Earthquake-All that you must know

Daily Graphic (Special Feature), Sat. January 23, 2010

Article by Rebecca Quaicoe-Duho
"Today's night 12:30 to 3:30 am, COSMIC RAYS entering Earth from Mars. Switch off your mobiles today's night. NASA BBC news, plz pass to all your friends." A harmless text message, perhaps unintended but interpreted wrongly.
Many Ghanaians on the dawn of Monday, January 18, 2010 sat on tenterhooks as they awaited for an earthquake to rock their homes. Their fears confirmed a Biblical saying that “for lack of knowledge my people perish”.
According to geological experts, not even countries in the advanced world with their sophisticated machines are able to determine exactly when an earthquake will occur in a particular place. Earthquakes, they say, are unpredictable. However a text message from a mobile phone and an unknown source was able to keep almost the whole country awake till morning when the rumours were dispelled by the experts. It may be that the recent Haiti disaster and other historical records and repeated tremors experienced in Accra and its environs heightened the fear of the occurrence of a damaging earthquake in the country.
Earthquakes in Ghana
A study in 1986 on the history of earthquakes in West Africa showed that Accra was the most seismically active area in the region.
According to Dr Paulina Ekua Amponsah, Geological Survey Department (GSD), a recent review of geological and instrumental recordings in 2002 shows that earthquakes have occurred in the past and are still likely to occur within the vicinity of the intersection of the Akwapim Fault Zone and the Coastal Boundary Fault.
There have been damaging earthquakes in 1615, 1636, 1862, 1906 and 1939. The 1615 earthquake destroyed what was then known as Takoradi and the fortress of Sao Jorge at Elmina.
In 1636, an earthquake occurred in Axim in the Western Region and the whole of East Nzema was badly shaken. It caused a widespread collapse of buildings in that area. A gold mine in Aboasi, northeast of Axim was reported to have collapsed, burying many of the miners.
In 1862 a very strong earthquake struck Accra and caused considerable damage to many important structures. The Osu Castle, some forts and all stone buildings were rendered uninhabitable. Three people were killed in that earthquake. The shock accompanying the earthquake was felt along the coast east of Togo and in Benin.
Two severe shock waves were felt in Eastern Ghana and Togo at about 9:00 p.m. and 9:20 p.m. on November 20, 1906. It was estimated at 6.2 on the Ritcher Scale. Many buildings were greatly affected by this event; some had cracks and others were partly destroyed. No casualties were reported for this event. It was also experienced by people in Togo and Benin and during the same month several minor shocks lasting three weeks were felt.
On February 11, 1907 a fairly strong tremor was felt in Accra and Lome. An earthquake located in the sea and accompanied by tidal waves destroyed the wharf at Lome in Togo on May 11, 1911. The same day at 3:21 p.m., an earthquake was felt in Accra but it did not cause any damage.
The most destructive earthquake in Ghana that caused a lot of damage and loss of life and property occurred on June 22, 1939. That earthquake, with a magnitude of 6.5, occurred at about 7:20 p.m. and was lasted between 20 and 30 seconds. The intensity of the shock was greatest in James Town, a suburb of Accra. Seventeen people were killed, 133 injured and property worth £1 million in those days was destroyed.
Presently, no law exists in the country that makes geological survey a requirement before one puts up structures, thereby making the housing sector vulnerable in the event of a high-magnitude earthquake.
Microseismic studies in the country indicate that the seismic activity is associated with active faulting, particularly near the intersection of the two major fault zones; the Coastal Boundary Fault and Akwapim Fault Zone. Most of the earthquakes are said to have had their epicentres near the junction of these faults. The epicentres are related to the level of activity of these faults. It is, therefore, not recommended that any infrastructure be located near them.
Earthquake prone zones
Weija, Accra, Ho, Axim, Elmina and Cape Coast have been mentioned as some of the earthquake-prone areas and it is estimated that any location within a 50-kilometre radius of these areas are earthquake-prone.
Weija and McCarthy Hill in the Greater Accra Region, Gomoa Nyanyano near Kasoa in the Central Region, Ho in the Volta Region and Akosombo in the Eastern Region have been declared Ghana’s earthquake epicentres.
