Friday, April 29, 2016

Can You Go Under Hawaii?

Then... there are queries that come in that I really have no idea how to answer. So I point out logic flaws that seem obvious to me (at least) and generally ask for some sort of clarification.

Q: Can you go under Hawaii?
- Christopher P

A: Your question makes no sense. Hawaii is a chain of volcanoes in the central Pacific Ocean. Islands do not float on water.

Q: Can you go under any land mass? Real question by the way.
- Christopher P

A: The deepest drill hole (Novaya Zemlya, Siberia) went to about 10 km. It cost somewhere in the tens of billions of rubles, and took 5+ years to drill, with several fails that had to be cut off and by-passed. The deeper you try to drill, the higher the cost and the complications - both are exponential. At 4 km depth in a diamond mine in South Africa, the rock temperature is already up to 60 C. Miners work only because refrigerated air is pumped down to them... and by the time that refrigerated air reaches 4 km depth, the increased pressure has raised its temperature to 45 C. Incidentally, any air gap in the rocks at even much shallower depths is inherently unstable, and it's just a matter of when, not if, it will fail catastrophically. Rock bolts are insurance, but not a guarantee. Hot rock will always close in on the drill stem, even if you can afford to put steel casing into a hole 10 km deep. Any regional strain pattern will soon deform that casing, and trap the drill bit below it. 

Except for bragging rights (and perhaps some limited scientific data), it's hard to imagine what argument was made to Soviet bureaucrats to justify expending so much money for a deep drill hole.

You can TUNNEL under mountains, or cities, and the London Underground and New York subway systems are more than a century old. It gets more expensive with time, as safety concerns and wages inevitably keep expanding. The Alaskan viaduct tunnel project in Seattle has been underway for many years, with the original budget of $2.8 Billion and a portal-to-portal length of about 2.8 km. It is still not done, and I'm not sure anyone has a clear idea of the final cost. Or when. Or for that matter, IF.

The BART system that goes under San Francisco Bay was really a dredge-and-lay operation, with reinforced concrete tubes fabricated and laid end to end in a big trench, and then sealed. At least sealed as well as part can be done. Pumps must operate 24/7 to keep it from filling up with seawater. The Chunnel from Pas-de-Calais France to Folkstone, UK, took about 6 years to build, and cost about $7 billion. It's about 38 km long under the Channel itself, and it gets about 75 meters deep at the lowest point. The Seikan Tunnel in Japan is longer, at 54 kilometers long and deeper, reaching 240 meters below sea level. I have personally developed and patented a technology that uses active electronic streamers dragged along the seafloor behind a ship. No matter how carefully I pot the take-outs, it's not a matter if IF, it's a matter of WHEN they will fail from saltwater intrusion at just 30 meters depth (that’s 8 times normal air pressure at the surface). For a 5-week offshore survey east of South Africa, we shipped down three different streamers. Two had failed, and the third was failing by the end of the survey. 

Detroit automakers used to call this sort of thing Planned Obsolescence. 

Bottom line: the costs - and risks - are so high that there must be a truly compelling reason to tunnel under any landmass, even for short distances. Tunneling under the seafloor is even harder and more expensive because you have to factor in some serious pumps and redundancy. When there is salt water that can reach any tunnel, then the integrity of any metallic components are going to be compromised with time, and you must factor in replacement-type maintenance. Just like airplanes. 

Friday, April 8, 2016

Petrified Forests

If you’ve never seen a petrified forest, you're in for an eye-catching treat. When I was young, having book-ends made from a petrified tree was a mark of sophistication. Never mind that petrified “wood” is close to 8 in hardness on the Mhos Scale (a scale where talc is 1 and diamond is 10), and cutting all those slabs must have cost more than a few diamond-edged rock-saw blades.

Q: I am a sixth grader at Kennedy Middle School. Our school is participating in something called Genius Hour which allows us to research a topic that interests us. We are required to interview a professional who is knowledgeable about our topic. My topic is the Petrified Forest
If you could please answer the questions below as soon as you get the chance, it would be greatly appreciated. Thank you for taking time out of your day to respond to this email.
Thank you for your time,
- Quinn C

My questions are:
Q: How was the Petrified Forest formed?

A: The one in NE Arizona was formed over 200 million years ago from fallen trees that had accumulated in log-jams along ancient river drainages. Sometime later ash from nearby volcanoes ​fell on the trees, and slowly over time the lignin and woody contents were replaced with silica from the overlying ash.

Q: What type of rock coated the trees?

A: The trees were not coated. Individual cells throughout their volumes have been replaced by silica leaching out of volcanic ash overlying them. ​

Q: How long did the process take?

​A: The time necessary for the process is poorly defined by actual data. In some cases the original tree material has not yet been completely replaced by the silica, and some lignin still remains in a petrified log after 211 million years. One example (below) appeared to have happened in only a few thousand years.
Q: Might this happen somewhere else?

A: There are petrified forests in North Dakota, Argentina, and Egypt, and likely other places. I have personally encountered bushes that are no more than 10,000 - 17,000 years old on the edges of former lakes in the southern Empty Quarter of southern Saudi Arabia and northern Yemen. The ​individual branches, in 5-cm to 15 cm fragments now, have been completely fossilized (silicified) this way.

 Q: How might this process affect the environment?

​A: It certainly preserves trees, and likely even some animals that have died in that time period. In the sense that it preserves trees over 200 million years old, it could be viewed as stopping or arresting the natural landscape evolution of these particular areas.​

 Q: Could this happen in the future?

​A: Yes. From the example above in north Yemen it is clearly happening now in some places. ​