are developed.
Abstract: Source parameters for historical earthquakes worldwide are compiled to develop a series of empirical relationships among moment magnitude ( M ), surface rupture length, subsurface rupture length, downdip rupture width, rupture area, and maximum and average displacement per event. The resulting data base is a significant update of previous compilations and includes the additional source parameters of seismic moment, moment magnitude, subsurface rupture length, downdip rupture width, and average surface displacement. Each source parameter is classified as reliable or unreliable, based on our evaluation of the accuracy of individual values. Only the reliable source parameters are used in the final analyses. In comparing source parameters, we note the following trends: (1) Generally, the length of rupture at the surface is equal to 75% of the subsurface rupture length; however, the ratio of surface rupture length to subsurface rupture length increases with magnitude; (2) the average surface displacement per event is about one-half the maximum surface displacement per event; and (3) the average subsurface displacement on the fault plane is less than the maximum surface displacement but more than the average surface displacement. Thus, for most earthquakes in this data base, slip on the fault plane at seismogenic depths is manifested by similar displacements at the surface. Log-linear regressions between earthquake magnitude and surface rupture length, subsurface rupture length, and rupture area are especially well correlated, showing standard deviations of 0.25 to 0.35 magnitude units. Most relationships are not statistically different (at a 95% significance level) as a function of the style of faulting: thus, we consider the regressions for all slip types to be appropriate for most applications. Regressions between magnitude and displacement, magnitude and rupture width, and between displacement and rupture length are less well correlated and have larger standard deviation than regressions between magnitude and length or area. The large number of data points in most of these regressions and their statistical stability suggest that they are unlikely to change significantly in response to additional data. Separating the data according to extensional and compressional tectonic environments neither provides statistically different results nor improves the statistical significance of the regressions. Regressions for cases in which earthquake magnitude is either the independent or the dependent parameter can be used to estimate maximum earthquake magnitudes both for surface faults and for subsurface seismic sources such as blind faults, and to estimate the expected surface displacement along a fault for a given size earthquake.
6,160 citations
01 Jan 1968
TL;DR: In many fields using empirical areal data there arises a need for interpolating from irregularly-spaced data to produce a continuous surface as discussed by the authors, and it is assumed that a unique number (such as rainfall in meteorology, or altitude in geography) is associated with each data point.
Abstract: In many fields using empirical areal data there arises a need for interpolating from irregularly-spaced data to produce a continuous surface. These irregularly-spaced locations, hence referred to as “data points,” may have diverse meanings: in meterology, weather observation stations; in geography, surveyed locations; in city and regional planning, centers of data-collection zones; in biology, observation locations. It is assumed that a unique number (such as rainfall in meteorology, or altitude in geography) is associated with each data point. In order to display these data in some type of contour map or perspective view, to compare them with data for the same region based on other data points, or to analyze them for extremes, gradients, or other purposes, it is extremely useful, if not essential, to define a continuous function fitting the given values exactly. Interpolated values over a fine grid may then be evaluated. In using such a function it is assumed that the original data are without error, or that compensation for error will be made after interpolation.
3,882 citations
TL;DR: Significant factors affecting the liquefaction (or cyclic mobility) potential of sands during earthquakes are identified, and a simplified procedure for evaluating the potential of sand during earthquakes is presented as mentioned in this paper.
Abstract: Significant factors affecting the liquefaction (or cyclic mobility) potential of sands during earthquakes are identified, and a simplified procedure for evaluating liquefaction potential which will take these factors into account is presented Available field data concerning the liquefaction or nonliquefaction behavior of sands during earthquakes is assembled and compared with evaluations of performance using the simplified procedure It is suggested that even the limited available field data can provide a useful guide to the probable performance of other sand deposits, that the proposed method of presenting the data provides a useful framework for evaluating past experiences of sand liquefaction during earthquakes and that the simplified evaluation procedure provides a reasonably good means for extending previous field observations to new situations When greater accuracy is justified, the simplified liquefaction evaluation procedure can readily be supplemented by test data on particular soils or by ground response analyses to provide more definitive evaluations
2,250 citations
TL;DR: In 1996, a workshop sponsored by the National Center for Earthquake Engineering Research (NCEER) was convened by Professors T. L. Youd and I. M. Idriss with 20 experts to review developments over the previous 10 years as mentioned in this paper.
Abstract: Following disastrous earthquakes in Alaska and in Niigata, Japan in 1964, Professors H. B. Seed and I. M. Idriss developed and published a methodology termed the ''simplified procedure'' for evaluating liquefaction resistance of soils. This procedure has become a standard of practice throughout North America and much of the world. The methodology which is largely empirical, has evolved over years, primarily through summary papers by H. B. Seed and his colleagues. No general review or update of the procedure has occurred, however, since 1985, the time of the last major paper by Professor Seed and a report from a National Research Council workshop on liquefaction of soils. In 1996 a workshop sponsored by the National Center for Earthquake Engineering Research (NCEER) was convened by Professors T. L. Youd and I. M. Idriss with 20 experts to review developments over the previous 10 years. The purpose was to gain consensus on updates and augmen- tations to the simplified procedure. The following topics were reviewed and recommendations developed: (1) criteria based on standard penetration tests; (2) criteria based on cone penetration tests; (3) criteria based on shear-wave velocity measurements; (4) use of the Becker penetration test for gravelly soil; (4) magnitude scaling factors; (5) correction factors for overburden pressures and sloping ground; and (6) input values for earthquake magnitude and peak acceleration. Probabilistic and seismic energy analyses were reviewed but no recommen- dations were formulated.
1,766 citations
TL;DR: In this paper, the authors clarified the meaning of the values of standard penetration resistance used in correlations of field observations of soil liquefaction with values of N1 measured in SPT tests.
Abstract: The purpose of this paper is to clarify the meaning of the values of standard penetration resistance used in correlations of field observations of soil liquefaction with values of N1 measured in SPT tests. The field data are reinterpreted and plotted in terms of a newly recommended standard, (N1)60, determined in SPT tests where the driving energy in the drill rods is 60% of the theoretical free‐fall energy. Energies associated with different methods of performing SPT tests in different countries and with different equipment are summarized and can readily be used to convert any measured N‐value to the standard (N1)60 value. Liquefaction resistance curves for sands with different (N1)60 values and with different fines contents are proposed. It is believed that these curves are more reliable than previous curves expressed in terms of mean grain size. The results presented are in good accord with recommended practice in Japan and China and should, thus, provide a useful basis for liquefaction evaluations in ...
1,180 citations