Characterizing the Performance of New Seismic Stations in Southeastern Region, Korea Using Seismic Noise Levels

2019 ◽  
Vol 23 (6) ◽  
pp. 321-327
Author(s):  
Jin Soo Shin ◽  
◽  
Yun-Jeong Seong ◽  
Minkyung Son
Keyword(s):  
Seismic Noise ◽  
Noise Levels ◽  
Seismic Stations ◽  
Southeastern Region

scholarly journals COVID-19 lockdown effects on the seismic recordings in Central America

Solid Earth ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 2127-2144
Author(s):  
Mario Arroyo-Solórzano ◽  
Diego Castro-Rojas ◽  
Frédérick Massin ◽  
Lepolt Linkimer ◽  
Ivonne Arroyo ◽  
...  
Keyword(s):  
Costa Rica ◽  
El Salvador ◽  
Central America ◽  
Seismic Noise ◽  
Temporal Variations ◽  
Noise Levels ◽  
Contributing Factors ◽  
Seismic Stations ◽  
Before And After ◽  
Seismic Records

Abstract. A noticeable decrease in seismic noise was registered worldwide during the lockdown measures implemented in 2020 to prevent the spread of COVID-19. In Central America, strong lockdown measures started during March of 2020. In this study, we used seismic stations from Costa Rica, Guatemala, El Salvador, and Nicaragua to study the effects of these measures on seismic records by characterizing temporal variations in the high-frequency band (4–14 Hz) via spectral and amplitude analyses. In addition, we studied the link between the reduction in seismic noise and the number of earthquake detections and felt reports in Costa Rica and Guatemala. We found that seismic stations near the capitals of Costa Rica, Guatemala, and El Salvador presented a decrease in their typical seismic noise levels, from 200 to 140, from 100 to 80, and from 120 to 80 nm, respectively. Our results showed that the largest reduction of ∼ 50 % in seismic noise was observed at seismic stations near main airports, busy roads, and densely populated cities. In Nicaragua, the seismic noise levels remained constant (∼ 40 nm), as no lockdown measures were applied. We suggest that the decrease in seismic noise levels may have increased earthquake detections and the number of felt reports of low-magnitude earthquakes. However, the variations observed in several seismic parameters before and after the lockdown are not significant enough to easily link our observations or separate them from other contributing factors. Our results imply that the study of seismic noise levels can be useful to verify compliance with lockdown measures and to explore their effects on earthquake detection and felt reports.

scholarly journals The effect of confinement due to COVID-19 on seismic noise in Mexico

Solid Earth ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 1411-1419
Author(s):  
Xyoli Pérez-Campos ◽  
Víctor H. Espíndola ◽  
Daniel González-Ávila ◽  
Betty Zanolli Fabila ◽  
Víctor H. Márquez-Ramírez ◽  
...  
Keyword(s):  
Signal Processing ◽  
Mexico City ◽  
Noise Level ◽  
Seismic Noise ◽  
Noise Levels ◽  
Traffic Light ◽  
Economic Activities ◽  
Seismic Stations ◽  
The World ◽  
The City

Abstract. The world experienced the beginning of the COVID-19 pandemic by the end of 2019 to the beginning of 2020. Governments implemented strategies to contain it, most based on lockdowns. Mexico was no exception. The lockdown was initiated in March 2020, and with it, a reduction in the seismic noise level was witnessed by the seismic stations of the national and Valley of Mexico networks. Stations located in municipalities with more than 50 000 people usually experience larger seismic noise levels at frequencies between 1 and 5 Hz, associated with human activity. The largest noise levels are recorded in Mexico City, which has the largest population in the country. The largest drop was observed in Hermosillo, Sonora; however, it was also the city with the fastest return to activities, which seems to correlate with a quick increase in confirmed COVID-19 cases. Mexico initiated a traffic-light system to modulate the re-opening of economic activities for each state. Therefore, since 1 June, noise levels have generally reflected the colour of the state traffic light. Furthermore, the reduction in the noise level at seismic stations has allowed identification of smaller earthquakes without signal processing. Also, people in cities have perceived smaller or more distant quakes.

scholarly journals The effect of confinement due to COVID-19 on seismic noise in Mexico

2020 ◽  
Author(s):  
Xyoli Pérez-Campos ◽  
Víctor H. Espíndola ◽  
Daniel González-Ávila ◽  
Betty Zanolli Fabila ◽  
Víctor H. Márquez-Ramírez ◽  
...  
Keyword(s):  
Signal Processing ◽  
Mexico City ◽  
Noise Level ◽  
Seismic Noise ◽  
Noise Levels ◽  
Traffic Light ◽  
Economic Activities ◽  
Seismic Stations ◽  
The World ◽  
The City

