Geology Word of the Week: T is for Travertine

Travertine terraces, Yellowstone, Western USA, Fall 2005.

After a month's absence because of the Fukushima interviews, I am resuming the geology word of the week. For my new readers, every week I blog about a geology word. Over the past several months, I have been working my way through the alphabet, from A is for Alluvium to S is for Speleothem. I hope you enjoy this weekly feature!

def. Travertine:
1. Formal and specific: "A chemically-precipitated continental limestone formed around seepages, springs, and along streams and rivers, occasionally in lakes and consisting of calcite or aragonite, of low to moderate intercrystalline porosity and often high mouldic or framework porosity within a vadose or occasionally shallow phreatic environment. Precipitation results primarily through the transfer (evasion or invasion) of carbon dioxide from or to a groundwater source leading to calcium carbonate supersaturation, with nucleation/growth occurring upon a submerged surface (Pentecost, 2005)."

2. Translation of the above + a little more: A type of limestone (a calcium-rich rock composed primarily of the CaCO3 minerals calcite and aragonite) which forms by chemical precipitation (the stuff that makes the rock falls out of solution) from certain types of shallow or surface waters, such as springs and rivers. The trigger for the precipitation is usually gain or loss of carbon dioxide (CO2), which causes a pH change and changes the solution chemistry so that CaCO3 precipitates. This gain or loss of CO2 usually happens very close to the Earth's surface as the CO2 is lost to or gained from the atmosphere. The waters that produce travertines are usually very acidic (low pH) or very alkaline (high pH). Often, travertines precipitate from acidic hotsprings, such as those at Yellowstone in the Western USA. However, contrary to many web sources (this wikipedia article, for instance), travertines do not always form at hotsprings; they can also form from cooler waters. Closely related to the word travertine is another T word: tufa. The difference between travertine and tufa is porosity-- tufa is a type of highly porous travertine that generally forms from cooler waters (not hotsprings).

A Blog Milestone

100,015 pageviews.

Fukushima spike.

Sometime yesterday my little geology blog passed 100,000 pageviews, a milestone that I expected to reach maybe by the end of 2011 or perhaps in 2012. I never expected to reach this milestone so quickly. I've only been blogging since November 2010, and when I first started blogging I was happy if I even had ten pageviews per day.

I have mixed feelings about reaching 100,000 pageviews. I am happy and sad. I am happy because so many people are interested in reading my blog, but I am sad because the primary reason I have so many pageviews is a result of interviews I've done with my father on the second-worst nuclear disaster in history. I must say, this is a depressing way to increase readership. However, I've noticed that a few of my "nuclear dad interview" readers are staying to read some of my geology-related posts. That makes me happy, at least.

Cederberg in Pictures

Contemplative in the Cederberg.

It's been awhile since I've done an "...in Pictures" post, so I thought I'd put up some pretty geology pictures today.

Exactly one week from today I fly to Cape Town, South Africa to visit my fiance and have a bit of a vacation after 4 1/2 months of hard work. I've only taken a weekend or two off since Christmas, so I'm definitely feeling tired and in need of some rejuvenation. This trip to South Africa is also an exciting one because I'm starting to make plans for my upcoming wedding and move; I plan to move to Cape Town permanently later this year.

I am really looking forward to doing some hiking and spending some time outdoors on my upcoming trip. My fiance and I plan to spend several days hiking in the Cederberg Mountains, which are a couple of hours drive from Cape Town. I've been to the Cederberg twice before-- once in January 2008 and again in September 2010-- but there is much to explore there. You could spend weeks hiking in the Cederberg and not see everything. I find the Cederberg a magical, wonderful, relaxing place. I'm very much looking forward to returning there.

I'll post some pictures of my upcoming trip to South Africa upon my return. Meanwhile, here are some pictures of my trip to the Cederberg in September 2010. Click on any of the pictures to enlarge.

Mini rock arch.

Hands.

On the Recent Japan Earthquake Sequence

Note: This is a guest post by my friend, Jean-Arthur Olive. Arthur volunteered to make these figures and write this post in response to my concern about the recent magnitude 6.6 earthquake that prompted an evacuation and knocked out power at the Fukushima Daiichi nuclear power plant facility for the better part of an hour. For more information on recent events at Fukushima, see: 

20th Interview with My Dad, a Nuclear Engineer, about the Fukushima Daiichi Nuclear Power Plant Disaster in Japan

Arthur's Post: 

The March 11^th (magnitude 9.0 – ‘mainshock’) earthquake followed a 2-day sequence of increased seismicity that included a strong (magnitude 7.2) earthquake. Such an event is commonly referred to as a ‘foreshock’, although its role as a trigger for the mainshock is not clear.

Click figure to view larger.

In the wake of the magnitude-9.0 earthquake, numerous aftershocks were triggered by the readjustment of stresses on the fault. In map view, the location of all these events roughly outlines the region that ruptured on March 11^th.

Click figure to view larger.

Aftershocks may keep happening for years, decades, or even more. In fact, after a long time, it becomes less and less clear whether an earthquake can be considered as an aftershock of some prior large event.

In 1894, Japanese seismologist Fusakichi Omori discovered that the number of aftershocks per day following a large earthquake is inversely proportional to the time elapsed since the earthquake. This is termed Omori’s law. The Japanese sequence seems to fit this empirical prediction rather well, which means that aftershocks should become less and less frequent over the next few months. However, we have no way of predicting what the magnitudes of these aftershocks might be.

Click figure to view larger.

Note: All the data plotted in the figures is from the ANSS composite earthquake catalog.

