Elastic Response of Soil-Structure Systems Subjected to Near-Fault Rupture Directivity Pulses

2010 ◽  
Author(s):  
Zeynab Azarhoosh ◽  
G. Reza Ghodrati Amiri
Keyword(s):  
Soil Structure ◽  
Elastic Response ◽  
Rupture Directivity ◽  
Fault Rupture ◽  
Near Fault

scholarly journals Seismic hazard assessment of Tehran, Iran with emphasis on near-fault rupture directivity effects

2018 ◽  
Vol 31 (1) ◽  
pp. 1-11 ◽  
Author(s):  
Ehsan Bazarchi ◽  
◽  
Reza Saberi ◽  
Majid Alinejad ◽  
◽  
...  
Keyword(s):  
Seismic Hazard ◽  
Hazard Assessment ◽  
Seismic Hazard Assessment ◽  
Rupture Directivity ◽  
Fault Rupture ◽  
Near Fault ◽  
Directivity Effects

Near-Fault Monitoring Reveals Combined Seismic and Slow Activation of a Fault Branch within the Istanbul–Marmara Seismic Gap in Northwest Turkey

2021 ◽  
Author(s):  
Patricia Martínez-Garzón ◽  
Virginie Durand ◽  
Stephan Bentz ◽  
Grzegorz Kwiatek ◽  
Georg Dresen ◽  
...  
Keyword(s):  
Seismic Gap ◽  
Marmara Region ◽  
Fault Rupture ◽  
Aseismic Slip ◽  
Near Fault ◽  
Fault Monitoring ◽  
Aftershock Sequences ◽  
Borehole Strainmeter ◽  
Seismic Moment Release ◽  
Fluid Diffusion

Abstract Various geophysical observations show that seismic and aseismic slip on a fault may occur concurrently. We analyze microseismicity recordings from a temporary near-fault seismic network and borehole strainmeter data from the eastern Marmara region in northwest Turkey to track seismic and aseismic deformation around the hypocentral region of an Mw 4.5 earthquake in 2018. A slow transient is observed that lasted about 30 days starting at the time of the Mw 4.5 event. We study about 1200 microseismic events that occurred during 417 days after the Mw 4.5 event around the mainshock fault rupture. The seismicity reveals a strong temporal clustering, including four episodic seismic sequences, each containing more than 30 events per day. Seismicity from the first two sequences displayed typical characteristics driven by aseismic slip and/or fluids, such as the activation of a broader region around the mainshock and swarm-like topology. The third and fourth sequences correspond to typical mainshock–aftershock sequences. These observations suggest that slow slip and potentially fluid diffusion along the fault plane could have controlled the seismicity during the initial 150 days following the Mw 4.5 event. In contrast, stress redistribution and breaking of remaining asperities may have caused the activity after the initial 150 days. Our observation from a newly installed combined dense seismic and borehole strainmeter network follows an earlier observation of a slow transient occurring in conjunction with enhanced local seismic moment release in the same region. This suggests a frequent interaction of seismic and aseismic slip in the Istanbul–Marmara seismic gap.

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.

Comparison of Ground Motions from Hybrid Simulations to NGA Prediction Equations

2011 ◽  
Vol 27 (2) ◽  
pp. 331-350 ◽  
Author(s):  
Lisa M. Star ◽  
Jonathan P. Stewart ◽  
Robert W. Graves
Keyword(s):  
Ground Motions ◽  
Rupture Directivity ◽  
Ground Motion Prediction Equations ◽  
Fault Rupture ◽  
Prediction Equations ◽  
San Andreas ◽  
Blind Thrust ◽  
Static Stress Drop ◽  
Basin Response ◽  
Directivity Effects

We compare simulated motions for a Mw 7.8 rupture scenario on the San Andreas Fault known as the ShakeOut event, two permutations with different hypocenter locations, and a Mw 7.15 Puente Hills blind thrust scenario, to median and dispersion predictions from empirical NGA ground motion prediction equations. We find the simulated motions attenuate faster with distance than is predicted by the NGA models for periods less than about 5.0 s After removing this distance attenuation bias, the average residuals of the simulated events (i.e., event terms) are generally within the scatter of empirical event terms, although the ShakeOut simulation appears to be a high static stress drop event. The intra-event dispersion in the simulations is lower than NGA values at short periods and abruptly increases at 1.0 s due to different simulation procedures at short and long periods. The simulated motions have a depth-dependent basin response similar to the NGA models, and also show complex effects in which stronger basin response occurs when the fault rupture transmits energy into a basin at low angle, which is not predicted by the NGA models. Rupture directivity effects are found to scale with the isochrone parameter.

