Travel time

Here we are only four days away from Honolulu, after some 2 weeks and a half at sea. This is my fourth cruise and it will be the longest one so far. And the first leg of the Shatsky Rise cruise lasted for 60 days! But, exactly how long will this second leg take? That is, with all the date and time changes, what will the real duration of the cruise be? We sailed off at around 8 am on March 24^th and will dock at approximately 8 am on April 15^th, which gives 22 days. We had one day change in which we went back in time and repeated April 8^th, so it's 23 days. Finally, when we get to Honolulu we will have made four hour changes of +1 hour, which means that we need to subtract 4 hours from the real time duration. Then my final approximate guess is 22 days and 20 hours. Is this correct?

Last day I posted was April Fools' Day, today is Cruise Picture Day. At 1 pm this afternoon, we all gathered in the muster deck, just behind the bridge, and arranged the picnic tables so that the people in the front could sit and the people in the back could prove that they had been in the cruise too. This may sound corny, but this is probably the best souvenir I will be taking home. Unfortunately, for the moment I can only tell you the story because the pictures are not uploaded yet, but I'm sure we will get to see at least one of them in one of the following posts.

But this is a science cruise, so I guess I'm supposed to have some science content in my posts. In the previous one I told you about my thesis main topic: travel-time tomography which is used to model wide-angle seismic (WAS) data. In this second leg of the Shatsky Rise cruise only MCS data have been acquired, so maybe some of you don't know exactly what WAS data is about. In the first leg of the cruise though, there were a couple of WAS data profile and if you check the older posts you will find all you need to know on the acquisition of this kind of seismic data. But once collected, what do we do with these data? That is precisely the purpose of tomo2d and tomo3d. From WAS data we obtain the time interval of seismic waves traveling from source to receiver: the observed travel times. From these, we want to recover a velocity model for the Earth subsurface. Briefly, what the two TTT codes do is simulate the source-to-receiver rays, calculate synthetic travel times for them, then compare these with the observed ones, and finally translate these differences in travel time, or travel-time residuals, to changes in the velocity model. This process is repeated until the resulting velocity model produces synthetic travel times that fit our data to a desired level of accuracy.

As you will know, Team Awesome is also Team Multilingual, and we have had time to learn some French, Chinese, Spanish and of course English. As this likely to be my last post, I'm going to leave you with a multiple choice question to improve your Spanish. The question is based on an anecdote that I'm glad didn't happen to me (you can ask me about it), and I think it will be useful if you ever get a cold while staying in Spain, although English takes you almost anywhere these days: What is the Spanish translation for “I have a cold”? (a) “Estoy constipado”, (b) “Tengo frío”, (c) “Estoy resfriado”, (d) Both (a) and (c) are correct, and (e) “Tengo un frío”. I realize that 5 possible answers is probably too many, so here is a hint, the literal translation of “I have a cold” is a wrong answer.

Oh, I almost forgot! In my first post I said I would tell you about the “First and Second Last Names Paradox”, from now on FSLNP. The FSLNP arises from the fact that in Spain newborns are given a last name from their father and another one from their mother. The tradition is that the first last name of your father be your first last name and the first last name of your mother, your second last name. But nowadays you can have that the other way around too. A funny consequence of the FSLNP is that when we travel to the US, our first last name is assumed to be our middle name and our second last name is picked as our last name. That is basically what happened here on the Langseth, where I've become Adrià M. Catalán.

"ah-dree-Ah"

Since this is my first post, I will begin by introducing myself. My name is Adrià (“ah-dree-Ah”), that written accent on top of the last A (à) meaning that stress falls on that last syllable. I hope this is helpful to those struggling a little bit with my first name. In the next post, I will discuss the Spanish issue with surnames, aka the First and Second Last Names Paradox. But I was introducing myself: (Hopefully) I'm on the last year (and a half) of my PhD degree, which focuses on travel time tomography (TTT). TTT is a method used to model wide-angle seismic data, which produces P-wave velocity models of the Earth subsurface usually reaching down to the upper mantle. Additionally, it may also be possible to define the geometry of strong geological discontinuities such as the top of the basement under a sedimentary layer, the interface between the two plates in a subduction or the Moho. Together with Jun, I've been developing a 3-D version of his code for TTT (tomo2d), and before I had also applied tomo2d to data acquired offshore Nicaragua to image the subduction zone. Jun invited me to this cruise to discuss the next steps in the development of the 3-D TTT code (tomo3d), and of course to help as a stand watcher. This is my fourth cruise, and although I don't particularly like ships, it wasn't exactly hard to make up my mind about this one when I learned that I would have the opportunity to visit Guam and Hawaii, and that I would be able to complete a trip around the world (Barcelona - London - Tokyo - Guam - Hawaii - San Francisco - Toronto - Vienna - Barcelona).

But enough of science for today. I'm told that April 1^st is April Fools' Day. Although in Spanish-speaking countries the equivalent celebration is on December 28^th ("Día de los Inocentes"), in the Spanish Balearic island of Menorca, April Fools' Day is also celebrated on April 1^st and known as "Dia d'enganyar", Catalan for "Fooling Day". In order to honor such a special day as this, I added a false fact somewhere in this post. You can make your guess, and either tell me in person or on a comment to this post.

Despite the first days of uneasy feeling in the stomach and the occasional rush to the toilet (we all know why), so far the cruise has been fun. I am a proud member of the A-Team, most commonly known as Team Awesome, alongside Sam and Cécilia. As such, I've already been invited to a couple of parties by Bern and Dave from the science tech crew. The first one was a Streamer Party, nothing illegal, no online streaming to watch TV series on the Internet, just a bunch of guys deploying the 6-km-long cable used to acquire multichannel seismic data. The second one included the same bunch of guys, some more coming and going of cables, and a guest star which goes by the name of Maggie (the magnetic sensor). For some reason, it stopped working and we had to recover it, change its cable, and put it back in the water. Even if it's cold outside, it's good to go up on deck from time to time, to escape the laboratory (actually a little bit too cold as well) and its screens (how many?) for a while. A mysterious and remarkable inhabitant of the lab, is the 8 ball. The old tales say that it can foretell everything, so I asked whether I would be marrying my girlfriend anytime soon, and the answer was positive. Now, I'm planning to ask my girlfriend to marry me during our mini-holidays in Hawaii.

Finally, I'd like to send out there a request for shelter for the first night in Hawaii. I'm staying until the 20^th but, knowing that on the first night we may sleep on the ship and that my girlfriend arrives the following day, I only booked a hotel for the other three nights. Any ideas on a place to crash or any advice will be much appreciated. I already have a list which includes beach (every day) and surfing lesson(s?), but I'm probably missing some sightseeing, for instance, an excursion to a crater.