scholarly journals A time-lapse gravity survey of the Coso geothermal field, China Lake Naval Air Weapons Station, California

2018 ◽  
Author(s):  
Geoffrey Phelps ◽  
Collin Cronkite-Ratcliff ◽  
Kelly Blake
Keyword(s):  
Time Lapse ◽  
Geothermal Field ◽  
Gravity Survey ◽  
Coso Geothermal Field ◽  
China Lake

Recent earthquake sequences at Coso: Evidence for conjugate faulting and stress loading near a geothermal field

1999 ◽  
Vol 89 (3) ◽  
pp. 785-795 ◽  
Author(s):  
Joydeep Bhattacharyya ◽  
Susanna Gross ◽  
Jonathan Lees ◽  
Mike Hastings
Keyword(s):  
Geothermal Field ◽  
Fault System ◽  
Fault Plane Solutions ◽  
Temporal Decay ◽  
Background Seismicity ◽  
Surface Ruptures ◽  
Temporal And Spatial Characteristics ◽  
Coso Geothermal Field ◽  
The One ◽  
Earthquake Sequences

Abstract Two recent earthquake sequences near the Coso geothermal field show clear evidence of faulting along conjugate planes. We present results from analyzing an earthquake sequence occurring in 1998 and compare it with a similar sequence that occurred in 1996. The two sequences followed mainshocks that occurred on 27 November 1996 and 6 March 1998. Both mainshocks ruptured approximately colocated regions of the same fault system. Following a comparison with the background seismicity of the Coso region, we have detected evidence of stress loading within the geothermal field that appears to be in response to the 1998 earthquakes. The ML = 5.2 mainshock in the 1998 sequence occurred at 5:47 a.m. UTC and was located approximately 45 km north of the town of Ridgecrest in the Coso range. The mainshock of the 1996 sequence had an ML magnitude of 5.3. There have been no observable surface ruptures associated with either of these sequences. Though the mainshocks for both sequences were located about 900 m apart and have nearly the same local magnitudes, the sequences differ in both their temporal and spatial characteristics. An analysis of the fault-plane solutions of the mainshocks and the aftershock locations suggests that the two sequences ruptured fault planes that are perpendicular to one another. We observe a much faster temporal decay of the 1998 sequence compared to the one in 1996; moreover, while the 1996 sequence was not followed by any sizeable (i.e., ML > 4.0) aftershocks, the 1998 sequence had four such events. From an estimate of the tectonic stressing rate on the fault that produced the 1998 sequence, we infer a repeat cycle of 135 years for an earthquake of comparable magnitude at Coso.

A joint geophysical analysis of the Coso geothermal field, south-eastern California

2013 ◽  
Vol 214 ◽  
pp. 25-34 ◽  
Author(s):  
Antony M. Wamalwa ◽  
Kevin L. Mickus ◽  
Laura F. Serpa ◽  
Diane I. Doser
Keyword(s):  
Geothermal Field ◽  
South Eastern ◽  
Coso Geothermal Field

Tidal modulation of seismicity at the Coso geothermal field

2022 ◽  
Vol 579 ◽  
pp. 117335
Author(s):  
Wei Wang ◽  
Peter M. Shearer ◽  
John E. Vidale ◽  
Xiaohua Xu ◽  
Daniel T. Trugman ◽  
...  
Keyword(s):  
Geothermal Field ◽  
Coso Geothermal Field

scholarly journals Problem Pengolahan Data Gaya Berat Mikro antar Waktu

2016 ◽  
Vol 3 (02) ◽  
pp. 130
Author(s):  
Supriyadi S
Keyword(s):  
Fourier Transform ◽  
Fast Fourier Transform ◽  
Frequency Domain ◽  
Time Domain ◽  
Groundwater Level ◽  
Time Lapse ◽  
Density Change ◽  
Gravity Survey ◽  
Micro Gravity

