Monitoring systems need developing

Editor: The editorial of the News Newspaper of Friday, December 31st, 2004, along with several related articles in that same issue (“Caribbean’s vulnerability to tsunamis low, says expert” and “Need for tsunami early-warning system says Prince”) have prompted me to write to clarify what appears to be some misunderstanding with regards to:

a) the threat of undersea volcanic eruptions in the Grenadines and the work of the Seismic Research Unit and b) the tsunami threat to the Caribbean.{{more}}

The Seismic Research Unit receives numerous reports of volcanic and other related activity every month from several of the Eastern Caribbean islands. In order to make the best use of the resources available a preliminary investigation is usually undertaken using local contacts to determine the appropriate response.

Depending on these preliminary investigations, a decision is taken on the most appropriate course of action. In the case of the warm water in the southern Grenadines our preliminary investigation suggested that it was most likely an area of geothermal activity and that an immediate site visit was unnecessary. Geothermal areas are quite abundant in the Eastern Caribbean and form when water seeps into the ground where it is heated by hot rock. These areas are quite abundant in the Eastern Caribbean and are often (but not always!) associated with volcanoes. Their presence certainly does NOT indicate that a volcanic eruption is imminent and there is no need presently for anyone in St. Vincent and the Grenadines to be unduly concerned about the reported area of warm water in the southern Grenadines.

In terms of possible eruptions from underwater volcanoes, it should be noted that although it is true that such an eruption can result in the generation of a tsunami (NOT a “tidal wave” as mentioned in the News editorial), it is NOT TRUE that all undersea eruptions of volcanoes result in the generation of such a wave.

In fact the ONLY underwater volcano in the region capable of generating any such wave is the Kick ’em Jenny volcano located off the north coast of Grenada. In the case of this volcano, our scientific opinion is that this is unlikely to generate a tsunami in the near future. One of the main reasons for this is that the current configuration and eruptive pattern of the volcano indicate that it will need a few more years of eruptive activity during which the summit must increase in height by at least 90 metres (>300 feet) of what it is currently.

The Seismic Research Unit is the agency responsible for monitoring earthquakes and volcanoes for the English-speaking islands of the Eastern Caribbean. In order to fulfil its basic function the Unit operates a network of seismographs and other geophysical instruments that cover the whole of the eastern Caribbean from Trinidad in the south to Saba in the north. This is the largest such network in the Caribbean region. A cadre of trained scientists and a pool of equipment are maintained at Unit headquarters ready to respond to emergencies in the region as they occur. Earthquake and volcanic monitoring involve continuous collection and analysis of data, development of monitoring techniques and instrument development and maintenance. These activities are the main work of staff members but all staff are also deployed as needed to any of the contributing countries. It is quite incorrect for anyone to suggest that there is insufficient monitoring of any of the volcanoes in the Eastern Caribbean and more so, for the Soufrière volcano of St. Vincent. Our work will always be limited by the resources we have at our disposal; but the existing network provides sufficient data to allow early warning in the event of future volcanic eruptions.

Due to the unfortunate disaster that has occurred in Asia, there have been numerous calls for the establishment of tsunami early warning systems in the Caribbean. While such calls are understandable, one must ensure that the correct perspective is brought to bear on the situation and that the response is appropriate. The fact is that tsunamis in the Caribbean are a hazard but a minor one when compared with other natural hazards that affect the region or to tsunamis in the Pacific. Potentially devastating tsunamis are rare events with a recurrence rate of the order of once or twice per century. There has been no event in the recorded history of the Caribbean in which tsunami-related deaths and destruction of property have amounted to more than a very small fraction of the total deaths and destruction of property that was caused by the generating earthquake. The tsunami hazard in the Caribbean is not negligible and the overall risk may be actually increasing because of increased vulnerability. However there is no need to exaggerate the facts.

There are two components that are essential for any tsunami warning system. The first is a network of instruments that allows us a) to rapidly determine when and where potentially tsunamigenic earthquakes occur and b) to determine whether a tsunami has actually been generated and if so, how big it is. To enable this to happen, we would need an efficient seismograph network and an efficient tide gauge network, both with real time response capability. The second component of the system is an efficient public information and education system that allows you to issue tsunami warnings and ensures that the public knows how to respond to the warnings. The second component is particularly important since it makes little sense to issue a warning unless people know how to respond.

Given the existing seismological organizations that operate in the Caribbean, we already have instruments to cater for the first of the two components needed for an early warning system. What we need to do now is not to establish anything new, but to develop on what already exists.

More importantly we need to educate vulnerable communities in the Caribbean on how to recognize the early symptoms of a tsunami and how to respond. We need to ensure there are clear protocols for the rapid and efficient transmission of information from monitoring scientists to national emergency officials and that the monitoring systems are robust enough to survive the impact of any natural hazard. These are some of the issues we must be discussing and finding solutions for.

We need a balanced and reasoned response that will enable sustainable systems to be established. Knee-jerk reactions and propagation of inaccurate information will not help the situation.

I trust that my comments have provided some balance to the discussion and that the general public in St. Vincent and the Grenadines is now better informed about the natural hazards we face in St. Vincent and the systems in place to monitor them. Further information on geological hazards and the work of the Seismic Research Unit can be found on the Unit’s website at www.uwiseismic.com.

Richard Robertson, PhD

Head of the Seismic Research Unit

The University of the West Indies

Trinidad, W.I.