“Earthquakes and Water” Course
Lecturer: Professor Shih-Jung Wang, PhD (Assistant Professor in Graduate Institute of Applied Geology, National Central University)
Earthquakes and Water [Open Access: Link]
Earthquakes and Water in Encyclopedia of Complexity and Systems Science [Link]
Earthquake Hidrology, book chapter in Treatise on Geophysics [Link]
Hydrologic Responses to Earthquakes and a General Metric, book chapter in Frontiers in Geofluids [Link]
Continental-scale water-level response to a large earthquake, book chapter in Crustal Permeability [Link]
Fluid Induced Seismicity [Link]
Scientists in this topic:
My paper reviews (Presentation will not be shown)
Paper Review 3
Paper Review 4
Some notes and resume:
Chapter I: Introduction
– studied about interaction between earthquakes and water (fluids)
– Stress from earthquake can be large; mainly two types i.e. static stress and dynamic (transient) stress [see Freed et al., 2005, Link]
– Static stress ΔCFS, decrease rapidly with distance (time independent) caused by permanent displacement of fault (near field) [decay with distance as 1/R^3]
– Dynamic stress ΔCFS(t) (time dependent) [decay with distance as 1/R^1.66]
– Stress perturbation from earthquake can enhance crustal permeability
– Concept of permeability enhancement can be seen in Rojstaczer et al. (Nature, 1995) [Link]
– Empirical formula from Elkhoury et al. (Nature, 2006) [Link]
ΔK = R. v/c where Δk is the change in permeability at the time of the earthquake, v is PGV in the vertical and c is the phase velocity of the seismic waves. The ratio v/c is approximately the imposed strain on the system, so R measures the permeability response to strain. The parameter R is a property of the well–aquifer system and is different for each well.
– Stress changes also can induced fluid pressure changes.
– All concept related to: dynamic strain and seismic energy density (dissipated energy density).
– Basic theories: groundwater flow, groundwater transport and hydro-mechanical coupling.
Chapter II: Liquefaction
– Keypoints: rigidity is reduced to zero, then sediments become fluid-like.
– Mainly based on the principle of effective stress: [Download here about The Terzaghi Theory of Effective Stress]
σ’zz = σzz – αP
effective stress = vertical stress – [alpha x pore pressure]
alpha = empirical parameter
or can be rewritten σ’ = σ – μ –> if σ = μ, then σ’ = 0
Means: pore pressure generated by surface load acts to reduce σ’zz by an amount of αP.
It means, when sediments consolidate in an undrained condition during earthquake, pore-pressure increase and then liquefaction occurred.
When loading from earthquake come, pore pressure become high (P increase) and then σ’zz decrease to ~ 0. Sediments become fluid like (liquefy).
– Important notes: In most cases, the liquefied sediments are sand (pasir) or silty sand (lumpur). Sometimes + well-graded gravel (kerikil).
– Liquefaction in near field: Terzaghi’s principle of effective stress; undrained consolidation.
[Seismic shaking can disturb grain-to-grain contacts to cause sediments to consolidate; vertical stress decrease, pore pressure increase, effective stress vanishes; sediments become fluid-like]
– Laboratory studies: Cyclic loading experiments, dissipated energy for liquefaction by undrained consolidation
– Threshold of diss. energy density to induce liquefaction: 30 J/m^3
– Liquefaction beyond near field: factors: hypocentral distance, style of Eq faulting, directivity effect, sediment type and grain size.
– Seismic energy density (e) as a metric for liquefaction distribution; note: e ~ PGV^2 [consistent with field data]: make empirical relation among e, r and M.
– Beyond near field: e below the threshold (30 J/m^3) to induce undrained consolidation
– Possible mechanism beyond near field: mechanism of pore-pressure spreading from nearby sources to sediment sites!
– For mitigation (as a mid-term question): (a) assess potential/vulnerability of soil liquefaction (liquefaction zoning); (b) microbial denitrification; (c) analysis and well-designed stucture/facilities; (d) understanding soil ageing; (e) densification, drainage and solidification.
– An unresolved issue is the complex relationship between liquefaction and the frequency of seismic waves. Current results from the field and laboratories are in conflict. Future work is needed to resolve these conflicts.
Chapter III: Mud volcanoes
Paper to read: Bonini et al., (2016) [Link]
Static stress changes can trigger eruptions through:
(1) Expanding magma reservoirs
(2) Compressing magma reservoirs
(3) Unclamping magma ascent paths
Dynamic stress changes can trigger eruptions through:
(1) Changing permeability
(2) Nucleating or mobilizing bubles
(3) Mobilizing magma
* In near field, triggering maybe combination of static and dynamic stress changes.
Other related papers:
Florian Fuchs, Dissertation, Dynamic triggering: The effects of remote earthquakes on volcanoes, hydrothermal systems and tectonics. University of Bonn, 2015 [Link]
Miguel Neves, Dissertation, Dynamic triggering of seismic activity in rifting and volcanic settings, University of Lisboa, 2016 [Link]
Maxwell Rudolph, Dissertation, Mechanical Controls on Eruptions, University of California Berkeley, 2012 [Link]
Matthew Weingarten, Dissertation, On the interaction between fluids and earthquakes in both natural and induced seismicity, University of Colorado Boulder, 2015 [Link]
Hill et al. (2002), Earthquake-Volcano Interaction [Link]
Manga and Brodsky (2006), Seismic Triggering of Eruptions in the Far Field: Volcanoes and Geysers [Link]
Manga et al. (2009), Earthquake triggering of mud volcanoes [Link]
Linde and Sacks (Nature, 1998), Triggering of volcanic eruptions [Link]
Difficulty to assess static stress changes to volcanoes: how to define feeder Dyke as receiver of stress.
Calculation of static stress changes: Click Here to see my tutorial
Chapter IV: Increased Stream Discharge
to be continued…