Abstract. The world experienced the beginning of the COVID-19 pandemic by the end of 2019, beginning of 2020. Governments implemented strategies to contain it, most based on lockdowns. Mexico was not the exception. The lockdown was initiated in March 2020 and with it, a reduction on the seismic noise level was witnessed by the seismic stations of the national and the Valley of Mexico networks. Stations located in municipalities with more than 50,000 people usually experience larger seismic noise levels at frequencies between 1 to 5 Hz, associated with human activity. The largest noise levels are recorded in Mexico City, with the largest population in the country. The largest drop was observed in Hermosillo, Sonora, however, it was also the city with the fastest return to activities, which seems to correlate with a quick increase in confirmed COVID-19 cases. Mexico initiated a traffic-light system to modulate the re-opening of economic activities for each state. Therefore, since 1 June, noise levels reflect, in general, the colour of the state traffic light. Furthermore, the reduction in the noise level at seismic stations has allowed identification of smaller earthquakes without signal processing. Also, people in cities have perceived smaller or distant quakes.

scholarly journals Covid-19 lockdown effects on the seismic recordings of Central America

2021 ◽  
Author(s):  
Mario Arroyo-Solórzano ◽  
Diego Castro-Rojas ◽  
Frédérick Massin ◽  
Lepolt Linkimer ◽  
Ivonne Arroyo ◽  
...  
Keyword(s):  
Costa Rica ◽  
El Salvador ◽  
Central America ◽  
Seismic Data ◽  
Seismic Noise ◽  
Temporal Variations ◽  
Noise Levels ◽  
Seismic Stations ◽  
Earthquake Detection ◽  
Seismic Records

Abstract. A noticeable decrease in seismic noise was registered worldwide during the lockdown measurements of 2020 to prevent the Covid-19. In Central America, strong lockdown measures started during March of 2020. We have used seismic stations from Costa Rica, Guatemala, El Salvador, and Nicaragua to study the effects of these measures on seismic records by characterizing temporal variations in the high-frequency band (4–14 Hz) via spectral and amplitude analyses. In addition, we study the link between the reduction of seismic noise and the number of earthquake detection and felt reports in Costa Rica and Guatemala. We found that seismic stations near the capitals of Costa Rica, Guatemala, and El Salvador, presented a decrease in the typical seismic noise level from 200 to 140 nm, 100 to 80 nm, and 120 to 80 nm, respectively. Our results showed that the largest reduction of ~50 % in seismic noise were observed in seismic stations near main airports, busy roads, and densely populated cities. In Nicaragua, the seismic noise levels remained constant (~40 nm) as no lockdown measures were applied. We noted that the decrease in seismic noise levels allowed to improve earthquake locations and increment the number of reports of low magnitude felt earthquakes. Our results imply that seismic data can be useful to verify the compliance of lockdown measures and to explore effects of the decrease in the seismic noise in the earthquake detection and felt reports.

Temporal evolution of relative seismic velocity in the Golf of Corinth - Greece.

2021 ◽  
Author(s):  
Estelle Delouche ◽  
Laurent Stehly
Keyword(s):  
Lower Crust ◽  
Seismic Noise ◽  
Seismic Velocity ◽  
Temporal Evolution ◽  
Velocity Variation ◽  
Extension Rate ◽  
Fluid Migration ◽  
Seismic Stations ◽  
Gulf Of Corinth ◽  
Seismic Swarms

<p>Our aim is to monitor the temporal evolution of the crust in Greece, with a particular focus on the Gulf of Corinth.  Indeed, Greece is one of the most exposed country to earthquakes in Europe. The Gulf of Corinth,  is known for its fast extension rate of about 15 mm/yr in the western part and 10mm/yr in the eastern part. This fast extension is associated with recurrent seismic swarms and by a few destructive earthquakes. This seismicity is likely the result of a combination of multiple driving processes including fluid migration at depth.</p><p>In the present work, we use seismic noise recorded from 2010 to 2020 by all seismic stations deployed in Greece, and in particular by the dense Corinth Rift Laboratory network, to compute the seismic velocity variation (dv/v) in several subregions. By comparing the result obtained at different periods, we are able to distinguish the temporal evolution of the upper, mid and lower crust. This temporal evolution is compared to the seismicity of the Gulf of Corinth.</p>

scholarly journals SEARCH FOR GEOTHERMAL SEISMIC NOISE IN THE EAST MESA AREA, IMPERIAL VALLEY, CALIFORNIA

Geophysics ◽  
1975 ◽  
Vol 40 (6) ◽  
pp. 1066-1072 ◽  
Author(s):  
H. M. Iyer
Keyword(s):  
Heat Flow ◽  
Seismic Noise ◽  
Critical Evaluation ◽  
Thermal Gradients ◽  
Noise Levels ◽  
Imperial Valley ◽  
Bureau Of Reclamation ◽  
Cultural Noise ◽  
Noise Experiment ◽  
The U.S

A seismic noise experiment was conducted in the East Mesa area of Imperial Valley, California, by the U.S. Geological Survey (USGS) in May 1972. There is a pronounced heat flow anomaly over the area, and between July 1972 and the present five deep test wells have been drilled over the anomaly by the U.S. Bureau of Reclamation (U.S. Bureau of Reclamation, 1974). At the time of our survey, we were aware of results from a preliminary seismic noise survey in East Mesa by Teledyne Geotech (Douze and Sorrells, 1972). A detailed noise survey was conducted by Teledyne Geotech soon after our experiment (Geothermal Staff of Teledyne Geotech, 1972). Both the Teledyne Geotech surveys show noise levels (in the 3.0 to 5.0 hz band) 12–18 db higher over the area where the thermal gradients and heat flow reach maximum values than in the surroundings. Our results, on the other hand, show that the seismic noise field in the area is dominated by cultural noise, and it is impossible to see a noise anomaly that can be related to the geothermal phenomena in East Mesa. We think that it is important to take into account this disagreement between the two results in order to make a critical evaluation of the utility of seismic noise as a geothermal prospecting tool. The purpose of this note is to put our findings on record.