20th Interview with My Dad, a Nuclear Engineer, about the Fukushima Daiichi Nuclear Power Plant Disaster in Japan

You can listen to all the interviews on the new vimeo channel Brandon and I created. You can also listen to most of the interviews on Brad Go's YouTube channel.

Here's the vimeo channel:

Georneys Nuclear Engineer Dad Interview Series on vimeo

Brad Go's YouTube channel: 

Georneys Nuclear Engineer Dad Interview Series on YouTube

This evening my dad and I recorded our 20th interview on the Fukushima nuclear power plant disaster. Please see the rest of the blog (sidebar) for previous interviews. If you would like to send a message to me or my father about this or any of the previous interviews, you can do so in a comment below or by sending an email to georneysblog (at) gmail (dot) com. You can also follow me on twitter @GeoEvelyn.

We thought that we were done with the Fukushima interviews, but because of a number of requests by email and in comments, we decided to conduct an interview tonight to comment on the upgrade of Fukushima from a 5 to a 7 on the International Nuclear and Radiological Event Scale (INES).  My dad highly recommends checking out this IAEA slideshow presentation to better understand this scale and the reason for the upgrade:

Slideshow on the INES Scale

My dad also recommends checking out this Associated Press article comparing and contrasting the Fukushima and Chernobyl nuclear disasters:

Questions and answers: Japan, Chernobyl disasters

As a geologist, I also wanted to comment on the recent magnitude 6.6 earthquake that prompted an evacuation and cut off power at Fukushima for the better part of an hour. Any event-- such as an earthquake-- that could lead to an extended loss of power is potentially quite serious for the Fukushima Daiichi reactors and spent fuel pools at Units 1-4, which remain "static but not stable."  Fortunately, the recent earthquake only caused a temporary evacuation and loss of power. There is the potential for more aftershocks in coming days, and an unfortunately located aftershock could potentially lead to another power loss.

However, I am a geochemist, not a geophysicist or an earthquake expert, so I am not qualified to speak in too much detail about earthquakes and aftershocks. Fortunately, two of my geophysicist friends came through with some more detailed information and analysis than I can provide. First, I want to direct you to a blog post about the recent Fukushima area earthquakes by geoblogger Chris Rowan.  Second, I want to direct you to a guest post (following this one) on my blog that has some figures and text written by Jean-Arthur Olive, a good friend of mine and a fellow PhD student in the MIT/Woods Hole Oceanographic Institution Joint Program. Thanks so much, Chris and Arthur! If any other geophysicists would like to add anything else, just let me know. I can post more information on my blog and/or post a link to another website. Here are links to the two posts I mentioned above:

Chris Rowan (Highly Allochthonous Blog): Earthquake location matters, part eleventy

Jean-Arthur Olive (guest post on Georneys Blog): On the Recent Japan Earthquake Sequence

In today's interview:
1. My dad gives an update about Fukushima

2. My dad discusses the upgrade on the INES scale and comments again on the evacuation zone.

Hope to have an audio link soon. Here is the interview on vimeo:


Please see the announcement page for more information about these interviews:

Announcement Page

If you have time and interest, please transcribe this interview or volunteer to transcribe Interviews 17, 18, and 19. At this time, we have no plans for future interviews.

A Quick Note: And We Thought We Were Done with the Interviews...

My dad and I wrapped up our regular Fukushima interviews last Saturday, but we did say that if something important happened we would consider commenting on it.

Well, the Fukushima nuclear disaster was just provisionally upgraded from a 5 (Three Mile Island level) to a 7 (Chernobyl level) by Japanese authorities. My dad is not surprised by this upgrade since he has long felt Fukushima to be higher than a level 5. Several people have asked us (begged, even) if we would consider commenting on the upgrade, so we've agreed to do another interview tonight. If you have any questions related to recent developments at Fukushima that you would like me to ask my father, we may have time to answer one or two questions. Post them in a comment below or send them to georneysblog (at) gmail (dot) com no later that 5 pm EDT.

Geology Pun Contest: The Winner

The prize: Gillian Turner's book "North Pole South Pole."

Cross-posted on Skepchick.

As I mentioned yesterday, this blog is now returning to its usual geological theme. I also mentioned yesterday that in the near future I will blog about the Oklo Natural Nuclear Reactor, which is a topic that I hope will appeal to both those interested in geology and those interested in nuclear power. I want a few days to read some papers and write up a proper post on the topic, and in the meantime I will return some of my usual geology posts, such as the Geology Word of the Week. I managed to take the Geology Word of the Week most of the way through the alphabet from A is for Alluvium to S is for Speleothem before halting all geology posts so that my dad and I could do our Fukushima interviews. This week I will be writing about a geology word starting with the letter T, so stay tuned!

Today I want to wrap-up a bit of unfinished blog business. Just before the Japan earthquake and tsunami, I announced a geology pun contest with the prize being a copy of Gillian Turner's book "North Pole South Pole: The Epic Quest to Solve the Mystery of Earth's Magnetism." I unfortunately haven't had time to read this book, but it has already been reviewed favorably by other geobloggers, such as Callan Bentley over at Mountain Beltway and Wayne Ranney over at Earthly Musings. I hope to read the book myself on an upcoming trip to South Africa.

Because I did not want to break up the Fukushima interviews, I never announced the winner of the geology pun contest, but I am now:

Best Geology Pun (made me laugh the most):

"I never got into geology. Seemed too crowded as so many geologists are out standing in the field."
-sisyphusrocks

Congratulations to sisyphusrocks! You have won the book. Please email your address to georneysblog (at) gmail (dot) com, and I'll send the book on its way.

For amusement, I've compiled the rest of the geology puns after the jump. Thanks to everyone who entered, and feel free to post more geology puns in the comments. There can never be too many geology puns :-).