scholarly journals Constraining the point source parameters of the 11 November 2019 Mw 4.9 Le Teil earthquake using multiple relocation approaches, first motion and full waveform inversions

2021 ◽  
Vol 353 (S1) ◽  
pp. 1-24
Author(s):  
Bertrand Delouis ◽  
Elif Oral ◽  
Marine Menager ◽  
Jean-Paul Ampuero ◽  
Aurélie Guilhem Trilla ◽  
...  
Keyword(s):  
Point Source ◽  
Source Parameters ◽  
Full Waveform ◽  
First Motion

Inversion of teleseismic body waves for the moment tensor of the 1978 Thessaloniki, Greece, earthquake

1981 ◽  
Vol 71 (5) ◽  
pp. 1423-1444
Author(s):  
Jeffrey S. Barker ◽  
Charles A. Langston
Keyword(s):  
Point Source ◽  
Moment Tensor ◽  
Source Parameters ◽  
Source Model ◽  
Body Waves ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Initial Rupture ◽  
Short Period ◽  
The Moment

abstract Seismograms from WWSSN and Canadian network stations were modeled to determine the source parameters of the 20 June 1978 Thessaloniki, Greece, earthquake (Ms = 6.4). The depth of the initial rupture was constrained to 11 ± 1 km by comparison of the arrival times of surface reflections with synthetic short-period seismograms. A focal sphere plot of first motion polarities provided little constraint on other focal parameters, except to indicate that predominantly normal faulting was involved. A generalized inverse technique utilizing the moment tensor formalism was applied to teleseismic P and SH waves for six increments of depth. The moment tensor obtained indicated a nearly horizontal, N-trending tension axis and a nearly vertical compression axis, and yielded the following double-couple source parameters: strike 280° ± 7°; dip 55° ± 3°; rake −65° ± 5°; seismic moment 5.7 × 1025 dyne-cm; and a skewed triangular source time function with a rise time of about 1 sec and duration of 6 to 8 sec. Due to indications of multiple or finite source effects for this event, and the assumption in the moment tensor formalism of a point source, a low-pass filter was applied to the data and the inversions were repeated. The results were nearly identical with those of the original inversion, suggesting that any individual sources had similar mechanisms, or that the point source model is sufficient for this earthquake.

scholarly journals Estimation of Appropriate Stack Height at Industrial Layout, Makurdi, Benue State

2015 ◽  
Vol 6 ◽  
pp. 150-157
Author(s):  
B A Ikyo ◽  
F Gbaorun ◽  
S A Awua ◽  
S A Sayid ◽  
G B Asaar
Keyword(s):  
Point Source ◽  
Pollution Control ◽  
Source Parameters ◽  
Atmospheric Stability ◽  
Environmental Safety ◽  
Gaussian Plume Model ◽  
Safety Standards ◽  
Gaussian Plume ◽  
Industrial Layout ◽  
National Environmental

The prediction of appropriate stack height at the Makurdi industrial layout in Benue State of Nigeria is carried out using the point source Gaussian plume model. The model takes into account the ambient environmental conditions and emission source parameters to calculate and estimate the appropriate stack height for three prevailing atmospheric stability classes, A, D and F within the Makurdi Industrial layout. The research estimates an appropriate stack height of ~65.0m for the Makurdi industrial layout. The results set a baseline for environmental safety standards for industries operating at the industrial layout and can be adopted by the National Environmental Standard Enforcement and Regulatory Agency (NESERA), and other concerned authorities in environmental monitoring and pollution control.

Inversion of regional surface-wave spectra for source parameters of aftershocks from the Loma Prieta earthquake

1991 ◽  
Vol 81 (5) ◽  
pp. 1726-1736
Author(s):  
Susan L. Beck ◽  
Howard J. Patton
Keyword(s):  
Surface Wave ◽  
Surface Waves ◽  
Focal Mechanism ◽  
Source Parameters ◽  
Strike Slip ◽  
Focal Mechanisms ◽  
P Wave ◽  
Wave Spectra ◽  
Short Period ◽  
First Motion

