Efficiency, stress drop, apparent stress, effective stress, and frictional stress of Denver, Colorado, earthquakes

1972 ◽  
Vol 77 (8) ◽  
pp. 1433-1438 ◽  
Author(s):  
Max Wyss ◽  
Peter Molnar
Keyword(s):  
Effective Stress ◽  
Stress Drop ◽  
Frictional Stress ◽  
Apparent Stress

Fault parameters determined by near- and far-field data: The Wakasa Bay earthquake of March 26, 1963

1974 ◽  
Vol 64 (5) ◽  
pp. 1369-1382 ◽  
Author(s):  
Katsuyuki Abe
Keyword(s):  
Effective Stress ◽  
Stress Drop ◽  
P Wave ◽  
Slip Angle ◽  
Polarization Angle ◽  
S Wave ◽  
Seismological Data ◽  
Fault Parameters ◽  
Wakasa Bay ◽  
Dip Angle

Abstract The source process of the Wakasa Bay earthquake (M = 6.9, 35.80°N, 135.76°E, depth 4 km) which occurred near the west coast of Honshu Island, Japan, on March 26, 1963, is studied on the basis of the seismological data. Dynamic and static parameters of the faulting are determined by directly comparing synthetic seismograms with observed seismograms recorded at seismic near and far distances. The De Hoop-Haskell method is used for the synthesis. The average dislocation is determined to be 60 cm. The overall dislocation velocity is estimated to be 30 cm/sec, the rise time of the slip dislocation being determined as 2 sec. The other fault parameters determined, with supplementary data on the P-wave first motion, the S-wave polarization angle, and the aftershocks, are: source geometry, dip direction N 144°E, dip angle 68°, slip angle 22° (right-lateral strike-slip motion with some dip-slip component); fault dimension, 20 km length by 8 km width; rupture velocity, 2.3 km/sec (bilateral); seismic moment, 3.3 × 1025 dyne-cm; stress drop, 32 bars. The effective stress available to accelerate the fault motion is estimated to be about 40 bars. The approximate agreement between the effective stress and the stress drop suggests that most of the effective stress was released at the time of the earthquake.

Source mechanism and surface-wave attenuation studies for Tibet earthquake of July 14, 1973

1979 ◽  
Vol 69 (3) ◽  
pp. 737-750
Author(s):  
D. D. Singh ◽  
Harsh K. Gupta
Keyword(s):  
Surface Wave ◽  
Stress Drop ◽  
Wave Attenuation ◽  
Source Parameters ◽  
High Stress ◽  
The Body ◽  
P Wave ◽  
Slip Angle ◽  
Apparent Stress ◽  
Crust And Upper Mantle

abstract Focal mechanism for Tibet earthquake of July 14, 1973 (M = 6.9, mb = 6.0) has been determined using the P-wave first motions, S-wave polarization angles, and surface-wave spectral data. A normal faulting is obtained with a plane having strike N3°W, dip 51°W, and slip angle 81°. The source parameters have been estimated for this event using the body- and surface-wave spectra. The seismic moment, fault length, apparent stress, stress drop, seismic energy release, average dislocation, and fault area are estimated to be 2.96 × 1026 dyne-cm, 27.4 km, 14 bars, 51 bars, 1.4 × 1022 ergs, 157 cm, and 628 km2, respectively. The high stress drop and apparent stress associated with this earthquake indicate that the high stresses are prevailing in this region. The specific quality factor Q is found to vary from 21 to 1162 and 22 to 1110 for Rayleigh and Love waves, respectively. These wide ranges of variation in the attenuation data may be due to the presence of heterogeneity in the crust and upper mantle.

Stress drop estimates for some aftershocks of the Ometepec, Guerrero, Mexico, earthquake of June 7, 1982

1987 ◽  
Vol 24 (8) ◽  
pp. 1727-1733 ◽  
Author(s):  
Cecilio J. Rebollar ◽  
Rosa M. Alvarez
Keyword(s):  
Stress Drop ◽  
Wave Attenuation ◽  
Seismic Energy ◽  
Coda Wave ◽  
Apparent Stress ◽  
Radiated Seismic Energy ◽  
Seismic Coda ◽  
Seismic Quality Factor ◽  
Single Station ◽  
Stress Drops

Brune's stress drop, apparent stress, and arms stress drop are estimated at a single station for 25 aftershocks of the Ometepec earthquakes (Ms = 6.9 and Ms = 7.0). The arms stress drops and apparent stresses are systematically smaller than Brune's stress drops. Stress drops from the root mean square of acceleration and apparent stress range from 0.01 to 10.2 bars (1 bar = 100 kPa) except for two values (21.4 and 33.0 bars). On the other hand, Brune's stress drops range from 0.6 to 239 bars. Seismic moments ranging from 0.5 × 1019 to 289 × 1019 dyn∙cm (1 dyn∙cm = 10 μN∙cm) were estimated for events with coda magnitudes between 0.6 and 2.2. Values of radiated seismic energy calculated by integration of the displacement spectra range from 2.5 × 1012 to 2.3 × 1016 dyn∙cm. The fmax values lie between 16 and 30 Hz. Seismic coda wave attenuation measured on narrow band-pass-filtered seismograms show a linear dependence of the seismic quality factor of the form [Formula: see text] in the range of frequencies from 3 to 24 Hz.

