Discrimination of fault planes from auxiliary planes based on simultaneous determination of stress tensor and a large number of fault plane solutions

1995 ◽  
Vol 100 (B5) ◽  
pp. 8327-8338 ◽  
Author(s):  
Shigeki Horiuchi ◽  
Guillermo Rocco ◽  
Akira Hasegawa
Keyword(s):  
Stress Tensor ◽  
Simultaneous Determination ◽  
Fault Plane ◽  
Fault Plane Solutions

Analysis of Shallow Microearthquakes in the South Sebec Seismic Zone, Maine, 1989–1990

1992 ◽  
Vol 63 (4) ◽  
pp. 557-566 ◽  
Author(s):  
William E. Doll ◽  
Carol D. Rea ◽  
John E. Ebel ◽  
Sandra J. Craven ◽  
John J. Cipar
Keyword(s):  
New England ◽  
Satellite Images ◽  
Fault Plane ◽  
Seismic Zone ◽  
Fault Plane Solutions ◽  
Motion Data ◽  
First Motion ◽  
High Level ◽  
Surface Geology

Abstract Fifteen years of regional monitoring by the New England Seismic Network indicated a locally high level of seismicity near South Sebec, between the towns of Milo and Dover-Foxcroft in central Maine. Most of the events were located in a diffuse zone south of the distinctive, ENE trending Harriman Pond Fault (HPF) which is indicated by brittle deformation in outcrop and is represented as a depression in topographic maps and satellite images. A portable network consisting of both digital and analog instruments was deployed during the summers of 1989 and 1990 in order to characterize the pattern of the microearthquakes and to determine high-resolution epicenters, depths, and fault plane solutions. Seventy-three events were detected during the experiment, of which 28 could be located. Many of the events south of the fault lie along a NNW trending line which has no major expression in the surface geology. Only, a few of the events are subparallel to the HPF. The first motion data were insufficient for the determination of any fault plane solutions.

scholarly journals Seismic evidence for the tectonics of Central and Western Asia

1959 ◽  
Vol 49 (4) ◽  
pp. 369-378
Author(s):  
A. E. Scheidegger
Keyword(s):  
Fault Plane ◽  
Stress System ◽  
Motion Direction ◽  
Fault Plane Solutions ◽  
Small Areas ◽  
Mountain Ranges ◽  
Central Asian ◽  
Western Asia ◽  
Tectonic Motion

Abstract A statistical analysis of the null axes of the fault-plane solutions of earthquakes in any one area permits determination of the average tectonic motion direction of that area. In the present paper this method has been applied to areas in central and western Asia for which several hundred fault-plane solutions are readily available in the literature. The investigation yields the result that (seismically) calculated tectonic motion directions in a series of small areas that are part of a larger unit are consistent with each other and that there is in every case an excellent correlation with the tectonic motion of the area as postulated from geological studies. This appears to justify completely the seismic method. The seismically determined tectonic motion in central Asia appears to be mainly in a north-south direction. The motion refers to the present time (since the earthquakes occur at the present time), but it is the same as that postulated in geology for an explanation of the folding of the central Asian mountain ranges. This demonstrates that the stress system which created the central Asian mountains is active at the present time.

scholarly journals Microearthquake Source Locations and Mechanisms: Ice Stream B, West Antarctica (Abstract)

1988 ◽  
Vol 11 ◽  
pp. 199-199
Author(s):  
S. Anandakrishnan ◽  
D. D. Blankenship ◽  
C. R. Bentley
Keyword(s):  
Depth Profile ◽  
Fault Plane ◽  
P Wave ◽  
West Antarctica ◽  
Precise Location ◽  
Fault Plane Solutions ◽  
Ice Flow ◽  
Ice Stream ◽  
Ice Stream B

