Strong Ground Motion Attributes of the 2010 Mw 8.8 Maule, Chile, Earthquake

2012 ◽  
Vol 28 (1_suppl1) ◽  
pp. 19-38 ◽  
Author(s):  
Rubén L. Boroschek ◽  
Víctor Contreras ◽  
Dong Youp Kwak ◽  
Jonathan P. Stewart
Keyword(s):  
Ground Motion ◽  
Fault Plane ◽  
Soft Soil ◽  
Strong Motion ◽  
Response Spectra ◽  
Rupture Directivity ◽  
Magnitude Scaling ◽  
Chile Earthquake ◽  
Rupture Distance ◽  
Strong Ground

The Mw 8.8 Maule, Chile, earthquake produced 31 usable strong motion recordings from currently accessible arrays over a rupture distance range of 30 to 700 km. Site conditions range from firm rock to soft soil but are most often competent soil (NEHRP Category C or C/D). Most of the data were recorded on analogue instruments, which was digitized and processed with low- and high-cut filters designed to maximize the usable frequency range of the signals. The stations closest to the fault plane do not exhibit evidence of ground motion polarization from rupture directivity. Response spectra of nearby recordings on firm ground and soft soil indicate pronounced site effects, including several cases of resonance at site periods. A prior GMPE for interface subduction events captures well the distance scaling and dispersion of the data, but under-predicts the overall ground motion level, perhaps due to too-weak magnitude scaling.

Extrapolating strong ground motion of the Silakhor earthquake (ML 6.1), Iran, using the empirical Green's function (EGF) approach based on a genetic algorithm

2009 ◽  
Vol 46 (11) ◽  
pp. 801-810 ◽  
Author(s):  
Ahmad Nicknam ◽  
Reza Abbasnia ◽  
Yasser Eslamian ◽  
Mohsen Bozorgnasab
Keyword(s):  
Genetic Algorithm ◽  
Ground Motion ◽  
Green's Function ◽  
Strong Ground Motion ◽  
Strong Motion ◽  
Response Spectra ◽  
Elastic Response ◽  
Elastic Response Spectra ◽  
Input Parameters ◽  
Strong Ground

The main objectives of this article are to develop a technique to find source models that allow one to replicate observed strong ground motion records and to extrapolate strong ground motion synthesis to locations where strong motion was not recorded. A technique including the well known empirical Green’s function (EGF) approach along with a genetic algorithm is used, which allows the optimization of differences between the synthesized and observed ground shakings. The technique used is performed by comparing the elastic response spectra of observed seismograms at two stations with those of simulated data using the EGF method incorporating recorded aftershocks taken at each station. Moreover, a genetic algorithm approach is used to reduce differences between the simulated and recorded data in the form of elastic response spectra by changing the input parameters in the admissible ranges. To validate the proposed approach the three components of strong motion recorded at other stations were synthesized incorporating the input parameters obtained at previous stations. A comparatively good match of the simulated and recorded response spectra confirms the ability of the proposed technique to generate synthetic seismograms with suitable elastic response spectra.

Concurrent Design Forces in Structures under Three-Component Orthotropic Seismic Excitation

2002 ◽  
Vol 18 (1) ◽  
pp. 1-17 ◽  
Author(s):  
K. Anastassiadis ◽  
I. E. Avramidis ◽  
P. Panetsos
Keyword(s):  
Ground Motion ◽  
Design Procedure ◽  
Strong Motion ◽  
Response Spectra ◽  
Concurrent Design ◽  
Motion Model ◽  
Specific Point ◽  
Extreme Stress ◽  
Seismic Motion

According to the model of Penzien and Watabe, the three translational ground motion components on a specific point of the ground are statistically noncorrelated along a well-defined orthogonal system of axes p, w, and v, whose orientation remains reasonably stable over time during the strong motion phase of an earthquake. This orthotropic ground motion is described by three generally independent response spectra Sa, Sb, and Sc, respectively. The paper presents an antiseismic design procedure for structures according to the above seismic motion model. This design includes a) determination of the critical orientation of the seismic input, i.e., the orientation that gives the largest response, b) calculation of the maximum and the minimum values of any response quantity, and c) application of either the Extreme Stress Method or the Extreme Force Method for determining the most unfavorable combinations of several stress resultants (or sectional forces) acting concurrently at a specified section of a structural member.