Seismic Noise Levels in Northern Baja California, Mexico

2019 ◽  
Vol 109 (2) ◽  
pp. 610-620 ◽  
Author(s):  
Erik E. Ramírez ◽  
J. Antonio Vidal‐Villegas ◽  
M. Alejandra Nuñez‐Leal ◽  
Jorge Ramírez‐Hernández ◽  
Adán Mejía‐Trejo ◽  
...  
Keyword(s):  
Seismic Noise ◽  
Baja California ◽  
Noise Levels

SEISMIC NOISE MEASUREMENTS IN YELLOWSTONE NATIONAL PARK

Geophysics ◽  
1974 ◽  
Vol 39 (4) ◽  
pp. 389-400 ◽  
Author(s):  
H. M. Iyer ◽  
Tim Hitchcock
Keyword(s):  
Yellowstone National Park ◽  
Seismic Noise ◽  
National Park ◽  
Hot Springs ◽  
Spectral Band ◽  
Spectral Characteristics ◽  
Frequency Noise ◽  
Noise Levels ◽  
High Noise ◽  
Geothermal Activity

In September and October, 1972 the U. S. Geological Survey made an investigation of seismic noise associated with the known geothermal phenomena in Yellowstone National Park. Eighty‐four stations, each recording for at least 48 hours, were operated. All major geyser basins were covered by the experiment. L-shaped three‐element arrays, three‐component stations, and single vertical component stations were operated. Four eight‐element mobile arrays were operated to study propagation characteristics of the noise. Preliminary analysis of data shows that high noise levels are associated with all the major thermal areas in the park. An elongated band of high noise envelops Lower and Upper Geyser Basins; noise levels are high around Norris Basin, Mammoth Hot Springs, Sulphur Mountain, and Mud Volcano; and a strong noise field exists around Lower and Upper Falls of the Yellowstone River. The seismic waves generated by the waterfalls have very different spectral characteristics from the waves associated with geothermal activity. The geothermal noise is predominantly in the spectral band of 2–8 hz, whereas the waterfall noise is predominantly around 2 hz. A mobile array operated near Norris Basin showed coherent wave trains radiating from seismic sources in the basin. Seismic noise measured around 50 m from Old Faithful Geyser showed amplitude fluctuations that followed the eruption cycles of the geyser. A few minutes after each eruption, the noise level starts rising slowly in ramplike fashion. Twenty to thirty minutes before the next eruption, sharp bursts of noise activity occur with increasing rapidity and continue for a few minutes after the eruption. The predominant energy of seismic noise generated by Old Faithful is at frequencies well above 8 hz. We postulate that only such high frequency noise is generated by the surface activity of geysers and hot springs and that the lower frequency noise found in and around the geyser basins is generated by a deeper convection system associated with the geothermal activity.

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

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Hiro Nimiya ◽  
Tatsunori Ikeda ◽  
Takeshi Tsuji
Keyword(s):  
Seismic Noise ◽  
Ambient Noise ◽  
Anthropogenic Activities ◽  
Leisure Activities ◽  
Time Of Day ◽  
Noise Levels ◽  
Economic Activities ◽  
State Of Emergency ◽  
Tokyo Metropolitan Area ◽  
Day Of The Week

AbstractSeismic ambient noise with frequencies > 1 Hz includes noise related to human activities. A reduction in seismic noise during the COVID-19 pandemic has been observed worldwide, as restrictions were imposed to control outbreaks of the SARS-CoV-2 virus. In this context, we studied the effect of changes in anthropogenic activities during COVID-19 on the seismic noise levels in the Tokyo metropolitan area, Japan, considering time of day, day of the week, and seasonal changes. The results showed the largest reduction in noise levels during the first state of emergency under most conditions. After the first state of emergency was lifted, the daytime noise reverted to previous levels immediately on weekdays and gradually on Sundays. This was likely because economic activities instantly resumed, while non-essential outings on Sundays were still mostly avoided. Furthermore, the daytime noise level on Sundays was strongly reduced regardless of changes on weekdays after the second state of emergency, which restricted activities mainly at night. Sunday noise levels gradually increased from the middle of the second state of emergency, suggesting a gradual reduction in public concern about COVID-19 following a decrease in the number of infections. Our findings demonstrate that seismic noise can be used to monitor social activities.

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