determine why blasts at the Wilkinson Quarry in Hamilton Parish have been causing damage to homes and businesses in the area.

The quarry is owned by Wilkinson Estates Limited and operated by Island Quarry Limited, a subsidiary of Island Construction Limited.

Dr. Calder was contacted earlier in the month while he was lecturing in Chile, South America, and asked if he could come and ascertain why the blasts were rocking nearby structures.

He told The Royal Gazette : "We looked at the current blast designs for the past few months and made suggestions as to how to redesign the blasts by changing the timing sequences.'' He set off a blast using the modified system with no adverse effects. David Summers, president of Bermuda-Caribbean Engineering Consultants Limited and a consultant for Wilkinson Estates Limited, called it "a perfect blast''.

They have also changed the setting of the seismograph, which measures ground and air vibrations, as it was not sensitive enough to record.

It now has a more sensitive triggering level which should record every blast.

Dr. Calder said a reading above 0.5 inches per second (ground vibration) was on the threshold of being able to cause damage to surrounding properties.

He said the legal limit used to be two inches per second in the US, but it is now 0.5 inches per second, an internationally accepted threshold value.

Bermuda has no legislation in place determining the maximum level of vibration in relation to blasting.

The blast set off by Dr. Calder yesterday was recorded by a seismograph near the Swizzle Inn at 0.125 inches per second.

When the blast took place, Dr. Calder was sitting in the Swizzle Inn with a Police officer from the explosives division who is in charge of issuing blasting permits, and Zane DeSilva, president of Island Quarry.

They spoke with pub manager Jay Correia, who said he had not noticed the blasts.

Dr. Calder will return to the Island in January when he will carry out further tests in other areas of the quarry at higher elevations closer to the Swizzle Inn.

He last visited the Island in 1996 when he made many recommendations for safe blasting in the quarry such as using blast mats made from recycled rubber tires, weighing over five tons each.

The blast mats prevent loose rock being hurtled into the air.

When asked how long the quarry could continue operating, Mr. Summer said: "At the current demands of the construction industry, we are hoping we have at least ten years and hopefully more in terms of reserves.

"This quarry is Bermuda's sole source of hard rock aggregate and consequently is a very important natural resource.'' continued Mr. Summers.

He said the rock in the quarry is the hardest in Bermuda as the calcification is so advanced that it is virtually impossible to detect the original layers of sand.

The rock is used predominantly for concrete, some for asphalt and more recently for concrete block as medium stone quarries have been worked out.

Mr. Summers added that asphalt is now almost exclusively made from imported aggregate and ironically this is a benefit to the quarry as it ensures the resources will last longer.

He said: "When this quarry is exhausted, there will be no option but to import all of our hard rock, and in Bermuda's diminutive scale, this will have a significant impact on our balance of payments in that Bermuda will be economically supporting a work force in another country, while those who become redundant will have to find other forms of employment.'' Mr. Summers said that in 1990, the Department of Planning advised him that 120 people were employed in Bermuda's quarrying industry.

He did not know how many were presently employed but estimated that at least 60 households derive their income directly from the industry, and a substantial number more in related industries such as block manufacture, trucking and so on.

Mr. Summers said Wilkinson Estates Limited would be opening and operating a new cave in the neighbouring area in the New Year so the company would have a vested interest in making sure the workings of the quarry were carried out with no risk of damage to other properties.

He said: "We don't want to have any damage, hence the reason we bring in the best expertise we can find.'' "We will be instituting an ongoing programme of retaining Dr. Calder subject to the Department of Immigration who have been very co-operative in recognising that Dr. Calder's scientific expertise is not a commodity readily available in Bermuda.'' Dr. Peter Calder