Source parameters of the Mw=6.3 Aroma crustal earthquake of July 24, 2001 (northern Chile), and its aftershock sequence

2007 ◽  
Vol 24 (1) ◽  
pp. 58-68 ◽  
Author(s):  
D. Legrand ◽  
B. Delouis ◽  
L. Dorbath ◽  
C. David ◽  
J. Campos ◽  
...  
Keyword(s):  
Source Parameters ◽  
Aftershock Sequence ◽  
Northern Chile ◽  
Crustal Earthquake

scholarly journals ASP: An Automated Seismic Processor for microearthquake networks

1982 ◽  
Vol 72 (1) ◽  
pp. 303-325
Author(s):  
T. V. McEvilly ◽  
E. L. Majer
Keyword(s):  
High Speed ◽  
Nuclear Explosion ◽  
Source Parameters ◽  
Aftershock Sequence ◽  
P Wave ◽  
Time Analysis ◽  
S Waves ◽  
Real Time Analysis ◽  
Data Output ◽  
Cerro Prieto

abstract ASP, a low-power, in-field Automated Seismic Processor of microearthquake network data has been designed, fabricated, and deployed for initial operation in four different field areas to monitor seismicity associated with two geothermal areas (The Geysers, California, and Cerro Prieto, Mexico), a nuclear explosion with its related collapse and aftershock sequence, and late (>1 year) activity in a major aftershock series (Livermore, California). A second ASP system, with a high-speed front-end, is used in acoustic emission (1 to 20 kHz) analysis for fracture monitoring. Each of the 15 channels of ASP (configured for up to 128 channels) automatically detects, measures times and amplitudes, and computes and fits FFT's for both the P and S waves on data sampled at 100 samples/sec. These data from each channel are then processed with a central microprocessor for hypocenter location, running b values, source parameters, event count, and P-wave polarities. The system is capable of processing a 15-station detection in approximately 40 sec, excluding printout. The initial trials have demonstrated that in-field real-time analysis of data maximizes the efficiency of microearthquake surveys allowing flexibility in experimental procedures, with a minimum of the traditional labor-intensive postprocessing. Current efforts are directed toward improving efficiency of computation and data output and in expanding software capabilities.

scholarly journals A SOURCE PARAMETERS STUDY OF THE AFTERSHOCK SEQUENCE OF THE KOZANI- GREVENA 1995 EARTHQUAKE BASED ON ACCELERATION RECORDS

2004 ◽  
Vol 36 (3) ◽  
pp. 1457 ◽  
Author(s):  
A. A. Panou ◽  
C. B. Papazachos ◽  
Ch. Papaioannou ◽  
P. M. Hatzidimitriou
Keyword(s):  
Source Parameters ◽  
Strong Motion ◽  
Aftershock Sequence ◽  
Propagation Path ◽  
Data Set ◽  
Near Surface ◽  
Anelastic Attenuation ◽  
Geological Formation ◽  
Good Agreement

Strong motion recordings of the May 13, 1995 Mw=6.6, earthquake sequence that occurred in the Kozani-Grevena region (Western Macedonia, Greece) have been analyzed for the determination of their source parameters. The data set for this study comes from a temporarily deployed accelerograph network and the source parameters using the shear-wave displacement spectra have been estimated. For this estimation the spectral records have been corrected for the site effects and for the propagation path (geometrical spreading and anelastic attenuation). The magnitude of each event was also re-calculated by estimating appropriate station corrections. The derived relationships arelogMo =(1.43 ±0.09) M, + (16.92 ± 0.29), 2.0 < ML< 5.0 (1)logfc = (-0.56± 0.08) · ML + (2.52 + 0.29), 2.0 < ML< 5.0 (2)logM0 = (-2.20 + 0.08) · log fc + (23.16 ± 0.84), 0.6 < fc < 10.0 (3)The near-surface attenuation parameter κ0 has also been determined for the strong motion stations sites. These values of κ0 are in good agreement with those of Margaris and Boore (1998) for the geological formation on which each station was positioned. The obtained source parameters are in good agreement with those from previous studies for the Aegean region.

scholarly journals A study of aftershocks of 20 October 1991 Uttarkashi earthquake

MAUSAM ◽  
2022 ◽  
Vol 46 (4) ◽  
pp. 435-444
Author(s):  
R S. DATTATRAYAM ◽  
V.P. KAMBLE
Keyword(s):  
Decay Constant ◽  
Source Parameters ◽  
Temporal Distribution ◽  
B Value ◽  
Aftershock Sequence ◽  
Himalayan Region ◽  
Aftershock Activity ◽  
Field Surveys ◽  
Macroseismic Observations ◽  
Good Agreement

The Uttarkashi earthquake of 20 October 1991, which caused widespread damage in the Galhwal Himalayan region, was followed by a prominent aftershock. activity extending over a period of about two months. The aftershock activity was monitored using temporary networks established after the mainshock and the permanent stations in operation in the region. About 142 aftershocks could be located accurately using the data of these stations. The b-value of the Gutenberg-Richter's relationship for the aftershock sequence works out to be 0.6. The temporal distribution of the aftershocks suggests a hyperbolic decay with a decay constant (p) of 1.17. Macroseismic observations derived from field surveys show good agreement with the instrumentally determined source parameters.  

