The evening of October 6, 2024, was a memorable one for many of Addis Ababa’s residents, particularly those who live in high-rise buildings. The sunset on what had been a quiet Sunday for most was followed by the tremors of an earthquake. In the weeks since, the capital has experienced no less than three tremors, though each of these was less noticeable than the first, which measured 4.9 on the Richter scale.
Though unusual for many, who may have only had a grasp of the danger posed by earthquakes through international news reports, the series of tremors highlights that Ethiopia is not a safe haven when it comes to seismic activity.
The phenomenon has given rise to a range of opinions on the subject of earthquakes in Ethiopia, but how accurate are they? How vulnerable is the country to earthquakes of a higher magnitude? What are the potential risks to cities, towns, buildings and major infrastructure projects? The Reporter Magazine’s Bewket Abebe spoke with Professor Gezahegn Yirgu, a distinguishedresearcher in Earth Sciences teaching at Addis Ababa University, to get a better idea. EXCERPTS:
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The Reporter Magazine: Tell us about your personal experience with the recent earthquake tremors that shook Addis Ababa, particularly from the magnitude 4.9 earthquake that struck Awash Fentale on October 6?
Gezahegn Yirgu (Prof.): I didn’t sense any of the last series of earthquakes. I live in the Bole Bulbula area, south of Bole International Airport and I felt none of them.
Are there any explanations as to why some parts of Addis Ababa felt the tremors while other parts did not?
All these things really depend on what we call the geology of a certain area. The earthquake does not choose [where it strikes]. It occurs in a certain place and spreads in different directions. You may feel it in some places and in other places, you might not depending on the nature of the rocks and features. There are many contributing factors. People who live in high-rise buildings like condominiums might have felt the last series of earthquakes. I just haven’t felt any.
You study earthquakes. What is your firsthand experience with earthquakes?
I’ve experienced earthquakes several times. The last one was in the Afar depression, around Semera, in 2005. At the time, there was a major series of earthquakes in north central Afar, in an area called Debahu. That was a major seismic event; a volcanic event that had never been studied before with that detail. We were traveling to the area to study in collaboration with other expatriates; scholars from European and American universities. That was a major geological event and I felt that. But earlier on, I had experienced earthquakes quite frequently while I was studying for my PhD in Italy. Earthquakes occur quite frequently. I was in a town called Pisa, where the leaning tower, one of the wonders of the world, is found. Every time there was an earthquake, which was not quite strong, at least at the time, people went out to see whether the tower had fallen.
My very first experience of an earthquake was in 1961 when I was a child. I was in school here in Addis and a very energetic earthquake occurred in a place called Karakorie. People were alarmed. The public was told to stay the night outside their homes.
Earthquakes are rare in Ethiopia and most Ethiopians only ever hear of them through international media reports when they occur elsewhere in the world. But data in the field suggests earthquakes are not as far away as they may seem. How prone to earthquakes is Ethiopia? And which particular parts of the country are most susceptible?
Here in Ethiopia, we are in what we call the Rift Valley. The Great East African Rift crosses Ethiopia, and within Ethiopia is what we call the Ethiopian Rift. There is also the Afar Depression, which is a wide and active rift. It is a continuation of the Red Sea. What happens in a rift is there are geodynamic processes occurring within the earth that we don’t see. We think that the earth is stable, dormant, and all these things. But that is not true. The internal part of the earth is in fact not stable and processes are taking place within the earth (at great depths of 60 to 100 kilometers). The effect of processes like the melting of rocks and others tear apart the crust or the upper part of the earth itself. What happens as a result is that the crust is under strain, which generates a valley; a depressed area. These places are very active geologically in generating seismic activity or earthquakes. Earthquakes themselves are the manifestations of what is happening beneath our feet. This Rift Valley, a long-depressed valley which is some 60 to 70 kilometers wide spreading from the north in Afar and extending through Metehara, Adama, and further south to the Ziway region, Langano, Hawassa, and even further south into the Arba Minch area, crossing all those Ethiopian regions and entering into Kenya ( you can also trace it in Tanzania and in Malawi) is a very long line of unstable crust. It is not stable. Meaning; the earth is fracturing. We are not talking about the soil. These are really hard rocks fracturing. Not so noticeable. We notice it only when there are movements like earthquakes. In earthquakes, there is a very sudden release of stressed energy and these are manifestations of what is taking place.
Afar is special in this regard given that it is the most stressed area.
Which other areas of Ethiopia are at high risk of experiencing earthquakes?
You can say the entire region of Afar, the Afar in Ethiopia, Djibouti, and Eritrea. When we say the Afar triangle, it refers to a wider area. It is susceptible not only seismically but also volcanically. We need to assess this. Apart from the famous Erta Ale, there are other hazardous volcanoes there. In June 2011, there was a major eruption called the Nabro Eruption. It was an ash eruption that covered the salt deposits in Afar. Thousands of goats, sheep, and camels were killed. Air flights were blocked to the north.
At the same time, we only sense earthquakes when they are big enough; a magnitude of 4.7 or greater. And the nearer you are to the original place where the earthquake occurred, the more you feel it. But there are frequent earthquakes of smaller magnitude that we don’t sense but are instrumentally detected. It is like soundwaves. The nearer you are, the better you hear it. Those frequent smaller earthquakes are indications that the Rift Valley is active and fracturing constantly in small measures. In general, Ethiopia is susceptible to earthquakes.
