Friday, December 11, 2015

Terraforming Mars

Here's a Q&A that has nothing to do with earthly geology, but may have some instructive content for future geologists. There is usually at least SOME science in SciFi novels!

Q: What would happen to the Martian atmosphere, over the course of the next 100 years, if we could build a machine on Mars that could output the equivalent quantity and composition of greenhouse gasses as are released on earth (approximately) every year?  Thanks for your time, hopefully this has not already been answered!  
- Kyle R

A: That's a rather unique question, but it begs several critical assumptions.

According to a recent Science article, Mars lost its original atmosphere billions of years ago because the planet lost (if it ever had) its magnetic field. As a result the solar wind (high energy charged particles blasted out from the Sun) stripped most of Mars' atmosphere away. So one assumption is that the planetary magnetic field is somehow restored.

Another assumption is a bit more obvious: where would the carbon and oxygen come from? Certainly not the planet's crust, as it has been degassing for billions of years and is a depleted desert now. Hundreds of trillions of tons of material would have to be brought to Mars' surface. This is actually not as unreasonable as it may sound: comets can do (and have done) this in the past... but it would require a number of pretty large comets. A colliding planetary body from the Oort Cloud on the scale of Sedna could bring the mass as well as restart the magnetic dynamo, however. A collision like that is thought to be the reason why we still have a magnetic field here on Earth... and a Moon as big as the one we have.

A final assumption is also necessary: a weaker planetary gravity field would make it easier for gases to escape the planet. So another assumption would be that somehow the planet became much more dense. A comet impact couldn't solve this one. A collision with something like Sedna would only marginally increase the gravity field of the planet. Weak gravity -> easier for atmospheric gases to escape.

I'm not a specialist in atmospheric dynamics, so I don't want to speculate what would happen if all three of these conditions were somehow met. I suspect that Mars' currently pink sky might end up a different color, however.

Q: Thanks for the thoughtful reply Jeff, I appreciate you taking the time.  The thrust behind my question was basically to get an understanding of the scale of the terraforming humans have engineered on Earth and what the impact would be if that same process was applied to another planet of similar size.  I guess looking back I should have simply asked what the impact might be of 'magically' pumping 7,000 million metric tons of  carbon dioxide into the Martian atmosphere every year (7000 million metric tons being an approximate average volume created by human factors on Earth).  Thanks again and enjoy your weekend!

A: Yes, I was fascinated by the book Dune and the movie Total Recall, but the physicist in me kept slapping me on the back of the head: There's no evidence of sequestered carbon on Mars except frozen CO2 at the poles. There is only rare (indirect) evidence of water - it's a desert world. Water being low density, it would be hard to hide it on a planet like Mars or Arrakis. THAT said, I participated in several expeditions across the Empty Quarter of Saudi Arabia. Ambient humidity there is about 2% (in an Arizona summer it is around 20%). It is so dry that you have to "snuff" a handful of water every hour all night long because your mucous membranes are on fire - and cracking from the desiccation. However, I did some geo-electrical soundings along our two routes to the Wabar Impact site and found evidence of conductors - probably above-bedrock water - in several locations at about 60 - 100 meter depths.

Friday, October 23, 2015

Why do I Need a Geologist in Order to Build my Deck?

Most of what the geoscience community does is profoundly practical. As you cross any bridge, enter any building, you have a professional geologist or engineering geologist  to thank for the fact that you are safe there. 

Q: I would like to extend (cantilever) my deck over my back slope. I am told by construction contractor that I will need a geologist to determine type of bedrock and/or soil and determine the depth required for installment of support piers (caissons) to support deck structure.

    Do I need to hire only a geologist for determining whether hillside slope will support a deck?
- Walter H

A: Laws and codes are different for different cities and in different states, and are different for flat or hilly ground, hurricane-, tornado-, or earthquake-prone terrains,  so I cannot directly answer this question. Some states require assessments by someone who has passed qualifying tests, and can designate "PG" (for professional geologist) after their name. Some states require an engineering geologist to do this sort of job. These people basically provide crucial experience and data to ensure conformance with local building codes. 

