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Petrinja earthquake – will deputies soon forget that they were escaping from the parliament?

Earthquakes have threatened human lives for millennia. In areas where the earthquake risk is medium to moderate, stronger earthquakes are less common compared to other natural disasters; unfortunately, they often sink into oblivion from our human consciousness.

Slovenia is a fairly typical example of an area that has experienced several strong earthquakes sporadically in the past. Earthquakes that occurred here hundreds or thousands of years ago are problematic as we do not have enough good data from them. The data we do have suggests that if an earthquake similar to 1511 in Idrija, the strongest on record, would occur again there would be thousands of deaths.

In Slovenia, 33.4 percent of the population lives in an area where a devastating earthquake is possible. Individual studies show that less than half of existing multi-apartment buildings meet modern construction requirements. In the Ljubljana region alone, a devastating earthquake would leave 30-70 percent of the population homeless. According to experts, material damage would amount to at least €7 billion (15 percent of Slovenia’s GDP) and plunge our country into an economically catastrophic situation. Many of these challenges can be solved by smart, integrated building renovation with natural materials from renewable sources like wood. In this way, we can add to earthquake safety, energy efficiency, positive environmental impact and occupant health and well-being.

So then, what can we learn from the recent Croatian case, and what must the state do?

First, Slovenia should address seismic rehabilitation of the most problematic building stock as soon as possible, that is, its critical infrastructure. The Medical Center Ljubljana would have survived (with injuries) a similar earthquake to yesterday’s seismic event Petrinja, but very old buildings that house clinics (infection clinic, oncology institute) would have suffered a significantly worse scenario. We should take as a reminder yesterday’s earthquake-induced roof collapse at the hospital in Sisak.

In Slovenia, we have many seismically problematic schools and kindergartens. Again, we should be reminded that yesterday the whole kindergarten in Petrinja collapsed. Fortunately, it was empty due to the holiday season; otherwise, the number of fatalities in our neighboring country would have been significantly higher.

If and when Slovenia is able to exercise sufficient prudence and seismically rehabilitate its own problematic infrastructure, we should go further and also renovate private building stock. Here we can be inspired by New Zealand and Italy. Both countries experienced earthquakes in the last decade that caused enormous material damage as well as numerous deaths. New Zealand transferred the burden of seismic renovation to building owners if the buildings did not meet at least one-third of today’s requirements for earthquake resistance. Italy provided extremely favorable financial assistance to those who opted for a comprehensive renovation.

Currently in Slovenia we have at our disposal many grants and repayable European funds to stimulate the economy after the COVID-19 pandemic. If at least part of these funds were invested in stimulating comprehensive facility renovations, we would be able to take a huge step forward. Not only would we finally start solving the pressing problem of seismic safety but we would also step away from merely renovating. So far, these partial building renovations have been limited to energy rehabilitation, in most cases due to unreasonable requirements and restrictions on the use of the European Structural and Investment Fund.

The last lesson to take from our neighbor’s catastrophe yesterday is the necessity of speeding up the process for updating the seismic hazard map, which is in progress, and considering more consistent control over construction projects, both in the design  and construction phases. The foundation soil’s acceleration in yesterday’s Petrinja earthquake was one-third higher than the usual project acceleration according to the Croatian map of earthquake danger for this area. This means that the strength of yesterday’s earthquake corresponded to an event that could be expected at the location in question more than every 1000 years and not 475 years, which is, in principle, the return period of the project earthquake. In fact, a similarly intense event in Petrinja took place more than 110 years ago. Footage of yesterday’s event also showed the complete demolition of buildings that were built during the period of validity of at least basic earthquake regulations or even later. Due to errors in design or implementation control, the buildings were not built properly. And since the Slovenian self-building tradition does not significantly differ from the Croatian one, we can imagine the safety of our own newer houses.

Let’s move from lessons to solutions. The Republic of Slovenia’s building stock needs a thorough and comprehensive renovation. Seismic safety is just one of the aspects we need to consider. In order to reduce negative environmental effects caused by construction in general, and to mitigate the speed and intensity of climate change in particular, we need to radically improve energy efficiency using construction materials and solutions that are as carbon neutral as possible. We also need to renovate buildings to have positive impact on people’s health and well-being. Therefore, if we use as much wood as possible in building stock renovation and  construction, we will go beyond mere earthquake remediation with classical procedures and materials.

Italy built replacements for residents who lost their homes during the L’Aquila earthquake in 2009 in the form of a multistory wooden version. Yugoslavia did the same after the Skopje earthquake in 1963, but the wooden construction at the time was meant to be temporary. In time, however, it became permanent and, unfortunately, acquired the negative connotation of “barracks”.

Due to the considerable progress of wooden construction since then, Italians are now extremely satisfied with the modern wooden design. Advanced engineered wood products (EWP) can be used to renovate buildings easily and efficiently because, with their low weight (five-times less than concrete), they hardly increase seismic forces and offer high load-bearing capacity. EWPs are also ideal for modular construction. With such wooden buildings, the state could dynamically regulate housing needs in and out of a crisis as they enable logistical combinations of modular accommodation units that can be used for housing refugees, shelter after natural disasters, temporary hospitals or upgrades to critical facilities. The Chinese built a hospital in 10 days during the first wave of the COVID-19 pandemic, and it is important to know that this type of building could be installed even faster in a light wooden version.

Better living conditions can be created with wood, compared to steel or concrete containers, that offer significantly less environmental impact. With a prudent approach, earthquake problems can be solved while also expanding capacity for other emergencies, promoting construction and wood processing industries, reducing environmental impacts, improving human health and well-being and using new European funds efficiently.

I hope that the memory of the deputies and government about the escape from the National Assembly building (which has basic seismic remediation) will not sink into oblivion too soon. When we look at demolished buildings and rescuers looking for survivors among the ruins in Japan, or even southern Italy, such events seem too far away to affect us. This time, however, we were just a shot away from the disaster. We have a great opportunity to sort things out and, perhaps, get prepared for the next strong earthquake that will be with us at some point (and it certainly will be). The will has been around for a long time. Now, funds are also available. After the COVID-19 pandemic, will we be able to renovate the damaged buildings in addition to the damaged relations?

Dr Iztok Šušteršič