scholarly journals Variability in earthquake stress drop and apparent stress

2011 ◽  
Vol 38 (6) ◽  
pp. n/a-n/a ◽  
Author(s):  
Annemarie Baltay ◽  
Satoshi Ide ◽  
German Prieto ◽  
Gregory Beroza
Keyword(s):  
Stress Drop ◽  
Apparent Stress

scholarly journals DOUBLET of DOMBAI EARTHQUAKES 2013 in FOCAL ZONE of CHKHALTA EARTHQUAKE 1963

2019 ◽  
pp. 362-369 ◽  
Author(s):  
Irina Gabsatarova ◽  
L. Koroletski ◽  
L. Malyanova
Keyword(s):  
Stress Drop ◽  
Strike Slip ◽  
Geodynamic Setting ◽  
Reverse Fault ◽  
Apparent Stress ◽  
S Waves ◽  
Greater Caucasus ◽  
Rupture Length ◽  
Focal Zone ◽  
Good Agreement

Two Dombai earthquakes were recorded on March 26, 2013, at 23h35m with КР=11.9 and on May 28, 2013, at 00h09m with КР=11.9 (Mw GCMT=4.9 and 5.2) in the focal area of two strong (I0=IX and I0=VII at MSK 64) Chkhalta of 1963 and Teberda of 1905 earthquakes. They were accompanied by aftershock pro-cesses. The estimates of dynamic parameters of foci (for March 26, 2013, then May 28, 2013): the rupture length is L=3.4, 3.8 km, the stress drop =55, 79 Pa, the apparent stress drop=1, 3 Pa, and the average displacement along the rupture u=0.25, 0.33 m, were obtained from the spectra of S-waves at “Anapa” and “Kislovodsk” stations. Earthquakes occurred under the action of near-horizontal (PL=12°, PL=18°) com-pressive stresses directed north-northeast (AZM=21°, AZM=30°). The nodal planes of both mechanisms have a similar strike. The type of movement in both foci is a reverse fault with some strike-slip components. The stretches of nodal planes and the types of movements in the foci are in good agreement with the geodynamic setting of the axial structures of the Greater Caucasus, and also are similar to the mechanism of the destructive Chkhalta earthquake of 1963.

Far-field radiated energy scaling in elastodynamic earthquake fault models

1998 ◽  
Vol 88 (6) ◽  
pp. 1457-1465
Author(s):  
Bruce E. Shaw
Keyword(s):  
Stress Drop ◽  
Field Energy ◽  
Far Field ◽  
Apparent Stress ◽  
Fault Models ◽  
Conservation Of Energy ◽  
Rupture Length ◽  
Radiated Energy ◽  
Sequence Of Events ◽  
Wide Range

Abstract Measurements of the far-field radiated energy in very simple elastodynamic fault models is presented, and the scaling of the radiated energy with moment and rupture length is examined. The models produce a complex sequence of events having a wide range of sizes as a result of a frictional-weakening instability. Thus, radiated energy from a broad range of sizes of events can be measured. Using conservation of energy, I am able to measure the far-field energy very accurately and efficiently. I study a range of frictions, from velocity weakening to slip weakening, in order to examine the effects of the physics of the rupture source on the radiated energy. Examining the scaling of radiated energy as a function of moment and rupture length, I find differences for slip-weakening as compared to velocity-weakening friction. I find distinct differences in how the apparent stress scales with moment and also how the apparent stress divided by the stress drop scales with moment for the different frictions. Most dramatically, the apparent stress divided by the stress drop is significantly smaller for slip weakening relative to velocity weakening. This suggests that measurements of radiated energy versus moment and rupture length in earthquakes, combined with forward elastodynamic modeling, can be used to constrain possible source physics.

A common model to explain similarities between injection-induced and natural earthquake swarms

2021 ◽  
Author(s):  
Philippe Danre ◽  
Louis De Barros ◽  
Frédéric Cappa
Keyword(s):  
Effective Stress ◽  
Stress Drop ◽  
Mechanical Model ◽  
Cluster Size ◽  
Earthquake Swarms ◽  
Aseismic Slip ◽  
Physical Processes ◽  
Total Moment ◽  
Seismic Swarms ◽  
Volume Of Fluids

<p>Fluid injections at depth can trigger seismic swarms and aseismic deformations. Similarly, some natural sequences of seismicity occur clustered in time and space, without a distinguishable mainshock. They are usually interpreted as driven by fluid and/or aseismic processes. Those seismic swarms, natural or injection-induced, present similarities in their behavior, such as a seismic front migration. The effective stress drop, defined as a ratio between seismic moment and cluster size, is also weak for all swarms, when compared to usual earthquakes values. However, the physical processes that drive both types of swarms, and that can explain such similarities are still poorly understood. Here, we propose a mechanical model in which the fluid primarily induces an aseismic slip, which then triggers and drives seismicity within and on the edges of the active zone. This model is validated using a global and precise dataset of 16 swarms, from natural or induced origins, in different geological contexts. Consequently, our measurements of the migration velocity of the seismicity front, and of the effective stress drop for our swarms can be related to the seismic-to-aseismic moment. Using our model, we are then able to compute an estimate of the volume of fluids circulating during natural earthquake swarms, assuming the total moment is related to the volume of fluids. Our study highlights common characteristics and novel insights into the physical processes at play during seismic swarms.</p>

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