Near-surface imaging from traffic-induced surface waves with dense linear arrays: an application in the urban area of Hangzhou, China

Geophysics ◽  
2021 ◽  
pp. 1-57
Author(s):  
Binbin Mi ◽  
Jianghai Xia ◽  
Gang Tian ◽  
Zhanjie Shi ◽  
Huaixue Xing ◽  
...  

Accurate understanding of near-surface structures of the solid Earth is challenging, especially in urban areas where active source seismic surveys are constrained and difficult to perform. The analysis of anthropogenic seismic noise provides an alternative way to image the shallow subsurface in urban environments. We present an application of using traffic noise with seismic interferometry to investigate near-surface structures in Hangzhou City, eastern China. Noise data were recorded by dense linear arrays with approximately 5 m spacing deployed along two crossing roads. We analyze the characteristics of traffic-induced noise using 36 hr continuous recordings. Coherent Rayleigh surface waves between 2 and 20 Hz are retrieved based on crosscorrelations within 1 hr time windows. Robust phase-velocity dispersion curves are extracted from virtual shot gathers using multichannel analysis of surface waves and coincide with the results from active seismic data, noise beamforming analysis, and measurements with the spatial autocorrelation method (SPAC). Shear-wave velocity profiles are derived for the top 100 m of the subsurface at the array locations. The estimated shear-wave velocities from traffic noise correspond to the velocities estimated from logging data. The 2D shear-wave velocity maps reveal different soil deposits and bedrock structures in the estuarine sedimentary area. The results demonstrate the accuracy and efficiency of delineating near-surface structures from traffic-induced noise, which has great potential for monitoring subsurface changes in urban areas.

Solid Earth ◽  
2019 ◽  
Vol 10 (2) ◽  
pp. 379-390 ◽  
Author(s):  
Yaniv Darvasi ◽  
Amotz Agnon

Abstract. Instrumental strong motion data are not common around the Dead Sea region. Therefore, calibrating a new attenuation equation is a considerable challenge. However, the Holy Land has a remarkable historical archive, attesting to numerous regional and local earthquakes. Combining the historical record with new seismic measurements will improve the regional equation. On 11 July 1927, a rupture, in the crust in proximity to the northern Dead Sea, generated a moderate 6.2 ML earthquake. Up to 500 people were killed, and extensive destruction was recorded, even as far as 150 km from the focus. We consider local near-surface properties, in particular, the shear-wave velocity, as an amplification factor. Where the shear-wave velocity is low, the seismic intensity far from the focus would likely be greater than expected from a standard attenuation curve. In this work, we used the multichannel analysis of surface waves (MASW) method to estimate seismic wave velocity at anomalous sites in Israel in order to calibrate a new attenuation equation for the Dead Sea region. Our new attenuation equation contains a term which quantifies only lithological effects, while factors such as building quality, foundation depth, topography, earthquake directivity, type of fault, etc. remain out of our scope. Nonetheless, about 60 % of the measured anomalous sites fit expectations; therefore, this new ground-motion prediction equation (GMPE) is statistically better than the old ones. From our local point of view, this is the first time that integration of the 1927 historical data and modern shear-wave velocity profile measurements improved the attenuation equation (sometimes referred to as the attenuation relation) for the Dead Sea region. In the wider context, regions of low-to-moderate seismicity should use macroseismic earthquake data, together with modern measurements, in order to better estimate the peak ground acceleration or the seismic intensities to be caused by future earthquakes. This integration will conceivably lead to a better mitigation of damage from future earthquakes and should improve maps of seismic hazard.


2019 ◽  
Vol 46 (16) ◽  
pp. 9497-9508 ◽  
Author(s):  
Y. Miao ◽  
Y. Shi ◽  
H. Y. Zhuang ◽  
S. Y. Wang ◽  
H. B. Liu ◽  
...  

2020 ◽  
Vol 91 (6) ◽  
pp. 3381-3390
Author(s):  
Hai-Yun Wang ◽  
Wei-Ping Jiang

Abstract The shear-wave velocity (VS) in soil is an important parameter to characterize dynamic soil properties. The Delaney Park downhole array was deployed in 2003 without measuring the shear- and compression-wave velocity (VS and VP) profiles. Thornley et al. (2019) measured the VS and VP profiles using the downhole method after the sensor was removed from the 61 m borehole with casing in the array. However, the waves propagating along the casing wall may have a great influence on the recognition of the first arrival of waves propagating in the soil. Using horizontal and vertical components of weak-motion data of eight local earthquakes recorded by the array, in situ VS and VP profiles were assessed by the seismic interferometry based on deconvolution, respectively. The results are as follows. The VS and VP profiles computed by this study and measured by Thornley et al. (2019) are in relatively good agreement at a depth of 10–45 m and at a depth of 30–45 m, respectively, and in very poor agreement at other depths. The average VS profiles computed by this study are more consistent with the derived VS from the standard penetration test data at the site with slower near-surface velocities relative to the downhole logging analysis. There are strong anisotropy in the strata below 45 m and weak anisotropy with various degrees at various depths in the strata above 45 m.


2006 ◽  
Vol 96 (5) ◽  
pp. 1897-1914 ◽  
Author(s):  
R. D. Andrus ◽  
C. D. Fairbanks ◽  
J. Zhang ◽  
W. M. Camp ◽  
T. J. Casey ◽  
...  

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