Urban Seismology: on the origin of earth vibrations within a city

Díaz, Jordi; Ruiz, Mario; Sánchez‐Pastor, Pilar; Romero, Paula

doi:10.1038/s41598-017-15499-y

Cited by 111 publications

(88 citation statements)

References 46 publications

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“…In the 1‐ to 20‐Hz frequency band, urban anthropogenic activities (Díaz et al, ) are likely to be the main source of the seismic noise recorded by the MeSO‐net stations, which are mainly located in schools. This is confirmed by the fact that daily and weekly variations are visible in the CC( t ) and d v / v ( t ) at most stations.…”

Section: Coseismic and Postseismic Response Of The Near Surface In Grmentioning

confidence: 99%

Complex Near‐Surface Rheology Inferred From the Response of Greater Tokyo to Strong Ground Motions

et al. 2018

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Strong ground motion can induce dynamic strains large enough for the Earth's subsurface to respond nonlinearly and to cause permanent, or plastic, damage. The 2011 Mw 9.0 Tohoku‐Oki earthquake, Japan, generated exceptional and well‐recorded ground motions in the greater Tokyo area. We use continuous records from 234 stations of the dense MeSO‐net seismic network to monitor the temporal evolution of the material properties of the shallow subsurface (upper ∼100 m). We apply the single‐station cross‐correlation method to reconstruct the near‐surface reflectivity response through time. We find that the strong ground motions from the mainshock caused large perturbations in the near‐surface structure, with significant drops in seismic velocities up to 11%. For most sites, we observe a logarithmic and complete recovery of the seismic wave speed, suggesting a relaxation process that can be explained by a viscoelastic rheology. Some sites exhibit an instantaneous and permanent change, which suggests a plastic rheology. Finally, dense seismic measurements allow for statistical inference between seismic velocity drops, recovery time scales, and permanent perturbations and ground motion strength and site conditions. This study highlights the potential for seismic interferometry to assess near‐surface rheology with dense seismic arrays.

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Section: Coseismic and Postseismic Response Of The Near Surface In Grmentioning

confidence: 99%

Complex Near‐Surface Rheology Inferred From the Response of Greater Tokyo to Strong Ground Motions

et al. 2018

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“…The idea is to involve the secondary school community in the recording and interpretation of seismic data acquired within cities. Previous results have shown that many citizen activities produce vibrations that can be recorded seismically, including traffic (Riahi and Gerstoft, 2015), subway systems (Sheen et al, 2009), music concerts (Green and Bowers, 2008) or football games (Díaz et al, 2017). The identification of the vibrations generated by this kind of sources is useful to correctly interpret ambient noise data, but also to attract the attention of mass media (journals, radio, TV) and social networks and be used as a valuable tool for spreading news related to seismology and, in general, Earth sciences to the main public.…”

Section: Introductionmentioning

confidence: 99%

Seismometers Within Cities: A Tool to Connect Earth Sciences and Society

et al. 2020

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The high degree of human activities in urban environments produces large background vibrations that makes it difficult to use data acquired in these areas for classical seismology. Seismometers installed within cities have been typically been used for the study of seismic hazard or for monitoring civil engineering problems. However, with the development of monitoring techniques based on the interpretation of the so-called seismic ambient noise, these data have gained scientific interest. Our objective is to discuss an additional utility of seismometers deployed within a city; its use as a tool to connect society with Earth sciences. Many citizen activities, from traffic to music concerts, produce vibrations that can be recorded seismically, and our experience shows that these records attract the attention of the media and social networks. With the emergence of low-cost and easy-to-use instruments in recent years, more citizens can now record ground motion and become interested in the interpretation of the recorded seismograms. The installation of permanent seismic networks in educational centers has proven to be a good approach to introduce students to Earth sciences at the national level and can also be developed at the urban scale using this new instrumentation. In this contribution we will first review the previous results related to the identification of the sources of vibration in urban areas and then present a new ongoing project based on the deployment of a seismic network in educational centers located in the city of Barcelona.

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“…The ambient seismic noise recorded by seismometers includes microseisms and anthropogenic or cultural noise. While microseisms are caused by the coupling between the ocean and the solid earth at frequencies mostly <1 Hz 1 , anthropogenic seismic noise, especially in urban areas, includes seismic signals generated by human activities such as moving people and industrial activities [2][3][4][5] . A recent study reported an increase in ambient seismic noise energy in response to an increase in the gross domestic product (GDP), which is associated with the magnitude of human activity 6 .…”

Section: Introductionmentioning

confidence: 99%

“…Since an increase in ambient noise energy can be attributed to a wide range of human activities, ambient seismic noise in urban areas tends to be stronger and more complex. For instance, Díaz et al 5 monitored road tra c and subway trains along an avenue about 150 m away for frequencies >1 Hz (maximum energy between 8-35 Hz) and 20-40 Hz band, respectively. They succeeded in detecting signals generated by various anthropogenic noise including rock concerts, football games, and road tra c. Considering the temporary absence of a speci c noise source, Green et al 7 monitored the ambient seismic noise during a complete shutdown of the subway system during an industrial strike, and found clearly evident reduction for frequencies >25 Hz within 100 m distance but no reduction at a distance of ~600 m from the nearest subway line.…”

Section: Introductionmentioning

confidence: 99%

Temporal changes in anthropogenic seismic noise levels associated with economic and leisure activities during the COVID-19 pandemic

Nimiya

Ikeda

Tsuji

2020

Preprint

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Seismic noise of frequencies >1 Hz includes noise that is strongly related to human activities. Reduction in seismic noise during the COVID-19 pandemic has been observed worldwide as restrictions were imposed on numerous human activities to control outbreaks of the virus. In this context, we studied the effect of reduced anthropogenic activities during COVID-19 on the noise levels in the Tokyo metropolitan area, Japan, considering seasonal variation. A significant reduction in noise was observed during the emergency, including that of frequencies >20 Hz, which was associated with school activities. After lifting the state of emergency, noise reverted to previous levels immediately for weekdays, but gradually for Sunday. This was likely because economic activities instantly resumed post-emergency on weekdays; however, most people still continued to avoid non-essential outings on Sunday. We also observed seasonal variation related to school holidays, energy consumption, and industrial activity. Noise levels in the frequency range of 1–5 Hz were found to be related to construction activity, which increased in winter and gradually decreased from 2017. Our findings demonstrate that seismic noise can be used to monitor economic activities and movement of people at a local scale.

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Urban Seismology: on the origin of earth vibrations within a city

Cited by 111 publications

References 46 publications

Complex Near‐Surface Rheology Inferred From the Response of Greater Tokyo to Strong Ground Motions

Complex Near‐Surface Rheology Inferred From the Response of Greater Tokyo to Strong Ground Motions

Seismometers Within Cities: A Tool to Connect Earth Sciences and Society

Temporal changes in anthropogenic seismic noise levels associated with economic and leisure activities during the COVID-19 pandemic

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