Variation of source properties: The Inangahua, New Zealand, aftershocks of 1968

1975 ◽  
Vol 65 (1) ◽  
pp. 261-276
Author(s):  
S. J. Gibowicz
Keyword(s):  
Seismic Moment ◽  
Source Parameters ◽  
Aftershock Sequence ◽  
Suitable Parameter ◽  
The Moment ◽  
Earthquake Sequences ◽  
Source Dimension ◽  
The Relationship ◽  
Frequency Magnitude

abstract A theoretical relationship between seismic moment and local magnitude ML is derived from the relationship between magnitude ML and source dimension given by Randall (1973). For a circular fault of radius smaller than about 0.5 km, the magnitude ML is proportional to the logarithm of the seismic moment Mo, and these values alone cannot specify other source parameters. For greater radii the values of Mo and ML define Brune's (1970) far-field spectrum and in these cases other source characteristics can be readily obtained. The seismic moment can be estimated from the long-period amplitudes, and therefore the moment-magnitude relation provides a convenient method for determination of the source properties. The relationship between the logarithm of the various source parameters and seismic moment is considered for a number of regions and earthquake sequences. It appears to be of linear form and, furthermore, it seems that the same slope coefficient can be used in different regions. Source properties show regional differences, and the most suitable parameter to describe these differences is the average displacement. Besides the regional variations, there seems to be a time variation of source properties. This is the case for the Inangahua aftershock sequence, during which the variation of the displacement residuals correlates with the variation of the coefficient b, which defines the frequency-magnitude relation.

scholarly journals Seismicity related to the eastern sector of Anatolian escape tectonic: the example of the 24 January 2020 Mw 6.77 Elazığ-Sivrice earthquake

2020 ◽  
Author(s):  
Mohammadreza Jamalreyhani ◽  
Pınar Büyükakpınar ◽  
Simone Cesca ◽  
Torsten Dahm ◽  
Henriette Sudhaus ◽  
...  
Keyword(s):  
Joint Inversion ◽  
Moment Tensor ◽  
Source Parameters ◽  
Aftershock Sequence ◽  
Seismic Gap ◽  
The North ◽  
Rupture Area ◽  
Surface Displacements ◽  
Dip Angle ◽  
Rupture Duration

Abstract. The 24 January 2020 Mw 6.77 Elazığ-Sivrice earthquake (Turkey), responsible for 42 casualties and ~ 1600 injured people, is the largest earthquake affecting the East Anatolian Fault (EAF) since 1971. The earthquake partially ruptured a seismic gap. The mainshock was preceded by two foreshocks with Mw ≥ 4.9 and small seismicity clusters occurring in the previous months close to the nucleation point of the main rupture. The significant aftershock sequence comprises twelve earthquakes with Mw ≥ 4.5 within 60 days. We jointly model quasi co-seismic static surface displacements from Interferometric Synthetic Aperture Radar (InSAR) and high-frequency co-seismic data from seismological networks at local, regional and teleseismic distances to retrieve source parameters of the mainshock. We reconstruct the rupture process using a Bayesian bootstrap based probabilistic joint inversion scheme to obtain source parameters and their uncertainties. Full moment tensor for 18 fore-/after-shocks with Mw ≥ 4.3 are obtained based on the modeling of regional broadband data. The posterior mean model for the 2020 Elazığ-Sivrice mainshock shows that the earthquake, with a magnitude Mw 6.77, ruptured at shallow depth (5 ± 2 km) with a left-lateral strike-slip focal mechanism, with a dip angle of 74° ± 2° and a causative fault plane strike of 242° ± 1°, which is compatible with the orientation of the EAF at the centroid location. The rupture nucleated in the vicinity of small foreshock clusters and slowly propagated towards WSW, with a rupture velocity of ~ 2100 ± 130 m s−1 and ~ 27 s rupture duration. The main rupture area, with a length of ~ 26 ± 5 km, only covered 70 % of the former seismic gap, leaving a smaller, unbroken segment of ~ 30 km length to the SE with positive stress change. The subsequent aftershock sequence extended over a broader region of ~ 70 km in length, spreading to both sides of the mainshock rupture patch into the regions experiencing a stress increase according to our Coulomb stress modeling. Our results support the hypothesis of a shallow locking depth of the Anatolian micro-plate, which has a possible implication to the seismic bursts along the EAF and alternating seismic activity on the North Anatolian and the East Anatolian faults.

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