Engineers examining the impact of recent hurricanes on the strong motion and seismic network here in the Virgin Islands. Photo: GIS

The storm surge that accompanied Hurricane Irma impacted several of the free field stations in coastal locations and caused erosion to internal components of many of the Strong Motion and Seismic Network's equipment. Photo: VINO/File

It was on September 2, 2005 that a Memorandum of Understanding (MOU) was signed between the University of Puerto Rico and the Government of the VI that saw the installation of “strong motion free field stations in the populated areas of Road Town and Spanish Town, seismic stations on Anegada and North Sound, Virgin Gorda, as well as seismically instrumenting the Government Administration Building and the Terrence B. Lettsome International Airport Control Tower,” a Government Information Services (GIS) Press Release dated October 28, 2015 said.

The last time the team was here was in October 2015 to carry out maintenance work at the sites.

While here the team visited sites on the four main islands of the territory as well as worked with the Department of Disaster Management to establish a plan for the restoration of the damaged equipment in the coming months, a GIS press release of February 8, 2018 said.

Damage Done

According to Professor Martinez-Cruzado, “Our frequent visits to the BVI over the years have allowed us to build a network of strong motion and seismic stations on several of the islands. This has provided a good reference point and has allowed us to appreciate the magnitude of the damage on the ground.”

He explained that, “The storm surge has impacted several of the free field stations in coastal locations and caused erosion to internal components of many of the equipment, especially those in the Central Administration Building. In some areas in this building we saw evidence of as much as 38’’[inches] of salt water.”

Retrieving data has not been without his challenges; however, the professor pointed out that, “The progress of electrical restoration has allowed us to verify that a couple of seismic stations recorded the vibration caused by high velocity winds on the structures and from debris hitting the seismic stations. However, there was significant damage caused by the incredibly strong winds to solar panels, antennas and other external components which now have to be replaced.”

Restoration costs

The press release explained that “The cost for the restoration will be financially supported by the Government of the BVI in the amount of $122,000 to establish the most critical units. The installation costs will be handled by the team which will comprise Professor Martinez-Cruzado, Jaffet Martinez and Erick Santana.”

The Puerto Rico Strong Motion Network started in the 1970s and Professor José Martínez-Cruzado took over the network in 1995. Since then several grants were received from the Federal Emergency Management Agency (FEMA) to develop and maintain a robust network throughout Puerto Rico, the US and [British] Virgin Islands.

The Puerto Rico Strong Motion Network has grown since the 1970's from seven free field strong motion stations and one instrumented building to over 60 strong motion stations and instrumented buildings with digital accelerographs.