scholarly journals Near-Source Simulation of Strong Ground Motion in Amatrice Downtown Including Site Effects

Geosciences ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 186
Author(s):  
Alessandro Todrani ◽  
Giovanna Cultrera
Keyword(s):  
Ground Motion ◽  
Site Effects ◽  
Central Italy ◽  
Strong Motion ◽  
Seismic Source ◽  
Spectral Ratio ◽  
Intensity Measures ◽  
Standard Spectral Ratio ◽  
Heavy Damage ◽  
Strong Ground

On 24 August 2016, a Mw 6.0 earthquake started a damaging seismic sequence in central Italy. The historical center of Amatrice village reached the XI degree (MCS scale) but the high vulnerability alone could not explain the heavy damage. Unfortunately, at the time of the earthquake only AMT station, 200 m away from the downtown, recorded the mainshock, whereas tens of temporary stations were installed afterwards. We propose a method to simulate the ground motion affecting Amatrice, using the FFT amplitude recorded at AMT, which has been modified by the standard spectral ratio (SSR) computed at 14 seismic stations in downtown. We tested the procedure by comparing simulations and recordings of two later mainshocks (Mw 5.9 and Mw 6.5), underlining advantages and limits of the technique. The strong motion variability of simulations was related to the proximity of the seismic source, accounted for by the ground motion at AMT, and to the peculiar site effects, described by the transfer function at the sites. The largest amplification characterized the stations close to the NE hill edge and produced simulated values of intensity measures clearly above one standard deviation of the GMM expected for Italy, up to 1.6 g for PGA.

Near-Source Magnitude Scaling of Spectral Accelerations: Analysis and Update of Kotha et al. (2020) Model

2021 ◽  
Author(s):  
Sreeram Reddy Kotha ◽  
Graeme Weatherill ◽  
Dino Bindi ◽  
Fabrice Cotton
Keyword(s):  
Model Uncertainty ◽  
Soft Soil ◽  
Strong Motion ◽  
Motion Models ◽  
Magnitude Scaling ◽  
Short Period ◽  
Hazard And Risk ◽  
Spectral Accelerations ◽  
Parametric Analyses ◽  
A Site

Abstract Ground-motion models (GMMs) are often used to predict the random distribution of spectral accelerations (SAs) at a site due to an earthquake at a distance. In probabilistic seismic hazard and risk assessment, large earthquakes occurring close to a site are considered as critical scenarios. GMMs are expected to perform well for such rare scenarios i.e., to predict realistic SAs with low prediction uncertainty. However, the datasets used to regress GMMs are usually deficient of data from rare/critical scenarios. The Kotha et al. (2020) GMM developed from the Engineering Strong Motion (ESM) dataset was found to predict decreasing short-period SAs with increasing \({M}_{W}\ge {M}_{h}=6.2\), and with large within-model uncertainty at near-source distances \({R}_{JB}\le 30km\). In this study, we analysed and updated the parametrisation of the GMM based on non-parametric and parametric analyses of ESM and the NEar Source Strong motion (NESS) datasets. By reducing \({M}_{h}\) to 5.7, we could rectify the \({M}_{W}\) scaling issue, while also reducing the within-model uncertainty on predictions at \({M}_{W}\ge 6.2\). We then evaluated the updated GMM against NESS data, and found that the SAs from a few large, thrust-faulting events in California, New Zealand, Japan, and Mexico are significantly higher than GMM median predictions. However, near-source recordings of these events were mostly made on soft-soil geology and contain anisotropic pulse-like effects. A more thorough non-ergodic treatment of NESS was not possible because most sites sampled unique events in very diverse tectonic environments. Therefore, for now, we provide an updated set of GMM coefficients, within-model uncertainty, and heteroskedastic variance models.