<span>At time lapse microgravity survey will be got data in place for difference period. The Anomaly <span>caused by subsidence and density change under surface which related to groundwater level <span>change. This matter become problem when will take one of the anomaly sources to processed <span>is furthermore. Reduction one of anomaly source cannot be done direct but must be done with <span>filtering process. Process filtering done by using FFT (Fast Fourier Transform), its principal is <span>to move data from time domain to frequency domain. At frequency domain this is mathematics <span>process conducted. On subsidence case study in Semarang by using this technique indicate that <span>subsidence value from time lapse micro gravity survey have tendency is equal to result from <span>geodesy survey.</span></span></span></span></span></span></span></span><br /></span>

Experiences with relative microgravity surveying

2020 ◽  
Author(s):  
Ola Eiken
Keyword(s):  
Random Noise ◽  
Measurement Techniques ◽  
Water Reservoir ◽  
Cold Atom ◽  
Time Lapse ◽  
Geothermal Field ◽  
Personnel Cost ◽  
Multiple Sensors ◽  
Accuracy Measure ◽  
Superconducting Gravimeters

&lt;p&gt;&lt;strong&gt;Measurement techniques&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;High-precision aerial gravity surveys can be carried out by relative spring meters, with ties to stable reference stations or absolute measurements for time-lapse studies. Instrument drift is controlled by frequent repeat measurement and repeatability of 1-3 &amp;#181;Gal has been common. &amp;#160;Free-fall gravimeters are heavier and costlier but provide absolute values and are immune to drift. Superconducting gravimeters are stationary and provide sub-&amp;#181;Gal resolution over days and weeks, while drift uncertainty can build up to several &amp;#956;Gal over years. Cold atom gravimeters are under development and may provide yet another survey alternative in the future.&lt;/p&gt;&lt;p&gt;Multiple sensors and multiple repeats are effective ways of improving survey precision, as much of the noise reduce at random noise (sqrt(N)). This holds also for the sensor drift residuals. An efficient, transparent and reproducible processing software is an integral part of such techniques.&lt;/p&gt;&lt;p&gt;&lt;strong&gt;Surface stations&lt;/strong&gt;&lt;/p&gt;&lt;p&gt;Stability of measurement platforms over years is required for &amp;#181;Gal time-lapse precision and can be achieved by installing geodetic monuments. For optimal monitoring of targets like a producing oil, gas or geothermal field, a water reservoir or a volcano, a grid of stations with spacing equal to or smaller than the overburden thickness is required. Surface subsidence or uplift requires sub-cm precision which can be obtained by optical leveling, InSAR or GPS.&lt;/p&gt;&lt;p&gt;Accuracy&lt;/p&gt;&lt;p&gt;Station repeatability is a robust accuracy measure for relative surveys with multiple occupations of each station. Together with multiple sensors they provide abundant statistics. The redundancy also allows for in-situ calibration of parameters for scale factor, tilt and temperature by minimizing residuals. Time-lapse precision can be judged at stations with minimal or known subsurface changes, and will be affected by gravity survey precision, accuracy of measured depth changes and other time-lapse effects such as benchmark stability and time-lapse signals outside interest. Groundwater variations could be one such noise term, unless the purpose is hydrology monitoring.&lt;/p&gt;&lt;p&gt;Efficiency and cost&lt;/p&gt;&lt;p&gt;Most microgravity projects have been carried out in a research or development setting, with one sensor, few stations repeat and implicit capital and personnel cost. In a more industrial setting, efficiency is likely to improve, together with reduced survey cost. More instruments and measurements will likely reduce the personnel and mobilization portion of the cost. Precision/cost tradeoffs and value of data will determine the economics of a project, whether in a scientific or commercial setting.&lt;/p&gt;&lt;p&gt;Conclusion&lt;/p&gt;&lt;p&gt;Currently proven survey repeatabilities of 1-2 &amp;#181;Gal may be regarded state-of-the-art and become commonplace for microgravity surveys using relative gravimeters. This can widen the range of applications and reduce monitoring intervals. Further instrument developments may improve this limitation.&lt;/p&gt;

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