• The world of tectonic plates and geothermal power went from high school to city hub
• I also picked insights on cost of poor urban planning and cause of frequent blackouts
Image: ELIZABETH KING'ORI
Alliance Française recently held a talk that piqued my interest as it revolved around geography, which I loved back in high school. It was titled: ‘The Landscape Evolution to Earthquake Hazard and Geothermal Potential in Africa’.
The audience was small and comprised people of all ages, either interested in the food and drinks that flowed freely, the message from the speakers or both.
The first speaker, Adrien Moulin, took us through Landscape Evolution and the Plate Tectonics in the Rift Valley.
The East African rift is a 4,000-mile (about 6437.38 km) depression running from Northern Ethiopia to Mozambique and Botswana. I was fascinated to hear that the rift is moving away from the rest of the continent at a rate of 4mm every year, resulting in intense volcanic and seismic activity. Kenya is on the eastern part of the rift.
Earthquakes occur both on land and in water, and are caused by the slipping of tectonic plates. In such cases, tectonic plates slide against each other in fault zones, and while friction does its best to slow them down, pressure builds up over long periods of time.
When the force of movement finally overcomes the friction, sections of the crust suddenly break or become displaced, releasing the pent-up pressure in the form of seismic waves, which cause the ground surface to shake.
The earthquakes vary in magnitude and intensity and are recorded by seismographs. The magnitudes can range from 0 to 10. Anything occurring above 6 is regarded as a major earthquake and can cause great damage and loss of lives.
EARLY WARNING SYSTEMS
Earthquake-prone areas include Japan, Indonesia and China, which have suffered major earthquakes of an average of 7.8 magnitude.
The most famous earthquake is the 1960 Valdivia earthquake that hit Valdivia town in Southern Chile at a 9.5 magnitude, leaving thousands dead and millions displaced. Kenya, on the other hand, is regarded to have a low-to-medium seismicity, though we did experience the 1928 Subukia valley earthquake, which had a magnitude of 6.9.
Water-occurring earthquakes usually lead to tsunamis — a series of extremely long waves caused by a large and sudden displacement of the ocean. This force creates waves that radiate outward in all directions away from their source, sometimes crossing entire ocean basins.
The Noto Earthquake that recently hit Japan at a 7.6 magnitude triggered a wave of tsunami. The Indian Ocean tsunami of 2004 struck several countries bordering the Indian Ocean at a magnitude of 9.1-9.3, and mostly hit the coast of Sumatra, Indonesia.
The tsunami killed over 230,000 people and caused extensive damage to infrastructure, homes and livelihoods. It was one of the deadliest natural disasters in modern history and highlighted the need for better early warning systems and disaster preparedness measures.
Earthquake warning systems include accelerometers, seismometers, communication, computers and alarms devised for notifying adjoining regions of a substantial earthquake while it is in progress.
An example is the ShakeAlert Earthquake Early Warning System, managed by the US Geological Survey, which detects significant earthquakes quickly enough so that alerts can be delivered to people and automated systems potentially seconds before shaking arrives. Countries like Japan, Taiwan and South Korea also have comprehensive nationwide earthquake early warning systems.
Other measures that have been adopted in earthquake-prone areas are the Insulated Concrete Forms (ICF) construction. ICF construction starts by being securely anchored to the building's foundation with rebar. Rebar is continuously added throughout the ICF wall, and then concrete is poured to set everything in place. The resulting structure is inherently earthquake-resistant.
In Nakuru, the construction of highrise buildings is highly discouraged due to the city’s susceptibility to an earthquake
GEOTHERMAL PROGRAMME
Our next speaker was Junior Kimata from KenGen. He took us through the geothermal programme in Kenya. The Olkaria Geothermal plants are found in Nakuru county.
First things first, Kenya ranks 6th globally in terms of geothermal use, with 944MW. Things are about to get even brighter, since with the new additions in construction, the country should soon join the geothermal GW country club.
