Map: anti-podal maps

(Via Armcontrolwonk) This map shows where the opposite (anti-podal) point on the earth is. i.e. North Pole corresponds to South Pole. One can easily check up one's anti-podal point by change the coodinate (change lattitude from N to S, then add/subtract 180 on longitude). But it is neat to view this on a globe.

ACW cited this when he read that vibration typically get 'magnified' on anti-podal points as noted by astronomers observing the moon and some planets. He thinks this may be used to measure earthquake (and nuclear tests).

The physical explanation may be quite simple, as the anti-podal point represents THE equi-distant (both on earth surface and via the mantle/core) point, such that all waves arrive IN PHASE (ignoring fluctuations in rock type/etc). This means it would be difficult to measure earthquake anti-podally since these are random events and one does not know where to place the probe in advance, but for monitoring nuclear tests with known sites this could be pretty effective.

A few interesting observations
  • Very few land has land as antipodal points, mainly because there are only 30% land on earth and most of it is on the northern hemisphere. (this makes ACW's plan more difficult/costly)
  • The few land-land pairs include (this site provides a great tool)- Beijing's anitpode is a few hundred km south of Buenos Aires, Xian and Santiago (Chile) are almost exact antipode pairs (perhaps the only major city pair). Jakarta/Bogota and Singapore/Quito are also close enough. New Zealand's antipode is Spain (auckland/Seville). -- play these games to test your geographic knowledge.
  • The Yucatan meteorite at Chicxulub crater, which allegedly killed the dinosaurs, would probably have had created some folding under the ocean between NW Australia and Cocos Islands in the Indian Ocean. However,  some people believe that the Chicxulub antipode is actually the Deccan Traps inside India because techtonic movement shifted the Indian subcontinent

The map above shows the wave-front of the DPRK shock (test). Ideally these contours should be circle, but they are distorted because of rock/water structure the p-wave passes through (changes the speed the sound wave travels).

Given these contours, it is now easy to measure future shocks (from the same location) much more accurately. The trick is to put an array of probes spaced on a chosen contour such that the signal these probes received are all "in phase". Adding these signals (time-plotted) up will result in strong signal since the noises are not in phase and tends to cancel out. This will achieve similar or even better results than a measure from the antipode.


How credible is DPRK's nuclear stockpile?

In 2006 North Korea claimed it conducted a "nuclear test". But many analyst suspected it was a faked test mimic by traditional explosive, for 2 reasons:
  1. the energy was only bout 1/3 of the Hiroshima bomb, showing that the explosion is likely really from a nuclear bomb. Because for a chain reaction to happen, there need to be at least certain critical mass of Uranium (or Plutonium), as demonstrated first by physicists Rudolph Pierls. And the Hiroshima bomb is just over the critical mass
  2. There had not really been confirmed radioactive trace from the surrounding international observation. (The US said the signal is "consistent" with a nuclear test, but radioactively of this small amount (for underground test) is easy fake. Note also the choice of word, "consistent" is a much weaker word that "confirm", which will mean consistency in both strengh, spectrum, and also spatial distribution. "consistency" only means that there is some radiation detected and that no obvious contradiction)
The most recent claim has a magnitude of 4.7 (vs 4.2 in the previous test). The energy is about 3 times larger ( 10^(4.7-4.2) = 3.1 ), making the total energy similar to that of the Hiroshima bomb.

For a nuclear test it still seems to be very minor. Two possibilities
  1. It is a real nuclear blast, but DPRK has barely enough Pu/U, so they used all the 'available' material for this "test"
  2. It is another fake test, they figured the previous test was 2/3 short in magnitude, and got the right amount to make a more credible fake (it would to too expensive to use more)
p.s. it is hard to accurately measure the energy with seimological measure, as the rock/water of the surrounding is complex and differ from the calibration references (for both seimic calibration and also underground nuclear test energy calibration). the most reliable data is perhaps the 'relative scale' (i.e. the difference) in energy for data taken by the same probe(s).
e.g., from one source (NEIC National Earthquake Info Center, which i think is the USGS) the numbers read 4.7 (2009) and 4.3 (2006) so the difference is 10^0.4<3.>


Cheung on RMB again

I am going to revisit this topic again and again, until Beijing listens. I think this is what Prof Cheung is trying to do. So what I have to do is to just check his blog regularly and quote him when he makes some (seemingly/relatively) new point(s).

Here are the key points I would like to emphasize
  1. China can made Shanghai a financial centre (at least at the regional level) if it opens up its currency, which means getting an independent (or currency market "neutral") anchor for the RMB -- i.e. the Commodity Basket!
  2. One key strength of the Commodity Basket is that it is (largely) linear independent of any existing currency (eg USD or EUR). It provides a new dimension for other currencies in the  world to "reference". I say "largely" because some currencies do depend on some commodity (eg OPEC on oil, and AUD on its minerals, etc) but all these dependencies are only partial and more importantly, they are influenced by human factors such as the macro-economic policies (interest rates, etc) of these countries. OTOH, a Commodity Basket peg provides a "pure" axis for other currencies in this world to reference on. Countries such as Singapore can use RMB as one of the main component of its basket (it can also chose its own basket, in which case it will help to stabilize the commodity price -- i.e. make it more difficult for speculators to influence the short term price fluctuation). I think this is the most important reason for adopting the Commodity Peg.
I agree with Cheung that many countries (esp developing countries) would use RMB as one of the reference in their currency peg. However, I do not agree with him that overseas Chinese would affect the demand of RMB (perhaps Koreans would be so patirotic as to put once own saving to the state, very few people from other nationality will, Chinese are no exception). The reason for anyone, ethnic Chinese or not, to put his money in RMB is because it provides a unique proxy that nom other exisiting currency provides, and that it has very clear transparency. Commodity Peg provides both.




















(五)也说过多次,无锚的货币制(fiat money)不可取。这一点,不少经济学者同意,只是以大国而言,他们想不出怎样把货币下一个固定的锚。十多年前跟进朱镕基的货币政策时,我霍然而悟,想出了可以用一篮子可以在市场成交的物价指数为货币之锚。