In June 2020, GSL published the landmark 500th volume of the Geological Society’s Special Publication series, SP500: Subaqueous Mass Movements and their Consequences: Advances in Process Understanding, Monitoring and Hazard Assessments, edited by: A. Georgiopoulou, L. A. Amy, S. Benetti, J. D. Chaytor, M. A. Clare, D. Gamboa, P. D. W. Haughton, J. Moernaut and J. J. Mountjoy (https://sp.lyellcollection.org/content/500/1). The first Special Publication was published over 50 years ago in 1964. To celebrate the publication of SP500 we have held a short Q&A with the Co-ordinating Editor of the book, Dr Aggeliki Georgiopoulou, about her research and experience publishing the volume. Dr Georgiopoulou is a Senior Lecturer at the University of Brighton, specializing in submarine landslides.
What can readers expect to find within SP500? Can you provide us with a short outline of the volume and its contents?
The papers in this book present the latest results in underwater landslide research. Geographically it covers almost the entire world, as you can see in the introductory paper (Mountjoy et al., https://doi.org/10.1144/SP500-2019-237) and includes diverse geological settings, from lakes and fjords to volcanic islands, passive and active margins. Traditionally our research has been descriptive and observation-based, but it is becoming more and more numerical and follows technological advances and this can be seen in many of the contributions in this volume. Quite promising for the field is that much of the research included here is by early career researchers (ECR; e.g. Couvin et al./https://doi.org/10.1144/SP500-2019-180, Kaminski et al./https://doi.org/10.1144/SP500-2019-149, Mollison et al./https://doi.org/10.1144/SP500-2019-160 and Nwoko et al./https://doi.org/10.1144/SP500-2019-146), who will be leading the way in the coming years.
In your opinion, what are/were some of the most exciting findings? Are there any findings that you weren’t expecting?
There are various very interesting findings and perspectives in these works, even if they tackle topics that have been studied for a long time. Submarine mass movements are very complex and there is still a lot to know about their dynamics and impact. A lot of this is also possible through new, higher resolution datasets, which make a big difference when we aim to pursue high detail characterizations and proper understanding of what causes them, how they move, how they stop moving and whether they reactivate. Forecasting these events is very difficult, almost impossible, but the research here brings us several steps closer to characterizing the hazard that exists for certain areas. Some of the most exciting results came from the 4D analysis work, where we can have a real dynamic feel of movement throughout the years and decades, such as in the studies by Chaytor et al. (https://doi.org/10.1144/SP500-2019-183) and Clare et al. (https://doi.org/10.1144/SP500-2019-173). This can only be possible through repeat surveys of specific areas and the implementation of monitoring systems for continuous record, which is probably where a lot of the future effort of marine research will focus. This is extremely important for tsunami hazards, of which we have seen quite a bit in the last decade or two.
The paper by Brackenridge et al., ‘Indonesian Throughflow as a preconditioning mechanism for submarine landslides in the Makassar Strait’ (https://doi.org/10.1144/SP500-2019-171), is one of our most downloaded Special Publication papers so far this year. Why do you think this paper is especially appealing?
One of the reasons is probably the proximity of the study area to the Bay of Palu, which was struck by the Palu-Sulawesi tsunami in 2018. The media picked up on the paper because of this and almost certainly exposed it to a wider audience. There was a considerable death toll from the combined effect of the earthquake and tsunami, in addition to all the material damage. Sadly, it is often when we, as a global population, suffer the consequences of such natural disasters that attention is paid to their historical occurrence. Brackenridge et al.’s paper is very valuable as it provides a scope of the size of the massive submarine landslides with tsunamigenic potential that occurred within the Strait of Makassar, all of them much larger than the Palu one in 2018. If a tsunami is generated by such massive failures, the impact on the surrounding coastal areas would be truly devastating, so we and local authorities and governments need to be aware of the risks.
One of the focuses of this volume is the societal impacts of subaqueous landslides and risks for inhabited areas. Can you explain why these issues are particularly relevant right now, especially in light of recent events.
The focus on the impact of underwater landslides on coastal areas has been increasing over the last two decades. For instance, previous compilations of works on subaqueous mass-movements would have included just a few papers focusing on tsunami risk and modelling, but throughout the years this has increased, with one of the drivers being the occurrence of recent destructive events by tsunamis where the world could see the consequences via TV images and social media. It becomes more relevant when people see these events and their aftermaths during their lifetime. It is the ‘out of sight, out of mind’ effect, and nowhere is this more relevant than for processes that take place beneath the ocean or lake surface. It is not that this kind of work was not being done before – for instance, there was the recent Anak Krakatau collapse and resulting tsunami on 22 December 2018. A 2012 piece of work by Giachetti et al. (https://doi.org/10.1144/SP361.7), published in another Geological Society Special Publication (Volume 361, Natural Hazards in the Asia–Pacific Region: Recent Advances and Emerging Concepts) had modelled such an event and their tsunami model was similar to what actually happened. However, at the time of its publication, the paper did not get the attention it probably should have. The recent events are a reminder that geohazards are all around us and can occur any time now; they are not just a thing of catastrophic events in history books. Policy-makers and insurance companies are also more aware of the importance of research into geohazards, again as a result of seeing things happening, and subaqueous landslides and tsunami hazards are increasingly accounted for in civil protection plans. The next challenge is to keep these hazards in the minds of the general public and policy-makers. The increasing efforts given to science, technology, engineering and mathematics (STEM) and related activities are crucial for this, so as scientists, apart from carrying out the actual research, we must also focus on outreach to create awareness about the impact of geohazards.
