Podcast: 5 minutes with Yu-Chun Chang

Dr Yu-Chun Chang, postdoctoral researcher, National Taiwan University

Episode Transcript

[00:10] Marissa Lo: Hello and welcome to 5 Minutes With, the podcast of Geoscientist magazine. My name is Marissa Lo, and today I’m joined by Dr. Yu-Chun Chang, who has just finished his PhD at the University of Manchester. Thank you for joining me, Yu-Chun, can you tell me about your PhD research on submarine landslides and volcanic islands?

[00:29] Yu-Chun Chang: Mostly I’m working on the sedimentary processes and the deposits around the Azores volcanic islands, to assess the implications for the natural hazards, such as the frequency and magnitude of earthquakes, submarine landslides and volcanic eruptions by using interdisciplinary methods.

The work was comprised of four parts. The first and second part are largely based on the geophysical data, such as marine seismic data, and bathymetry data, and the backscatter image of the submarine seafloor data. I actually identified and classified more than 1200 submarine landslides around the five Azores volcanic islands. I used numerical calculations and some statistical methods to assess their triggering mechanisms or slope stability and wave heights of the induced tsunami.

And for the second research: it’s a study of sediment waves develop on the submarine slopes of the volcanic islands. We found that sediment waves are more abundant on the northern flanks of five studied islands on the bathymetric data. This observation favours explanations involving more extreme wave conditions from the northwest of the Azores islands, hence more active submarine sediment transport. And this observation is important because sediment flow activity is important information to assess for the long-term safety of seafloor foundations.

For the third and fourth research, it’s largely based on the core analysis. I start from identifying the volcaniclastic-rich bed in the cores to differentiate different types of the volcaniclastic beds from tephra fallout beds and primary volcaniclastic turbidites and secondary volcaniclastic turbidites. Let’s make it simple, it’s like eruption-origin turbidites and landslide-origin turbidites and tephra fallout. This discrimination is important because it reflects the mechanism behind, so, it tells you you have more eruption or you have more submarine landslides in this region. Surprisingly, we found that a major portion of the volcanic-rich beds are actually eruption feed beds, so it likely suggests that volcanic activity are in the Azores. So, to better understand the frequency of such eruption- or landslide-origin events, I further collect some marine fossils from the ocean to obtain the radiocarbon dates to have better ideas about the occurrence state of this event. So, by having the time constraint, we have more ideas about the sedimentation rate and frequency of the events. In the other parts of the work, we further like extend the discussion to if this kind of frequency change is associated with the climate changes.

[03:36] Marissa Lo: So, what is your favourite thing about your research?

[03:39] Yu-Chun Chang: I quite enjoy studying a topic which can be used to better understand, not only our planet, also enhance the safety of our population living in some coastal areas. It’s also quite interesting that because I work in a diverse topic, but eventually I’m focusing on the hazards and processes on the volcanic island, so it’s like I examine the topics from different angles.

[04:08] Marissa Lo: Finally, what advice would you give to someone that’s hoping to work in your field?

[04:14] Yu-Chun Chang: As a multidisciplinary researcher, I would say expect probably more uncertainty and unknowns from your field because you need to combine very different data sets and at the beginning of your research, expect you will face a lot of unknown things. As a marine scientist, if you are joining a cruise, you always need to have a list and think about everything before you start your work on the sea.

[04:49] Marissa Lo: That’s great. Thank you so much Yu-Chun for coming onto Five Minutes With.

[04:51] Yu-Chun Chang: Thank you.