Annual modulation of triggered seismicity following the 1992 Landers earthquake in California

Nature ◽  
2000 ◽  
Vol 406 (6795) ◽  
pp. 500-504 ◽  
Author(s):  
Stephen S. Gao ◽  
Paul G. Silver ◽  
Alan T. Linde ◽  
I. Selwyn Sacks
Keyword(s):  
Annual Modulation ◽  
Landers Earthquake ◽  
Triggered Seismicity ◽  
1992 Landers Earthquake

scholarly journals Co-seismic displacements of the 1992 landers earthquake sequence

1994 ◽  
Vol 84 (3) ◽  
pp. 625-645 ◽  
Author(s):  
K. W. Hudnut ◽  
Y. Bock ◽  
M. Cline ◽  
P. Fang ◽  
Y. Feng ◽  
...  
Keyword(s):  
Measurement Errors ◽  
Line Length ◽  
Fault Rupture ◽  
Seismic Displacement ◽  
Landers Earthquake ◽  
Displacement Vectors ◽  
Length Changes ◽  
Model Residuals ◽  
Seismic Displacements ◽  
1992 Landers Earthquake

Abstract We present co-seismic displacement vectors derived from Global Positioning System (GPS) measurements of 92 stations in southern California. These GPS results are combined with five well-determined GPS displacement vectors from continuously tracking stations of the Permanent GPS Geodetic Array, as well as line-length changes from USGS Geodolite and two-color laser trilateration observations, to determine a self-consistent set of geodetic data for the earthquake. These combined displacements are modeled by an elastic dislocation representation of the primary fault rupture planes. On average, the model residuals are about twice the estimated measurement errors.

scholarly journals Continuous monitoring of seismic energy release associated with the 1994 Northridge earthquake and the 1992 Landers earthquake

1996 ◽  
Vol 86 (1A) ◽  
pp. 255-258 ◽  
Author(s):  
Sharon Kedar ◽  
Hiroo Kanamori
Keyword(s):  
Frequency Band ◽  
Southern California ◽  
Seismic Energy ◽  
Northridge Earthquake ◽  
Time Frequency ◽  
Landers Earthquake ◽  
Long Period ◽  
1992 Landers Earthquake ◽  
Large Earthquakes ◽  
1994 Northridge Earthquake

Abstract We have developed a method to detect long-period precursors for large earthquakes observed in southern California, if they occur. The method allows us to continuously monitor seismic energy radiation over a wide frequency band to investigate slow deformation in the crust (e.g., slow earthquakes), especially before large earthquakes. We used the long-period records (1 sample/sec) from TERRAscope, a broadband seismic network in southern California. The method consists of dividing the record into a series of overlapping 30-min-long windows, computing the spectra over a frequency band of 0.00055 to 0.1 Hz, and plotting them in the form of a time-frequency diagram called spectrogram. This procedure is repeated daily over a day-long record. We have analyzed the 17 January 1994 Northridge earthquake (Mw = 6.7), and the 28 June 1992 Landers earthquake (Mw = 7.3). No slow precursor with spectral amplitude measured over a duration of 30 min larger than that of a magnitude 3.7 was detected prior to either event. In other words, there was no precursor whose moment was larger than ∼0.003% of the mainshock.

scholarly journals Wave-equation based traveltime seismic tomography – Part 2: Application to the 1992 Landers earthquake (<i>M</i><sub>w</sub> 7.3) area

2014 ◽  
Vol 6 (2) ◽  
pp. 2567-2613 ◽  
Author(s):  
P. Tong ◽  
D. Zhao ◽  
D. Yang ◽  
X. Yang ◽  
J. Chen ◽  
...  
Keyword(s):  
Wave Equation ◽  
High Resolution ◽  
Seismic Tomography ◽  
Lower Crust ◽  
Poisson’S Ratio ◽  
Arrival Time ◽  
Poisson's Ratio ◽  
S Wave ◽  
Landers Earthquake ◽  
1992 Landers Earthquake

