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Li YE, Chen XZ, and Chen LJ (2021). Joint analysis of b-value and apparent stress before the 2011 MW9.0 Tohoku-Oki, Japan earthquake. Earthq Sci 34(4): 323–333,. DOI: 10.29382/eqs-2021-0036
Citation: Li YE, Chen XZ, and Chen LJ (2021). Joint analysis of b-value and apparent stress before the 2011 MW9.0 Tohoku-Oki, Japan earthquake. Earthq Sci 34(4): 323–333,. DOI: 10.29382/eqs-2021-0036
shu

Joint analysis of b-value and apparent stress before the 2011 MW9.0 Tohoku-Oki, Japan earthquake

  • 1.

    Institute of Geophysics, China Earthquake Administration, Beijing 100081, China

  • 2.

    Chongqing Earthquake Agency, Chongqing 401147, China

More Information
  • Corresponding author:

    Xuezhong Chen, cxz8675@163.com

  • Received Date: 08 Aug 2021
  • Revised Date: 13 Sep 2021
  • Accepted Date: 14 Oct 2021
  • Available Online: 18 Nov 2021
  • Published Date: 11 Nov 2021
    Abstract
  • Key points:
    • The negative correlation between decrease in b-value and simultaneous increase in apparent stress were found, which lasted for approximately 8 years prior to the 11 March 2011 MW9.0 Tohoku-Oki, Japan earthquake. • The spatial pattern of the relative change in b-value shows that the area associated with drastic b-value decreases was concentrated near the 2011 mainshock epicenter. • Variations of apparent stress and b-value might provide tectonic stress information to understand the process of large events.
    Detecting tempo-spatial changes of crust stress associated with major earthquakes has implications for understanding earthquake seismogenic processes. We conducted a joint analysis of b-value and apparent stress in the source region before the March 11, 2011 MW9.0 Tohoku-Oki, Japan earthquake. Earthquakes that occurred between January 1, 2000 and March 8, 2011 were used to estimate b-values, while source parameters of events with magnitudes of Ms5.0–6.9 between January 1, 1997 and March 8, 2011 were used to calculate the apparent stresses. Our results show that the average b-value decreased steadily from 1.26 in 2003 to 0.99 before the Tohoku-Oki mainshock. This b-value decrease coincided with an increase in the apparent stress from 0.65 MPa to 1.64 MPa. Our results reveal a clear negative correlation between the decrease in b-value and increase in apparent stress, which lasted for approximately eight years prior to the 2011 mainshock. Additionally, spatial pattern results of the relative change in b-value show that the area associated with drastic b-value decreases (25% or greater) was concentrated near the 2011 mainshock epicenter. The joint analysis of b-value and apparent stress provides a promising method for detecting anomalies that could serve as potential indicators of large earthquakes.
    • FullText(HTML)

  • Earthquake occurrence is generally considered to involve stress accumulation over substantial periods, which is followed by a sudden release of stored energy. Studying the stress variation before large earthquakes has long been an approach for understanding earthquake genesis and recurrence. However, it is challenging to measure stress levels in direct proximity of earthquake sources at depths that range from a few to tens of kilometers, while monitor them longer term is even more difficult.

    The slope in the Gutenberg-Richter relationship can be used to indicate crustal stress levels. The b-value is usually one. On a global scale, but in actuality it varies around one. Therefore, b-value variation can be used to study crustal stress state changes (; ). Low b-values are typically associated with asperity, especially for regions where strong earthquakes occur (; ; ; ; ; ). In laboratory experiments, and Scholz () found that the b-value decreased prior to rock fracture, which indicated a negative correlation between b-values and stress; i.e., low b-values were associated with high stress. Many seismicity studies have reported a reduction in b-value prior to strong earthquakes (; ; ; ; ; ; ). Wang JH et al. () conducted statistical studies on the relationship between the duration for which the b-value decreases and the magnitudes of major earthquakes. They found that a larger earthquake magnitude is associated with a longer precursor time. However, it remains uncertain whether the decrease in b-value is universally observed prior to all earthquakes. Case studies suggest that the decreasing trend in b-value is not evident before large earthquakes (), while other studies have observed an increase in b-value prior to strong earthquakes ().

    In addition to the b-value, apparent stress is also a parameter that can reflect crustal stress levels. The apparent stress is the product of shear modulus and ratio of radiated energy of an earthquake to the seismic moment (). It is often used to analyze stress variation before a strong earthquake. Previous studies indicate that apparent stress near source areas increased significantly before large earthquakes (; , ; ). In particular, recent studies have found that apparent stress increases and decreases before and after the occurrences of large earthquakes, respectively (). However, a comparison between the apparent stress estimated from the foreshocks and aftershocks of the April 6, 2009 MW6.1 L'Aquila earthquake found no significant increase in the apparent stress before the mainshock ().