An array of nine seismographic stations, each sensitive to all three components of motion, was deployed on Ice Stream B, West Antarctica, during the austral summer of 1985–86. The network was sensitive to high-frequency (=400 Hz) seismic activity within a 350 km2 area of the ice stream, and the deployment geometry allows the precise determination of depths for events beneath the 10 km2 array. Microearthquakes from both beneath and beside the ice stream were detected and recorded (Blankenship and others 1987). Inversion of P-wave and S-wave travel times and radiation patterns allows the determination of locations and fault-plane solutions for many of these events.We find that bottom events involve low-angle thrusting, in the down-stream direction, of ice or till; displacement is ∼½ cm per event over a (15 m)2 area. Such faulting is rare and releases an insignificant part of the total energy dissipated by ice flow. However, this is a possible mechanism for plucking of the ice-stream bed.Fault-plane solutions for most major surface events are consistent with the opening of tensional fractures oriented transverse to ice flow. Precise location of these events shows that they correspond to open crevasses, mapped by Vornberger and Whillans (1986), that are oriented transverse to ice flow.In addition, shear-wave splitting observed on some of the microearthquakes shows that the c-axes in the ice stream are slightly, but not strongly, anisotropic. Precise location of the sources requires the use of a detailed velocity-depth profile in the firn, which was obtained by seismic short-refraction studies (Anandakrishnan and others 1988, this volume). A density-depth profile calculated from these velocities agrees well with direct density measurements on a single core nearby (Alley and Bentley 1988, this volume).

Stress tensor orientation derived from fault plane solutions in the southwestern Alps

1997 ◽  
Vol 102 (B4) ◽  
pp. 8171-8185 ◽  
Author(s):  
E. Eva ◽  
S. Solarino ◽  
C. Eva ◽  
G. Neri
Keyword(s):  
Stress Tensor ◽  
Fault Plane ◽  
Fault Plane Solutions ◽  
Southwestern Alps

scholarly journals Microearthquake Source Locations and Mechanisms: Ice Stream B, West Antarctica (Abstract)

1988 ◽  
Vol 11 ◽  
pp. 199
Author(s):  
S. Anandakrishnan ◽  
D. D. Blankenship ◽  
C. R. Bentley
Keyword(s):  
Depth Profile ◽  
Fault Plane ◽  
P Wave ◽  
West Antarctica ◽  
Precise Location ◽  
Fault Plane Solutions ◽  
Ice Flow ◽  
Ice Stream ◽  
Ice Stream B

An array of nine seismographic stations, each sensitive to all three components of motion, was deployed on Ice Stream B, West Antarctica, during the austral summer of 1985–86. The network was sensitive to high-frequency (=400 Hz) seismic activity within a 350 km2 area of the ice stream, and the deployment geometry allows the precise determination of depths for events beneath the 10 km2 array. Microearthquakes from both beneath and beside the ice stream were detected and recorded (Blankenship and others 1987). Inversion of P-wave and S-wave travel times and radiation patterns allows the determination of locations and fault-plane solutions for many of these events. We find that bottom events involve low-angle thrusting, in the down-stream direction, of ice or till; displacement is ∼½ cm per event over a (15 m)2 area. Such faulting is rare and releases an insignificant part of the total energy dissipated by ice flow. However, this is a possible mechanism for plucking of the ice-stream bed. Fault-plane solutions for most major surface events are consistent with the opening of tensional fractures oriented transverse to ice flow. Precise location of these events shows that they correspond to open crevasses, mapped by Vornberger and Whillans (1986), that are oriented transverse to ice flow. In addition, shear-wave splitting observed on some of the microearthquakes shows that the c-axes in the ice stream are slightly, but not strongly, anisotropic. Precise location of the sources requires the use of a detailed velocity-depth profile in the firn, which was obtained by seismic short-refraction studies (Anandakrishnan and others 1988, this volume). A density-depth profile calculated from these velocities agrees well with direct density measurements on a single core nearby (Alley and Bentley 1988, this volume).

Sign in / Sign up

Export Citation Format

Share Document