Hi all. I had found this sometime ago, and while cleaning out the excess garbage in my document file I came across it again. This could be the very thing that ear toners are hearing and may also be one of the causes of “earthquake lights” Take Care…Don in creepy town

Prepared for presentation at "6th Conference on AE/MS Activity in Geologic Structures and Materials" Pennsylvania State University June 11-13, 1996.

PREDICTION OF EARTHQUAKES
WITH AE/MS? WHY NOT
H.L. Dunegan
May, 1996

INTRODUCTION

Earthquakes account for more loss of life and property than any other natural phenomena. In spite of this fact, and the fact that we know why and how earthquakes occur, there is a great deal of pessimism from both the scientific community and Government agencies concerning one's ability to accurately predict earthquakes. This pessimism is evidenced by the large amount of funds expended in earthquake preparedness programs compared to the funds available for research concerning earthquake prediction. The primary reason for the lack of an earthquake prediction model is the inability of low frequency surface mounted seismic instrumentation to detect the higher frequencies associated with small fractures that occur prior to a large movement of a fault. The high frequencies associated with these small events are attenuated by the upper mantel and never make it to the surface.

It is shown in this report that the use of Acoustic Emission techniques for predicting failure in materials and structures with the use of high frequency sensors can find parallel applications in predicting movements of a fault in the earth. The primary difference is simply a matter of scale Acoustic emission applications utilize frequencies to 1Mhz, to detect events on the order of 1 micron. Its parallel in geophysical applications would be the use of frequencies of 1 Hz to detect events on the order of 1 meter. The primary difference with this simple analogy is that most acoustic emission applications involve detecting stress waves in plates. In this situation stress waves due to crack growth from a one micron area can produce plate waves of much lower frequency as the wave propagates and therefore can be detected with sensors in the Khz range of frequencies. Whereas a fracture from a fault producing a 1 meter area would have a fundamental frequency of approximately 2Khz and would not undergo the same type of dispersion and mode conversion observed in plates. We know from experience that a 1Hz ground seismometer cannot detect a 1 meter fracture for any practical distance. The only hope of detecting frequencies of 1Khz or more in the earth is to place very sensitive sensors in deep wells and space them in a 5 to 10 kilometer grid in order to get adequate coverage of an area of interest (such as downtown Los Angeles)

Once the higher frequency events due to small fractures occurring from a fault are detected, it is proposed that the data be handled in a fashion similar to that used for acoustic emission data from man made structures. Therefore some discussion of the procedures used for handling acoustic emission data will be presented, and analogies drawn to their use for earthquake prediction.

It has been reported by Rikitake, 1976 (Internet) that the ratio of the P wave velocity to the S wave velocity decreases prior to a large earthquake by approximately 10% and returns to normal immediately before and following the earthquake. The diffusion of gases into the crack and subsequent contact of the crack surfaces to ground water could account for the presence of radon gas in deep wells reported prior to an earthquake. If hydrocarbons are present in the chamber created by the crack, the high pressures generated during a seismic event could possibly force these hot gases to the surface where ignition would occur. This could account for the "earthquake lights" reported by many observers during an earthquake. The presence of hydrocarbons in gaseous form under such high pressures and temperatures could produce a higher chain molecule through polymerization which would account for the presence of petroleum bearing rocks in regions of high fault activity. These cracks could also account for the decrease in electrical resistance of the earth prior to a large earthquake.

• Prediction Of Earthquakes With AE/MS