Microfracture processes in the breakdown zone during dynamic shear rupture inferred from laboratory observation of near-fault high-frequency strong motion

1994 ◽  
Vol 142 (3-4) ◽  
pp. 713-734 ◽  
Author(s):  
Naoyuki Kato ◽  
Kiyohiko Yamamoto ◽  
Tomowo Hirasawa
Keyword(s):  
High Frequency ◽  
Strong Motion ◽  
Dynamic Shear ◽  
Laboratory Observation ◽  
Near Fault ◽  
Shear Rupture

scholarly journals Determination of near-fault impulsive signals with multivariate naïve Bayes method

2021 ◽  
Author(s):  
Deniz Ertuncay ◽  
Giovanni Costa
Keyword(s):  
Naive Bayes ◽  
Strong Motion ◽  
Naïve Bayes ◽  
Strike Slip ◽  
Naive Bayes Classifier ◽  
Bayes Classifier ◽  
Naïve Bayes Classifier ◽  
Earthquake Physics ◽  
Near Fault ◽  
A Site

AbstractNear-fault ground motions may contain impulse behavior on velocity records. To calculate the probability of occurrence of the impulsive signals, a large dataset is collected from various national data providers and strong motion databases. The dataset has a large number of parameters which carry information on the earthquake physics, ruptured faults, ground motion parameters, distance between the station and several parts of the ruptured fault. Relation between the parameters and impulsive signals is calculated. It is found that fault type, moment magnitude, distance and azimuth between a site of interest and the surface projection of the ruptured fault are correlated with the impulsiveness of the signals. Separate models are created for strike-slip faults and non-strike-slip faults by using multivariate naïve Bayes classifier method. Naïve Bayes classifier allows us to have the probability of observing impulsive signals. The models have comparable accuracy rates, and they are more consistent on different fault types with respect to previous studies.

scholarly journals Response of Steel Moment and Braced Frames Subjected to Near-Source Pulse-Like Ground Motions by Including Soil-Structure Interaction Effects

2017 ◽  
Vol 3 (1) ◽  
pp. 15-34 ◽  
Author(s):  
Pooriya Ayough ◽  
Sara Mohamadi ◽  
Seyed Ali Haj Seiyed Taghia
Keyword(s):  
Seismic Response ◽  
High Frequency ◽  
Soil Structure ◽  
Steel Structures ◽  
Soil Structure Interaction ◽  
Ductility Demand ◽  
Structure Interaction ◽  
Near Fault ◽  
Frequency Components ◽  
Pulse Type

Most seismic regulations are usually associated with fixed-base structures, assuming that elimination of this phenomenon leads to conservative results and engineers are not obliged to use near-fault earthquakes. This study investigates the effect of soil–structure interaction on the inelastic response of MDOF steel structures by using well known Cone method. In order to achieve this, three dimensional multi-storey steel structures with moment and braced frame are analysed using non-linear time history method under the action of 40 near-fault records. Seismic response parameters, such as base shear, performance of structures, ductility demand and displacement demand ratios of structures subjected to different frequency-contents of near-fault records including pulse type and high-frequency components are investigated. The results elucidate that the flexibility of soil strongly affects the seismic response of steel frames. Soil–structure interaction can increase seismic demands of structures. Also, soil has approximately increasing and mitigating effects on structural responses subjected to the pulse type and high frequency components. A threshold period exists below which can highly change the ductility demand for short period structures subjected to near-fault records.

Dynamic Shear Rupture in Frictional Interfaces: Speeds, Directionality, and Modes

2007 ◽  
pp. 183-213 ◽  
Author(s):  
A.J. Rosakis ◽  
K. Xia ◽  
G. Lykotrafitis ◽  
H. Kanamori
Keyword(s):  
Dynamic Shear ◽  
Shear Rupture

What Is Fling Step? Its Theory, Simulation Method, and Applications to Strong Ground Motion near Surface Fault Ruptures

2021 ◽  
Author(s):  
Yoshiaki Hisada ◽  
Shinya Tanaka
Keyword(s):  
Velocity Structure ◽  
Seismic Velocity ◽  
Strong Motion ◽  
Theoretical Method ◽  
Simulation Method ◽  
Near Surface ◽  
Seismic Velocity Structure ◽  
Strong Motion Records ◽  
Near Fault ◽  
Fling Step

