1. CAP, CSB Study on Spatial and Temporal Variation of LURR
in Southern California and Its Implication to
Earthquake Tendency in This Region
Yongxian Zhang, Xiangchu Yin & Keyin Peng
Center for Analysis and Prediction(CAP),
China Seismological Bureau(CSB),
Beijing , China (
phone ;
fax: ).
CAP, CSB

2. Outline About LURR Fault System in Southern California(SC)
CAP, CSB
About LURR
Fault System in Southern California(SC)
Field Stress in SC
Calculation of Y/Yc
Variation of Y/Yc before Some Strong Earthquakes in SC
Earthquake Tendency in SC
Discussion

3. LURR—Load/Unload Response Ratio
Put forward by Prof. Xiangchu Yin in 1987
- Yin X.C.(1987), A new approach to earthquake prediction, Earthquake Research
in China, 3,1-7(in Chinese with English abstract)
Basis:
The seismogenic process is nonlinear and irreversible
so that the response to loading is different from that
to unloading.
Y=X+/X X+-- response rate under loading condition
X--- response rate under unloading condition
Y--LURR

4. How to calculate LURR? 1. Find a easy way to calculate LURR
Where E denotes AE energy;
“+” means loading
“–” means unloading.
m=1, Em is exactly the energy itself;
m=1/2, Em denotes the Benioff strain;
m=0, ∑Em denotes the number of events.
--Xiang-Chu Yin, et al.(2000), Pure and applied Geophysics,157(2000),

5. How to calculate LURR? 2. Criteria to Judge loading and unloading
Loading--the rate of Coulomb failure stress is positive.
Unloading-- the rate of Coulomb failure stress is negative.
--Xiang-Chu Yin, et al.(2000), Pure and applied Geophysics,157(2000),
-normal stress
-shear stress
-coefficient of
internal friction

6. Obtaining high confident LURR?
Y(LURR) is sensitive to the number of earthquakes, when
Y is greater than the critical value(Yc), the confidence of Y
Anomaly is higher.
N Yc(90%) Yc(95%) Yc(99%) ……
--Zhuang and Yin(1999), Earthquake research in China, 15( ).
So we express the LURR by Y/Yc. When Y/Yc is
greater than 1, the anomaly of LURR is confident.

7. Outline About LURR Fault System in Southern California(SC)
CAP, CSB
About LURR
Fault System in Southern California(SC)
Field Stress in SC
Calculation of Y/Yc
Variation of Y/Yc before Some Strong Earthquakes in SC
Earthquake Tendency in SC
Discussion

8. understanding of California's fault system
understanding of California's fault system. The 1994 Fault Activity Map of California and Adjacent Areas by Charles W. Jennings (available from the California

9. CALIFORNIA SOUTHERN REGION dominated primarily by
northwest-trending , generally of a right-lateral strike-slip nature

10. CALIFORNIA NORTHWEST REGION,
every kind of fault type can be found here.

11. MOJAVE REGION, dominated by northwest-trending,
right-lateral strike-slip faults

12. BASIN AND RANGE REGION
characterized by roughly north-south trending valleys
and mountain ranges, bounded typically by normal faults

13. NORTHWEST REGION
dominantly a region of reverse faulting, but faults of every sort
can be found on this map

14. Outline About LURR Fault System in Southern California(SC)
CAP, CSB
About LURR
Fault System in Southern California(SC)
Field Stress in SC
Calculation of Y/Yc
Variation of Y/Yc before Some Strong Earthquakes in SC
Earthquake Tendency in SC
Discussion

15. Tectonic Stress of America

16. Outline About LURR Fault System in Southern California(SC)
CAP, CSB
About LURR
Fault System in Southern California(SC)
Field Stress in SC
Calculation of Y/Yc
Variation of Y/Yc before Strong Earthquakes in SC
Earthquake Tendency in SC
Discussion

17. 1. Division of Southern CaliforniaX Z A2
NC02
NC04
NC01
NC03 T W Q A1 R Y1
SC08
NC07 S
SC11 P O
SC09
SC05 M N
SC06 K L
SC04
SC03 C E I D
SC10 J
SC01 H B
SC02 A F1 G F