    Before a strong earthquake, an increase in stress in the hypocenter vicinity may lead to a decrease in the b-value and a simultaneous increase in the apparent stress (). We studied the March 11, 2011 MW9.0 earthquake that occurred offshore of Tohoku-Oki, Japan, to analyze the variation relationship between b-value and apparent stress before this great earthquake. This was the largest earthquake ever recorded in the region and occurred at the boundary between the Pacific Plate and North American Plate. We investigated the enhancement process in the genesis of the earthquake. In addition, we analyzed the relationship between the decrease in b-value and epicenter of the 2011 mainshock.

    2.1   Earthquake catalogs

    In Figure 1 below, the study region is shown by the black line, and is slightly larger than the aftershock area. To perform b-value analysis for the March 11, 2011 Tohoku-Oki earthquake, we collected the data on 6503 earthquakes of magnitudes M ≥ 4.0 between January 1, 2000 and March 8, 2011 from the United States Geological Survey (USGS) catalog (https://earthquake.usgs.gov/earthquakes/search/).

    Figure 1. Distributions of events used in this study in (a) b-value and (b) apparent stress analyses. The red star denotes the epicenter of the March 11, 2011 Tohoku-Oki mainshock. The black polygon encompasses the study region.
    Figure  1.  Distributions of events used in this study in (a) b-value and (b) apparent stress analyses. The red star denotes the epicenter of the March 11, 2011 Tohoku-Oki mainshock. The black polygon encompasses the study region.
    DownLoad: Full-Size Img PowerPoint

    Additionally, we obtained the source parameters of 135 earthquakes (5.0 ≤ MS ≤ 6.9) between January 1, 1997 and March 8, 2011 from the Global Centroid Moment Tensor (GCMT) catalog (http://www.globalcmt.org/CMTsearch. HTML) to perform apparent stress estimation. Figure 1 shows the 2011 Tohoku-Oki mainshock and event locations used for b-value (Figure 1a) and apparent stress (Figure 1b) analyses in this study.

    2.2   b-value analysis

    We applied the maximum likelihood method to estimate the b-value, which is expressed as ()

    b=loge¯M−Mmin (1)

    where \overline M and Mmin represent the average and minimum magnitudes of the group of events used to estimate the b-value.

    The 95%-confidence standard deviation of b is expressed as

    \sigma \left(b\right)=1.96\frac{b}{\sqrt{N-1}}, (2)

    where N is the total number of earthquakes. A smaller standard deviation indicates a more stable b-value result. Equation (2) shows that the standard deviation is inversely correlated with the number of earthquakes.

    The b-value was calculated as a function of time using a time window comprising a constant number of events N. The window moves incrementally in time by a number of events. We applied a constant number of events in each window (rather than windows with a constant time width) to ensure that the analysis was not influenced by sample size changes.

    2.3   Apparent stress analysis

    The apparent stress is defined as follows ()

    {\sigma _{\rm{a}}} = \mu \frac{{{E_{\rm{S}}}}}{{{M_0}}}, (3)

    where μ is the shear modulus (for the crustal material, μ can be considered as 3 × 104 MPa), and Es and M0 are the radiated seismic energy and seismic moment, respectively. In this study, they were determined based on the source parameters obtained from the GCMT catalog (http://www.globalcmt.org/CMTsearch.HTML). Source parameters of 153 earthquakes that occurred between January 1, 1997 and March 8, 2011 (MW ≥ 5.0, the maximum MW = 6.9) in the study region are listed in Table S1. Using the seismic moment and MS given in Table S1, ES was determined using Equation (4). Equation (3) was then applied to obtain the apparent stresses of the earthquakes in Table S1 ().

    {\rm{Log}}{E_{\rm{S}}} = 1.5{M_{\rm{S}}} + 11.8. (4)

    The MS of certain earthquakes are not included in the GCMT catalog; therefore, the MS of those earthquakes was obtained using the linear regression relationship between mb magnitude and MS (Figure 2). Figure 2 displays the MS and mb of the earthquakes in the study region occurring during the study period. A linear regression yields the following relationship between MS and mb:

    Figure 2. MS versus mb plot for the earthquakes in the study region.
    Figure  2.  MS versus mb plot for the earthquakes in the study region.
    DownLoad: Full-Size Img PowerPoint
    {M_{\rm{S}}} = 1.1518 m_{{b}} - 1.0154 \pm 0.4755 r = 0.84. (5)

    Among the 153 earthquakes that occurred in the selected study area, MS magnitude for 29 earthquakes are missing, which account for approximately 18.9% of the total number of earthquakes. The MS marked by a “*” in Table S1 were calculated using Equation (5), and the apparent stress values are provided in Table S1.

