ELF/VLF waves as Earthquake precursor – A case study (May 12, 2008 Wenchuan, China earthquake) Rajesh Singh, A.K. Maurya, B. Veenadhari, P. Pant 1 , A.K. Singh 2 Indian Institute of Geomagnetism New Panvel, Navi Mumbai - 410218 India 1 ARIES, Manora Peak, Nainital – 263129, India 2 Physics Department, B.H.U. , Varanasi – 221005 India
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ELF/VLF waves as Earthquake precursor – A case study (May 12, 2008 Wenchuan, China earthquake)
ELF/VLF waves as Earthquake precursor – A case study (May 12, 2008 Wenchuan, China earthquake). Rajesh Singh , A.K. Maurya , B. Veenadhari, P. Pant 1 , A.K. Singh 2 Indian Institute of Geomagnetism New Panvel, Navi Mumbai - 410218 India. 1 ARIES, Manora Peak, Nainital – 263129, India - PowerPoint PPT Presentation
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ELF/VLF waves as Earthquake precursor– A case study
(May 12, 2008 Wenchuan, China earthquake)
Rajesh Singh, A.K. Maurya, B. Veenadhari, P. Pant1, A.K. Singh2
Indian Institute of GeomagnetismNew Panvel, Navi Mumbai - 410218 India
This statement is true if the only tools for prediction are those of Siesmology and Geodesy: Earthquakes can indeed not be predicted
Because what ever the probability models for prediction available in seismology are based on past seismograph data and geological records
- Friedemann, T.F. Current Science, 94, 311, 2008
The data that goes into these models are retrospective: The knowledge acquired over the past events is used to forecast future events – Statistical Analysis
So, even the most elaborate models is inadequate because it is not based on information that might become available in real time about a specific earthquake that looms ahead
In last couple of decades scientific community is trying to investigate problem of earthquake prediction by looking into:
(i) Are there other signals that rock produce when subjected to ever increasing stress?
(ii) If such signals are produced at depth, can they be transmitted or somehow carried from the seismogenic region to region of the earth?
Prospective pre-earthquake signals
Anomalous behavior in Low/Ultra low electromagnetic emissions recorded all around the globe
Local magnetic field variations over a wide range of timescales
Enhanced infrared emissions from the epicentral region
Change in the atmosphere near the ground and at altitudes up to ~ 1000 m
Unusual animal behaviour, etc
Perturbations in the lower ionosphere above the epicentral region
The scientific community has been deeply divided over these signals and whether or not they are indeed pre-earthquake indicators
(Henderson et al., JGR, 1993; Rodger et al, Radio Sci., 1999 and others)
VLF/LF radio sounding Search for Seismo-ionospheric perturbations:
Previous Works
First attempt was done by Russian workers (Gokhberg et al., 1982; Gufeld et al., 1992). They studied long VLF path form Reunion Omega transmitter to Omsk and Moscow, looking for any earthquake effect in the Caucasia region – Found anomaly for Spitak earthquake
Kobe Earthquake (7.3 M) in 1995
Reported significant shift in the terminator times before the earthquake, inferring daytime felt by VLF signal is elongated for a few days around the earthquake.
– Hayakawa et al., 1996
Later a much more extensive study by Molchanov and
Hayakawa, 1998 based on much more events during 13
years for same propagation path Tushima to Inubo came to
following conclusions:
(i) For shallow earthquakes (depth < 30 km), terminator time
anomaly was found similar to Kobe earthquake
(ii) When the depth is in medium range of 30-100 km, different
type of terminator time anomalies were found
(iii) Deep (> 100 km) earthquakes did not showed any anomaly
– Hayakawa et al., 2007
Sumatra Earthquake – 26 December, 2004
– Hayakawa et al., 2007
May 12, 2008 Wenchuan, China earthquake (19th deadliest earthquake of all time)