Engineering observations on ground motion at the Van Norman Complex after the 1994 Northridge earthquake

1996 ◽  
Vol 86 (1B) ◽  
pp. S333-S349 ◽  
Author(s):  
J. P. Bardet ◽  
C. Davis
Keyword(s):  
Ground Motion ◽  
Earthquake Engineering ◽  
Low Frequency ◽  
Strong Motion ◽  
Response Spectra ◽  
Vertical Acceleration ◽  
Northridge Earthquake ◽  
Peak Acceleration ◽  
Geotechnical Earthquake Engineering ◽  
1994 Northridge Earthquake

Abstract During the 1994 Northridge earthquake, the Van Norman Complex yielded an unprecedented number of recordings with high acceleration, in the close proximity of the fault rupture. These strong-motion recordings exhibited the pulses of the main event. One station recorded the largest velocity ever instrumentally recorded (177 cm/sec), resulting from a 0.86 g peak acceleration with a low frequency. Throughout the complex, the horizontal accelerations reached peak values ranging from 0.56 to 1.0 g, except for the complex center, where the peak acceleration did not exceed 0.43 g. The vertical acceleration reached maximum peak values comparable with those of the horizontal acceleration. The acceleration response spectra in the longitudinal and transverse directions were significantly different. Such a difference, which is not yet well documented in the field of geotechnical earthquake engineering, indicates that the amplitude and frequency content of the ground motion was directionally dependent in the Van Norman Complex.

30 Ooctober 2020 Samos-Sigacik Earthquake: On Strong Ground Motion and Local Site Amplification

2021 ◽  
Author(s):  
Eser Çakti ◽  
Karin Sesetyan ◽  
Ufuk Hancilar ◽  
Merve Caglar ◽  
Emrullah Dar ◽  
...  
Keyword(s):  
Ground Motion ◽  
Structural Damage ◽  
Strong Ground Motion ◽  
Epicentral Distance ◽  
Strong Motion ◽  
Aegean Sea ◽  
Site Amplification ◽  
Local Site ◽  
Basin Effects ◽  
Strong Ground

<p>The Mw 6.9 earthquake that took place offshore between the Greek island of Samos and Turkey’s İzmir province on 30 October 2020 came hardly as a surprise. Due to the extensional tectonic regime of the Aegean and high deformation rates, earthquakes of similar size frequently occur in the Aegean Sea on fault segments close to the shores of Turkey, affecting the settlements on mainland Turkey and on the Greek Islands. Samos-Sigacik earthquake had a normal faulting mechanism. It was recorded by the strong motion networks in Turkey and Greece. Although expected, the earthquake was an  outstanding event in the sense of  highly localized, significant levels of building damage as a result of amplified ground motion levels. This presentation is an overview of strong ground motion characteristics of this important event both regionally and locally. Mainshock records suggest that local site effects, enhanced by basin effects could be responsible for structural damage in central Izmir, the third largest city of Turkey located at 60-70 km epicentral distance. We installed a seven-station network in Bayraklı and Karşıyaka districts of İzmir within three days of the mainshock in search of site and basin effects.  Through analysis of recorded aftershocks we explore the amplification characeristics of soils in the two aforementioned districts  and try to understand the role basin effects might have played in the resulting ground motion levels and consequently damage. </p>

Analysis of Strong Ground Motion Characterization in the 2013 Lushan Earthquake

2014 ◽  
Vol 580-583 ◽  
pp. 1499-1505 ◽  
Author(s):  
Tian Yu ◽  
Ming Lu ◽  
Xiao Jun Li
Keyword(s):  
Ground Motion ◽  
Hanging Wall ◽  
Lushan Earthquake ◽  
Wall Effect ◽  
Earthquake Ground Motion ◽  
Rupture Directivity ◽  
Directivity Effect ◽  
Rupture Area ◽  
Hanging Wall Effect ◽  
Rupture Distance