Abstract. High-resolution 3-D P and S wave crustal velocity and Poisson's ratio models of the 1992 Landers earthquake (Mw 7.3) area are determined iteratively by a wave-equation based traveltime seismic tomography (WETST) technique as developed in the first paper. The details of data selection, synthetic arrival-time determination, and trade-off analysis of damping and smoothing parameters are presented to show the performance of this new tomographic inversion method. A total of 78 523 P wave and 46 999 S wave high-quality arrival-time data from 2041 local earthquakes recorded by 275 stations during the period of 1992–2013 is used to obtain the final tomographic models which costs around 10 000 CPU h. Checkerboard resolution tests are conducted to verify the reliability of inversion results for the chosen seismic data and the wave-equation based traveltime seismic tomography method. Significant structural heterogeneities are revealed in the crust of the 1992 Lander earthquake area which may be closely related to the local seismic activities. Strong variations of velocity and Poisson's ratio exist in the source regions of the Landers and three other strong earthquakes in this area. Most seismicity occurs in areas with high-velocity and low Poisson's ratio, which may be associated with the seismogenic layer. Pronounced low-velocity anomalies revealed in the lower crust along the Elsinore, the San Jacinto and the San Andreas faults may reflect the existence of fluids in the lower crust. The recovery of these strong heterogeneous structures are facilitated by the use of full wave equation solvers and WETST and verifies their ability in generating high-resolution tomographic models.

Testing a model of earthquake nucleation

1995 ◽  
Vol 85 (6) ◽  
pp. 1873-1878
Author(s):  
Rachel E. Abercrombie ◽  
Duncan C. Agnew ◽  
Frank K. Wyatt
Keyword(s):  
Slow Slip ◽  
Dynamic Rupture ◽  
Short Term ◽  
Landers Earthquake ◽  
Earthquake Nucleation ◽  
Short Term Prediction ◽  
Stress Drops ◽  
1992 Landers Earthquake ◽  
Precursory Slip ◽  
Laboratory Models

Abstract Some laboratory models of slip find that a critical amount (or velocity) of slow slip is required over a nucleation patch before dynamic failure begins. Typically, such patch sizes, when extrapolated to earthquakes, have been thought to be very small and the precursory slip undetectable. Ohnaka (1992, 1993) has proposed a model in which foreshocks delineate a growing zone of quasi-static slip that nucleates the dynamic rupture and suggests that it could be large enough (∼10 km across) to be detectable and thus useful for short-term earthquake prediction. The 1992 Landers earthquake (M 7.3) had a distinctive foreshock sequence and initiated only 70 km from the strain meters at the Piñon Flat Observatory (PFO). We use this earthquake to investigate the validity and usefulness of Ohnaka's model. The accurate relocations of Dodge et al. (1995) show that the foreshock zone can be interpreted as expanding from an area of 800 m (along strike) by 900 m (in depth), to 2000 by 3200 m in the 6.5 hr before the mainshock. We have calculated the deformation signals expected both at PFO and 20 km from the foreshock zone, assuming either constant slip or constant stress drop on a circular patch expanding at 5 cm/sec over 6.5 hr. We find the slips or stress drops would have to have been implausibly high (meters or kilobars) to have been detectable on the strain meters at PFO. Slightly better limits are possible only 20 km from the source. Even though the distance from Landers to PFO is small compared with the average spacing of strain meters in California, we are unable to prove or disprove Ohnaka's model of earthquake nucleation. This suggests that even if the model is valid, it will not be useful for short-term prediction.

Surface breakage of the 1992 Landers earthquake and its effects on structures

1994 ◽  
Vol 84 (3) ◽  
pp. 547-561
Author(s):  
Carlos A. Lazarte ◽  
Jonathan D. Bray ◽  
Arvid M. Johnson ◽  
Robert E. Lemmer
Keyword(s):  
Concrete Slabs ◽  
Fault Rupture ◽  
Earthquake Fault ◽  
Landers Earthquake ◽  
Major Fault ◽  
Surface Ruptures ◽  
Earthquake Fault Rupture ◽  
Step Over ◽  
1992 Landers Earthquake ◽  
Surface Breakage

Abstract The Landers, California, earthquake (Mw = 7.3) provides an exceptional opportunity to study surface rupture of an earthquake fault. Detailed maps of the lateral distribution of fracturing adjacent to main traces show that rupture patterns are much more complex than documented in past studies of surface ruptures. The rupture occurs in tabular zones, up to hundreds of meters wide. A main trace within each rupture zone accommodates much of the shear deformation, but considerable fracturing occurs throughout the tabular zone. The en-echelon pattern of fracturing in step-over zones between main traces is typically even more complex than those along major fault zones. Inspection of several on-grade concrete slabs indicates that unreinforced concrete foundations generally crack when subjected to distinct ground ruptures beneath them or when they are twisted because of differential ground movements across broad zones. Methods of mitigating the potential hazards associated with earthquake fault rupture are presented.

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