INTRODUCTION

Abuja, the capital of Nigeria and sixth most populous city in the country has been experiencing earth tremors. Over the last couple of years a series of earth tremors have been reported particularly in the areas of Mpape, Katampe, and Maitama. The notable incidents were reported in 2018 and 2019 with the recent one occurring in September 2024.

DIFFERENCE BETWEEN TREMORS AND EARTHQUAKES

To understand the nature of these tremors, it is crucial to explore their causes and how they impact society and the environment. For example, earthquake tremors are natural geological events that occur when there is a sudden release of energy in the Earth’s crust caused by some geological factors such as plate tectonics, underground fluids, and volcanic eruptions. But primarily, most earthquakes are caused by the movement of large, solid pieces of the Earth’s crust, called tectonic plates.

Tectonic plates are massive, irregularly shaped pieces of solid rock that make up the Earth’s crust and have been constantly in motion for billions of years (USGS). As such, friction at their edges can cause them to get stuck and when the stress on the edge overcomes the friction, the plates release energy in waves as mentioned earlier.

The release of energy generates what is called seismic waves, which are of two types, including body waves and surface waves. Body waves travel through the earth’s interior after being generated and are the first seismic waves to arrive at the seismograph. Surface waves, on the other hand, travel along the earth’s surface and are responsible for the significant impacts that we see depending on some factors such as the local geology, depth, and magnitude.

It is also crucial to understand that the magnitude of the wave is what differentiates an earthquake and an earth tremor. When a tremor exceeds “Five” on the moment magnitude scale (which goes from 0 to 10), it is called an earthquake.

WHY TREMORS IN ABUJA?

So why is Abuja experiencing these tremors when Nigeria isn’t located in major seismic zone? Well, remember we said earthquakes occur when there is a sudden release of energy in the earth’s crust caused by the sudden movement along a fault plane, which is a fracture in the earth’s crust along which displacement has occurred? Such fault lines are known to exist beneath Abuja and nearby areas.

Ifewara-Zungeru fault is considered the primary natural geological feature responsible for most tremors experienced in Nigeria (Akpan and Yakubu, 2010), including those occurring in Abuja, as it runs through a large portion of the country and is considered the main source of seismic activity in the region; therefore, recent tremors in Abuja could be linked to geological activities along this fault line.

Even though the primary cause of earth tremor remains natural. Human activities, such as rock blasting, indiscriminate mining, and improper borehole drilling in the area, can exacerbate the natural stress buildup, contributing to the occurrence of tremors. It is noteworthy that Abuja has already been exposed to unregulated drilling and blasting of rocks by quarrying companies and artisanal miners.

After the September 2018 Abuja tremor, the Presidential Committee set up by the Federal government reported the need to regulate the exploitation of groundwater resources in Abuja via indiscriminate sinking of boreholes.

Some key questions linger in our minds: Will these tremors keep happening? What are the impacts on the environment and livelihoods? One thing is certain, the phenomenon is typical in regions with active fault lines, and may likely reoccur in Abuja.

WHAT DO WE DO?

While it is not entirely possible to prevent the natural occurrence of tremors and earthquakes, several mitigation strategies and safeguard measures can be employed to lessen their impact:

1. Ensuring that buildings and infrastructure are constructed in such a way that they can withstand ground shaking, especially in the areas prone to tremors (Mpape, Katampe, and Maitama).
2. Strict regulations for quarry miners should mandate the adoption of controlled blasting techniques, compliance with environmental impact assessments, and mandatory seismic evaluations to minimize risks, especially in fault-line areas where blasting may need to be restricted or banned.
3. Engineers and planners should work with geologists and seismologists to map tremor-prone zones, advise local authorities on restricting certain infrastructure developments like hospitals and schools, designate safe zones for new projects, and advocate relocating vulnerable infrastructure from high-risk areas.
4. Residents should be educated on safety measures and life-saving actions to help them during and after a tremor. Similarly, residents should develop family emergency plans, keep emergency kits with essentials, identify safe spots in their homes, follow earthquake-proofing guidelines, and be trained in basic emergency response techniques like “Drop, Cover, and Hold On.
5. Establishing and expanding more seismic monitoring stations across the Federal Capital Territory and ensuring real-time tracking of seismic activities, accurate data, and prompt alerts.

REFERENCES

1. Thomas, J & George, Nyakno & Ekanem, Aniekan & Nathaniel,. (2020). Preliminary investigation of earth tremors using total electron content: a case study in parts of Nigeria. NRIAG Journal of Astronomy and Geophysics. 9. 220-225. 10.1080/20909977.2020.1723866.
2. Advances in Multidisciplinary and scientific Research Journal Publication. (2017). https://doi.org/10.22624/aims
3. Akpan, O.U., Yakubu, T.A. A review of earthquake occurrences and observations in Nigeria. Earthq Sci 23, 289–294 (2010). https://doi.org/10.1007/s11589-010-0725-7
4. Earthquakes: Tremors from below | AMNH. (n.d.). American Museum of Natural History. https://www.amnh.org/explore/ology/earth/earthquakes-tremors-from-below
5. Earthquake tremor causes & effects. (n.d.). History. https://vocal.media/history/earthquake-tremor-causes-and-effects
6. THE ABUJA EARTH TREMORS – THISDAYLIVE. (2024, September 25). https://www.thisdaylive.com/index.php/2024/09/25/the-abuja-earth-tremors/
7. What is a tectonic plate? [This Dynamic Earth, USGS]. (n.d.). https://pubs.usgs.gov/gip/dynamic/tectonic.html