scholarly journals The 2003Mw7.2 Fiordland subduction earthquake, New Zealand: aftershock distribution, main shock fault plane and static stress changes on the overlying Alpine Fault

2007 ◽  
Vol 169 (2) ◽  
pp. 579-592 ◽  
Author(s):  
Peter McGinty ◽  
Russell Robinson
Keyword(s):  
New Zealand ◽  
Main Shock ◽  
Fault Plane ◽  
Static Stress ◽  
Aftershock Distribution ◽  
Subduction Earthquake ◽  
Alpine Fault ◽  
Stress Changes

Study on Aftershocks Triggering by Static Stress Changes of the Minxian-Zhangxian 6.6 Earthquake

2014 ◽  
Vol 527 ◽  
pp. 77-80
Author(s):  
Fang Bin Liu ◽  
Ai Guo Wang
Keyword(s):  
Main Shock ◽  
Fault Plane ◽  
Elastic Half Space ◽  
Static Stress ◽  
Gansu Province ◽  
Data Sets ◽  
Space Model ◽  
Main Shocks ◽  
Stress Changes ◽  
Better Than

On July 22, 2013, an Ms6.6 earthquake occurred in Minxian-Zhangxian, Gansu Province, China, which caused serious damages. Because of the abundance and clear relationship with the main shocks, aftershocks sequences are typical types of behavior and provide useful data sets. To better understand the aftershocks triggering by static stress changes of the main earthquake, based on Okada’s elastic half-space model, we used accept fault plane consistent with the source and accept fault plane as the optimal models to calculate the stress changes on aftershock focuses by the Minxian-Zhangxian 6.6 Earthquake respectively. The results show that the latter model is better than former, more than 90% of aftershocks located in NWW and SEE, the stress increased areas, which is consistent with strike of Lintan-Tanchang fault (LTF), in other words, the Coulomb static stress changes of the main shock can induce the aftershocks.

scholarly journals The Alpine Fault hanging-wall viewed from within: Structural analysis of the ultrasonic image logs in the DFDP-2B borehole, New Zealand

2021 ◽  
Author(s):  
C Massiot ◽  
B Célérier ◽  
ML Doan ◽  
TA Little ◽  
John Townend ◽  
...  
Keyword(s):  
New Zealand ◽  
Fault Plane ◽  
Hanging Wall ◽  
Anisotropic Permeability ◽  
Ultrasonic Image ◽  
Feature Sets ◽  
Alpine Fault ◽  
American Geophysical ◽  
American Geophysical Union ◽  
Topographic Relief

©2018. American Geophysical Union. All Rights Reserved. Ultrasonic image logs acquired in the DFDP-2B borehole yield the first continuous, subsurface description of the transition from schist to mylonite in the hangingwall of the Alpine Fault, New Zealand, to a depth of 818 m below surface. Three feature sets are delineated. One set, comprising foliation and foliation-parallel veins and fractures, has a constant orientation. The average dip direction of 145° is subparallel to the dip direction of the Alpine Fault, and the average dip magnitude of 60° is similar to nearby outcrop observations of foliation in the Alpine mylonites that occur immediately above the Alpine Fault. We suggest that this foliation orientation is similar to the Alpine Fault plane at ∼1 km depth in the Whataroa valley. The other two auxiliary feature sets are interpreted as joints based on their morphology and orientation. Subvertical joints with NW-SE (137°) strike occurring dominantly above ∼500 m are interpreted as being formed during the exhumation and unloading of the Alpine Fault's hangingwall. Gently dipping joints, predominantly observed below ∼500 m, are interpreted as inherited hydrofractures exhumed from their depth of formation. These three fracture sets, combined with subsidiary brecciated fault zones, define the fluid pathways and anisotropic permeability directions. In addition, high topographic relief, which perturbs the stress tensor, likely enhances the slip potential and thus permeability of subvertical fractures below the ridges, and of gently dipping fractures below the valleys. Thus, DFDP-2B borehole observations support the inference of a large zone of enhanced permeability in the hangingwall of the Alpine Fault.

scholarly journals The Alpine Fault hanging-wall viewed from within: Structural analysis of the ultrasonic image logs in the DFDP-2B borehole, New Zealand

