scholarly journals The source mechanism of the seismic events during the sequence of the moderate-size crustal earthquake of November 22, 2014 of Vrancea region (Romania)

2019 ◽  
Vol 61 (6) ◽  
Author(s):  
Andreea Craiu ◽  
Cristian Ghita ◽  
Marius Craiu ◽  
Mihail Diaconescu ◽  
Marius Mihai ◽  
...  
Keyword(s):  
Source Mechanism ◽  
Seismic Events ◽  
Moderate Size ◽  
Crustal Earthquake ◽  
Vrancea Region

scholarly journals Analysis the 1978–2008 crustal and sub-crustal earthquake catalog of Vrancea region

2012 ◽  
Vol 12 (5) ◽  
pp. 1321-1325 ◽  
Author(s):  
L. Telesca ◽  
V. Alcaz ◽  
I. Sandu
Keyword(s):  
Seismic Hazard ◽  
Hazard Assessment ◽  
Seismic Hazard Assessment ◽  
Earthquake Catalog ◽  
B Values ◽  
Crustal Earthquake ◽  
Quarry Blast ◽  
Vrancea Region ◽  
Completeness Magnitude

Abstract. The crustal and sub-crustal seismicity that occurred in the Vrancea area from 1978 to 2008 is investigated. Due to quarry blast contamination, the analysis of the crustal seismicity was restricted to events that occurred between 20 km and 60 km, considering sub-crustal events as all those that occurred at depths larger than 60 km. The completeness magnitude was estimated between 2.3 and 2.5 for the crustal seismicity and between 2.9 and 3.1 for the sub-crustal one. The Gutenberg-Richter b-values show clear differences between crustal and sub-crustal seismicity, with values around 0.9 and 1.3–1.4, respectively. The analysis performed in this study represents a preliminary issue for the seismic hazard assessment of surrounding regions like Moldova, for which the earthquakes generated in Vrancea represent an important threat.

Simultaneous microseismic event localization and source mechanism determination

Geophysics ◽  
2015 ◽  
Vol 80 (1) ◽  
pp. KS1-KS9 ◽  
Author(s):  
Oksana Zhebel ◽  
Leo Eisner
Keyword(s):  
Oil And Gas ◽  
Signal To Noise Ratio ◽  
Moment Tensor ◽  
Microseismic Monitoring ◽  
Primary Objective ◽  
Gas Production ◽  
Source Mechanism ◽  
Seismic Events ◽  
Near Surface ◽  
Microseismic Event

Microseismic monitoring has become a tool of choice for the development and optimization of oil and gas production from unconventional reservoirs. The primary objective of (micro) seismic monitoring includes localization of (micro) seismic events and characterization of their source mechanisms. Most seismic events are of a nonexplosive nature, and thus, there are waveform (polarity) differences among receivers. Specifically, double-couple sources represented a challenge for migration-based localization techniques. We developed and applied a new migration-type location technique combined with source mechanism inversion that allowed for constructive interference of signal in seismic waveforms. The procedure included constructing image functions by stacking the amplitudes with compensated polarity changes. The compensation weights were calculated by using moment tensor inversion. This method did not require any picking of arrivals at individual receivers, but it required receivers to be distributed in multiple azimuths and offsets. This made the technique suitable for surface or near-surface monitoring, in which a low signal-to-noise ratio (S/N) can be overcome by stacking. Furthermore, the advantage of this technique was that in addition to the position in time and space, we also determined the source mechanism. We determined with numerical tests that the proposed technique can be used for detection and location of events with S/Ns as low as 0.05 at individual (prestacked) receivers. Furthermore, we found that other source mechanism parameters such as magnitude, volumetric, or shear components of the source mechanism were not suitable for the location. Finally, we applied the proposed technique to a microseismic event of moment magnitude [Formula: see text] induced during the hydraulic fracturing treatment of a gas shale reservoir in North America.

Source mechanism of mining induced seismic events — Resolution of double couple and non double couple models

2008 ◽  
Vol 456 (1-2) ◽  
pp. 3-15 ◽  
Author(s):  
Jan Šílený ◽  
Alexander Milev
Keyword(s):  
Source Mechanism ◽  
Seismic Events ◽  
Double Couple ◽  
Couple Models

Shallow seismic events with combined source mechanism

1988 ◽  
Vol 152 (3-4) ◽  
pp. 283-296 ◽  
Author(s):  
Jan Šílený ◽  
Jan Kozák
Keyword(s):  
Source Mechanism ◽  
Seismic Events ◽  
Shallow Seismic

An application of statistical discrimination to classify seismic events

1964 ◽  
Vol 54 (3) ◽  
pp. 961-971
Author(s):  
Aaron Booker ◽  
Walter Mitronovas
Keyword(s):  
Statistical Method ◽  
Shear Waves ◽  
Statistical Discrimination ◽  
The Other ◽  
Source Mechanism ◽  
Seismic Events ◽  
Multivariate Normal ◽  
Normal Populations ◽  
Earthquake Source Mechanism

Abstract A basic statistical method is presented for the classification of observations into one of two multivariate, normal populations. This theory is applied to the identification of seismic events by considering one of the “populations” to consist of measurements on seismic recordings of earthquakes, the other of explosions. The measurements, or parameters, consist of ratios of the “energies” contained within predetermined “velocity windows” on the seismograms. The choice of velocity windows is guided by the assumption that earthquake source mechanism is extended both in time and space and generates a larger fraction of energy in shear waves as compared to explosion source mechanism. The best separation of twenty earthquakes and twenty-seven explosions is achieved when only seven of the nine ratios calculated are used in the statistical discriminator. Based on this data we have about 85% probability of correctly classifying a given event either as an explosion or as an earthquake.

Radon levels assessment in relation with seismic events in Vrancea region

2012 ◽  
Vol 293 (2) ◽  
pp. 655-663 ◽  
Author(s):  
M. Zoran ◽  
R. Savastru ◽  
D. Savastru
Keyword(s):  
Seismic Events ◽  
Vrancea Region
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