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.

scholarly journals Effect of coronavirus lockdowns on the ambient seismic noise levels in Gujarat, northwest India

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ketan Singha Roy ◽  
Jyoti Sharma ◽  
Santosh Kumar ◽  
M. Ravi Kumar
Keyword(s):  
Urban Areas ◽  
Seismic Noise ◽  
Anthropogenic Activities ◽  
Anthropogenic Activity ◽  
Noise Levels ◽  
Geological Conditions ◽  
Northwest India ◽  
Almost All ◽  
Cultural Noise ◽  
The Impact

AbstractThe Covid-19 pandemic created havoc and forced lockdowns in almost all the countries worldwide, to inhibit social spreading. In India as well, as a precautionary measure, complete and partial lockdowns were announced in phases during March 25 to May 31, 2020. The restricted human activities led to a drastic reduction in seismic background noise in the high frequency range of 1–20 Hz, representative of cultural noise. In this study, we analyse the effect of anthropogenic activity on the Earth vibrations, utilizing ambient noise recorded at twelve broadband seismographs installed in different environmental and geological conditions in Gujarat. We find that the lockdowns caused 1–19 dB decrease in seismic noise levels. The impact of restricted anthropogenic activities is predominantly visible during the daytime in urban areas, in the vicinity of industries and/or highways. A 27–79% reduction in seismic noise ground displacement (drms) is observed in daytime during the lockdown, in populated areas. However, data from station MOR reveals a drastic decrease in drms amplitude both during the day (79%) and night times (87%) since factories in this area operate round the clock. The noise at stations located in remote areas and that due to microseisms, shows negligible variation.

GEOTHERMAL GROUND‐NOISE SURVEYS

Geophysics ◽  
1972 ◽  
Vol 37 (5) ◽  
pp. 813-824 ◽  
Author(s):  
E. J. Douze ◽  
G. G. Sorrells
Keyword(s):  
Heat Flow ◽  
High Surface ◽  
Noise Levels ◽  
Imperial Valley ◽  
Geothermal Resources ◽  
Field Surveys ◽  
Short Period ◽  
Gravity Measurements ◽  
Ground Noise

In recent years there has been increasing interest in the role of geothermal steam as a source of energy. Only recently has geophysical exploration begun to play a major role in the exploration for geothermal resources; heat flow, gravity, and resistivity measurements have been the techniques most used. One recent development is the discovery that high surface‐noise levels are associated with the presence of geothermal reservoirs below the surface. Field surveys using short‐period seismographs have been conducted in the Imperial Valley of California in areas where heatflow measurements or drilling have indicated the presence of a geothermal deposit. In all three surveys abnormally high noise levels were found above the reservoir in the frequency range of 0.5 to 5.0 hz. The ground‐noise anomalies show a more complex pattern than the associated heat flow and gravity measurements. A theoretical model has been developed in which small, random pressure variations in a convecting geothermal reservoir are suggested as the source of the noise. Using this model, the noise level above one of the anomalies was duplicated, using a reasonably sized reservoir with pressure variations of less than 1 millibar.

High-frequency seismic noise as a function of depth

1991 ◽  
Vol 81 (4) ◽  
pp. 1101-1114
Author(s):  
Jerry A. Carter ◽  
Noel Barstow ◽  
Paul W. Pomeroy ◽  
Eric P. Chael ◽  
Patrick J. Leahy
Keyword(s):  
New York ◽  
High Frequency ◽  
Seismic Noise ◽  
Low Frequency ◽  
Time Variability ◽  
Orthogonal Components ◽  
The Difference ◽  
Frequency Coherence ◽  
Cultural Noise ◽  
Natural Wind

Abstract Evidence is presented supporting the view that high-frequency seismic noise decreases with increased depth. Noise amplitudes are higher near the free surface where surface-wave noise, cultural noise, and natural (wind-induced) noise predominate. Data were gathered at a hard-rock site in the northwestern Adirondack lowlands of northern New York. Between 15- and 40-Hz noise levels at this site are more than 10 dB less at 945-m depth than they are at the surface, and from 40 to 100 Hz the difference is more than 20 dB. In addition, time variability of the spectra is shown to be greater at the surface than at either 335- or 945-m depths. Part of the difference between the surface and subsurface noise variability may be related to wind-induced noise. Coherency measurements between orthogonal components of motion show high-frequency seismic noise is more highly organized at the surface than it is at depth. Coherency measurements between the same component of motion at different vertical offsets show a strong low-frequency coherence at least up to 945-m vertical offsets. As the vertical offset decreases, the frequency band of high coherence increases.

‘Backwards talk’ in Smith Island, Maryland

2021 ◽  
pp. 1-47
Author(s):  
Natalie Schilling
Keyword(s):  
Atlantic Coast ◽  
Critical Evaluation ◽  
Central Function ◽  
Smith Island ◽  
The Face ◽  
Nonliteral Language ◽  
Potential Loss ◽  
Community Continuity ◽  
The U.S

This article presents an exploration of the discourse-level phenomenon known as ‘backwards talk’ in Smith Island, a small, endangered dialect community in Maryland’s Chespaeake Bay, on the U.S. mid-Atlantic coast. The article examines how backwards talk, basically pervasive, highly creative irony, compares with irony more generally; how it patterns across generations and contexts; how important it is to island residents, who view backwards talk as the defining feature of their dialect; and why the feature has gained such importance in the face of dialect loss - and potential loss of community continuity as well. Because backwards talk is irony, it has important solidarity functions. As playful, nonliteral language, it serves as a symbol of the performed ‘islandness’ that islanders increasingly take up as they come into more and more contact with outsiders. Finally, as a means of offering critical evaluation of outsiders, backwards talk can be seen as a form of anti-language or counterlanguage, with a central function of resistance against outside forces.