2021 ◽  
Author(s):  
C Massiot ◽  
B Célérier ◽  
ML Doan ◽  
TA Little ◽  
John Townend ◽  
...  
Keyword(s):  
New Zealand ◽  
Fault Plane ◽  
Hanging Wall ◽  
Anisotropic Permeability ◽  
Ultrasonic Image ◽  
Feature Sets ◽  
Alpine Fault ◽  
American Geophysical ◽  
American Geophysical Union ◽  
Topographic Relief

©2018. American Geophysical Union. All Rights Reserved. Ultrasonic image logs acquired in the DFDP-2B borehole yield the first continuous, subsurface description of the transition from schist to mylonite in the hangingwall of the Alpine Fault, New Zealand, to a depth of 818 m below surface. Three feature sets are delineated. One set, comprising foliation and foliation-parallel veins and fractures, has a constant orientation. The average dip direction of 145° is subparallel to the dip direction of the Alpine Fault, and the average dip magnitude of 60° is similar to nearby outcrop observations of foliation in the Alpine mylonites that occur immediately above the Alpine Fault. We suggest that this foliation orientation is similar to the Alpine Fault plane at ∼1 km depth in the Whataroa valley. The other two auxiliary feature sets are interpreted as joints based on their morphology and orientation. Subvertical joints with NW-SE (137°) strike occurring dominantly above ∼500 m are interpreted as being formed during the exhumation and unloading of the Alpine Fault's hangingwall. Gently dipping joints, predominantly observed below ∼500 m, are interpreted as inherited hydrofractures exhumed from their depth of formation. These three fracture sets, combined with subsidiary brecciated fault zones, define the fluid pathways and anisotropic permeability directions. In addition, high topographic relief, which perturbs the stress tensor, likely enhances the slip potential and thus permeability of subvertical fractures below the ridges, and of gently dipping fractures below the valleys. Thus, DFDP-2B borehole observations support the inference of a large zone of enhanced permeability in the hangingwall of the Alpine Fault.

Variation of the frequency-magnitude relation during earthquake sequences in New Zealand

1973 ◽  
Vol 63 (2) ◽  
pp. 517-528 ◽  
Author(s):  
S. J. Gibowicz
Keyword(s):  
New Zealand ◽  
Main Shock ◽  
Earthquake Swarm ◽  
Rock Deformation ◽  
Laboratory Studies ◽  
Aftershock Sequences ◽  
Stress Changes ◽  
Earthquake Sequences ◽  
Largest Aftershock ◽  
Frequency Magnitude

abstract Seven New Zealand earthquake sequences are studied statistically. These comprise six aftershock sequences and one earthquake swarm. The magnitude-stability law of Lomnitz does not hold. During the aftershock sequences the coefficient b, governing the frequency-magnitude relationship, is found to increase rapidly after the main shock, and then to decrease until the occurrence of the largest aftershock, when it again begins to increase. During the earthquake swarm, the coefficient b decreases logarithmically with time. This can be explained in terms of stress changes and is consistent with laboratory studies on rock deformation.

Determining hydrological and soil mechanical parameters from multichannel surface-wave analysis across the Alpine Fault at Inchbonnie, New Zealand

2013 ◽  
Vol 11 (4) ◽  
pp. 435-448 ◽  
Author(s):  
L.A. Konstantaki ◽  
S. Carpentier ◽  
F. Garofalo ◽  
P. Bergamo ◽  
L.V. Socco
Keyword(s):  
New Zealand ◽  
Surface Wave ◽  
Mechanical Parameters ◽  
Wave Analysis ◽  
Alpine Fault

The San Salvador Earthquake of October 10, 1986—Seismological Aspects and Other Recent Local Seismicity

1987 ◽  
Vol 3 (3) ◽  
pp. 419-434 ◽  
Author(s):  
Randall A. White ◽  
David H. Harlow ◽  
Salvador Alvarez
Keyword(s):  
Main Shock ◽  
Fault Plane ◽  
Vertical Plane ◽  
Aftershock Sequence ◽  
Central American ◽  
Fault Plane Solution ◽  
San Salvador ◽  
The North ◽  
Volcanic Chain ◽  
Plane Solution