    To estimate b-values, the completeness of earthquake catalogue should be thoroughly considered with respect to the observed Gutenberg-Richter relationship via visual inspection. The event frequency-magnitude plot (Figure 3) suggests the threshold of completeness to be Mc = 4.0. Considering that magnitude determination may vary in different regions or periods, we set Mmin = 4.5 for the earthquakes we used to calculate the b-value. To calculate the b-value as a function of time, 1167 earthquakes in the study region with M ≥ 4.5 were selected. A sliding time period containing 500 events and increments of one event was utilized.

    Figure 3. Gutenberg-Richter relationship
    Figure  3.  Gutenberg-Richter relationship
    DownLoad: Full-Size Img PowerPoint

    The b-value variation with time is shown in Figure 4, with its 95% confidence limit. The b-value was greater than 1.26 before 2003 and then began to decline. By 2009, the b-value was reduced to 0.99 (Figure 4c), constituting a 21% decrease.

    Figure 4. Variations in b-values (red line, left vertical axis) and apparent stress (blue line, right vertical axis) with time. Sample size was 300 (a), 400 (b), 500 (c), and 600 (d), respectively. The gray area indicates the 95% confidence limit of the b-value according to Eq. (2). The black arrow marks the time of the March 11, 2011 Tohoku-Oki earthquake.
    Figure  4.  Variations in b-values (red line, left vertical axis) and apparent stress (blue line, right vertical axis) with time. Sample size was 300 (a), 400 (b), 500 (c), and 600 (d), respectively. The gray area indicates the 95% confidence limit of the b-value according to Eq. (2). The black arrow marks the time of the March 11, 2011 Tohoku-Oki earthquake.
    DownLoad: Full-Size Img PowerPoint

    The b-value exhibited a significant decrease eight years prior to the 2011 Tohoku-Oki MW9.0 mainshock. We further investigated this result by analyzing the variation in the apparent stress. The stress level in the study area can be represented by the average value of the apparent stress associated with a selected number of earthquakes. In contrast to using time windows containing the same number of events for calculating the b-value, it is more reasonable to use time windows of the same length in the apparent stress analysis. In this study, we used sliding time windows of three years, with increments of three months. The average apparent stress obtained represents the mean apparent stress of earthquakes that occurred during the three-year time windows. The occurrence time of the latest event in each time window was used as the average apparent stress value time. The average apparent stress variation with time is shown in Figure 4. We clearly see that the average apparent stress remained stable before 2003, and then began to rise steadily between 2003 and 2009. The average apparent stress before 2003 (0.65 MPa) was slightly higher than the global average of 0.47 MPa (). In early 2009, the average apparent stress reached 1.64 MPa, which was 2.4 times greater than that before 2003. The apparent stress then fluctuated around a high value (1.64 MPa) until the mainshock occurred on March 11, 2011.

    To test the influence of different sampling numbers on the results, we calculated b-values with 300, 400, 500, and 600 earthquakes (Figure 4). When the samples decrease, the standard deviation of b-values will increase, conversely, an increase in sample number corresponds to a decrease in the standard deviation of b. The time resolution will decrease with an increase in sampling. However, the results show that the variation trend of b-values obtained by different sampling numbers is consistent.

    By comparing the variations of b-value and apparent stress over time, we see a clear negative correlation between b-value and apparent stress, which indicates that there was a significant stress enhancement in the study region before the MW9.0 earthquake on March 11, 2011.

    We also examined the relationship between the spatial pattern of relative change in b-value (∆b/b) and mainshock epicenter. Consequently, we calculated the relative change in b-value. As shown in Figure 5, we used a grid technology strategy () by dividing the space into 0.1° × 0.1° grid nodes, with each grid node as the center and a 3° × 3° area being the sub-region. To obtain stable b-values, the sample size needs to be approximately 50–100 events (). In each sub-region, we used samples containing 100 events and calculated the b-value change with time for each event. To obtain a reliable b-value change trend, we required a minimum of ten b-values.