    I can indirectly answer your question by sharing my own experience, which may or may not be relevant. I chose a home with a great territorial view. The price I must pay for this view is that the home is built on a slope, of course. Any slope - especially something graded within the past 20-50 years and not already covered with semi-mature trees, is inherently unstable. For instance, after just ten years I had to pay for a rock retaining wall to be built at the bottom of my back yard/slope - because the soil was slowly creeping downward and had already buried my neighbor's fence 20 cm deep. In this area there are known/mapped slow or creeping landslides, also. On one public trail that I often walk, you can see hundreds of trees that are bent almost horizontal at the base, and then curve to vertical as they go up - a sure sign of a slow or creeping landslide.

    As part of the negotiation for my new house, the company selling it agreed to build a deck in the back. The distance from my bedroom door to the ground at that time was about 15 meters. That's a long first step if you are sleep-walking, so local building code had required the outside of the door to be boarded. I had no idea what the real costs of the final deck were, but an engineer came twice to my door and apologized. First, that he would have to make it wider than my realtor had suggested - to meet code. Second, he would have to connect each of three decks by stairs - to meet code. It had to serve as a fire escape suitable for children. Then an excavator came in and dug a 2-meter-deep trench, a meter wide and the width of my house, behind the house. They set up molds and brought in a monster machine that looked like a Snuffelupagus, and poured 5 concrete cylinders a meter wide and 2 meters tall each. These were even more deeper anchored with some kind of rebar to about 3 meters below ground surface. They brought in a small grader that covered/filled in the trench. To the imposing concrete pylons they bolt-anchored five pressure-treated beams (several of them 15 meters long!). THEN they began building the deck. When I asked the builder why so much precaution (it seemed like massive over-kill to me), he said that building ANY deck on ANY slope was fraught with problems, and from experience this was the MINIMUM precautions they must take. These precautions were built right into the building code.

    “Precautions against what?" I asked.

    "Against your deck joining your neighbor's party," was the reply.

     In the 12 years since the deck was built (it remains stable) I have seen several things including the bent trees and my own sliding lower backyard slope that convince me he was correct. 

     So much for my theory that I could get away with a couple of cinder blocks with some posts standing on them and do it myself. 

Sunday, March 29, 2015

Is Your Job Dangerous?

Q: For a school assignment, I was told to ask a geologist some questions that I have about volcanoes. Is your job dangerous?
- Malayah M

A: It CAN be dangerous. I've walked out the toe of an evolving lava flow from Kilauea volcano, and accidentally stepped directly on the magma several times. It damaged my boots. Surprisingly, it sounds like Rice Crispies when you pour milk over a bowl of this cereal. This is because the outer millimeter or so of the lava "freezes" in the colder air and flakes off - it's the sound of ultra-thin glass breaking continuously. 

Most volcanologists I know are or were personally acquainted with people who are now dead - killed by a volcanic eruption. These deaths usually involved a silica-rich volcano that exploded violently. They were visiting during a time of volcanic unrest, and the explosion happened so fast that it didn't give them time to get far enough away. This type of high-silica volcano tends to form stratocones, so you have an idea of its potential to cause great destruction just by looking at it. Think: Mount Fuji in Japan. Avachinskiy in Kamchatka. Mount St Helens in the United States (it was a nice cone before 1980).

As a result, the volcanolgists still living, whom I personally work with, have become very careful and cautious. They don't take unnecessary risks - but being a volcanologist almost by definition means you must take SOME risks. 

Q: What do you do when a volcano is showing restless activity, and you have predicted that it will erupt soon?

A: We notify public safety authorities at the first reliable hint that something might happen. We make it a practice to drill with them and review the possible things that can happen, ahead of time. When Mount St Helens erupted in 2004-2008 the interaction between the USGS volcanologists and the federal, state, and county safety authorities was almost seamless.

Q: Have you ever witnessed a volcano eruption??

