The mystery of too-deep earthquakes

Look at the depth distribution of earthquakes on Earth (Fig. 1):

Fig. 1: Depths of earthquakes on Earth. Shallow earthquakes (0-60 km) are in red, intermediate-depth earthquakes (60-300 km) in purple and deep earthquakes (>300 km) in blue. Data from the International Seismological Centre.

In general, earthquakes are located at the boundaries between tectonic plates. Shallow earthquakes (< 60 km) happen at all plate boundary types, but intermediate (60-300 km) and deep (> 300 km) earthquakes mainly occur in subduction zones, where one plate moves beneath another. Because these earthquakes are located either within the subducting plate or between the two plates, they get deeper and deeper the further they are from the surface trace of the plate boundary. Because the plate located west of South-America moves towards the east and is subducted under South-America (Fig. 2), the earthquakes on the west coast of South-America get deeper from west to east (Figs 1, 2). Continue reading

An adventure on the JOIDES Resolution: One year later

Fig. 1 – (Top) One of the many magnificent sunrises observed by scientists on board the JR; (Bottom) View of the derrick, tower that holds the drill string, from the Bridge Deck, and (Top-left) all Expedition 360 participants. Images credits: William Crawford, Exp. 360 Senior Imaging Specialist; Jiansong Zhang, Exp. 360 Education/Outreach Officer.

Earlier this year Barbara wrote about ‘Life on board of a scientific drilling vessel’. That interview gave some hints in the unique experience my colleagues and I shared on board the Joides Resolution. Now, you might wonder what Joides Resolution (JR) exactly is. The JR is a drilling vessel dedicated to scientific research on ocean and ocean crust dynamics. Different disciplines are involved, from geology (to elucidate the formation of the oceanic crust), to climate change science (to understand how the Earth handled past climatic events), oceanography (to study global water circulation), or microbiology (to track extreme life in rocks forming the ocean floor).Cores of rocks are drilled under the ocean floor, giving scientists a glimpse into Earth’s dynamics. The JR works for the international research program IODP (International Ocean Discovery Program), a marine research collaboration that aims at recovering data recorded in seafloor sediments and rocks, and monitoring subseafloor environments. Continue reading

An ocean on land

Science is not all about books or laboratories, but also includes fieldwork. Unlike what people might think, this is not a holiday (although you get to bring home a lot of beautiful pictures) but work. And it is crucial for geology! But what do we do? And why? Standing in a beautiful landscape surrounded by rocks that contain information you are looking for, science shows a very different and adventurous side. Since our blog is about oceanic rocks, fieldwork can involve going on a ship. However, an ocean can be found also on land, and as we will show you in this movie, Oman hosts oceanic rocks with plenty of interesting features.

From Volcanoes to Atolls: Science below a Disney/Pixar Short film

Image 1: Disney/Pixar®

Science, Hollywood, a smiling volcano…. What do those things have in common? The Disney/Pixar short film presented with Inside Out! Science in films is not often successful or “scientific”. Just have a look at 2012, The Core, Japan sinks, Volcano, Dante’s peak, and maybe many others. Therefore it is a nice surprise to see that there can be science below this recent short film called “Lava”.

This film tells the story of a volcanic island “in the middle of the sea”, from its active state to its extinction. It’s based on Big Island (Hawaii) and its evolution. I propose you have a look at the science of “Lava” just by following the lyrics. Continue reading

The story of the oceanic crust and the deep carbon cycle

Where does a story start? Or should we better ask: Where does it end? Some stories even run in circles, happening all the time. One of those stories is the global cycle of chemical elements, a topic many geoscientists are investigating. In the ABYSS project, we all study phenomena that are more or less related to the formation of new oceanic crust. That is the start of a story: magma from the Earth’s mantle rises underneath mid-ocean ridges, where plates are moving apart below kilometers of water; the magma crystallizes and the resulting rocks form these new plates. We can already tell a lot of stories about the processes that happen while new crust is formed, in this dynamic zone of interactions between water, rocks and magma. But in this post, I would like to put those into a larger context: the story does not end after the oceanic crust cools down and is carried away from the mid ocean ridges, where it formed.

Sketch of the deep carbon cycle – how carbon is transported through Earth`s interior.

Continue reading

“Geology isn’t a real science!”

Dr. Sheldon Cooper, physicist, from “The Big Bang Theory”, and his strange relationship with geology! (still image from “The Big Bang Theory”)
Dr. Sheldon Cooper, physicist, from “The Big Bang Theory”, and his strange relationship with geology! (Still image from “The Big Bang Theory”)

Some of you probably know “The Big Bang Theory” sitcom and if not I strongly suggest it. One of the characters in this funny American sitcom is a physicist and he firmly believes that geology cannot be considered as a real science. This is a pretty strong statement and it makes us think …..So let’s borrow this exclamation “Geology isn’t a real science!” and reflect about what geology is.

You probably know the stereotype of a geologist: shorts with a thousand pockets, a hammer, a compass and a magnifying glass. But what is this sort of David Attenborough looking for? Continue reading