    Figure 5. Spatial patterns of the relative changes in b-value for (a) the whole region, (b) region with ∆b/b ≤ −10%, (c) region with ∆b/b ≤ −20%, and (d) region with ∆b/b ≤ −25%. The black polygon in (a) represents the spatial distribution range of grid node used in the study region for calculating the relative change in b-value. The open red star indicates the epicenter of the March 11, 2011 Tohoku-oki mainshock.
    Figure  5.  Spatial patterns of the relative changes in b-value for (a) the whole region, (b) region with ∆b/b ≤ −10%, (c) region with ∆b/b ≤ −20%, and (d) region with ∆b/b ≤ −25%. The black polygon in (a) represents the spatial distribution range of grid node used in the study region for calculating the relative change in b-value. The open red star indicates the epicenter of the March 11, 2011 Tohoku-oki mainshock.
    DownLoad: Full-Size Img PowerPoint

    Figure 5a shows the spatial distribution range of 7139 grid nodes in accordance with the relative change of b-values (∆b/b), which was calculated using data from January 1, 2005 to March 8, 2011. Figure 5a to Figure 5d show results for the spatial distribution of ∆b/b, ∆b/b ≤ −10%, ∆b/b ≤ −20%, and ∆b/b ≤ −25%, respectively. The resulting pattern of the relative b-value changes shows strong spatial variations (Figure 5a). Regions with larger relative decreases in b-values are located closer to the source area of the 2011 Tohoku-oki mainshock. The mainshock epicenter correlates with the region experiencing relatively large decreases in b-value (Figure 5d). To test this result, we changed the event sample numbers from 60 to 120 to calculate the b-values. The spatial distributions of the relative b-value change were similar. As mentioned previously, when calculating the change in b-value over time with more number of samples, less b-value is obtained, the time resolution decreases, and the relative change range of the b-value tends to decrease.

    The variation in b-value with time shows a decreasing trend (by approximately 21%) from 1.26 in 2003 to 0.99 in 2009. From 2009 to March 8, 2011, the b-value remained steady at approximately 0.99. Our findings show that the b-value may have different short-scale variations over time, but the decreasing trend remains prominent; this result is consistent with previous studies (; ).

    Our findings also show that the average apparent stress increased gradually from 0.65 MPa to 1.64 MPa in 2009, which was more than double when compared to that before 2003. From 2009 to the 2011 Tohoku-Oki mainshock, the apparent stress fluctuated at high values.

    Prior to the 2011 Tohoku-Oki earthquake, a strong negative correlation was observed between the decrease in b-value and the increase in apparent stress during the eight years. Nanjo et al. () showed that the b-value began to decrease in 2004 near the epicenter. The reduction in the b-value observed by Tormann et al. () lasted for more than ten years. Owing to the strong heterogeneity of b-value at the regional scale, we suggest that the difference in the durations of the b-value reductions determined by different researchers might be caused by the different event selection criteria. In this study, the apparent stress was also used to discuss the change in stress. The average apparent stress remained stable at approximately 0.65 MPa before 2003, without showing an increasing trend. After 2003, the average apparent stress began to increase gradually. This is consistent with our results, suggesting that the b-value started to decrease in 2003.

    The spatial pattern of the relative change in b-value shows that the area with a relative change ∆b/b ≤ −25% coincides with the source region of the 2011 Tohoku-Oki earthquake.

    In summary, our b-value and apparent stress analyses suggest that long-term trends of b-value reductions and apparent stress increased before the March 11, 2011 MW9.0 earthquake, and the epicenter of the mainshock was closely related to the region with the largest decrease in b-value. The joint analysis of b-value and apparent stress may serve as an important means for detecting possible indicators of anomalies before major earthquakes.

    This study is supported by China National Key Research and Development Program (No. 2018YFC1503405). The authors acknowledge the course ‘English Presentation for Geophysical Research’ of Peking University (Course #01201110) for improving the manuscript.

    Supplementary material

    Table S1. Source parameters and apparent stress for earthquakes in this study region prior to 2011 MW9.0 Tohoku-Oki earthquake.