A: Several times I've witnessed a volcanic eruption:
- Mutnovskiy volcano in Kamchatka erupted as I was inside the main caldera in 2004. Fortunately it was a mild eruption, but the Russians with us gave us no warning (I don't think they had realized what was happening before we did). 
- Kilauea has been erupting continuously since 1983, and I have visited the flow-front a number of times. There is an interesting photo here: - look in the upper right-hand corner. When you're near a lava-tube like that, the ground moans and quivers. It's truly eery, even unnerving.
- I was the first person to see and photograph the new dacite dome coming up from under the glacier at Mount St Helens on October 12, 2004. I was orbiting in a helicopter inside the crater at the time. There was steam everywhere, and the glacier was fissured almost to the point of crumbling. Then I saw something grayish-pink that was NOT ice. 

- In addition, I've been on several restless volcanoes that were showing activity like fumeroles and weak earthquakes (Mount Lassen, in California; Akutan in the Aleutian Chain, etc.).

Friday, March 27, 2015

The question was typical. The follow-up question was definitely NOT.

Q: Hey I'm wondering how many earthquakes occur every week ? And how powerful they are......
--Rossy K

A:  The answer to your question depends on how BIG the earthquakes are that you are talking about. The smaller the earthquake, the more common they are. This means that there are probably many undetected (very small) earthquakes happening around the world every second. This also means that the really big ones - the ones that get in the news - are not very common at all.

    The US Geological Survey estimates that several million detectable earthquakes occur in the world each year. Many go undetected because they originate in remote areas or they have very small magnitudes. The National Earthquake Information Center now locates about 50 earthquakes each day, or about 20,000 a year, worldwide. They have to be above a certain minimum threshold before an effort is made to even try to locate them.

    There are far fewer large events than small earthquakes, and this table will show you how these are parsed out according to magnitude:

Frequency of Occurrence of Earthquakes
Magnitude                         Average Annually
8 and higher                            1                                             
7 - 7.9                                    15                                          
6 - 6.9                                    134                                        
5 - 5.9                                    1319                                      
4 - 4.9                                    13,000   (estimated)       
3 - 3.9                                    130,000 (estimated)       
2 - 2.9                                    1,300,000 (estimated)

    I would recommend that you visit this web-page:
    There are lots of interesting statistics here.


Q: What’s the meaning of life?
--Rossy K

A: Ask your parents, and they will give you a start on answering that question. I just answer questions about geology.

On average you have upwards of 70 more years to figure this out yourself. That's pretty much the whole point of your being on this planet. 

Saturday, February 7, 2015

Do Small Earthquakes Prevent Large Earthquakes?

Here's another question about earthquakes. It doesn't really address "slow-slip" earthquakes or induced seismicity, but clearly the questioner has been reading...

Q: Do small earthquakes prevent larger earthquakes from occurring? 
- Laurie F

A: There is an argument to that effect within the earthquake research community. Theoretically, a series of small events might accommodate (re-equilibrate, redistribute) at least some of the strain being built up by tectonic forces. In the practical world this works only imperfectly. For instance, we know: 

2....that waste water injection into oil wells north of Denver, CO, led to a significant cluster of micro-earthquakes. Apparently the fluid lubricated fault surfaces that were collecting strain. There wasn't a lot of energy released by this process, but it caused earthquake scientists to sit up and listen.

2....that there are "slow slip" earthquakes on subduction faults that cannot normally be felt, but are only "seen" by noting slow displacement changes in continually-recording GPS instruments. An example of this has been measured in the Olympic Peninsula of Washington State, and another example has been observed on the south coast of the Big Island of Hawai'i. 

This small-event re-equilibration process works for parts of a subduction fault surface - for instance the shallow and deep parts of the down-going Juan de Fuca oceanic crustal slab currently being subducted beneath the Pacific Northwest Cascades. However, there is a section of this (and other) subduction fault(s) that does NOT release strain in small increments like this. This part remains "locked."

