From the AGU: An atmospheric precursor to the recent Japan megaquake
Most scientists believe that earthquakes are inherently unpredictable, and reports of various kinds of earthquake precursor signals have been difficult to verify. However, in a new study, Heki reports a possible ionospheric precursor to the devastating 11 March 2011 magnitude 9 Tohoku earthquake in Japan. Analyzing data from the Japanese GPS network, he detects an increase in the total electron content (TEC) in the ionosphere above the focal region of the earthquake beginning about 40 minutes before the quake.
The TEC enhancement reached about 8 percent above the background electron content. The increase in TEC was greatest above the earthquake epicenter and diminished with distance from the epicenter. The researcher also analyzes GPS records from previous earthquakes and finds that similar ionospheric anomalies occurred before the 2010 magnitude 8.8 Chile earthquake, possibly the 2004 Sumatra magnitude 9.2 earthquake, and possibly the 1994 magnitude 8.3 Hokkaido earthquake, but TEC enhancements were not seen before smaller earthquakes.
Although previous studies have shown that earthquakes could trigger atmospheric waves that travel upward and disturb the ionosphere, it is unclear how an ionospheric disturbance could occur before an earthquake begins. In addition, the ionosphere is highly variable, and solar storms can trigger large TEC changes, so nonearthquake causes of any TEC enhancement need to be ruled out. The researcher states that, unlike previously suggested earthquake precursors, the TEC enhancement before the Tohoku quake had obvious spatial and temporal correlation between the quake and precursor signal as well as clear magnitude dependence. Further research is needed to verify that TEC enhancements can indeed be a precursor to large earthquakes.
Source: Geophysical Research Letters, doi:10.1029/2011GL047908, 2011 http://dx.doi.org/10.1029/2011GL047908
Title: Ionospheric electron enhancement preceding the 2011 Tohoku-Oki earthquake
Key Points
- Positive TEC anomaly appears before M9 class events
- The anomaly occurs above the epicenter and lasts ~1 hour
- M9 class earthquakes can be predicted
Kosuke Heki
Department of Natural History Sciences, Hokkaido University, Sapporo, Japan
Abstract
The 2011 March 11 Tohoku-Oki earthquake (Mw9.0) caused vast damages to the country. Large events beneath dense observation networks could bring breakthroughs to seismology and geodynamics, and here I report one such finding. The Japanese dense network of Global Positioning System (GPS) detected clear precursory positive anomaly of ionospheric total electron content (TEC) around the focal region. It started ∼40 minutes before the earthquake and reached nearly ten percent of the background TEC. It lasted until atmospheric waves arrived at the ionosphere. Similar preseismic TEC anomalies, with amplitudes dependent on magnitudes, were seen in the 2010 Chile earthquake (Mw8.8), and possibly in the 2004 Sumatra-Andaman (Mw9.2) and the 1994 Hokkaido-Toho-Oki (Mw8.3) earthquakes, but not in smaller earthquakes.
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May I pause and cite minus 1 point for a generating a strawman argument?
Notwithstanding the fact that the ‘research’ above says “detects an increase in the total electron content (TEC) in the ionosphere above the focal region of the earthquake beginning about 40 minutes before the quake” and you’re assuming that TEC_only_ increases due to an impending earthquake __whereas__ TEC may increase for a number of other known reasons as well … therefore, cite an additional minus 1 point again for overgeneralizing the usefulness or utility of noting a TEC increase without including sufficient differentiating factors to specifically indicate the imminent occurance of an earthquake.
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It’s ALWAYS in the back of our minds or on the tips of our tongues … it is the lash and whip of moderation that drives our ordinate fear and compliance to the rules, however.
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Tōhoku earthquake with 40 minute warning added to 15 to 30 minute delay for arrival of possible tsunami?
Better than nothing.
Jim says: “Ever tried creeping up the stairs stealthily in an old wooden frame structure? Nigh unto impossible given the creaking noises that emanate from every dried old joint that sees the least little bit of flexure with body weight exerted through a foot … extending that a bit, it would not take a lot of movement, but a fair bit of ‘force’ on a structure to induce pent-up tension (or compression) in a structure to release, given the right combination of factors … perhaps a slow precursor ‘roll’ in the quake caused something in the house to go ‘snap’?”
First wave the normally hits is the P (Primary) wave, which is a compression wave. It travels faster than the secondary or surface waves. Energy release seems to be directional, for if you sit along the extended plane of slippage, you can really get thumped pretty hard. If you In the larger quakes, you get the initial thump from the P-wave and see what you get to ride out next. That night we felt both P and S waves. But something happened before the house started shaking.
Homes up here are mostly wood frame construction sitting on a cinder block / concrete foundation, as they need to flex on a regular basis. They get moved around all the time, even by the wind, and do not store up a lot of unreleased energy.
Take a look at the url for earthquake lights. Interesting phenomena. Haven’t seen them yet. Hope not to, as they seem tied to larger quakes. Thanks for the conversation and observations. Cheers –
@oMan
“don’t catfish sense electrical field strength with their whiskers? ”
I don’t know. I’m not a catfish. But who would you rather trust – a catfish or a climate scientist?
Phenomena like this, as with ocean wave riding (surfing), are very often known, noted and then ridden by a cadre of technical radio enthusiasts (ham radio operators; including in their ranks a great many engineers, scientists, astronomy etc specialists) who live for rare ‘contact’ through the most obscure of propagation modes such as the auroral contact discussed on a thread within the last week here on WUWT or the more exotic Lightning scattering mode which lasts for a fraction of a second.
On that note, I would be very surprised to learn the ‘earthquake lights’ are in any way electrical. Of note also in this discussion would be the NLDS – the National Lightning Detection Network which should be able to detect any broad-band source of RF energy with spectral content within the frequency range of the NLDS network (somewhere in the LW range I think). Researchers have access to this kind of information from NLDS; it would be an easy ‘prove’ and the basis for a paper were something there (again, I do not think there is anything to it but that does not a paper make.) All this does not make me a cynic, it just that I have spent a LOT of hours listening to radios often tuned to ’empty’ channels listening, for anything, often hearing lighting (on the lower freqs) or DX (distant) stations or ‘pirate’ stations (running anywhere from a few watts to 100’s W) to milliwatt HF beacons like this one shown in this vid:
A couple years ago, a friend on a drive with his wife swung through then state where this beacon is located; within a few miles a beacon of this nature has more ‘skywave’ (more energy from high radiation angles, like in excess of 50 degrees from horizontal) even from 5 miles away and is a very difficult animal to pin down (DF) and drive up to it!
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