18. Determine the limit magnitude of earthquakes
Earthquake Catalogue: from CNSS

19. SC01
ML:
Gutenberg-Richter relation

20. Scaning parameters:
Temporal window: 12 months
Time moving step: month
Spatial window: R=100km
Space moving window:
Nmin=20 R

21. Outline About LURR Fault System in Southern California(SC)
CAP, CSB
About LURR
Fault System in Southern California(SC)
Field Stress in SC
Calculation of Y/Yc
Variation of Y/Yc before Some Strong Earthquakes in SC
Earthquake Tendency in SC
Discussion

22. 1980-2001 M>=6.5 in California Loma Prieta Coalinga Hecter Mine
Northridge
Landers
Superstition Hills

23. For 1983-05-02 Coalinga 6.7 earthquake

29. For 1987-11-24 Superstition Hills 6.6 earthquake

35. For 1989-10-18 Loma Prieta 7.0 earthquake
California: An Interpretive History ,
by James Rawls and Walton Bean, 7th edition (McGraw-Hill, 1998).
The Elusive Eden: A New History of California ,
by Rice, Bullough, and Richard Orsi, 2nd edition (McGraw-Hill, 1996).
Geosystems: An Introduction to Physical Geography ,
by Robert Christopherson, 3rd edition, (Prentice-Hall, 1997).

41. For 1992-6-28 Landers 7.3 earthquake

45. For 1994-1-17 Northridge 6.6 earthquake
On January 17,1994 the most expensive earthquake in the
United States, a 6.7, hit Southern California. It was caused
by a deeply buried thrust fault 11 miles underground,
beneath the San Fernando Valley.

49. For 1999-10-16 Hector Mine 7.1 earthquake

53. Remarks Future earthquake located near region of anomalous Y/Yc.
Date
Epicenter
Magnitude/ (km)
Max Y/Yc
Lasting Time of anomalous Y/Yc
Coalinga
6.7/? ?
Superstition Hills
6.6/0
1.4
21m
Loma Prieta
7.0/100
1.2
24m
Landers
7.3/100
1.0
18m
Northridge
6.6/80
25m
Hector Mine
7.1/100
15m
Remarks
Future earthquake located near region of anomalous Y/Yc.
Anomalous Y/Yc lasts about 1-2 years before upcoming earthquake.

54. Outline About LURR Fault System in Southern California(SC)
CAP, CSB
About LURR
Fault System in Southern California(SC)
Field Stress in SC
Calculation of Y/Yc
Variation of Y/Yc before Some Strong Earthquakes in SC
Earthquake Tendency in SC
Discussion

63. Earthquake Tendency in Southern California
There might be moderate earthquake about 5 around
(36N, 119W) and (36N, 121.6W) within about 1 year.
The results also show that there are no LURR anomalies
in other regions, which implicates that there is less strong
earthquake hazard in Southern California in the near future.

64. Outline About LURR Fault System in Southern California(SC)
CAP, CSB
About LURR
Fault System in Southern California(SC)
Field Stress in SC
Calculation of Y/Yc
Variation of Y/Yc before Some Strong Earthquakes in SC
Earthquake Tendency in SC
Discussion

65. Discussion LURR is a promising approach to mid-term earthquake
prediction. However, calculation of LURR depends on
high quality earthquake catalogue and other data. Up to
now, we can not give an exact earthquake prediction by
LURR, but an approximate one.
For earthquakes greater than 6.5 in Southern California,
the size of anomalous LURR are among km,
which might imply the seismogenic region size. In
addition, evolution of anomalous LURR is complex.

66. Acknowledgements
QUAKES
NSFC(Grant , )
CNSS, SCEC

67. SC02
ML:

68. SC03
ML:

69. SC04
ML:

70. SC05
ML:

71. SC06
ML:

72. SC07
ML:

73. SC08
ML:

74. SC09
ML:

75. SC10
ML:

76. SC11
ML:

77. Tangshan

78. zhangjiakou Ml:4.7

79.
zhangbei 5.6

80.
zhangbei 5.6

81.
zhangbei 5.6

82.
zhangbei 5.6

83.
zhangbei 5.6

84.
zhangbei 5.6

85.
zhangbei 5.6

86.
hunyuan Ml:4.6

87.
hunyuan Ml:4.6

88.
hunyuan Ml:4.6

89. considering the influence of random
factors on LURR.