Lushan earthquake on 20th April, 2013 was another thrust fault earthquake occurred at Longmen Mountain Fault Zone after 2008 Wenchuan Ms8.0 earthquake. Based on ground motion attenuation model, this paper has chosen 45 strong motion records with rupture distance less than 200km, to analyze the hanging wall effect, topographic effect and rupture directivity effect of Lushan earthquake. The results show that hanging wall effect in Lushan earthquake was not obvious as 2008 Wenchuan earthquake; ground motion in mountain areas attenuated with increasing rupture distance more quickly than that in plain areas; rupture directivity effect is obvious for two components of horizontal ground motion, which are fault-perpendicular and fault-parallel components. PGA in the forward rupture area is larger than those in the backward rupture area. With the period increased, the gap between backward and forward rupture area become small, and finally PGD in backward rupture area is greater than those in the forward rupture area.

The 23 October 2011 MW7.0 Van (Eastern Turkey) Earthquake: Interpretations of Recorded Strong Ground Motions and Post-Earthquake Conditions of Nearby Structures

2014 ◽  
Vol 30 (2) ◽  
pp. 657-682 ◽  
Author(s):  
V. Akansel ◽  
G. Ameri ◽  
A. Askan ◽  
A. Caner ◽  
B. Erdil ◽  
...  
Keyword(s):  
Fault Plane ◽  
Ground Motions ◽  
Hanging Wall ◽  
Strong Motion ◽  
Thrust Fault ◽  
Building Structures ◽  
Epicentral Area ◽  
Historical Structures ◽  
Strict Compliance ◽  
Strong Ground

A major thrust-fault earthquake of MW = 7.0 occurred on 23 October 2011 at 10:41:21 UTC in the eastern Anatolian region of Turkey, severely affecting the nearby towns of Van and Erciş. In this study, a few strong-motion records from the epicentral area are analyzed in order to investigate the characteristics of the ground motions. Also reported are the post-earthquake field observations for various types of structures, such as buildings, bridges, historical structures, tunnels, and dams within the vicinity of the fault plane. The spatial distribution of damage indicates a noticeable hanging-wall effect. The special-type structures are observed to experience far less damage, as opposed to the building structures in the region pointing to the need for strict compliance to seismic building code and the corresponding construction requirements.

Too-Late Warnings by Estimating Mw: Earthquake Early Warning in the Near-Fault Region

2020 ◽  
Vol 110 (3) ◽  
pp. 1276-1288
Author(s):  
Mitsuyuki Hoshiba
Keyword(s):  
Real Time ◽  
Ground Motion ◽  
Early Warning ◽  
Strong Motion ◽  
Earthquake Early Warning ◽  
Motion Generation ◽  
Near Fault ◽  
Time Gap ◽  
Fault Region ◽  
Strong Ground

ABSTRACT Earthquake early warning (EEW) systems aim to provide advance warnings of impending strong ground shaking. Many EEW systems are based on a strategy in which precise and rapid estimates of source parameters, such as hypocentral location and moment magnitude (Mw), are used in a ground-motion prediction equation (GMPE) to predict the strength of ground motion. For large earthquakes with long rupture duration, the process is repeated, and the prediction is updated in accordance with the growth of Mw during the ongoing rupture. However, in some regions near the causative fault this approach leads to late warnings, because strong ground motions often occur during earthquake ruptures before Mw can be confirmed. Mw increases monotonically with elapsed time and reaches its maximum at the end of rupture, and ground motion predicted by a GMPE similarly reaches its maximum at the end of rupture, but actual generation of strong motion is earlier than the end of rupture. A time gap between maximum Mw and strong-motion generation is the first factor contributing to late warnings. Because this time gap exists at any point of time during the rupture, a late warning is inherently caused even when the growth of Mw can be monitored in real time. In the near-fault region, a weak subevent can be the main contributor to strong ground motion at a site if the distance from the subevent to the site is small. A contribution from a weaker but nearby subevent early in the rupture is the second factor contributing to late warnings. Thus, an EEW strategy based on rapid estimation of Mw is not suitable for near-fault regions where strong shaking is usually recorded. Real-time monitoring of ground motion provides direct information for real-time prediction for these near-fault locations.

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