I am writing to comment on a series of articles that have recently been published in the Guardian newspapers relating to the proposed construction of a children's hospital in Couva.As I understand it, queries have been raised and cautions have been issued by Dr Joan Latchman, head of the Seismic Research Centre and by chairman of the National Building Code Committee, Mr Shyankaran Lalla.
The warnings relate to the location of the proposed hospital within ten kilometres of the Central Range Fault Zone along which approximately 65 per cent of the (relative eastward) movement of the Caribbean plate is taking place. Dr Latchman is reported to have warned that earthquakes of a magnitude of 7.5 or higher on the Richter Scale can be expected.
Let me give a brief note of explanation. The Caribbean Plate is moving eastwards relative to the South American plate in the south and the North American Plate in the north. The fault lines along which the movements take place are well known to geoscientists including seismologists.
The Sunday Guardian of August 12, 2013, has reported that the Minister of Housing has expressed confidence in the chosen "design-finance-construct" contractor Shanghai Construction Group and that he has indicated that the hospital will not be re-located. He is quoted as saying, "We are convinced that the technical work has been done by the construction company and Udecott. We do not see a problem there."
He also, according to the Guardian, stated that many other countries erect buildings along or near to faults and fault zones and that one should just factor that into the engineering design.Following are the comments I wish to make:
There is absolutely no doubt that Dr Latchman's statements about the fault zone are correct. There is overwhelming geologic evidence to support this. In fact two years ago, the Geological Society of Trinidad and Tobago, of which I was then president-elect, ran a seminar on geo-hazards which both the ODPM and the Seismic Research Centre attended and participated in. During this seminar, this particular fault zone and its potential hazards were discussed at length.
Also in attendance was Dr John Weber, the geo-scientist who has over the past ten years documented exhaustively the movement of the plates and recognised that the Central Range Fault has most likely been locked for at least 500 years.For the record, the longer a fault is locked, the larger is the potential earthquake that will result. The 2010 quake in Haiti, which sits on a mirror image of our fault, measured 7.0 on the Richter scale. There were at least 52 aftershocks measuring 4.5 or greater recorded.
An estimated three million people were affected by the quake. Death toll estimates were around 220,000. The government of Haiti estimated that 250,000 residences and 30,000 commercial buildings had collapsed or were severely damaged. Many notable landmark buildings were significantly damaged or destroyed, including the Presidential Palace, the National Assembly building, the Port-au-Prince Cathedral, and the main jail.
By way of comparison, the San Andreas Fault System in California is another strike-slip system where two plates are sliding past one another. The San Francisco earthquake of 1906, which was extremely destructive is estimated to have had a magnitude as high as 8.3.
While I agree with the minister that many other countries erect buildings along or near to faults and fault zones and that you can factor that into your engineering design, my concern is the design parameter relating to the strength of the earthquake the hospital was designed to withstand.
I, therefore, urge the relevant authorities and agencies to re-examine the design parameters that were used relating to maximum earthquake size expected, and if less than 7.5, it is imperative that the design be redone to ensure that the hospital meet the appropriate standards.These comments are made in what I believe to be in the best interest of the country and there are no political motivations.
Krishna Persad, PhD
La Romaine