Typically, signals are received from man-made dipole antennas placed in the ground, some of which are very elaborate and strech for several kilometers. But there's a very effective dipole antenna growing outside your window today, as discovered by Stanford University Electrical Engineering and Geophysics Research Professor Emeritus Antony C. Fraser-Smith. While at Stanford, Fraser-Smith instrumented trees to measure low frequency electromagnetic signals in the Earth. The results from using a tree as antenna compared favorably to man-made ones. The amplifier and even suggested tree types are described in some detail in Fraser-Smith's 1978 Nature paper: ULF Tree Potentials and Geomagnetic Pulsations. Using conventional antennas, Fraser-Smith and A. Bernardi found possibly discernible signals coming from the Earth hours before the 1989 Loma Prieta, California earthquake as described in their 1990 paper in Geophysical Research Letters: Low-Frequency Magnetic Field Measurements near the Epicenter of the Ms 7.1 Loma Prieta Earthquake.
Earthquakes can happen at any time in any place in the world. They're widely expected in the "Rim of Fire" around the periphery of the Pacific Ocean, but earthquakes also happen in Africa, Asia, and Europe. We propose placing Fraser-Smith-Bernardi-style sensors and amplifiers in as many places as possible around the world and broadcasting their signals in near-real-time over the Internet. (We would hope to have especially good coverage in common earthquake zones like California, Japan, etc., but nodes anywhere are wanted.) The resulting network of sensors and the means of distributing and receiving data mean that researchers anywhere can use the data to look for earthquake precursor signals in order to possibly generate earthquake warnings. Note that we are proposing to publish the raw, uninterpreted signal data for analysis by others. We may also try to create models to explain the data, but the goal of this project is to make the raw data widely available in near-real-time to researchers around the world. A warning of even a few minutes has the potential to save millions of lives in the event of a major earthquake. Governments and other official bodies have demonstrated little interest in pursuing this potentially life-saving tool, but the technology for collecting and broadcasting the raw data is easily within the reach of many Internet users who are also electronics hobbyists. If you have an Internet connection and know how to solder electronics, please consider setting up a node and adding it to this informal network. The life you save may be your own.
References from the above [pardon the differing citation format]
- Chapman, S., and J. Bartels (1940), Geomagnetism, vol. 2, Oxford Univ. Press, London.
- Fraser-Smith, A. C. (1999), Cancellation of natural geomagnetic field fluctuations: An opportunity for new discoveries in the Earth sciences using superconducting magnetic field gradiometers, Final Tech. Rep. A416.1 (for the U.S. Geological Survey), Space, Telecommun. and Radiosci. Lab., Stanford Univ., Stanford, Calif., Feb.
- Fraser-Smith, A. C., A. Bernardi, P. R. McGill, M. E. Ladd, R. A. Helliwell, and O. G. Villard Jr. (1990), Lowfrequency magnetic field measurements near the epicenter of the Ms 7.1 Loma Prieta earthquake, Geophys. Res. Lett., 17(9), 1465.1468. [linked below]
- Fraser-Smith, A. C., P. R. McGill, R. A. Helliwell, and O. G. Villard Jr. (1994), Ultra-low frequency magnetic field measurements in southern California during the Northridge earthquake of 17 January 1994, Geophys. Res. Lett., 21(20), 2195.2198.
- Hayakawa, M., R. Kawate, O. A. Molchanov, and K. Yumoto (1996), Results of ultra-low-frequency magnetic field measurements during the Guam earthquake of 8 August 1993, Geophys. Res. Lett., 23(3), 241.244.
- Kopytenko, Y. A., T. G. Matiashvili, P. M. Voronov, E. A. Kopytenko, and O. A. Molchanov (1993), Detection of ultra-low-frequency emissions connected with the Spitak earthquake and its aftershock activity, based on geomagnetic pulsations data at Dusheti and Vardzia observatories, Phys. Earth Planet. Int., 77, 85.95.
- Molchanov, O. A., Y. A. Kopytenko, P. M. Voronov, E. A. Kopytenko, T. Matiashvili, A. C. Fraser-Smith, and A. Bernardi (1992), Results of ULF magnetic field measurements near the epicenters of the Spitak (Ms = 6.9) and the Loma Prieta (Ms = 7.1) earthquakes: Comparative analysis, Geophys. Res. Lett., 19(14), 1495.1498.
- Moore, G. W. (1964), Magnetic disturbances preceding the 1964 Alaska earthquake, Nature, 203, 508.509.