Geothermal power is a more sustainable and cleaner source of energy for the current and future generations. It also reduces vulnerability to climate by diversifying power supply away from hydropower, which is the largest source of electricity in Kenya currently.
Kimata encouraged us to book a date and visit the geothermal spa, where the pool is heated 24-7, especially during the cold season, when it provides a more satisfying experience.
After the presentations by the speakers, we had an interactive session, where we asked questions and mingled. Seated next to me at my table were two gentlemen; an urban planner who wanted to switch careers and venture into geospatial engineering, and an architect.
I had a couple of questions I wished to raise with the architect. For example, with the construction of numerous highrise buildings in areas like Kilimani and Kileleshwa, wouldn’t it progressively cause pressure build-up due to the weight of the buildings?
I know for a fact that in Nakuru, the construction of highrise buildings is highly discouraged due to the city’s susceptibility to an earthquake.
The architect told me about the various analyses and measures taken in construction, right from setting and laying a foundation of any building. For starters, the depth of any foundation shouldn’t exceed 30 meters.
“Buildings have two types of loads: dead loads, which is the weight of the building without anything in it, and then there is the superimposed load, which is all other loads besides the dead load,” the architect said.
“Therefore, it is highly unlikely for an earthquake to be caused by the weight of buildings from the top of the earth’s crust.”
Anthropometrics was also another topic that popped up. It is the practice of taking measurements of the human body and providing categorised data that can be used by designers.
Anthropometrics help designers collect useful data; for example, head circumferences when designing a safety helmet. It is also used in interior house design. The average height of men is 1.7m and for women is 1.6m, hence most doors are 2m in height.
Females have shorter torsos and males have longer torsos, therefore, kitchen cabinet placements mostly favour the taller ones. For someone short like me, climbing stools so as to reach an upper shelf is a norm.
URBAN PLANNING
As the audience was dispersing, I cornered Kimata as I had a burning question. In 2019, while I was in high school in Limuru, I remember how we felt a tremor (we thought it was an earthquake). It was in the middle of night preps, and the room suddenly started shaking.
Screams ensued as everyone dashed for the door. It was really frightening. As you can imagine, it was a ‘survival for the fittest’ moment.
A fatal stampede could easily have occurred as some jumped from the first floor to save their lives. Luckily, not much damage was done. I, therefore, asked him why such a cold region like Limuru could even be susceptible to a tremor, let alone an earthquake.
“The tremor was equally felt in some parts of Nairobi, too, and the shockwaves must have also been propagated up to Limuru,” Kimata said.
Since he works at KenGen, I asked about the frequent power blackouts that affect the country.
“KenGen is responsible for generation of electricity, while Ketraco steps up the generated electricity and transmits it to a step-down substation, where the electricity is stepped down for KPLC to distribute it to the final consumers,” he said.
“The problem comes with the limited capacity of the power lines with the growing population of people who need electricity. Therefore, this strain causes more frequent power shortages in some parts of the country than others.”
Kimata has also spent time in the Netherlands, and so we ended up having a conversation on the differences in urban planning between Kenya and the Netherlands.
In the Netherlands, some areas are set aside specifically for residential or industrial purposes, while here in Kenya, it is too common to find both a church and school in a residential area.
Unless you live in the high-end areas in Kenya, you know that poor planning in housing is rampant. This is thanks to the rise of cartels (and of course, corruption), creating loopholes in our construction sites. Every now and then, a building collapses, and you’re left wondering who gave the go-ahead for its construction and completion.
Recently, a gas explosion hit Mradi, Embakasi, where a lorry carrying gas canisters exploded, leaving hundreds injured and six others dead. Turns out, the gas depot was illegally being run in a residential area, and so you can imagine how many people had to be bribed to turn a blind eye to the running of that depot.
At the end of it all, I left the Science Cafe with my brain stimulated. I went home with a lot of knowledge pounding in my head, and I wished that more of such talks would be frequently held.