    Date (a-mo-d)Latitude (°N)Longitude (°E)MWmbMSDepth (km)Moment (×1025erg)σapp(MPa)
    1997-02-1937.40141.075.55.3 5.0*96.10.2070.29
    1997-03-0434.89139.045.65.35.315.00.2790.60
    1997-05-1137.09140.915.95.55.357.90.9010.19
    1997-12-0737.70141.595.35.3 5.0*83.70.1190.50
    1998-04-0936.92140.825.55.3 5.0*88.90.2150.28
    1998-05-0334.87138.985.55.15.333.70.2560.66
    1998-05-1440.25143.255.95.85.719.01.0010.67
    1998-05-3039.03143.446.15.75.715.01.9100.35
    1998-06-1435.37140.525.75.55.323.00.4370.39
    1998-08-1637.22141.555.35.35.0*34.00.1180.51
    1998-09-0339.72140.765.85.75.715.00.6541.03
    1998-10-1340.03143.305.55.45.017.00.2110.28
    1998-10-2733.49141.405.65.35.815.00.2753.45
    1998-11-2337.98141.485.25.4 5.2*72.10.0841.43
    1999-01-2138.65142.905.85.35.420.00.6630.36
    1999-02-2035.51141.825.45.05.215.00.1810.66
    1999-02-2035.38142.095.24.85.017.10.0870.69
    1999-03-0235.59141.755.95.45.615.00.8740.54
    1999-04-2536.44140.475.35.3 5.0*62.30.1060.56
    1999-10-0240.19143.045.75.85.425.00.3910.61
    1999-11-1538.30142.315.75.75.248.00.3850.31
    2000-03-1937.99141.345.35.3 5.0*71.80.1060.57
    2000-04-2640.31143.335.35.45.144.60.1300.65
    2000-04-2640.18143.245.55.65.149.00.2380.36
    2000-06-0335.55140.466.15.65.648.01.8500.26
    2000-06-2934.19139.145.35.15.115.00.1110.76
    2000-06-2934.06139.565.55.15.033.60.1890.32
    2000-06-2934.03139.365.55.35.215.00.2380.50
    2000-07-0134.22139.136.16.06.115.01.7901.49
    2000-07-0234.08139.235.65.45.315.00.3510.48
    2000-07-0434.11139.165.45.45.015.00.1650.36
    2000-07-0834.08139.295.45.15.015.00.1610.37
    2000-07-0834.05139.135.85.95.615.00.6850.69
    2000-07-1134.19139.185.25.05.015.00.0900.66
    2000-07-1234.18139.205.24.95.015.00.0830.72
    2000-07-1434.15139.105.45.25.015.00.1470.41
    2000-07-1434.12139.225.45.35.016.00.1490.40
    2000-07-1534.32139.266.05.55.920.31.3800.97
    2000-07-2034.03139.275.24.95.015.00.0870.69
    2000-07-2036.51140.986.06.15.446.51.1600.21
    2000-07-2135.18141.075.75.5 5.3*16.00.4510.37
    2000-07-2334.13139.125.55.55.315.00.2590.65
    2000-07-2734.21139.375.55.35.215.00.2570.46
    2000-07-2734.20139.255.55.15.115.00.2040.41
    2000-07-3033.93139.355.75.55.415.00.3900.61
    2000-07-3033.90139.386.56.06.515.06.0501.76
    2000-07-3139.58143.585.45.15.324.90.1501.12
    2000-08-1834.13139.185.75.65.515.00.4560.74
    2000-08-2334.07139.455.35.05.015.00.1180.51
    2000-10-0340.28143.126.25.65.715.02.8500.24
    2001-02-2437.22142.155.95.45.527.00.7540.45
    2001-10-0237.74141.775.65.25.037.00.2760.22
    2001-11-2639.19143.045.25.15.227.20.0751.60
    2001-12-0239.40141.096.46.1 6.0*123.75.6300.34
    2002-02-1236.59140.955.55.65.038.00.2470.24
    2002-05-1239.22140.995.35.3 5.0*107.70.1160.52
    2002-07-2337.25142.225.65.75.226.00.3370.35
    2002-10-1237.75142.625.55.55.128.00.2180.39
    2002-11-0338.89141.986.45.76.144.04.9600.54
    2002-12-0438.73142.195.35.05.037.00.1270.47
    2002-12-1034.30141.605.55.25.715.00.2312.91
    2003-03-0237.68141.725.85.75.338.00.5520.31
    2003-04-0736.30141.685.85.55.531.00.5870.57
    2003-05-1735.59140.555.35.4 5.2*50.00.1250.95
    2003-05-2638.85141.577.06.7 6.7*61.038.8300.55
    2003-07-2538.42141.006.06.05.815.01.4660.65
    2003-07-2638.48141.005.25.4 5.2*15.00.0901.33
    2003-09-2035.00140.175.65.4 5.2*63.20.3370.35
    2003-10-3137.81142.627.06.16.815.035.4500.85
    2003-11-0137.79143.165.05.3 5.0*15.00.0341.75
    2003-11-0137.74143.085.85.95.515.00.7300.46
    2003-11-1436.40141.075.75.75.236.00.3940.30
    2004-02-0440.15141.695.25.4 5.2*63.20.0701.70