The volume also discusses the range and variability of past events. Are there any in particular that you find especially interesting?
Variability is a ‘popular’ topic when discussing underwater landslides … the scale and variability are actually a very big focus for our scientific community. Some of the editors of this volume are collaborating on an international effort to create a global database of subaqueous landslides so we can have an easier way to access and compare information of past events. These provide clues to what can happen in the near (or far future), so we need to know about their preconditioning and major triggers. In terms of any in particular … that is hard to say – it’s like choosing your favourite child! Even though my own research does not focus on landslides in lakes these are the ones drawing my attention a lot lately and this is why, as a group, we decided to have a lake on the cover of the volume. The cover image comes from the work by Daxer et al. (https://doi.org/10.1144/SP500-2019-179), another ECR-led paper. Landslides in lakes and generally confined environments, so fjords and inlets too, can be even more hazardous than ones in marine settings as they tend to have larger populations around them and the perception of tsunami risks is even lower.
What are the most important unanswered questions in this field? Where does the subaqueous landslide research community go next?
There are many … one of the first challenges we encounter is to compare across scales. We can study subaqueous landslides exposed on outcrops, on seafloor bathymetry and direct sampling, on ultra-high resolution seismic or on ‘standard’ seismic data buried several hundred to thousands of metres beneath the seafloor or lake floor … all these different scales of analysis provide different data that are often challenging to integrate. One question that comes to mind relates to the recurrence of events. How long is the gap between events and what controls the events and therefore the recurrence interval? This gets very challenging the older and the larger these events are, as they often end up being complexes with various amalgamated or fused deposits. Understanding their dynamics is also a challenge as what we tend to see are ‘still frame shots’ of the final result, the deposit, which is the ‘dying’ stage of an underwater landslide, not its most dynamic. For some we can infer, with some degree of uncertainty, that they were slow-moving, others fast-moving and others a mix of evolving processes, transitioning from one to another, that we may not be able to resolve entirely. This leads to something I mentioned earlier, and where I see a part of the future of this research: 4D evolution through continuous monitoring. This may provide a lot of new data and perspectives on the study of these events.
What’s it like being a part of this community?
Our community is very collaborative, very friendly, very passionate about science and landslides, inclusive and helpful. There is no competition and no in-fighting and this is why we are all so open to share data and create databases. You will see that many of the papers we produce are multi-authored, which reflects not only the requirement our science has for collaboration but also that spirit of collegiality. It is quite exciting and has allowed me to get to know a lot of really nice people. Our biannual dedicated conference (International Symposium on Subaqueous Mass Movements and Their Consequences), such as the one that led to this Special Publication (although the conference has been postponed to 2021 because of the pandemic), is actually a meeting of old friends catching up on work and life, and a platform for new people to join us. As a result of these frequent and friendly interactions SLATE (Submarine landslides and Their impact on European continental margins) was created, a major European Training Network funded by the EU to train the next generation of subaqueous landslide experts through integrated innovative research. Examples of this work can be seen in the papers by Barrett et al. (https://doi.org/10.1144/SP500-2019-187), Zengaffinen et al. (https://doi.org/10.1144/SP500-2019-201), Gatter et al. (https://doi.org/10.1144/SP500-2019-184), Mencaroni et al. (https://doi.org/10.1144/SP500-2019-176) and Badhani et al. (https://doi.org/10.1144/SP500-2019-175), all led by SLATE PhD researchers.
We’re really excited that this is our 500th Special Publication! What are your thoughts on Special Publications in general and being the 500th volume?
We are really excited about that too! It is a real landmark to reach 500 volumes of this collection and you have our most heartfelt congratulations! Each of these volumes is very well regarded as a high-quality, up-to-date source of knowledge on a focused topic and this is the quality we tried to bring to our volume too. Personally, I have several on my shelf which are regular go-to resources for my research and my teaching. Many of the older volumes I read as an undergraduate and then postgraduate student of Geology. Creating the 500th volume is a very proud moment for me and the team! Beyond the valuable landmark of such a round number, it will also make our volume number easy to remember!