Yet, one important thing remains important to consider: that earthquakes are natural phenomena. They don’t come to hurt us. The hazard comes because we expose ourselves. It is all about what we construct and where we live. We go out there and do constructioneverywhere, the population grows, and that way the exposure becomes wider. If there were no construction, no huge infrastructure, no overpopulation, there would be no damage.
But it is also natural for populations to grow and cities to expand, making those areas densely populated over time. Is there anything the government, institutions and individuals can do in terms of preventing or minimizing potential damage from earthquakes?
There is so much we can do. Earthquakes are natural phenomena. We cannot avoid them. But we can adapt to them. Take the experience of countries like Japan. Japan is a very seismic country. The term ‘Tsunami’ is now a well-known one. Everybody is familiar with it. A tsunami is the result of an earthquake, or the sea being disturbed by earthquakes. Japan has experienced the largest earthquakes ever recorded. What do they do? Leave their country? No, they live with the earthquakes. They take care of their construction; their urban development. They have buildings 70, 80 stories high. But during these earthquakes, none of these buildings are damaged or collapsed. This is because they use their knowledge and construct their infrastructure in such a way that they can resist.
Take the Americans. They live in cities like San Francisco. San Francisco was destroyed by earthquakes several times before. But they took lessons. Now, their urban development is well planned. They have managed to minimize damages.
We can take care of ourselves by following codes. There need to be codes that we follow. We can at least minimize damage by applying those standard codes while constructing buildings, major dams, and major infrastructure. Every time we do these things, every time we construct, we need to be aware that there are potential earthquake risks. And there are well-known codes and structures we can apply. They might be a bit expensive but we can still do that.
Have you encountered any similar practices in Ethiopia, such as contractors or project owners consulting with experts like yourself regarding earthquake-resistant designs? Have you personally had any experience with this in your work?
In some cases, there have been experts [seismologists] here at Addis Ababa University and elsewhere who have been approached to give their recommendations while buildings are constructed. But it is not common. From what I know, the new UNECA headquarters were built with such precautions. There are some other buildings that took potential earthquake occurrence into account. But there are only a few. In other countries, there are regulations. You cannot just build certain buildings without taking care of this; without the seismologist and geologists approving. That is where we should come in. We should really apply the science, the experiences, and the expertise of people. If we do that, people will not be at risk as such. We can certainly minimize the risk.
At the same time, we have to raise public awareness. People usually panic when they experience such things. Sometimes we feel like we’re dying of panic. We have to organize a system in which people can learn about it so that we can minimize potential damages due to panic.
Can individuals recognize the early warning signs of an earthquake?
Earthquakes are all sudden incidents. There can be a very sudden warning. Of course, that requires monitoring. And such early warnings come from previous studies.
But when they occur, there are a series of things that can be done easily. Raising public awareness is important in this regard. In many countries, they have a national team of experts that provide guidance, information and some sort of support. In such ways, you can organize better. The follow-up is very important. There are lots of experiences out there. The awareness is important not only for the public but also to policymakers so that we can be better prepared.
Let me give you an example of Tanzania. I think it was in Dodoma, which is found in the Rift Valley. A major earthquake occurred and shook the parliamentary building while the parliament was in session. That gave a great awareness. They are now better aware and provide better funding for the science itself. Sometimes, you understand it better when you feel the damage.
As you might have already noticed, in the most recent cases we have been discussing, the United States Geological Survey was the first to indicate [the earthquakes] to us while we were here in the country. They have the capability. They monitor so many instruments all over the world. Among those instruments are the ones that are here in Addis. And here in Ethiopia, we also have a network of monitors at the Institute of Geophysics. They receive information from all these and they have the capability to use all these sensors, precisely locate the earthquake, and understand broader characteristics of the events. That is how it works.
It is not the first time. And it is not going to be the last. We have to be better prepared not only for earthquakes but also for other natural hazards.
Since the initial tremor, there have been concerns about the potential damage these earthquakes could cause to large buildings in Addis Ababa and other areas, as well as to large dams like the GERD. What is your assessment of this risk?
That is of particular concern. As I was trying to discover early, the areas affected by earthquakes in the past, currently, and in the future are well-identified. They fall within the Rift Valley area. Fortunately, the GERD is far away from this region. So, it is free from such risks. In fact, one of the selection criteria of the specific places where the GERD is built was this. You cannot build such a huge project in the Rift Valley area. This has been confirmed, which falsifies the argument from some Egyptians.
But as you come to the Rift Valley area, earthquakes occur frequently and in largermagnitudes. As I said before, it is not earthquakes that come to hurt us. It is us who go to the earthquakes and get exposed. When you build larger structures there, you are putting a load on the earth. When you build dams in such areas, the rocks beneath are loaded, which means they can generate earthquakes on their own, especially if they are near major earthquake-prone areas. This is a caution. What has already been built is one thing. But the future constructionof big projects should consider earthquakes as major hazards.
A team of researchers at Semera University have recently indicated serious potential seismic risks to nearby dams. What are your thoughts on this matter?
That is a sensitive area that I don’t want to talk about. There are a number of implications. Broadly, any structure that is built in such an area; heavy structures like dams, major railway stations, airports, or towns; are exposed given that the area is already not stable. But it is still manageable.