    2004-03-1136.30140.895.35.25.133.00.1300.65
    2004-04-0337.20142.064.84.95.222.40.0196.33
    2004-04-0336.43141.015.95.75.634.00.9920.48
    2004-05-2937.75141.885.85.75.234.00.5600.21
    2004-05-2934.25141.416.35.66.612.03.1694.74
    2004-06-0134.49141.395.25.25.016.00.0860.70
    2004-06-0934.28141.525.05.35.112.00.0461.85
    2004-08-1039.63141.965.65.7 5.5*46.00.3371.00
    2004-09-0136.96141.615.75.35.131.00.4180.20
    2004-10-0635.95139.925.75.5 5.3*70.50.4780.35
    2004-10-1636.19141.345.45.45.431.00.1361.75
    2004-10-1636.24141.305.85.55.432.00.5500.43
    2004-11-0238.84142.775.25.65.112.00.0701.21
    2004-12-1936.38141.405.14.95.132.00.0621.36
    2005-01-1234.09141.565.05.25.118.70.0451.89
    2005-01-1934.06141.496.55.86.415.08.1100.93
    2005-01-2033.86141.515.45.3 5.0*13.00.1330.45
    2005-01-2134.02141.555.55.35.714.10.2572.62
    2005-01-2134.00141.375.75.35.513.00.4020.84
    2005-02-2640.73142.385.75.8 5.6*47.00.3871.23
    2005-04-1035.60140.405.96.15.450.00.9880.24
    2005-05-1935.43140.835.35.5 5.3*34.00.1291.30
    2005-06-1935.61140.485.75.45.148.00.4030.21
    2005-07-0239.51143.135.35.15.318.00.1181.43
    2005-07-0933.42140.825.85.8 5.6*33.00.5670.84
    2005-07-2335.50139.985.96.1 6.0*61.91.0361.83
    2005-08-0736.33141.375.55.55.232.00.2060.58
    2005-08-1638.28142.047.26.56.837.076.4000.39
    2005-08-2438.56142.995.96.05.612.00.8510.56
    2005-08-2537.74143.075.15.25.115.00.0631.33
    2005-08-3038.48143.186.05.85.713.01.0940.61
    2005-09-2434.30140.825.25.3 5.0*54.30.0750.80
    2005-10-1936.40140.846.36.26.537.03.9522.69
    2005-10-2237.15140.935.55.6 5.4*51.00.2321.03
    2005-11-1533.34141.355.75.55.316.00.4910.34
    2005-12-0238.09142.126.56.16.334.06.2730.85
    2005-12-0437.88142.445.25.55.031.00.0880.68
    2005-12-1638.51141.906.05.85.636.01.3540.35
    2006-01-1837.77142.135.55.85.020.00.2310.26
    2006-02-0336.16141.455.75.55.432.00.4860.49
    2006-04-2034.86139.215.65.35.612.00.2971.60
    2006-06-1640.35143.715.55.65.613.40.1912.49
    2006-10-1037.20142.665.75.86.019.10.3834.94
    2007-01-1534.89138.645.95.75.9169.8 0.8481.58
    2007-04-1333.59140.815.45.3 5.0*46.20.1420.42
    2007-08-1535.38140.275.25.35.237.30.0941.27
    2007-11-2637.39141.595.95.75.941.80.9581.40
    2007-12-2538.50142.036.15.46.144.21.5681.71
    2008-05-0736.18141.546.25.76.223.92.4111.57
    2008-05-0736.16141.766.15.96.123.21.5871.68
    2008-05-0736.16141.526.86.16.826.323.7101.27
    2008-05-0836.11141.685.55.65.623.10.2661.79
    2008-07-2137.19142.055.95.76.029.60.9372.02
    2008-07-2339.80141.466.86.66.898.819.2801.56
    2008-12-0338.59142.885.85.65.823.60.5631.69
    2008-12-0438.57142.895.35.35.331.10.1331.27
    2008-12-0538.53143.005.55.25.521.30.2521.33
    2008-12-1838.43143.005.35.45.321.40.1131.49
    2008-12-2036.54142.436.36.06.312.03.9301.36
    2008-12-2036.67142.045.45.35.221.30.1360.88
    2008-12-2136.54142.325.95.65.912.00.7911.69
    2009-01-3136.72141.155.75.65.841.50.5261.80
    2009-02-1540.24142.245.76.15.748.00.4521.49
    2009-06-0635.48140.915.85.85.828.00.5361.77
    2009-06-2338.85142.395.65.75.636.10.2911.63
    2009-12-1736.37139.485.15.3 5.0*79.50.0660.90
    2009-12-1833.57141.085.25.4 5.2*28.50.0721.67
    2010-01-1737.94143.605.65.75.618.60.2971.60
    2010-02-1640.33143.655.35.25.313.80.0961.75
    2010-02-2834.83141.475.45.45.616.90.1413.36
    2010-03-1234.90141.605.25.25.220.00.0921.30
    2010-03-1337.59141.305.55.75.675.30.2312.06
    2010-03-1437.74141.596.56.36.545.97.8421.36
    2010-06-1337.37141.625.96.35.933.20.9901.35