Source characteristics of earthquakes along the southern San Jacinto and Imperial fault zones (1937 to 1954)

1990 ◽  
Vol 80 (5) ◽  
pp. 1099-1117 ◽  
Author(s):  
Diane I. Doser
Keyword(s):  
Heat Flow ◽  
Source Parameters ◽  
Waveform Inversion ◽  
High Heat ◽  
Seismogenic Zone ◽  
Data Sets ◽  
Imperial Valley ◽  
Rupture Length ◽  
Lower Heat ◽  
Inversion Techniques

Abstract Body waveform inversion techniques are used to study the source parameters of four earthquakes occurring between 1937 and 1954 along the southern San Jacinto and Imperial faults (1937 Buck Ridge, 1940 Imperial Valley, 1942 Borrego Mountain, and 1954 Salada Wash events). All earthquakes had simple rupture histories with the exception of the 1940 Imperial Valley main shock, which consisted of at least four subevents whose relative locations indicate unilateral rupture toward the southeast. Earthquakes in regions of high heat flow (>80 mW/m2) had focal depths near the base of the seismogenic zone (8 to 10 km). The 1937 Buck Ridge earthquake, located in a region of lower heat flow, however, appears to have occurred at a shallow (3 ± 2 km) depth. The location, mechanism, and aftershock distribution for the 1942 Borrego Mountain earthquake suggest it could have occurred along the Split Mountain fault, a recently identified northeast-trending cross fault located between the Elsinore and Coyote Creek faults or along an unnamed fault that parallels the trend of the Coyote Creek fault. Moment and rupture length estimates obtained from this study agree well with estimates obtained in previous studies that used different data sets.

Oye Shelly

2018 ◽  
pp. 33-66
Author(s):  
Miroslava Chávez-García
Keyword(s):  
English Language ◽  
Letter Writing ◽  
Imperial Valley ◽  
Green Card ◽  
1960S And 1970S ◽  
The 1960S ◽  
Working And Living Conditions ◽  
Cultural Tools ◽  
The U.S

To explore the ways in which migrants negotiated longing, gender, intimacy, courtship, marriage, and identity across the U.S.-Mexico borderlands in the 1960s and 1970s, chapter 1 opens by examining and analyzing the broader racial, labor, and environmental contexts shaping José Chávez’s—the author’s father—experience as a Mexican laborer in Imperial Valley in the 1950s and 1960s. Specifically, it pays attention to working and living conditions in el valle and how those contributed to his loneliness, isolation, and ambivalence as a border dweller, despite his status as a green card holder and his ability to engage in return migration. Next, it examines letter writing as a form of courtship as detailed in the love letters he crafted and the cultural tools—stylized letter writing, the English language, portraits, songs, movies, and the radio—he drew upon to convince Maria Concepción “Conchita” Alvarado—the author’s mother—to accept his marriage proposal. Finally, it shows that while Conchita never formally agreed to the nuptials, she walked down the aisle and married José, an act that set her life on a new course. Indeed, within a few days, she left her hometown and relocated with José to the Mexicali-Calexico border, where they set out to create a new future for themselves.

To: “Search for Geothermal Seismic Noise in the East Mesa Area, Imperial Valley, California,” (v. 40, December 1975, p. 1066–1072).

Geophysics ◽  
1976 ◽  
Vol 41 (2) ◽  
pp. 335-335
Author(s):  
H. M. Iyer
Keyword(s):  
Seismic Noise ◽  
Imperial Valley

In the article, “Search for Geothermal Seismic Noise in the East Mesa Area, Imperial Valley, California,” by H. M. Iyer (v. 40, December 1975, p. 1066–1072), the following corrections should be made:

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

scholarly journals COVID-19 Societal Response Captured by Seismic Noise in China and Italy

2020 ◽  
Vol 91 (5) ◽  
pp. 2757-2768 ◽  
Author(s):  
Han Xiao ◽  
Zachary Cohen Eilon ◽  
Chen Ji ◽  
Toshiro Tanimoto
Keyword(s):  
Human Activities ◽  
Seismic Noise ◽  
Mainland China ◽  
Transportation Systems ◽  
Noise Power ◽  
Travel Restrictions ◽  
Noise Data ◽  
Seismic Records ◽  
Cultural Noise ◽  
The Relationship

Abstract Seismic noise with frequencies above 1 Hz is often called “cultural noise” and is generally correlated quite well with human activities. Recently, cities in mainland China and Italy imposed restrictions on travel and day-to-day activity in response to COVID-19, which gave us an unprecedented opportunity to study the relationship between seismic noise above 1 Hz and human activities. Using seismic records from stations in China and Italy, we show that seismic noise above 1 Hz was primarily generated by the local transportation systems. The lockdown of the cities and the imposition of travel restrictions led to an ∼4–12  dB decrease in seismic noise power in mainland China. Data also show that different Chinese cities experienced distinct periods of diminished cultural noise, related to differences in local response to the epidemic. In contrast, there was only ∼1–6  dB decrease of seismic noise power in Italy, after the country was put under a lockdown. The noise data indicate that traffic flow did not decrease as much in Italy and show how different cities reacted distinctly to the lockdown conditions.

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