ABSTRACT We present the theory of the fling step and a theoretical method for simulating accurately the near-fault strong motions, and apply it to reproduce various strong-motion records near surface faults. Theoretically, the fling step is the contribution of the static Green’s function in the representation theorem (Hisada and Bielak, 2003), and we show that this theory holds for any seismic velocity structure. We first demonstrate the validity of this theory using theoretical solutions of a circular fault model in a homogeneous full-space. Next, we apply the theory to layered half-spaces, present a theoretical method based on the wavenumber integration method, and introduce various techniques to simulate the near-fault ground motions including fling steps with high accuracy. Finally, we demonstrate the effectiveness of the method by reproducing various strong-motion records near surface fault ruptures and discuss the characteristics of near-fault strong motions including the fling step and the forward directivity pulse. We made all of the software and data used in this article available on the internet.

Source parameter analysis from strong motion records of the Friuli, Italy, earthquake sequence (1976-1977)

1987 ◽  
Vol 77 (4) ◽  
pp. 1127-1146
Author(s):  
Giuseppe De Natale ◽  
Raul Madariaga ◽  
Roberto Scarpa ◽  
Aldo Zollo
Keyword(s):  
Frequency Domain ◽  
Stress Drop ◽  
High Frequency ◽  
Epicentral Distance ◽  
Strong Motion ◽  
Source Model ◽  
Parameter Analysis ◽  
Corner Frequency ◽  
Spectral Parameters ◽  
Single Station

Abstract Time and frequency domain analyses are applied to strong motion data recorded in Friuli, Italy, during 1976 to 1977. An inversion procedure to estimate spectral parameters (low frequency level, corner frequency, and high frequency decay) has been applied to displacement spectra using a simple earthquake source model with a single corner frequency. The data were digitized accelerograms from ENEA-ENEL portable and permanent networks. Instrument-corrected SH waves were selected from a set of 138 three-component, hand-digitized records and 28 automatically digitized records. Thirty-eight events with stations having 8 to 32 km epicentral distance were studied. Different stress drop estimates were performed showing high values (200 to 300 bars, on the average) with seismic moments ranging from 2.8 × 1022 to 8.0 × 1024 dyne-cm. The observation of systematic higher values of Brune stress drop (obtained from corner frequencies) with respect to other time and frequency domain estimates of stress release, and the evidence on time series of multiple rupture episodes suggest that the observed corner frequencies are most probably related to subevent ruptures rather than the overall fault size. Seven events recorded at more than one station show a good correlation between rms, Brune, and dynamic stress drops, and a constant scaling of this parameter as a function of the seismic moment. When single station events are also considered, a slight moment dependence of these three stress drop estimates is observed differently. This may be explained by an inadequacy of the ω−2 high-frequency decay of the source model or by high-frequency attenuation due to propagation effects. The high-frequency cutoff of acceleration spectra indicates the presence of an Fmax in the range of 5 to 14 Hz, except for the stations where local site effects produce spectral peaks.

Rupture Process of the Mainshock of the 2019 Ridgecrest Earthquake Sequence from Waveform Inversion with Empirical Green’s Functions

2021 ◽  
Author(s):  
Shuang-Lan Wu ◽  
Atsushi Nozu ◽  
Yosuke Nagasaka
Keyword(s):  
Green's Functions ◽  
Green’S Functions ◽  
Ground Motions ◽  
Strong Motion ◽  
Rupture Process ◽  
Earthquake Sequence ◽  
Slip Model ◽  
Near Fault ◽  
Empirical Green’S Functions ◽  
Empirical Green's Functions

ABSTRACT The 2019 Mw 7.1 mainshock of the Ridgecrest earthquake sequence, which was the first event exceeding Mw 7.0 in California since the 1999 Hector Mine earthquake, caused near-fault ground motions exceeding 0.5g and 70  cm/s. In this study, the rupture process and the generation mechanism of strong ground motions of the mainshock were investigated through waveform inversions of strong-motion data in the frequency range of 0.2–2.0 Hz using empirical Green’s functions (EGFs). The results suggest that the mainshock involved two large slip regions: the primary one with a maximum slip of approximately 4.4 m was centered ∼3  km northwest of the hypocenter, which was slightly shallower than the hypocenter, and the secondary one was centered ∼25  km southeast of the hypocenter. Outside these regions, the slip was rather small and restricted to deeper parts of the fault. A relatively small rupture velocity of 2.1  km/s was identified. The robustness of the slip model was examined by conducting additional inversion analyses with different combinations of EGF events and near-fault stations. In addition, using the preferred slip model, we synthesized strong motions at stations that were not used in the inversion analyses. The synthetic waveforms captured the timing of the main phases of observed waveforms, indicating the validity of the major spatiotemporal characteristics of the slip model. Our large slip regions are also generally visible in the models proposed by other researchers based on different datasets and focusing on lower frequency ranges (generally lower than 0.5 Hz). In particular, two large slip regions in our model are very consistent with two of the four subevents identified by Ross et al. (2019), which may indicate that part of the large slip regions that generated low-frequency ground motions also generated high-frequency ground motions up to 2.0 Hz during the Ridgecrest mainshock.

