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Wednesday, August 31, 2016

Do Water Dams Create Earthquakes? It Appears So.

I am a large believer in hydroelectric power.    I think we need to do more of it, even at the expense of some frogs and such. 

However, is there a larger price to be paid for some of these dams?

https://thearchernews.wordpress.com/2013/04/25/chinese-dam-blamed-for-recent-earthquakes/

https://arxiv.org/pdf/1007.2155.pdf

Abstract Two  and  a half years  prior  to China’s  M7.9 Wenchuan earthquake of May
2008, at least  300 million  metric  tons  of water  accumulated with  additional seasonal water  level changes  in the Minjiang  River Valley
at the eastern margin  of the Longmen Shan.  This  article  shows that static surface  loading  in the  Zipingpu  water  reservoir  in- duced  Coulomb  failure  stresses  on the  nearby Beichuan thrust fault  system  at <17km depth. Triggering stresses  exceeded  levels of daily  lunar  and  solar tides  and  perturbed a  fault  area  measuring 416±96km2 .  These  stress  perturbations, in  turn, likely  ad- vanced  the clock of the mainshock and directed the initial  rupture propagation upward towards the  reservoir  on  the  ”Coulomb-like” Beichuan fault  with  rate-and-state  de- pendent frictional behavior. Static triggering perturbations  produced up  to  60 years (0.6%) of equivalent tectonic loading,  and show strong  correlations to the coseismic slip. Moreover,  correlations between  clock advancement and  coseismic slip, observed  during the  mainshock beneath the  reservoir, are  strongest for a longer  seismic  cycle (10kyr) of M>7 earthquakes. Finally, the  daily  event rate  of the  micro-seismicity (M≥ 0.5) correlates well with  the  static stress  perturbations, indicating destabilization.

Keywords  Earthquake · Geomechanics · Geoengineering · Triggered Earthquakes ·
Water Reservoir  · Tides  · Sun · Moon · Gravitation · Seismology


1 Introduction

The  Wenchuan earthquake of May  12, 2008 occurred in the  Sichuan  province  of the People’s Republic of China. This M7.9 event ruptured along the border  of the Longmen Shan  margin  of the  Tibetan plateau in the  West  and  the  Sichuan  basin  in the  East. The  earthquake’s nucleation point was at Long=103.364 and  Lat=30.986 at about 16 km depth. The  epicentral error  is 5 km and  the  focal depth estimation error  is 10 to 15 km (Huang  et al. 2008).
The  Beichuan fault  system, consisting of listric  and  NNW  dipping  reverse  faults, broke  250-300  km  parallel   along  the  Longmen  Shan  thrust belt  (Fig.  1)  (Burchfiel Christian D. Klose Think Geohazards, New York,  USA E-mail: christian@cdklose.com
2


et  al.  1995).  This  intra-continental region  has  been  extensively studied both  prior  to and  after  the  M7.9 earthquake in 2008, including  a) paleo-seismicity studies  (Burchfiel et  al.  1995; Densmore  et  al.  2007; Zhang  et  al.  2009; Zhou  et  al.  2007; Burchfiel  et al.  1995; Chen  et  al.  1994),  b)  instrumental  recordings of the  seismicity  prior  to  and after  the  mainshock (1970-2009)  (Hu  2007; Lei et al. 2008), c) inversion  data analyses of teleseismic  body  waves of the  mainshock (Wang et al. 2008a; Zhang  et al. 2009), d) studies  on coseismic ground  deformations (Lin et al. 2008; Zhang  et al. 2009). Finally, the  trigger  mechanism of the  2008 M7.9 Wenchuan earthquake has been debated since the earthquake’s occurrence (Klose 2008; Lei et al. 2008). Some studies  suggest  that the mainshock might have been triggered by pore pressure  diffusion within  the earth’s  crust resulting from  a nearby artificial lake,  the  Zipingpu  water  reservoir  (Lei  et  al.  2008; Ge et al. 2009). Other studies  reject  the  hypothesis of triggering due to pore  pressure diffusion  (Deng  et al. 2010; Gahalaut and  Gahalaut 2010). It  can  be anticipated that the earthquake cycle was already in its late stage in 2005 and close to failure conditions, because  the Wenchuan earthquake ruptured in 2008. But,  did the surface loading  affect the  earthquake cycle and  the  initial  rupture? How many  years  of equivalent tectonic loading  would the  artificial loading  advance the  clock of the  mainshock and  how much of the  coseismic  slip would  it produce?
This study shows that observations and data modeling support the initial  argument that lithostatic stress  changes  and  the  poroelastic response  of the  earth’s  crust  due to the  weight of the  Zipingpu  reservoir  on the  earth’s  crust  most  likely triggered the  2008
M7.9 Wenchuan earthquake (Klose 2008). The article  provides  further evidence  that a) surface  loading  due  to water  mass  accumulations within  the  Zipingpu  water  reservoir in the  Minjiang  River  Valley  between  2005 and  2008 induced  Coulomb  failure  stress changes  in the earth’s  crust  and b) triggering stress perturbations beneath the artificial lake likely advanced the  clock of the  Wenchuan earthquake, while affecting  the  initial rupture propagation. Furthermore, the  water  reservoir  impounding generated static triggering stress  perturbations in the  earth’s  crust  beginning in 2005 that biased  daily stress  alterations due  to  tidal  elongations of the  moon  and  the  sun.  Furthermore, it could  have  changed  the  natural earthquake cycle and  advanced the  clock of the  2008
Wenchuan earthquake by several  decades.

4 comments:

  1. seen this theory being bandied about on some forums.. it is interesting to say the least

    ReplyDelete
    Replies
    1. Yep, we don't need to add danger to our Toxic environment, lol, ouch.

      Delete
  2. Actually if you think about ot, we have only scratched the surface of the total uranium in the earths core. If you do the calcs, natural transmuted to plutonium and/or spontaneous fission happens more than you would like to admit. Thus its qyite possible there are mini Oklo's occuring deep in the earths crust. Radiation does heat the core. Its quite entirely possible all life on this planet is made possible by the physics you hate. Hate is bad.

    ReplyDelete
  3. Actually if you think about ot, we have only scratched the surface of the total uranium in the earths core. If you do the calcs, natural transmuted to plutonium and/or spontaneous fission happens more than you would like to admit. Thus its qyite possible there are mini Oklo's occuring deep in the earths crust. Radiation does heat the core. Its quite entirely possible all life on this planet is made possible by the physics you hate. Hate is bad.

    ReplyDelete

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