Key to Understanding Pre-Earthquake Phenomena

Transcription

1 Stress-Activated Positive Hole Charge Carriers Key to Understanding Pre-Earthquake Phenomena Friedemann Freund Carl Sagan Center Physics Department NASA Ames Research Center

2 Pre-seismic Co-seismic Post-seismic Magnetic Field Anomalies ULF/ELF Emissions ULF Pulse Activity Geo-Electric Signals Earthquake Lights Radon Emanation Fog/Haze/Clouds Air Ionization/Air Conductivity Atmospheric Gravity Waves Ionospheric Perturbations Ground Water Chemistry Microseismicity Instant Warning <30 sec First responders Organized help Clean-up Recovery Months Weeks Days Hours Seconds Hours Days Weeks Months Time before earthquake 0 Time after earthquake

3 Hidden in plain sight Rocks themselves offer a solution Dormant electronic charge carriers exist in rocks They become activated when stresses wax They go back to sleep when stresses wane Ready to wake up again next time. Positive Holes have been overlooked by the scientific community

4 Peroxy defects are the parents of positive hole charge carriers e O 3 Si/ OO \SiO 3 [SiO 4 ] 4! {O 3 Si/ O O /SiO 3}! O 3 Si/ O O /SiO 3 [SiO 4 ] 3 peroxy link O 2 matrix broken peroxy link broken peroxy link h Dormant Transient Trapped electron Positive hole

5 A positive hole is a missing electron in the O 2- sublattice a defect electron in the valence band positively charged an electronic state that can move through mineral grains and beyond can travel fast and far meters in the lab, presumably tens of kilometers in the field

6 Positive holes have been characterized by their effects on Electrical conductivity Thermal expansion Dielectric susceptibility Magnetic susceptibility Infrared and Raman spectroscopy X-ray photoelectron emission Electron spin resonance spectroscopy Muon spin relaxation spectroscopy and more

7 Why positive holes? Observation: many pre-eq phenomena point to electrical processes inside the Earth s crust and at the ground-air interface Examples: Transient regional magnetic field variations EM emissions ranging from ULF to VIS Air ionization Ionospheric perturbations Question: Can positive holes help us understand these and other alleged pre-eq phenomena?

8 Charge flowing out

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10 400,000 V/cm 100 ppm 10 ppm Surface potential 100 ppm 10 ppm Electric field Calculated for a dielectric constant ε = 10 King and Freund, Phys. Rev. 1984

11 What can happen at the surface? Surface potential Surface electric field Step I Field-ionization of air molecules Step II Corona discharge Step III Recombination of positive holes Vibrationally excited surface states Infrared emission / temperature increase Electronically excited O atom emission

12 We can measure the surface potential V - e h

13 ± ion currents through air gap A ± - e h

14 Ionization processes at surface: Positive airborne ions Negative & positive ions O e - 2 O O 2 N O e - 2 Step II 2 O2 O N 2 2 O 2 O e - O 2 O 2 O 2 e - e - e - e - e e e - e - - e h e - Step III

15 We can build a rock battery

16 The rock battery works even when the currents need to run through dust/sand/soil

17 Positive hole currents flow through dust, soil, sand and back into solid rock A h dust, soil, sand

18 Concept of Rock Battery if stresses activate charge carrier at different concentration levels in different parts of the crust, we ll have electric potentials and electric currents. However, battery currents can only flow, if and when the battery circuit is closed.

19 How can the Battery Circuit close? It s easy in the lab: just run a Cu wire from the stressed to the unstressed rocks. However, Nature does not run Cu wires. However, Nature provides other means to close the battery circuit.

20 What happens when positive holes flow into water? The current continues to flow h Water/brine

21 While positive holes flow into water, they cannot re-enter the rock indicating that something happens at the rock-water interface A X Water/brine h

22 An h is equivalent to an O O is an oxygen radical, highly oxidizing. Stoichiometrically oxidizes H 2 O to H 2 O 2 : 2 O surface 2 H 2 O solution 2 OH surface H 2 O 2 solution

23 Analyze for H 2 O 2 H 3 O e h H2O We built the world s first battery without any metal parts or wires

24 Positive hole charge carriers allow us to look at alleged EQ precursors in a new way provide a physical basis for many types of reported pre-eq signals provide a causal link between them

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26 It is wonderful to be part of a meeting, first of its kind in decades, that brings together an interdisciplinary community with interest and knowledge about earthquakes and earthquake precursors.

27 Current Disaster Management Cycle Planning Recovery Mitigation Sit and wait Response EQ

28 Future Disaster Management Cycle Planning Recovery Mitigation or monitor for pre-eq signals Response EQ

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