Abstract Surface waves recorded at regional distances are used to study the source parameters for three of the larger aftershocks of the 18 October 1989, Loma Prieta, California, earthquake. The short-period P-wave first-motion focal mechanisms indicate a complex aftershock sequence with a wide variety of mechanisms. Many of these events are too small for teleseismic body-wave analysis; therefore, the regional surface-waves provide important long-period information on the source parameters. Intermediate-period Rayleigh- and Love-wave spectra are inverted for the seismic moment tensor elements at a fixed depth and repeated for different depths to find the source depth that gives the best fit to the observed spectra. For the aftershock on 19 October at 10:14:35 (md = 4.2), we find a strike-slip focal mechanism with right lateral motion on a NW-trending vertical fault consistent with the mapped trace of the local faults. For the aftershock on 18 October at 10:22:04 (md = 4.4), the surface waves indicate a pure reverse fault with the nodal planes striking WNW. For the aftershock on 19 October at 09:53:50 (md = 4.4), the surface waves indicate a strike-slip focal mechanism with a NW-trending vertical nodal plane consistent with the local strike of the San Andreas fault. Differences between the surface-wave focal mechanisms and the short-period P-wave first-motion mechanisms are observed for the aftershocks analyzed. This discrepancy may reflect the real variations due to differences in the band width of the two observations. However, the differences may also be due to (1) errors in the first-motion mechanism due to incorrect near-source velocity structure and (2) errors in the surface-wave mechanisms due to inadequate propagation path corrections.

scholarly journals Optimizing point-source parameters for scanning satellite surveys

2009 ◽  
Vol 398 (4) ◽  
pp. 2074-2084 ◽  
Author(s):  
F. van Leeuwen ◽  
A. N. Morgan ◽  
D. L. Harrison
Keyword(s):  
Point Source ◽  
Source Parameters

Rapid Estimation of Magnitudes of Large Damaging Earthquakes in and around Japan Using Dense Seismic Stations in China

2019 ◽  
Vol 109 (6) ◽  
pp. 2545-2555
Author(s):  
Qiang Yao ◽  
Dun Wang ◽  
Lihua Fang ◽  
Jim Mori
Keyword(s):  
Source Parameters ◽  
Tohoku Earthquake ◽  
Disaster Mitigation ◽  
Limiting Factor ◽  
Origin Time ◽  
Seismic Stations ◽  
Emergency Rescue ◽  
Full Waveform ◽  
Shallow Earthquakes ◽  
Large Earthquakes

Abstract The rapid and reliable estimation of the magnitudes of large earthquakes is critical for determining the potential shaking damage and tsunami hazards. The primary challenge to rapidly and accurately estimating the magnitude of large earthquakes is the need to wait for the full waveform in order to calculate the source parameters. We used data of the M≥7.0 shallow earthquakes in Japan from 2008 to 2016, recorded at 10°–60° (regional to teleseismic distances), to establish an operational method to quickly determine their magnitudes. Our results suggest that earthquake magnitudes can be estimated accurately 6–12 min after their origin times. The only time‐limiting factor on our method is the epicentral distances to the seismic stations. For the case of the 2011 great Tohoku earthquake, the magnitude was estimated as M 8.9–9.1 at 6–12 min after the origin time. Resolutions of the results were further investigated by bootstrap and jackknife tests and subarray analysis. Therefore, we propose building a system for determining the magnitude of large earthquakes in and around Japan using real‐time seismic data in China and worldwide. This will assist in disaster mitigation immediately after a damaging earthquake, especially for the purpose of tsunami evacuation and emergency rescue.

Source parameter estimation for large, bermed, surface chemical explosions

1992 ◽  
Vol 82 (1) ◽  
pp. 406-421
Author(s):  
Sharon K. Reamer ◽  
Brian W. Stump
Keyword(s):  
Rayleigh Waves ◽  
Source Parameters ◽  
Spectral Ratio ◽  
Body Waves ◽  
P Wave ◽  
Corner Frequency ◽  
Surface Charges ◽  
Full Waveform ◽  
Test Beds ◽  
Explosion Test

Abstract Near-source accelerograms (0.2 to 2.0 km range) were acquired from a series of bermed surface charges (0.075 to 1.65 kilotons) detonated in alluvium at a test site near Yuma, Arizona. The areal extent of the explosion test beds (radii from 18 to 54 m) affords the unique opportunity to study wave propagation from and source parameters of large surface explosions at near-source ranges. P and SV-Rayleigh phases are identified using particle motions. Rayleigh waves at an intermediate range transition to a combination of higher mode and fundamental mode Rayleigh waves at the farthest range. The power law decay rates for body waves (radial at r−1.8 and vertical at r−1.4) and surface waves (radial at r−1.0 and vertical at r−0.8) are further indication of complex propagation effects in the shallow alluvial geology. As a result of this complexity and the two-orders-of-magnitude range of explosive yields available, seismic source parameters are obtained with full-waveform spectral ratios. Source corner frequency is proportional to the radius of the explosion test beds and long-period-level (relative moment) scales linearly with yield. Spectral ratio yield estimates using smaller explosions as standard or calibration events gave absolute yield estimates within 6 to 35% of the true yield with a linear scaling law. The precision of individual yield estimates is reflected by multiplicative errors of 1.11 to 1.17. Full-waveform spectral ratio corner frequency estimates compare favorably with reglonal P-wave corner frequencies and validate the use of the spectral ratio technique for near-source seismic data.

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