DAM SURGES DETERMINE RUPTURE DURATIONS

Earthquakes caused by dams.

A study of displacements during significant earthquakes.

© 2016 Ramaswami Ashok Kumar

19 October 2016 Rev 2 November 2016.

A study of displacements during 12 significant earthquakes of the world caused by combined action of all surface water bodies on land (Ref 1) shows that the rupture duration of the earthquakes (Ref 2) is determined by the sum of the dam content changes occurring in all the reservoirs: Figure 2Ch2 (Data from Table 1):

The dam content change occurring in the dry season, October to June is taken as negative while that in the monsoon is taken as positive.

1. The rupture duration of the earthquake in seconds(s) correlates linearly  with the absolute value of the dam content change denoted by ABSdbcm, measured in billion cubic meters(BCM) significant: CORREL(ABSdbcm, s):

R                                          df           t                     p                           R^2 0.772659733 10 3.848907 0.003217957 0.597003

R^2 is 0.597.

2. A non-linear correlation of the rupture duration, s with the absolute value of the dam content change which is shown also in Figure 2Ch2 is a cubic fit with R^2 = 0.8801 or R= 0.9385. The cubic fit is

y = -9E-09x³ + 9E-05x² - 0.0322x + 49.414
R² = 0.8801

Less than 12% of the variations are not explained by this fit.

3. Note also that the linear correlation between the energy released at the hypocentre of the quake, Es in Joules and the ABS(dam content Change),BCM  is

          R             Df            T                  P

0.9392

10

8.649598

5.9052E-06

4. And that the linear correlation between the Power in Terawatts of the energy release at the quake is

         R              Df            T                  P

0.872757

10

5.653733

0.000211361

5. And the probability of all these occurring simultaneously due to chance is equal to  product of three probabilities at 1, 3 and 4 and  is   4.01643E-12.

For the values of dam content change due to energy release Es in Joules at the quake hypocentre, the energy released Es, the rupture duration in seconds, s , the power of the energy release at the hypocentre. Terawatts, and other derived values, see rows 44 to 60 in Table 1. Data for Latur Earthquake is from Ref 3.

Following  Ref 4 Earthquakes Caused By Dams, I extend Table 1 for 8 more significant earthquakes and as shown there water Moment determines earthquakes: Water Moment is modeled as dam content change, dbcm, measured in BCM multiplied by the hypocentre displacement,d measured in meters, dbcmxd. 
Note that d=(Distance between centre of gravity of water masses behind dams and the hypocentre of the earthquake measured in kilometers)/(5x10E1.25).
The rupture duration data is from USGS Moment Rate Function of Finite Fault Analysis.Where this data is unavailable, the rupture duration is taken as twice the half duration from USGS Moment Tensor data for seismic moment.
The data is shown in Table 2:

Figure 2 shows the correlations.

Figure 2: Linear and 4 degree polynomial  correlations show the ground reality of dams rigidly controlling the earthquakes. Only less than 7 percent of the variations of rupture duration are not explained by the 4 degree polynomial.

References:

1. predicting earthquakes: The science of dams causing earthquakes and climate change at

http://predictingquakes.blogspot.in/2015/04/the-science-of-dams-causing-earthquakes.html

2. USGS: Significant Earthquakes of the World at

 http://earthquake.usgs.gov/earthquakes/browse/significant.php

3.PROCEEDINGS OF SMiRT-13-POST CONFERENCE SEMINAR-16

SEISMIC EVALUATION OF EXISTING NUCLEAR FACILITIES

LATUR EARTHQUAKE AND ITS IMPACT ON THE ASEISMIC DESIGN

OF STRUCTURES IN INDIA

P.C. BASU

Atomic Energy Regulatory Board, INDIA

XA9952647

www.iaea.org/inis/collection/NCLCollectionStore/_Public/30/053/30053310.pdf

 

4. Ashok Kumar R. 2005. Earthquakes Caused by Dams at
http://earthquakescausedbydams.blogspot.in/2006/07/title-earthquakes-caused-by-dams.html