Newsletter 4 - June 2020
EDITORIAL
By Philippe Gueguen
Seismic risk at the time of Covid-19
The recent global Covid-19 lockdown period is unique. It imposes on our daily life, which until now seemed immutable, modifications of our social relations, our professional activities and more generally our individual and collective behaviors. It will bring about changes that we all hope will contribute to a better anticipation of exceptional events with a high impact on our environment and our well-being. Even if the causes of this unprecedented situation are far from our fields of expertise, this imposed period gives us the opportunity to think about our scientific practices and how to exploit and disseminate our knowledge, whatever our field of expertise. This is all the more true in the seismic risk.
In the field of seismic risk, the existence of earthquakes with low probability but high consequences illustrates, in the manner of the Black Swan theory proposed by Taleb (2010), the cognitive bias that leads us to the erroneous conclusion that exceptional phenomena will not occur. However, we know from observation of geological markers and historical events that remarkable earthquakes have already occurred in moderate seismic prone regions in Europe, and that others may occur. The erroneous belief that these events do not exist can have adverse effects on the protection, regulation and resilience of our environment. The result would be, as in the current health crisis, fatalities and reduced economic activity and development, with significant economic losses.
Disasters hinder the achievement of objectives of all kinds (environment, education, economy). They often point out the failures of development actions, which increase the vulnerability of populations to risks. Yet a study by the US Geological Survey (USGS) confirms that a $40 million investment in prevention measures worldwide in the 1990s reduced economic losses by $280 million (Benson and Twigg, 2004). These prevention actions, identified as priorities in the international framework for disaster risk reduction, known as the Sendai Framework, address the whole components involved, from understanding the processes that lead to disasters until acting effectively before, during and after. This implies that risk reduction is also highly dependent on the behavior of political and administrative decision makers. The latter have the possibility to limit the consequences through their decisions or actions. However, they must be able to do so on the basis of sound scientific assessments.
This is where we scientists are involved. Because the most remarkable events are rare, it is difficult to make public authorities, especially local ones, aware of the need for recurrent preventive actions, especially since the return period of these events far exceeds our ordinary time scales. This is one of the greatest difficulties we have to overcome in terms of seismic risk, through education, information, simulation of the consequences and reflection on innovative measures to raise awareness and make appropriate decisions. In this respect, our research work and the way in which it is disseminated are essential and contribute to mitigating the consequences and preparing for the earthquake crisis management.
How did the COVID-19 affect our ESRs ?
Paulina Janusz - ESR 3.1
"Covid-19 has certainly changed how we work and live. Even though the epidemic hasn’t skipped Switzerland, the introduced isolation rules are not so strict as in many countries: we are allowed to travel, go for a walk or hike, etc. if we observe the rules of social distancing.
For me, the lockdown is not affecting my work capabilities a lot because my main working tool is my computer. I had to postponed the measurement campaign I was planning but hopefully, I will be able to conduct it by the end of May. I think that I am now a bit less distracted than usual and working maybe more efficient. However, it is more difficult to separate private life from work.
Social distancing is difficult, hours of videoconferences are tiring and interactions are limited. Eventhough my working group organizes video coffee breaks and common online lunches to socialize, it's not the same."
Riccardo Minetto - ESR 2.2
“The confinement is an unexpected opportunity to test yourself and know your limits. In other words, having a lot of time to dedicate to your project makes you realize how long you can stay focused and how much you can push yourself.”
"Since the start of the confinement I have not had any type of issue. In fact, I feel I can work much more staying at home. I had time to do things that I would have never been able to do. I can also follow my rythm and make breaks when I want.
If I have to find something negative, I would say that, at least for me, it certainly affects negatively the body. I really move too little and I am sure it affects life expectancy!
Luckly in my case, a simple exchange of information via emails and video calls with my supervisor
is enough to guarantee a steady progress, but there may be situations that require a more direct contact to solve problems. In these cases the confinement could be quite detrimental to productivity."
“For me, working at home is not as efficient as working in the Lab.”
"I spent all my lockdown in Milan which is a serious place during COVID-19. To decrease the rate of dangerous, I start to work at home according to the instructions of Policy.
Normally I take some PhD courses online and communicate with supervisors by email. Most of my work is about numerical simulations so I could work anywhere . I contact my supervisor regularly and she gives me a lot of help about research. Other colleagues in this team also help me a lot.
At the beginning, I thought it would be finished in a really short time so it didn't influence much. Later, I found it may last for a quite long time then I suffered a difficult period. Now everything is fine and actually I learn a lot from this difficult time. Anyway, I positively trust that everything will be solved and looking forward to back to lab again! And, I do need a travel after finish this period."
What are the COVID-19 impacts on the URBASIS project ?
The URBASIS project progress
Delivrable 3.4 : Existence of forbidden frenquency bands due to the presence of meta-materials at the geophysical scale.
Tall buildings clustered together could excitingly act as strong sub-wavelength resonators when they interact with seismic waves. The concept of site-city interaction is not new and it is well known that buildings act as secondary sources and affect the ground motion within the city. They can potentially scatter, deviate and even cancel the ground vibration. Wave control efforts in elasticity have been inspired by previous accomplishments in electromagnetism and acoustics through structured composite materials. Lately, these concepts of wavefield manipulation on smaller scales have been extended and applied to seismic waves on the geophysical scale. The various lab and field experiments conducted as part of the METAFORET project can have many urban-scale implications. Buildings can be considered as scaled-up version of trees. Moreover, unlike the case of trees, we expect to observe the hybridization of surface waves at much lower frequencies which are of primary interest in earthquake engineering. The goal is to discern the nature of seismic waves propagating in a dense urban environment which can act as a giant geophysical 'metamaterial’ on the scale of a city and eventually help design the future metacities.
What about the ESC2020 ?
More information
What progress has been made regarding research activities ?
Paulina is studying the variability of site response in the city of Lucerne in central Switzerland. In November 2019, she installed the local temporal seismic monitoring network there to record weak ground motions from low-magnitude or distant earthquakes. The network was supposed to be there until the end of March, however, due to the COVID-19 pandemic, the removal of the seismic stations has only started in the middle of May. It is probably the only profit of the current crisis for the URBASIS-EU project because Paulina was able to keep her network operating longer than planned. One of the dismantled stations was located in the Swiss Transport Museum (Verkehrshaus der Schweiz) close to the tracks of a toy train.
Starting from October 2017, the Maurienne Valley (French Alps) experienced a period of intense seismic activity that lasted until December 2018. Several events of ML > 3 were recorded and a clear clustering of seismicity was observed.
The data used for this study were acquired from March 2017 to October 2019 by a local seismic network of 6 broadband stations: one station part of AlpArray (A181A) and 5 stations installed by ISTerre after the largest event. The SISmalp catalog
contains information on about 5400 events that occurred in Maurienne. This catalog was built using standard techniques commonly employed in seismological centres. The first objective of the study was to improve the SISmalp catalog in terms of number of detections and location accuracy.
A double-difference location method was employed to locate the detections with high accuracy. We first relocated the templates considering both catalog and cross-correlation differential times. The new locations were then used to relocate the detections using only cross-correlation times. In this last step, the detections were only linked to detections belonging to the same cluster. A total of 24000 events could be relocated using this method.
