scholarly journals SITE RESPONSE AND SEISMIC WAVEFIELD IN TOLUCA CITY, MEXICO, FROM STRONG MOTION RECORDS

2006 ◽  
pp. 83
Author(s):  
Hugo Ferrer-Toledo ◽  
Martín Cárdenas-Soto ◽  
Francisco J. Chávez-García
Keyword(s):  
Site Response ◽  
Strong Motion ◽  
Strong Motion Records ◽  
Seismic Wavefield

The accuracy of soil response estimates using soil-to-rock spectral ratios

1996 ◽  
Vol 86 (2) ◽  
pp. 519-523
Author(s):  
Igor A. Beresnev ◽  
Kuo-Liang Wen
Keyword(s):  
Site Response ◽  
Soft Soil ◽  
Strong Motion ◽  
Finite Depth ◽  
Spectral Ratios ◽  
Site Specific ◽  
Soil Response ◽  
Strong Motion Records ◽  
The Real ◽  
Specific Amplification

Abstract Spectral ratios between soft soil and reference rock sites are often used to predict the sedimentary site response to earthquakes. However, their relationship with the genuine site-specific amplification function is often unclear. We compare the soil-to-rock spectral ratios between the stations that are 3.3 km apart with the “genuine” response given by the ratios between the surface and 17 and 47 m downhole. Data from the SMART1 array in Taiwan are used. The “weak” and “strong” motion records are addressed separately to allow for nonlinear soil response. The soil-to-rock spectral ratios are nearly identical to the “true” amplification at the frequencies from 1 to 10 Hz, if the finite depth of the borehole is taken into account. They correctly capture the strong-motion deamplification effect. However, the soil-to-rock spectral ratios are roughly 1.4 times more uncertain than surface-to-47-m ratios. In summary, the soil-to-rock spectral ratios can be considered as the reliable estimates of the real site response.

Simulating strong motions of large earthquakes using recordings of small earthquakes: the Loma Prieta mainshock as a test case

1995 ◽  
Vol 85 (4) ◽  
pp. 1144-1160
Author(s):  
Arthur Frankel
Keyword(s):  
Stress Drop ◽  
Site Response ◽  
Strong Motion ◽  
Site Effect ◽  
Corner Frequency ◽  
Simple Method ◽  
Strong Motion Records ◽  
Loma Prieta Earthquake ◽  
Loma Prieta ◽  
Large Earthquakes

Abstract A simple method is developed for predicting ground motions for future large earthquakes for specific sites by summing and filtering recordings of adjacent small earthquakes. This method is tested by simulating strong-motion records for the Loma Prieta earthquake (M 7.0) using aftershocks (M 3.7 to 4.0) recorded at the same sites. I use an asperity rupture model where the rms stress drop averaged over the fault plane is constant with moment. The observed spectra indicate that stress drop remains constant from the M 3 aftershocks up to the M 7 mainshock, about six orders of magnitude in seismic moment. Each simulation sums the seismogram of one aftershock with time delays appropriate for propagating rupture and incorporates directivity and site response. The simulation scales the spectrum in accordance with a constant stress drop, ω−2 source model. In this procedure, the high-frequency energy of the aftershock sum above the corner frequency of the aftershock is not reduced when it is convolved with the mainshock slip velocity function, unlike most previous methods of summation. For most cases, the spectra (0.6 to 20 Hz), peak accelerations, and durations of the simulated mainshock records are in good agreement with the observed strong-motion records, even though only one aftershock waveform was used in each simulation. This agreement indicates that the response of these soil sites is essentially linear for accelerations up to about 0.3 g. The summed aftershock records display the same site-dependent values of fmax as the mainshock records, implying that fmax is a site effect rather than a property of the mainshock rupture process.

Strong-Motion Records for Site-Specific Analysis

2003 ◽  
Vol 19 (3) ◽  
pp. 557-578 ◽  
Author(s):  
Praveen K. Malhotra
Keyword(s):  
Ground Motion ◽  
Site Response ◽  
Response Spectrum ◽  
Strong Motion ◽  
Response Spectra ◽  
Seismic Events ◽  
Site Specific ◽  
Strong Motion Records ◽  
Specific Analysis ◽  
Selection Of

A procedure is presented to select and scale strong-motion records for site-specific analysis. The procedure matches records’ smooth response spectra with the site response spectrum by scaling of the acceleration histories. The parameters defining the smooth spectrum of various records are computed and tabulated to allow easy selection of records. Hazard de-aggregation is used to identify closer and distant seismic events, which are simulated by the scaled ground motion histories. The procedure can also be used to obtain ground motion pairs in orthogonal directions for multidimensional dynamic response analyses.

Topographical and geological amplifications determined from strong-motion and aftershock records of the 3 March 1985 Chile earthquake

1987 ◽  
Vol 77 (4) ◽  
pp. 1147-1167
Author(s):  
M. Çelebi
Keyword(s):  
Site Response ◽  
Strong Motion ◽  
Spectral Ratios ◽  
Data Set ◽  
Frequency Dependent ◽  
Central Chile ◽  
Strong Motion Records ◽  
Chile Earthquake ◽  
Populated Region ◽  
Geological Formations

Abstract Site-response experiments were performed 5 months after the MS = 7.8 central Chile earthquake of 3 March 1985 to identify amplification due to topography and geology. Topographical amplification at Canal Beagle, a subdivision of Viña del Mar, was hypothesized immediately after the main event, when extensive damage was observed on the ridges of Canal Beagle. Using frequency-dependent spectral ratios of aftershock data obtained from a temporarily established dense array, it is shown that there is substantial amplification of motions at the ridges of Canal Beagle. The data set constitutes the first such set depicting topographical amplification at a heavily populated region and correlates well with the damage distribution observed during the main event. Dense arrays established in Viña del Mar also yielded extensive data which are quantified to show that, in the range of frequencies of engineering interest, there was substantial amplification at different sites of different geological formations. To substantiate this, spectral ratios developed from the strong-motion records of the main event are used to show the extensive degree of amplification at an alluvial site as compared to a rock site. Similarly, spectral ratios developed from aftershocks recorded at comparable stations qualitatively confirm that the frequency ranges for which the amplification of motions occur are quite similar to those from strong-motion records. In case of weak motions, the denser arrays established temporarily as described herein can be used to identify the frequency ranges for which amplification occurs, to quantify the degree of frequency-dependent amplification and used in microzonation of closely spaced localities.

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