A preliminary report on the earth tremor that had been occurring in Saki town, Saki West Local Government, in Oyo State is an impending signal to a damaging earthquake in South West region of the country, in the next four years, precisely before 2020.
This was disclosed in a report by Dr Adepelumi Adekunle Abraham of the Department of Geology, Obafemi Awolowo University, Ile-Ife, Osun State, in a report entitled “PRELIMINARY ASSESSMENT OF EARTH TREMOR OCCURRENCE IN SHAKI AREA, SHAKI WEST LOCAL GOVERNMENT, OYO STATE”.
Adepelumi had carried out a research after a similar tremor occurred in Abeokuta, Ogun State, September 11, 2009, suggesting that the risk of the quake in South West region was 2.8 per cent, but stated that the risk had risen to 91.1 per cent.
In recent months, residents of Saki, especially Medinat, Veterinary, Salam Salam, Abimbola layout and Ogbooro areas, had been living in palpable fear over the recurring sound of a earth tremor, which had been brought to the attention of the state and federal governments.
Recently, a state government delegation led by the Commissioner for Environment and Water Resources, Chief Teju Ishola who visited the scene, appealed to the residents to remain calm, adding that government both at the state and federal level would proffer solution to the problem.
Before then, member representing Saki-West/Saki-East and Atisbo local governments at the House of Representatives, Honourable Olajide Olatubosun, had also raised the issue at the floor of the House under matter of urgency.
Olatubosun in a letter dated June 9, 2016, which was addressed to the Speaker, House of Representatives, Honourable Yakubu Dogara and entitled: “Matter of urgent public importance (standing Order VIII rule 46) urgent call on the Federal Government to investigate the persistence earth tremor currently being experienced in Saki, the headquarters of Saki-West local government area of Oyo State,” called the attention of the House and Federal Government to the “persistent vibrations/tremor in Saki.”
According to him “anytime the earth vibration/tremor occurs, the building and other physical structures in the affected areas would shake violently and this, he said was responsible for a large army of internally displaced persons (IDP), as they had to vacate their homes, farmlands and their places of business.”
However, Dr Adepelumi who led a team of Geologists and Seismologists from the Federal Government through the Center for Geodesy and Geodynamics and Geodesy (CGG), Toro, Bauchi State to assess the situation as reported by the people of the community confirmed their fear, as well as the danger to the South Western part of the country.
Adepelumi stated that “After the earth tremor of 2009 in South western Nigeria, was felt in several towns and villages in Oyo, Osun and Ogun States, a detailed short-term propabilistic earthquake prediction was carried out by our team, our findings indicated the probability of earthquake occurrence in the study area between the year 2009 and 2028 increased from 2.8% to 91.1%. The result also showed that the probability of three events occurring has the highest likelihood within the predicted years. Also, found that the Weibull probability density model predicts a damaging earthquake (M= 5) before year 2020.
“Our findings showed that the earth tremor that was experienced in the Shaki area is a series of fore-shock, main-shock and after-shock of a small scale earth-tremor with local magnitude 2.5 on the Richter scale that originated along the Ifewara, Romanche and Charcot fault system in the Atlantic ocean that passed through Shaki town. These mega structure are supposedly the longest linear feature within the Precambrian basement complex of Nigeria, and extends northwards from Ijebu-Ode area in southwestern Nigeria through Okemesi area to Zungeru and beyond to Kalangai in northwestern Nigeria (They are deep-seated mega-lineaments) that transcends the south-western part of the country.”
He then suggested that an earthquake monitoring device called seismometer be installed in Saki for proper monitoring in case of an earthquake.
Concluding his report, Dr Adepelumi warned: “It is concluded that earthquake monitoring device called seismometer should be install in Shaki town for proper and effective monitoring of the likely occurrence of earthquake precursors, foreshocks, main-shocks and after-shocks that may likely occur in the area in the very nearest future. A preliminary assessment of the reported earth tremor in Shaki area gave a focal depth 5 km within the upper crust with a stress drop of about 0.115 bar and a 1.8 km radius rupture. Considering the areas where the tremor was felt, the rupture process propagated up to north-east to south-west direction. The majority of the fault plane solutions for the rupture process suggested a normal dip-slip mechanism with a local magnitude (ML) of 2.5. An analysis of the series of the event provided a normal fault mechanism with median solution of strike 180°, dip 45° and rake -90°.” (Sunday Tribune)