Also low-lying areas, reclaimed lands and hills are said to be at risk and the southern part of the country, according to a geologist with the National Disaster Management Organisation (NADMO), Mr Philip Yaw Oduro Amoako, should always prepare against an imminent earthquake which could happen any time, but nobody can tell the exact day and time one can happen.
Earthquake and earth tremors
Although many people know about these two, most of them do not know the difference. Experts say if the measurement is between one and 4.9 on the Richter Scale, it is known as a tremor and from five to 10 is an earthquake.
The country experienced earth tremors in 1997 and 2003 with the most recent being in 2005.
The 1997 tremors were felt in all the regional capitals and it occurred on January 8, February 14 and March 6, 1997.
Historical earthquakes of magnitude greater than 6.0 and current local tremors with magnitudes ranging from 1.0 to 4.8 on the Richter Scale have been recorded since the establishment of a seismograph station in the country.
Instrumental recording of earthquakes in Ghana began in 1914 when the colonial government installed a Milne’s single-boom seismograph in the country. It operated until 1933 when it ceased recording due to financial constraints. Several minor shocks were said to have been recorded during the period when the seismograph was in operation.
In March 1973, a seismograph observatory equipped with a world-wide Standard Seismograph Network (WWSSN) system was established at Kukurantumi in the Eastern Region. It operated continuously until October 1974 and then intermittently until continuous recording began again in 1977. At present, a nine-station radio telemetric network analogue recording system with a central recording station at the GSD in Accra is said to have broken down.
How prepared are we as a country?
The analogue seismograph, an instrument used in measuring the movement of the earth, which is the only one the country has, broke down two years ago but through the intervention of the Minister of Lands and Natural Resources, Alhaji Collins Dauda, the Ministry of Finance and Economic Planning on December 29, 2009 was asked to release an $3million which had been approved by the government for the purchase of a digital seismograph.
However, logistical constraints has over the years made it impossible for the GSD to identify earthquake-prone areas in the northern part of the country. Residents will, therefore, not know their fate.
The Director of GSD, Mr John Agyei Duodu, has stressed the need for the country to step up its preparedness in respect of the occurrence of an earthquake because earthquakes are unpredictable, hence the need to prepare by sensitisation and mass education on what to do before, during and after an earthquake.
He called for a step-up in the education on the measures needed to be taken in the event of an earthquake and the formation of voluntary groups to handle emergencies, among other things.
“People should know what to do before, during and after an earthquake”, he said.
Also according to experts, buildings that have unsupported arches are likely to collapse in the event of an earthquake but the current building regulations in Ghana do not take cognisance of seismic disasters.
Registration of SIM cards
A directive from the National Communications Authority indicated that from June 30, 2010 all new mobile SIM cards will have to be registered in the name of the user before they can be activated for use on any network. Existing subscribers will have a period of 18 months from the said date to submit to the new directive.
Although the directive is aimed at enhancing security and eliminating fraud and crime, it has not gone down well with many Ghanaians because of the involvement of the National Security.
The Monday, January 20, 2010 earthquake hoax originated from a mobile phone and the information was circulated across the country but till date no one knows where the message came from as the United States National Aeronautics and Space Administration (NASA) and British Broadcasting Corporation (BBC) who were mentioned as the source have denied any knowledge of it.
Recently, a group of about 200 scientists and research officers of the International Network for the Demographic Evaluation of Populations and their Health in Developing Countries (INDEPTH) from across the world who went to Puni, India for their 10th annual general and scientific meeting were given only two registered SIM cards from India’s Ministry of Communication as the source of communication for the whole group.
Unlike how one can easily buy a SIM card on the street in this country, it is not easy to acquire a SIM card in India where you will have to write a letter of intent to the Ministry of Communications for them to consider the application before you are given one to use.
In other places one will have to produce an identity card such as passport before a SIM card is sold to one.
According to a Deputy Information Minister, Mr Sam Okudzeto Ablakwa, the rumours of the impending earthquake reinforced the need for mobile phone operators to register SIM cards because if operators had records of all their customers, it would have been easy to trace the origin of the hoax earthquake message.