Inductance effect of passive electromagnetic dampers on building-damper system subjected to near-fault earthquakes

2019 ◽  
Vol 23 (2) ◽  
pp. 320-333
Author(s):  
Wei Guo ◽  
Xiaoli Wu ◽  
Xinna Wei ◽  
Yao Cui ◽  
Dan Bu
Keyword(s):  
High Frequency ◽  
Large Error ◽  
Client Server ◽  
Near Fault ◽  
Electromagnetic Model ◽  
High Frequency Excitation ◽  
Frequency Excitation ◽  
Near Fault Earthquakes ◽  
Story Building ◽  
Electromagnetic Damper

The passive electromagnetic damper was commonly simplified into the linear viscous model in numerical analysis, while this simplification may produce large error when the damper inductance is obvious. In this article, an optimal passive electromagnetic damper with good performance and economy characteristic is proposed by parameter optimization, where the damping density is set as the optimization objective. The hysteresis behavior of the passive electromagnetic damper is verified, and by neglecting the inductance effect, the passive electromagnetic damper can be simplified into the linear viscous model in some cases, but actually the inductance effect is obvious under the high-frequency excitation. Subsequently, the effect of inductance on seismic performance of building damper system under the near-fault earthquake is investigated by comparing the simplified linear viscous model and the accurate passive electromagnetic model. The passive electromagnetic damper was supplemented in a 9-story building, and the analysis of the accurate passive electromagnetic model was carried out by the co-simulation of MATLAB and OpenSees based on the client–server technology. It concludes that the inductance effect is obvious and causes large error when the building damper system is subjected to the near-fault earthquake, and the energy dissipation performance described by the linear viscous model is overestimated.

Nonuniformity of crack-growth resistance and breakdown zone near the propagating tip of a shear crack in brittle rock: A model for earthquake nucleation to dynamic rupture

1990 ◽  
Vol 68 (9) ◽  
pp. 1071-1083 ◽  
Author(s):  
Mitiyasu Ohnaka
Keyword(s):  
Crack Growth ◽  
Constitutive Relation ◽  
High Frequency ◽  
Crack Growth Resistance ◽  
Earthquake Source ◽  
Source Process ◽  
Zone Model ◽  
The Earth ◽  
Shear Rupture ◽  
Propagating Shear

This paper reviews our recent studies on (i) slip failure nucleation, which leads to the mechanical instability that gives rise to a dynamically propagating shear rupture, (ii) constitutive behavior during the local breakdown process near the propagating tip of the slipping zone, and (iii) the physical modeling of the earthquake-source process based on the constitutive relation inferred from laboratory experiments. Laboratory studies were done using a simulated fault in rock in the brittle regime under a mode II crack-growth condition, to gain a deeper understanding of the earthquake-source process, which is considered to be dynamically propagating shear rupture in the earth. A stable but accelerating phase of nucleation locally precedes an unstable dynamically propagating rupture even in the brittle regime. The appearance of a sizable zone of such nucleation is related to a nonuniform distribution of the crack-growth resistance on the fault. The local shear strength degrades to a residual friction stress level with ongoing slip near the propagating tip of the slipping zone. This slip-dependent constitutive relation shows that there is a breakdown zone near the propagating tip over which shear stress, slip displacement, slip velocity, and slip acceleration are highly nonuniform. This nonuniformity is responsible for generating high-frequency elastic radiation. A model of the breakdown zone, which incorporates the laboratory-based constitutive relation, does not give rise to unrealistic singularities of slip acceleration and stresses at and near the dynamically propagating tip of the slipping zone. The breakdown zone model enables one to give a common interpretation to both small-scale slip failure in the laboratory and large-scale shear failure as earthquake faulting in the earth, and it can explain the earthquake-source strong motion characterized by the high-frequency content.

Sign in / Sign up

Export Citation Format

Share Document