{"id":145,"date":"2014-09-12T23:38:52","date_gmt":"2014-09-12T23:38:52","guid":{"rendered":"http:\/\/www.oceanblogs.org\/being-a-young-marine-scientist\/?p=145"},"modified":"2014-09-16T02:36:15","modified_gmt":"2014-09-16T02:36:15","slug":"what-happened-the-two-last-days","status":"publish","type":"post","link":"https:\/\/www.oceanblogs.org\/being-a-young-marine-scientist\/2014\/09\/12\/what-happened-the-two-last-days\/","title":{"rendered":"What happened the two last days"},"content":{"rendered":"

6 o\u2019clock in the morning. I\u2019m awake now since two hours. The sun is rising and the temperature outside is of 28\u00b0C. A good starting day!<\/p>\n

6h du matin. Je suis r\u00e9veill\u00e9e depuis deux heures. Le soleil est en train de se lever et la temp\u00e9rature ext\u00e9rieure est de 28\u00b0C. Une belle journ\u00e9e en perspective !<\/em><\/p>\n

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Temperature outside the lab at 4 o’clock in the morning.. Temp\u00e9rature ext\u00e9rieure \u00e0 4h du matin..<\/em><\/p><\/div>\n

We are now recorded 3D seismic data with the P-Cable system but before telling you what is going on right now onboard, let me catch what happened the two last days…<\/p>\n

We deployed the 2D system on Thursday morning above our target (a sedimentary ridge southwest off Taiwan) and started recording data up to 7 o\u2019clock yesterday morning. Our initial plan was to collect 2D seismic lines above the ridge and deploy later on the OBS stations on the spots that would have been the most interesting to image. Unfortunately, a typhoon is coming in our study area in the next few days. We will thus leave the place and go back to the harbor during that time. As we have to leave soon and don\u2019t have enough time to deploy, shoot and recover the OBS, we continue shooting 2D lines and decided to start collecting 3D data.<\/p>\n

Nous sommes maintenant en train d’acqu\u00e9rir des donn\u00e9es sismiques 3D avec le syst\u00e8me P-Cable mais avant de vous en dire davantage sur ce qui est actuellement en train de se passer \u00e0 bord, je vais vous raconter ce que nous avons fait les deux derniers jours…<\/em><\/p>\n

Nous avons d\u00e9ploy\u00e9 le syst\u00e8me d’acquisition sismique 2D jeudi matin au-dessus de notre zone d’\u00e9tude (une ride s\u00e9dimentaire localis\u00e9e au sud-ouest de Ta\u00efwan) et avons collect\u00e9 des donn\u00e9es jusque hier matin vers 7h. Notre plan de d\u00e9part \u00e9tait de collecter des donn\u00e9es sismiques 2D au-dessus de la ride et de d\u00e9ployer, plus tard, les stations OBS sur les zones que nous aurions trouv\u00e9 int\u00e9ressantes \u00e0 imager lors de l’analyse des donn\u00e9es 2D. Malheureusement, un typhon est actuellement en train de se diriger sur notre zone d’\u00e9tude et sera l\u00e0 d’ici quelques jours. Nous allons donc quitter notre position actuelle pour repartir vers le port le temps que le typhon passe. Devant partir d’ici deux jours, nous n’avons pas le temps de d\u00e9ployer les stations OBS, d’acqu\u00e9rir les donn\u00e9es et de r\u00e9cup\u00e9rer ces derni\u00e8res. Nous continuons donc d’acqu\u00e9rir des donn\u00e9es 2D et avons d\u00e9cid\u00e9 de commencer l’acquisition des donn\u00e9es 3D (P-Cable).<\/em><\/p>\n

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Illustration of the acquisition system for the 2D data. The streamer is located in the background (in green) and the airgun source, in the front (right to the white and blue buoy). Illustration du dispositif d’acquisition 2D. La fl\u00fbte sismique est localis\u00e9e \u00e0 l’arri\u00e8re plan de l’image (en vert) et la source d’air comprim\u00e9, au premier plan (\u00e0 droite de la bou\u00e9e blanche et bleue).<\/em><\/p><\/div>\n

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Zoom on the airgun source. Zoom sur la source d’air comprim\u00e9.<\/em><\/p><\/div>\n

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Last verification before to deploy the streamer into the sea. Derni\u00e8re v\u00e9rification avant de d\u00e9ployer la fl\u00fbte sismique dans l’eau.<\/em><\/p><\/div>\n

We deployed the P-Cable system in the afternoon. We firstly put the GPS antennas on each paravane and connected them to our computer in order to record their position during the acquisition of the data (shooting). Then, we deployed the 15 streamers (containing the hydrophones), the second paravane and the source (airgun). The picture below highlights the geometry of the system.<\/p>\n

Nous avons d\u00e9ploy\u00e9 le syst\u00e8me d’acquisition 3D dans l’apr\u00e8s-midi. Dans un premier temps, nous avons positionn\u00e9 les antennes GPS sur chacun des paravents et avons connect\u00e9 ces derniers \u00e0 un ordinateur afin d’enregistrer leur position au fur et \u00e0 mesure de l’acquisition des donn\u00e9es. Nous avons ensuite d\u00e9ploy\u00e9 les 15 fl\u00fbtes (contenant les hydrophones), le deuxi\u00e8me paravent puis la source (airgun: air comprim\u00e9). La figure, ci-dessous, illustre la g\u00e9om\u00e9trie du dispositif. <\/em><\/p>\n