The San Salvador earthquake of October 10, 1986 originated along the Central American volcanic chain within the upper crust of the Caribbean Plate. Results from a local seismograph network show a tectonic style main shock-aftershock sequence, with a magnitude, Mw, 5.6. The hypocenter was located 7.3 km below the south edge of San Salvador. The main shock ruptured along a nearly vertical plane toward the north-northeast. A main shock fault-plane solution shows a nearly vertical fault plane striking N32\sz\E, with left-lateral sense of motion. This earthquake is the second Central American volcanic chain earthquake documented with left-lateral slip on a fault perpendicular to the volcanic chain. During the 2 1/2 years preceeding the earthquake, minor microseismicity was noted near the epicenter, but we show that this has been common along the volcanic chain since at least 1953. San Salvador was previously damaged by a volcanic chain earthquake on May 3, 1965. The locations of six foreshocks preceding the 1965 shock show a distinctly WNW-trending distribution. This observation, together with the distribution of damage and a fault-plane solution, suggest that right-lateral slip occurred along a fault sub-parallel with Central American volcanic chain. We believe this is the first time such motion has been documented along the volcanic chain. This earthquake was also unusual in that it was preceded by a foreshock sequence more energetic than the aftershock sequence. Earlier this century, on June 08, 1917, an Ms 6.4 earthquake occurred 30 to 40 km west of San Salvador Volcano. Only 30 minutes later, an Ms 6.3 earthquake occurred, centered at the volcano, and about 35 minutes later the volcano erupted. In 1919 an Ms 6 earthquake occurred, centered at about the epicenter of the 1986 earthquake. We conclude that the volcanic chain is seismically very active with variable styles of seismicity.

scholarly journals The fluid budget of a continental plate boundary fault: Quantification from the Alpine Fault, New Zealand

2016 ◽  
Vol 445 ◽  
pp. 125-135 ◽  
Author(s):  
Catriona D. Menzies ◽  
Damon A.H. Teagle ◽  
Samuel Niedermann ◽  
Simon C. Cox ◽  
Dave Craw ◽  
...  
Keyword(s):  
New Zealand ◽  
Plate Boundary ◽  
Boundary Fault ◽  
Continental Plate ◽  
Alpine Fault

Static stress changes associated with normal faulting earthquakes in South Balkan area

2006 ◽  
Vol 96 (5) ◽  
pp. 911-924 ◽  
Author(s):  
E. Papadimitriou ◽  
V. Karakostas ◽  
M. Tranos ◽  
B. Ranguelov ◽  
D. Gospodinov
Keyword(s):  
Static Stress ◽  
Normal Faulting ◽  
Stress Changes ◽  
Balkan Area

The foreshock sequence of the 1986 Chalfant, California, earthquake

1988 ◽  
Vol 78 (1) ◽  
pp. 172-187
Author(s):  
Kenneth D. Smith ◽  
Keith F. Priestley
Keyword(s):  
Main Shock ◽  
Slip Surface ◽  
Body Waves ◽  
Aftershock Distribution ◽  
Time Period ◽  
Main Shocks ◽  
Short Period ◽  
Local Shear ◽  
Stress Drops ◽  
Foreshock Activity

Abstract The ML 6.4 Chalfant, California, earthquake of 21 July 1986 was preceded by an extensive foreshock sequence. Foreshock activity is characterized by shallow clustering activity, including 7 events greater than ML 3, beginning 18 days before the earthquake, an ML 5.7 foreshock 24 hr before the main shock that ruptured only in the upper 10 km of the crust, and an “off-fault” cluster of activity perpendicular to the slip surface of the ML 5.7 foreshock associated with the hypocenter of the main shock. The Chalfant sequence occurred within the local short-period network, and the spatial and temporal development of the foreshock sequence can be observed in detail. Seismicity of the July 1986 time period is largely confined to two nearly conjugate planes; one striking N30°E and dipping 60° to the northwest associated with the ML 5.7 foreshock and the other striking N25°W and dipping 70° to the southwest associated with the main shock. Focal mechanisms for the foreshock period fall into two classes in agreement with these two planes. Shallow clustering of earthquakes in July and the ML 5.7 principal foreshock occur at the intersection of the two planes at a depth of approximately 7 km. The seismic moments determined from inversion of the teleseismic body waves are 4.2 × 1025 and 2.5 × 1025 dyne-cm for the principal foreshock and the main shock, respectively. Slip areas for these two events can be estimated from the aftershock distribution and result in stress drops of 63 bars for the principal foreshock and 16 bars for the main shock. The main shock occurred within an “off-fault” cluster of earthquakes associated with the principal foreshock. This cluster of activity occurs at a predicted local shear stress high in relation to the slip surface of the 20 July earthquake, and this appears to be the triggering mechanism of the main shock. The shallow rupture depth of the principal foreshock indicates that this event was anomalous with respect to the character of main shocks in the region.

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