    2010-07-0339.06140.715.15.4 5.2*12.00.0482.48
    2010-07-0439.70142.376.36.46.335.33.3011.62
    2010-09-2937.26139.885.55.65.512.00.1941.73
    2011-01-2535.13141.115.35.65.318.60.1021.65
    2011-02-1037.14141.285.45.55.343.30.1720.98
    2011-02-1538.32143.165.25.25.521.80.0863.91
    Note: *: calculated using equation 5.
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    • References (32)
  • Aki K (1965). Maximum likelihood estimate of b in the formula logN=a-bM and its confidence limits. Bull Earthq Res Inst Univ Tokyo 43(2): 237–239.
    Calderoni, G., Rovelli, A., & Giovambattista, R. Di (2019). Stress drop,apparent stress, and radiation efficiency of clustered earthquakes in the nucleation volume of the 6 April 2009, Mw 6.1 L'Aquila earthquake. Journal of Geophysical Research 124: 10360– 10375.
    Chan CH, Wu YM, Tseng TL, Lin TL, and Chen CC (2012). Spatial and temporal evolution of b-values before large earthquakes in Taiwan. Tectonophysics 532–535: 215–222
    Chen XZ, Li YE, Gong Y, and Chen LJ (2021). . Variations in apparent stress and b value in the rupture area before the 2019 MS6.0 Changning earthquake. Progr Earthq Sci 51(2): 49–58 (in Chinese with English abstract). doi: 10.3969/j.issn.2096-7780.2021.02.001
    Choy GL, and Boatwright JL (1995). Global patterns of radiated seismic energy and apparent stress. J Geophys Res:Solid Earth 100(B9): 18205 – 18228 . doi: 10.1029/95JB01969
    Ghosh A, Newman AV, Thomas AM, and Farmer GT (2008). Interface locking along the subduction megathrust from b-value mapping near Nicoya Peninsula, Costa Rica. Geophys Res Lett 35(1): L01301. doi: 10.1029/2007GL031617
    Gutenberg B, and Richter CF (1956). Magnitude and energy of earthquakes. Ann Geophys 9(1): 1–15.
    Imoto M (1991). Changes in the magnitude-frequency b-value prior to large (M≥6.0) earthquakes in Japan. Tectonophysics 193(4): 311–325. doi: 10.1016/0040-1951(91)90340-X
    Li YE, and Chen XZ (2017). Temporal and spacial variations of apparent stress in the rupture volume before and after the 2011 Tohoku, Japan, MW9.1 earthquake. Earthquake 37(4): 10–21 (in Chinese with English abstract).
    Li YE, and Chen XZ (2021). Variations in apparent stress and b value preceding the 2010 Mw8.8 Bio-Bío, Chile earthquake. Pure Appl Geophys 178: 4797 – 4813 . doi: 10.1007/s00024-020-02637-3
    Li YE, Chen XZ, and Wang HX (2012). Temporal and spatial variation of apparent stress in Sichuan area before the Ms8.0 Wenchuan earthquake. Earthquake J 32: 113–122 (in Chinese with English abstract)
    Mogi K (1962). Magnitude-frequency relations for elastic shocks accompanying fracture of various materials and some related problems in earthquakes. Bull Earthquake Res Inst Univ.Tokyo 40: 851–853.
    Nanjo KZ, Hirata N, Obara K, and Kasahara K (2012). Decade-scale decrease in b value prior to the M9-class 2011 Tohoku and 2004 Sumatra quakes. Geophys Res Lett 39(20): L20304.
    Narteau C, Byrdina S, Shebalin P, and Schorlemmer D (2009). Common dependence on stress for the two fundamental laws of statistical seismology. Nature 462(7273): 642–645. doi: 10.1038/nature08553
    Nuannin P, Kulhanek O, and Persson L (2005). Spatial and temporal b value anomalies preceding the devastating off coast of NW Sumatra earthquake of December 26, 2004. Geophys Res Lett 32(11): L11307. doi: 10.1029/2005GL022679
    Öncel AO, and Wyss M (2000). The major asperities of the 1999 Mw = 7.4 Izmit earthquake defined by the microseismicity of the two decades before it. Geophys J Int 143(3): 501–506. doi: 10.1046/j.1365-246X.2000.00211.x
