The Influence of Geographical Resolution of Urban Exposure Data in an Earthquake Loss Model for Istanbul

2010 ◽  
Vol 26 (3) ◽  
pp. 619-634 ◽  
Author(s):  
Ihsan Engin Bal ◽  
Julian J. Bommer ◽  
Peter J. Stafford ◽  
Helen Crowley ◽  
Rui Pinho

Exposure data available to developers of earthquake loss models are often very crudely aggregated spatially, and in such cases very considerable effort can be required to refine the geographical resolution of the building stock inventory. The influence of the geographical resolution of the exposure data for the Sea of Marmara region in Turkey is explored using several different levels of spatial aggregation to estimate the losses due to a single earthquake scenario. The results show that the total damage over an urban area, expressed as a mean damage ratio (MDR), is rather insensitive to the spatial resolution of the exposure data if a sufficiently large number of ground-motion simulations are used. However, the variability of the MDR estimates does reduce as the spatial resolution becomes higher, reducing the number of simulations required, although there appears to be a law of diminishing returns in going to very high exposure data resolution. This is largely due to the inherent and irreducible spatial variability of ground motion, which suggests that if only mean MDR estimates are needed, the effort required to refine the spatial definition of exposure data is not justified.

Author(s):  
Luigi Lombardo ◽  
Hakan Tanyas

AbstractGround motion scenarios exists for most of the seismically active areas around the globe. They essentially correspond to shaking level maps at given earthquake return times which are used as reference for the likely areas under threat from future ground displacements. Being landslides in seismically actively regions closely controlled by the ground motion, one would expect that landslide susceptibility maps should change as the ground motion patterns change in space and time. However, so far, statistically-based landslide susceptibility assessments have primarily been used as time-invariant.In other words, the vast majority of the statistical models does not include the temporal effect of the main trigger in future landslide scenarios. In this work, we present an approach aimed at filling this gap, bridging current practices in the seismological community to those in the geomorphological and statistical ones. More specifically, we select an earthquake-induced landslide inventory corresponding to the 1994 Northridge earthquake and build a Bayesian Generalized Additive Model of the binomial family, featuring common morphometric and thematic covariates as well as the Peak Ground Acceleration generated by the Northridge earthquake. Once each model component has been estimated, we have run 1000 simulations for each of the 217 possible ground motion scenarios for the study area. From each batch of 1000 simulations, we have estimated the mean and 95% Credible Interval to represent the mean susceptibility pattern under a specific earthquake scenario, together with its uncertainty level. Because each earthquake scenario has a specific return time, our simulations allow to incorporate the temporal dimension into any susceptibility model, therefore driving the results toward the definition of landslide hazard. Ultimately, we also share our results in vector format – a .mif file that can be easily converted into a common shapefile –. There, we report the mean (and uncertainty) susceptibility of each 1000 simulation batch for each of the 217 scenarios.


Author(s):  
Athanasius Cipta ◽  
Phil Cummins ◽  
Masyhur Irsyam ◽  
Sri Hidayati

We use earthquake ground motion modelling via Ground Motion Prediction Equations (GMPEs) and numerical simulation of seismic waves to consider the effects of site amplification and basin resonance in Jakarta, the capital city of Indonesia. While spectral accelerations at short periods are sensitive to near-surface conditions (i.e., Vs30), our results suggest that, for basins as deep as Jakarta’s, available GMPEs cannot be relied upon to accurately estimate the effect of basin depth on ground motions at long periods (>1 s). Amplitudes at such long periods are influenced by entrapment of seismic waves in the basin, resulting in longer duration of strong ground motion, and interference between incoming and reflected waves as well as focusing at basin edges may amplify seismic waves. In order to simulate such phenomena in detail, a basin model derived from a previous study is used as a computational domain for deterministic earthquake scenario modeling in a 2-dimensional cross-section. A Mw 9.0 megathrust, a Mw 6.5 crustal thrust and a Mw 7.0 instraslab earthquake are chosen as scenario events that pose credible threats to Jakarta, and the interactions with the basin of seismic waves generated by these events were simulated. The highest PGV amplifications are recorded at sites near the middle of the basin and near its southern edge, with maximum amplifications of PGV in the horizontal component of 200% for the crustal, 600% for the megathrust and 335% for the deep intraslab earthquake scenario, respectively. We find that the levels of ground motion response spectral acceleration fall below those of the 2012 Indonesian building Codes's design response spectrum for short periods (< 1 s), but closely approach or may even exceed these levels for longer periods.


1988 ◽  
Vol 132 (6-7) ◽  
pp. 354-358 ◽  
Author(s):  
Yu.N. Moiseev ◽  
V.M. Mostepanenko ◽  
V.I. Panov ◽  
I.Yu. Sokolov

2021 ◽  
Author(s):  
Tohid Nozadkhalil ◽  
Semih Ergintav ◽  
Ziyadin Cakir ◽  
Ugur Dogan ◽  
Thomas R. Walter

