Saturday, January 14, 2012

Weather And Earthquakes - Can They Be Predicted?

This following question opens up the whole prediction/triggering question about earthquakes. Since the questioner threw in weather as a possible factor, I'll address that too. It's all part of the Earth we live on, all part of geoscience.


Hello..I was just wondering first if the increased number of earthquakes is a sign of something bigger to come and since the earthquake in Japan knocked our earth off of its axis a few feet is that the reason for the severe weather we have had lately like all the floods in the south and tornadoes and severe storms any info would be great…thanks so much.
Wendy M.


Available information (from the Global Positioning System) indicates that the Earth's axis was tilted about 10 cm by the Great Tohoku earthquake - about 4 inches. It requires some very sophisticated equipment and a lot of measurement time to arrive at that tiny amount of offset. To put things in perspective, if you stepped 10 cm north, I'm sure you wouldn't notice a change in the weather.

While there is evidence that continents were at hugely different latitudes in ages past (freshwater swamp dinosaur skeletons have been recovered from Antarctica), a 10-cm tilt change will not cause any measurable effect on weather. A long and slow tilt in the Earth's axis has been documented over time, but the operative word here is "slow" - we're talking in the millions of years slow. There is also the complication that the continental plates have been moving around at the same time. Since we didn't have observers using sextants to track where Polaris is/was 50 million years ago, these are understandably hard to sort out. Making matters even more complicated, the Earth's axis wobbles - the pole star was not Polaris, but Vega, 12,000 years ago. This effect is called nutation.

One scientist I know made an estimate that at least $15,000,000,000 has been spent over the past half century, in science agencies all over the planet, to be able to predict earthquakes. So far, at least - and I'm acquainted with some of the truly brilliant people who have worked on this problem - there has been no payout. Scientists can forecast, but not predict, earthquakes. By forecast, I mean to give a 30% statistical probability that the Hayward Fault in the San Francisco Bay Area will rupture in the next 30 years. They can calculate $165,000,000,000 in damage when it does. To predict means that I could tell you when to sell your house in Oakland - and that can't be done. You can very roughly predict a volcanic eruption, and your timing precision will improve steadily from "weeks to months" to "hours to days" as the event approaches, and as the physical evidence of inflation and ruptured rocks from seismometers and GPS telemetry accumulate.

You can predict a hurricane up to a week ahead of time, and a tornado up to hours ahead of time. But you can't predict earthquakes.

There is an on-going discussion about earthquakes triggering other earthquakes. Large earthquakes have been shown to "light up" restive volcanic areas like Yellowstone and Long Valley with clusters of increased micro-earthquakes. However, the current scientific consensus is that distant earthquakes do not have any effect on faults not part of that earthquake's own fault system. In other words, the earthquake in Chile in the Spring of 2010 did not trigger the earthquake in New Zealand in the Fall of 2010, and that one didn't trigger the Great Tohoku earthquake in March 2011 near Sendai, Japan. Among other things, there were months separating each one. Researchers have also studied syzygy - the effects of Sun and Moon tides - on earthquakes and have found no statistical correlation.

All THAT said, there HAS been a measurable, undeniable (and steadily ramping-up) increase in the carbon dioxide content of the Earth's atmosphere in the last several centuries - since you asked about weather. CO2 has a measurable greenhouse effect on atmospheric temperatures. Methane - there are far more cows on the planet than there were a century ago - has 37 times more of a greenhouse effect than CO2 for the number of molecules released. Virtually all scientists not paid to say otherwise readily acknowledge that there is a large anthropogenic component to this greenhouse gas increase - i.e., humans burning hydrocarbons, destroying forests, raising cattle, etc. are mostly responsible for these increased gases in our atmosphere.

It's still being argued - mainly through ever-increasingly complicated mathematical models - how much this has actually changed our weather. There are a huge number of variables involved, so one model may disagree with another in detail - but not in gross conclusions. There are certain undeniable influences on weather (the Solar flux and the great ocean currents, for instance). However, you and I may not remember huge hurricanes and tornado clusters from our childhood, but that may just be our imperfect memory. The apparent increase in wild weather events may also be an artifact of how records have become increasingly more detailed and complete over time. Keep in mind that earthquakes and probably to some extent anomalous weather events are essentially (or at least largely) random. They don't come like a ticking clock, but often in clusters, and our very human minds remember the most recent cluster best.

Using a statistically more reliable approach - comparing Atlantic hurricanes and their strengths for say, the 19th Century against the 20th Century - we are also hamstrung in that there were far fewer people to record (or even see) hurricanes 150 years ago, and thus correspondingly fewer and sparser records kept then. Scientists would say that there is a bias in the data - a sampling bias. It's sort of like trying to predict the snowfall from stories you heard your grandfather tell you when you were a kid. You know: he walked to school in three feet of snow, and both ways were uphill.


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