When these locked sections "rip" (fail) there can be many meters of abrupt displacement. THIS process is the source of the greatest earthquakes ever recorded, including the last great Cascadia earthquake of January 1700 AD, which caused an "orphan tsunami" that devastated the Sendai coast of Japan many hours later without any warning.

Friday, January 16, 2015

What kind of house base absorbs the most shock

There are real, practical consequences from geology that affect every single one of us. Here's another, though you have to think like an engineer to understand all the issues involved.

Q: What kind of house base absorbs the most shock during an earthquake? - Maddie D-N

A: There are two different aspects of the same issue here: a "walking" building, vs a shock-absorbing building.

1. A building foundation that is anchored in bedrock will SHIFT the least. The foundations of my house in Washington State are built (excavated) down into bedrock. In addition, all parts of the foundation are tied together with reinforced concrete. This will keep my house from "doing the splits" when the next Cascadia earthquake hits. Being anchored in bedrock means I have a better chance that my house won't take a ride - walk - over to my neighbor's property, either.  During the Loma Prieta earthquake of 1989 in northern California, some houses that "walked" and some that "did the splits." They were build on landfill in North Beach, landfill made up largely of debris from the 1906 Earthquake dumped there nearly a century earlier. Their foundations failed - sagged, did the splits - because they were not tied together, nor were they anchored in bedrock. That landfill turned partially liquid with the shock waves passing through it. In geology-ese, this is "liquifaction."

2. There are some (generally rare) structures designed with shock-absorbing materials between the bedrock-grounded base and the structure itself. Some examples include the Trans-Alaska pipeline, and the underground facilities hosting NORAD (North American Air Defense Command) in Colorado Springs, CO. Designing a structure to ABSORB the most shock is a very expensive thing to do, however, and when NORAD was built during the early Cold War, cost was not an issue. 
   However, no matter what the structure is, engineers must decide on how BIG an event to design for.(i.e., how much displacement can they anticipate). There is not enough money to design everything in the country to survive a magnitude 8 or 9 earthquake, as we sadly learned with the Great Tohoku earthquake of 2011. The Fukushima Dai-Ichi nuclear plant had been built to survive a Magnitude 7+ event. It was unable to withstand the consequences of a magnitude 9 event (the initial shaking and the 15-meter tsunami that followed). To build it for this, the facility would have cost one or two orders of magnitude more than it did, and no one had ever experienced a M = 9 event in Japan before. 

People around the Pacific Rim will live for many years with the consequences of that structural inadequacy. 

Friday, January 2, 2015

Landscape Change - The Consequences

Landscapes change – sometimes gradually, but also sometimes in fits and spurts. There are real-life consequences to this change.

Q: When the area drifting from Africa eventually fully separates will any animals become extinct? How many new animals would be expected to evolve? How long would it take for the scenery to greatly differ from how it once was?
- Veronica V

A: Your question is ambiguous, so I will take it upon myself to infer that you mean the ~6,000-kilometer-long Great Rift Valley of Africa.

That name itself is somewhat ambiguous, since it combines features from a number of separate although related rift and fault systems stretching from Jordan to Mozambique. This continental split has been forming since at least the Miocene, 22–25 million years ago, and is currently pulling apart at a rate of about 7 mm per year. At that rate of extension, a complete rupture will occur within 10 million years, and the Somalian plate will break off, forming a new sea between it and Africa not unlike the Red Sea.

As to the animals, well, if history is any predictor of the future you can expect several things:

1. VAST numbers of animal species will go extinct this century. This is due to habitat elimination, over-hunting, and climate change. You are watching this “Sixth Extinction” happen right now, as poachers decimate African Rhinos and Elephants for their horns and tusks, and Tigers in Asia for their internal organs and bones, just to satiate a bottomless appetite in Yemen and China.

2. Those that survive on the “New Madagascar” that will be the eventual Somali Island will evolve to fit their altered ecosystem. Often this means they will grow smaller – evolve to better use the limited resources of a now-limited landscape.