<p>Westward migration of M>7 earthquakes along North Anatolian fault with the latest one, Izmit 1999 event, led focus of studies to the seismic gap in the main Marmara fault. For this purpose, the coastal ranges of the Marmara Sea, mainly Istanbul megacity, are renowned for earthquake and ground motion hazards, associated with faulting, landslides and sediment compaction processes. Ground motion associated with man-made activities, however, have been barely studied. The Thrace region of Turkey, some 50 km to the North of the Marmara Sea, expresses pronounced ground motions affecting large areas. We use the Persistent InSAR technique to monitor the Marmara region using Sentinel-1 satellites’ TOPSAR data between 2014 and 2020. Results for both ascending (T131 and T58) and descending (T36) tracks reveals 10 mm/yr rate of subsidence in the Thrace region of Turkey, affecting an area ~15400km² with dimensions of ~110 km by ~140 km. There are two plausible mechanisms for this deformation; (1) excessive pumping of groundwater for agricultural purposes, or (2) natural gas extraction activities taking place in the region. To better understand the observed deformation source, as a first step, we model potential gas extraction by volume change. No piezometric data are available for this region for the time being. Thick sediments including sandstone, reefal carbonates, amongst others, are aimed for gas exploration in the Thrace basin for more than half century. Depth of gas extraction wells and sediment thickness is compiled from previous studies to compare the subsided area with sediment and well depth variations. </p><p>We use  the Poly3D boundary element method to model the surface. Poly3D uses planar triangular elements of constant model to model displacement’s source. Using triangular elements provides models with complex and smooth 3D surfaces avoiding overlaps or gaps, and hence allowing one to construct realistic models. Poly3dinv inverse model applies a fast non-negative/non-positive least squares solver to optimize the solution. We construct a surface enveloping tips of the wells and use it to produce deformation at surface due by allowing opening on it. Small residuals between the observation and model based on opening suggests that deformation is likely caused by natural gas extraction.</p>


2020 ◽  
Author(s):  
Seyhan Okuyan Akcan ◽  
Can Zulfikar

<p>Marmara region located on the western end of the North Anatolian Fault Zone is a tectonically active region in Turkey. There have been frequent severe earthquakes in the region and will continue to occur. There was no serious earthquake in the region after the 1999 Mw7.4 Kocaeli and Mw7.2 Düzce earthquakes. A Marmara Sea offshore earthquake Mw5.8 close to Silivri Town of Istanbul Metropolitan City has occurred on September 26, 2019 daytime at 13:59. The earthquake happened at the coordinate of 40.87N – 28.19E with a depth of 7.0km on the Kumburgaz segment of the North Anatolian Fault line. It was felt in almost all Marmara region. In some settlements in Istanbul City, slight to moderate damages were observed. A foreshock earthquake of Mw4.8 occurred on the same segment on 24 September, 2019. 150 aftershock events ranging from M1.0 to M4.1 have been recorded within the 24 hours after the mainshock. The ground motions have been recorded in the region by the several institutions including AFAD (Disaster and Emergency Management Presidency), KOERI (Kandilli Observatory and Earthquake Research Institute) and IGDAS (Istanbul Gas Distribution Industry and Trade Inc.). The ground motion records and selected parameters have been examined in this study. The ground motion parameters (MMI, PGA, PGV, Sa, Sv, Sd) distribution have been achieved and checked by the recent NGA-West2 ground motion prediction equations (GMPEs); ASK2014, CY2014 and BSSA2014. The compatibility of the GMPEs for a moderate size Marmara Sea earthquake has been examined.</p>


2012 ◽  
Vol 7 (6) ◽  
pp. 693-700 ◽  
Author(s):  
Saburoh Midorikawa ◽  
◽  
Hiroyuki Miura ◽  
Tomohiro Atsumi

Many strong motion records were obtained during the 2011 Off the Pacific Coast of Tohoku earthquake owing to the implementation of dense strong motion observation in Japan. The earthquake provides an opportunity to examine the characteristics of strong ground motion from a gigantic earthquake. Attenuations of peak acceleration and velocity are examined by comparing them to curves from existing attenuation relationships. When the shortest distance from the fault plane of the slip distribution model is used, curves for Mw8.0 to 8.3 give the smallest deviation from data, suggesting the saturation of ground motion intensity at large magnitudes. When the shortest distance from the strong motion generation areas is used, however, the scattering of data becomes smaller and the curve for Mw9.0 fits acceleration data. Results thus change with the definition of distance. This suggests that a consideration of the rupture heterogeneity is important in strong motion prediction for gigantic earthquakes.


2006 ◽  
Vol 166 (2) ◽  
pp. 635-651 ◽  
Author(s):  
A. Akinci ◽  
L. Malagnini ◽  
R. B. Herrmann ◽  
R. Gok ◽  
M. B. Sørensen

1997 ◽  
Vol 13 (4) ◽  
pp. 683-701 ◽  
Author(s):  
David S. Brookshire ◽  
Stephanie E. Chang ◽  
Hal Cochrane ◽  
Robert A. Olson ◽  
Adam Rose ◽  
...  

Earthquakes generate a variety of economic impacts. To obtain a consistent measure, the actual damage state must be linked to the dollar losses of the capital stock, and then translated into direct business interruption losses and the ensuing ripple effects that occur throughout the economy. The Earthquake Loss Estimation Methodology (HAZUS) facilitates a consistent set of loss estimations. The direct loss module of HAZUS calculates loss estimates for repair and replacement of building stock (structural and nonstructural), building contents and inventory, and business interruption losses. The direct losses information provides the inputs to the indirect loss module. The indirect loss module estimates the impacts by economic sectors over time and accounts for both earthquake-induced supply shortages and demand reductions. The results of a case study are presented that focus on the economic impacts of various scenario earthquakes that might occur in the Boston metropolitan area.


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