\"\"<\/a>

Illustration of the P-Cable system using to collect the 3D seismic data. The source is located in the middle of the system. Behind it are located the two paravanes and the streamers (lines). Figure from C. Berndt Illustration du syst\u00e8me d’acquisition 3D (P-Cable). La source est localis\u00e9e au centre du dispositif. Derri\u00e8re celle-ci se trouvent les deux paravents (\u00e0 chaque extr\u00eamit\u00e9) ainsi que les fl\u00fbtes. Image: C. Berndt<\/em><\/p><\/div>\n

\"\"<\/a>

Deployment of one of the paravane of the P-Cable system. D\u00e9ploiement d’un des paravents du syst\u00e8me d’acquisition 3D (P-Cable).<\/em><\/p><\/div>\n

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Deployment of the paravane. D\u00e9ploiement dans l’eau d’un des paravents.<\/em><\/p><\/div>\n

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Starting the deployment of the streamers. D\u00e9but du d\u00e9ploiement des fl\u00fbtes sismiques. <\/em><\/p><\/div>\n

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Zoom on one of the streamer used during the 3D acquisition. Agrandissement de l’une des fl\u00fbtes sismiques utilis\u00e9es pour l’acquisition des donn\u00e9es 3D.<\/em><\/p><\/div>\n

\"connected-the-streamer-3\"<\/a>

Connecting the other streamers.. Connection des autres fl\u00fbtes sismiques au dispositif.<\/em><\/p><\/div>\n

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Our PI connecting the last streamer t the system. Notre chef de mission connectant le dernier streamer au dispositif.<\/em><\/p><\/div>\n

It is really important to know the exact geometry of the system (i.e. where are located the source and the paravanes) to process the data. That\u2019s why during the deployment the length of each cable was measured as well as the position of the GPS antenna that stands on the ship. Knowing the geometry of the system and the exact position of the paravanes enable us to determine the exact location of the source for each shot.<\/p>\n

As to the processing of the data, Sina and Timo are working on it!<\/p>\n

Il est primordial de conna\u00eetre la g\u00e9om\u00e9trie exacte du syst\u00e8me d’acquisition (i.e. o\u00f9 sont localis\u00e9s la source et les paravents) afin de traiter les donn\u00e9es. C’est pourquoi durant le d\u00e9ploiement, la longueur de chaque c\u00e2ble a \u00e9t\u00e9 mesur\u00e9e ainsi que la position de l’antenne GPS localis\u00e9e sur le pont arri\u00e8re du bateau. Une bonne connaissance de la g\u00e9om\u00e9trie du syst\u00e8me ainsi que de la position exacte des paravents nous permet de d\u00e9finir la position exacte de la source au cours de l’acquisition (i.e. pour chaque tir).<\/em><\/p>\n

Quant au traitement des donn\u00e9es, Sina et Timo sont actuellement en train de travailler dessus !<\/em><\/p>\n

\"Sina<\/a>

Sina and Timo working on the processing of the 3D data. Sina et Timo travaillant sur le traitement des donn\u00e9es 3D.<\/em><\/p><\/div>\n","protected":false},"excerpt":{"rendered":"

6 o\u2019clock in the morning. I\u2019m awake now since two hours. The sun is rising and the temperature outside is of 28\u00b0C. A good starting day! 6h du matin. Je suis r\u00e9veill\u00e9e depuis deux heures. Le soleil est en train de se lever et la temp\u00e9rature ext\u00e9rieure est de 28\u00b0C. Une belle journ\u00e9e en perspective […]<\/p>\n","protected":false},"author":100,"featured_media":159,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-145","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/www.oceanblogs.org\/being-a-young-marine-scientist\/wp-json\/wp\/v2\/posts\/145","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.oceanblogs.org\/being-a-young-marine-scientist\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.oceanblogs.org\/being-a-young-marine-scientist\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.oceanblogs.org\/being-a-young-marine-scientist\/wp-json\/wp\/v2\/users\/100"}],"replies":[{"embeddable":true,"href":"https:\/\/www.oceanblogs.org\/being-a-young-marine-scientist\/wp-json\/wp\/v2\/comments?post=145"}],"version-history":[{"count":19,"href":"https:\/\/www.oceanblogs.org\/being-a-young-marine-scientist\/wp-json\/wp\/v2\/posts\/145\/revisions"}],"predecessor-version":[{"id":190,"href":"https:\/\/www.oceanblogs.org\/being-a-young-marine-scientist\/wp-json\/wp\/v2\/posts\/145\/revisions\/190"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.oceanblogs.org\/being-a-young-marine-scientist\/wp-json\/wp\/v2\/media\/159"}],"wp:attachment":[{"href":"https:\/\/www.oceanblogs.org\/being-a-young-marine-scientist\/wp-json\/wp\/v2\/media?parent=145"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.oceanblogs.org\/being-a-young-marine-scientist\/wp-json\/wp\/v2\/categories?post=145"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.oceanblogs.org\/being-a-young-marine-scientist\/wp-json\/wp\/v2\/tags?post=145"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}