Deterministic 3D Ground-Motion Simulations (0–5 Hz) and Surface Topography Effects of the 30 October 2016 Mw 6.5 Norcia, Italy, Earthquake

2021 ◽  
Author(s):  
Arben Pitarka ◽  
Aybige Akinci ◽  
Pasquale De Gori ◽  
Mauro Buttinelli
Keyword(s):  
Surface Topography ◽  
Ground Motion ◽  
Seismic Station ◽  
Ground Motions ◽  
Peak Ground Velocity ◽  
Earth Model ◽  
Rupture Directivity ◽  
Epicentral Area ◽  
Near Fault ◽  
Local Topography

ABSTRACT The Mw 6.5 Norcia, Italy, earthquake occurred on 30 October 2016 and caused extensive damage to buildings in the epicentral area. The earthquake was recorded by a network of strong-motion stations, including 14 stations located within a 5 km distance from the two causative faults. We used a numerical approach for generating seismic waves from two hybrid deterministic and stochastic kinematic fault rupture models propagating through a 3D Earth model derived from seismic tomography and local geology. The broadband simulations were performed in the 0–5 Hz frequency range using a physics-based deterministic approach modeling the earthquake rupture and elastic wave propagation. We used SW4, a finite-difference code that uses a conforming curvilinear mesh, designed to model surface topography with high numerical accuracy. The simulations reproduce the amplitude and duration of observed near-fault ground motions. Our results also suggest that due to the local fault-slip pattern and upward rupture directivity, the spatial pattern of the horizontal near-fault ground motion generated during the earthquake was complex and characterized by several local minima and maxima. Some of these local ground-motion maxima in the near-fault region were not observed because of the sparse station coverage. The simulated peak ground velocity (PGV) is higher than both the recorded PGV and predicted PGV based on empirical models for several areas located above the fault planes. Ground motions calculated with and without surface topography indicate that, on average, the local topography amplifies the ground-motion velocity by 30%. There is correlation between the PGV and local topography, with the PGV being higher at hilltops. In contrast, spatial variations of simulated PGA do not correlate with the surface topography. Simulated ground motions are important for seismic hazard and engineering assessments for areas that lack seismic station coverage and historical recordings from large damaging earthquakes.

Numerical Modeling of Near Fault Seismic Ground Motion for Denali Fault

2021 ◽  
Vol 12 (2) ◽  
pp. 0-0
Keyword(s):  
Ground Motion ◽  
Peak Ground Acceleration ◽  
Numerical Study ◽  
Ground Motions ◽  
Numerical Results ◽  
Fault Rupture ◽  
Ground Acceleration ◽  
Denali Fault ◽  
Near Fault ◽  
Good Agreement

An effective earthquake (Mw 7.9) struck Alaska on 3 November, 2002. This earthquake ruptured 340 km along Susitna Glacier, Denali and Totschunda faults in central Alaska. The peak ground acceleration (PGA) was recorded about 0.32 g at station PS10, which was located 3 km from the fault rupture. The PGA would have recorded a high value, if more instruments had been installed in the region. A numerical study has been conducted to find out the possible ground motion record that could occur at maximum horizontal slip during the Denali earthquake. The current study overcomes the limitation of number of elements to model the Denali fault. These numerical results are compared with observed ground motions. It is observed that the ground motions obtained through numerical analysis are in good agreement with observed ground motions. From numerical results, it is observed that the possible expected PGA is 0.62 g at maximum horizontal slip of Denali fault.

Near-fault seismic monitoring reveals the long-lasting activation of a local fault in the Marmara region controlled by slow slip 

2021 ◽  
Author(s):  
Patricia Martínez-Garzón ◽  
Virginie Durand ◽  
Stephan Bentz ◽  
Taylan Turkmen ◽  
Grzegorz Kwiatek ◽  
...  
Keyword(s):  
Temporal Distribution ◽  
Marmara Region ◽  
Slow Slip ◽  
Fault Rupture ◽  
Aseismic Slip ◽  
Seismic Sequences ◽  
Near Fault ◽  
Aftershock Sequences ◽  
Nw Turkey ◽  
Different Characteristics

<p>Recent laboratory and field observations show that fault seismic and aseismic slip may occur concurrently. Here, we combine microseismicity recordings from a temporary near-fault seismic network (SMARTnet) and borehole strainmeter data from the eastern Marmara region in NW Turkey to track seismic and aseismic deformation around the hypocentral region of a M<sub>W</sub> 4.5 earthquake that occurred in 2018. The strainmeter data show a clear strain signal transient starting at the time of the M<sub>W</sub> 4.5 event and lasting for about 150 days. We study about 1,200 microseismic events following the mainshock within and beyond the mainshock fault rupture. The temporal distribution of the seismicity reveals a strong temporal clustering, including four semi-periodic seismic sequences each containing more than 50 events in two days. Two seismic sequences occurred during the strain transient showing different characteristics compared to two sequences occurring afterwards. Seismicity occurring during the transient displayed typical characteristics driven by aseismic slip, such as the activation of a broader region from the mainshock, and the absence of a clear mainshock in each sequence. Seismic sequences occurring after the transient correspond to typical mainshock-aftershock sequences and activated a region closer to the original M<sub>W</sub> 4.5 mainshock. We suggest post-strain transient seismicity originate from stress redistribution and breaking of remaining asperities. Our observations from a newly installed combined dense seismic and strainmeter network in the eastern Sea of Marmara region allows identifying repeated triggering of aseismic transients within an observation period of three years suggesting these may occur more often than previously thought.</p>

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