    Picozzi M, Bindi D, Zollo A, Festa G, and Spallarossa D (2019). Detecting long-lasting transients of earthquake activity on a fault system by monitoring apparent stress, ground motion and clustering. Sci Rep 9: 16268 . doi: 10.1038/s41598-019-52756-8
    Scherbaum F, and Kisslinger C (1984). Variations of apparent stresses and stress drops prior to the earthquake of 6 May 1984 (mb = 5.8) in the Adak Seismic Zone. Bull Seismol Soc Am 74(6): 2577 – 2592 . doi: 10.1785/BSSA0740062577
    Scholz CH (1968). The frequency-magnitude relation of microfracturing in rock and its relation to earthquakes. Bull Seismol Soc Am 58(1): 399–415. doi: 10.1785/BSSA0580010399
    Schorlemmer D, Wiemer S, and Wyss M (2004). Earthquake statistics at Parkfield: 1. Stationarity of b values. J Geophys Res:Solid Earth 109(B12): B12307. doi: 10.1029/2004JB003234
    Schorlemmer D, Wiemer S, and Wyss M (2005). Variations in earthquake-size distribution across different stress regimes. Nature 437(7058): 539–542. doi: 10.1038/nature04094
    Schurr B, Asch G, Hainzl S, Bedford J, Hoechner A, Palo M, Wang RJ, Moreno M, Bartsch M, Zhang Y, Oncken O, Tilmann F, Dahm T, Victor P, Barrientos S, and Vilotte JP (2014). Gradual unlocking of plate boundary controlled initiation of the 2014 Iquique earthquake. Nature 512(7514): 299–302. doi: 10.1038/nature13681
    Shi HX, Meng LY, Zhang XM, Chang Y, Yang ZT, Xie WY, Hattori K, and Han P (2018). Decrease in b value prior to the Wenchuan earthquake (MS 8.0). Chinese J Geophys 61(5): 1874– 1882 (in Chinese with English abstract).
    Smith WD (1981). The b-value as an earthquake precursor. Nature 289: 136–139. doi: 10.1038/289136a0
    Sobiesiak M, Meyer U, Schmidt S, Götze HJ, and Krawczyk CM (2007). Asperity generating upper crustal sources revealed by b value and isostatic residual anomaly grids in the area of Antofagasta, Chile. J Geophys Res:Solid Earth 112(B12): B12308. doi: 10.1029/2006JB004796
    Tormann T, Wiemer S, and Hardebeck JL (2012). Earthquake recurrence models fail when earthquakes fail to reset the stress field. Geophys Res Lett 39(18): L18310. doi: 10.1029/2012GL052913
    Tormann T, Wiemer S, and Mignan A (2014). Systematic survey of high-resolution b value imaging along Californian faults: inference on asperities. J Geophys Res:Solid Earth 119(3): 2029– 2054 . doi: 10.1002/2013JB010867
    Wang JH, Chen KC, Leu PL, and Chang CH (2016). Precursor times of abnormal b-values prior to mainshocks. J Seismol 20(3): 905–919. doi: 10.1007/s10950-016-9567-7
    Wiemer S, and Wyss M (1997). Mapping the frequency-magnitude distribution in asperities: An improved technique to calculate recurrence times? J Geophys Res:Solid Earth 102(B7): 15115 – 15128 . doi: 10.1029/97JB00726
    Wiemer S, and Wyss M (2002). Mapping spatial variability of the frequency-magnitude distribution of earthquakes. Adv Geophys 45: 259–302.
    Wyss M (1970). Apparent stresses of earthquakes on ridges compared to apparent stresses of earthquakes in trenches. Geophys J Int 19(5): 479–484. doi: 10.1111/j.1365-246X.1970.tb00153.x
    Zhao YZ, and Wu ZL (2008) Mapping the b-values along the Longmenshan fault zone before and after the 12 May 2008, Wenchuan, China, MS8.0 earthquake. Nat Hazards Earth Syst Sci 8(suppl):1375–1385
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    Article Contents
    Abstract
    1.   Introduction
    2.   Data and methods
    2.1   Earthquake catalogs
    2.2   b-value analysis
    2.3   Apparent stress analysis
    3.   Results
    4.   Discussion and conclusions
    Acknowledgments
    References

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