Aon Benfield Research partner, Dr Kristy Tiampo, Aon Benfield/ICLR Chair in Earthquake Hazard Assessment at the University of Western Ontario said:
“The recent example from Haiti illustrates the vulnerability that still exists in many parts of the world to large, but not extreme, magnitude earthquakes. The resulting catastrophe was preventable with better preparation and building codes. The challenge now is to transfer what we have learned from this and other events to regions with similar hazards and poor levels of preparation.”
Dr Simon Day of the Aon Benfield Hazard Research Centre comments:
– The 2010 earthquake may be only the first of several earthquakes to afflict southern Haiti in the 21st century
– The earthquake relieved little of the strike-slip stress that has been stored up so the near-term seismic hazard remains high in Port-au-Prince
– Similar characteristics to other earthquakes in mainly strike-slip fault zones such as California, Iran and China
“The main fault zones in Haiti are the Septentrional fault along the north coast and the complex Enriquillo-Plantain Gardens Fault Zone (EPGFZ) that runs south of Port-au-Prince and to the west along the Tiburon peninsula, continuing under the sea to Jamaica. The EPGFZ has long been considered responsible for most of the historic earthquakes in southern Haiti, including a series of destructive earthquakes in the mid-18th century that were the last earthquakes to cause major damage to Port-au-Prince prior to 2010.
The initial assumption about the 12 January 2010 earthquake was that it was caused by strike-slip fault rupture on a segment of the EPGFZ to the south-west of the city, and indeed it seems that the earthquake began in this way. However, detailed analysis of global earthquake records point to a different interpretation of the earthquake. It was a complex, overlapping sequence of ruptures on buried or “blind” thrust faults to either side of the EPGFZ itself.
The earthquake therefore resulted more from the slow convergence of the Caribbean and North American plates, and the uplift of Hispaniola, than from the dominant strike-slip plate motion. It bears comparison with other earthquakes in mainly strike-slip fault zones that involved at least a component of movement on buried thrust faults, such as the 1989 Loma Prieta (California), 2003 Bam (Iran) and 2008 Wenchuan (China) earthquakes.
An important practical result from the scientific work that led to these conclusions is that the 2010 earthquake relieved little of the strike-slip stress that has been stored up on the EPGFZ since the earthquakes of the mid-18th Century. The near-term seismic hazard to Port-au-Prince and other parts of southern Haiti therefore remains high. This point is underlined by the numerous damaging earthquakes in this part of the country and in the neighbouring Dominican Republic during the 17th and 18th centuries, in contrast to the lower levels of earthquake activity in southern Hispaniola during the 19th and 20th centuries.
Indeed, the sequences of earthquakes that occurred in the early historic period in Hispaniola and comparisons with some other complex strike-slip fault zones suggest that the 2010 earthquake may be only the first of several earthquakes to afflict southern Haiti in the 21st century. Much more geological and geophysical research needs to be done, however, to determine whether this scenario will actually develop.”
Source : AON Benfield Press Release
