Short History

The Puerto Rico Strong Motion Network started in the 1970' when the Eng. José L. Capacete asked to several agencies to economically contribute to buy several accelerographs. The Electrical Power Authority, the Aqueduct and Wastewater Authority, and the Association of Architects, Engineers and Surveyor provided enough money to buy nine Strong Motion Accelerographs (SMA-1) from Kinemetrics. The United States Geological Survey was contacted to provide the expertise in installing and maintaining the stations. A total of seven free field stations were established and the north building of the Minillas Government Center was instrumented.

In 1987 the Puerto Rico Strong Motion Network passed to the hands of the Civil Engineering Department of the University of Puerto Rico at Mayagüez. Prof. Rafael Jiménez, who was in charge of the network, obtained a grant from National Science Foundation to install additional eight strong motion stations. Prof. Jiménez leave to the university and Prof. Milton R. Martínez-Delgado became in charge of the network. Eight SSA-2, also from Kinemetrics were bought but were not installed until January of 1994. Prof. M. Martínez was responsible for the instrumentation with 15 sensors of the Plaza Inmaculada Building, a 26-story structure with an aspect ratio greater than seven.

During the summer of 1995 Prof. José A. Martínez-Cruzado took over the network. Since then two main grants have been obtained from the Federal Emergency Management Agency; with the first one four main projects were carried out; first of all, all the free field stations with SMA-1 installed during the 70's were substitute for ETNA's, also from Kinemetrics. The instrumentation of the Minillas Government Building was replaced with a six-channel K2; the second project was to install 13 strong motion free field stations in the San Juan Metropolitan Area. The third project was to install a local strong motion network of nine instruments in the city of Mayagüez. Finally, the fourth project was to install six joint stations with the Puerto Rico Seismic Network. These joint stations include an FBA-23 triaxial sensor from Kinemetrics and a Broadband Seismometer from Guralp. The PRSN is actually obtaining the data via telemetry.

The second main grant includes several other projects. Some of them are: the establishment of fourteen additional free field station around the Island, a local strong motion network in the city of Ponce, the instrumentation of the Lucchetti concrete dam in the town of Yauco, and the seismic instrumentation of two bridges. Prof. Daniel Wendichansky is in charge of the instrumentation of the two bridges.

In conclusion, the Puerto Rico Strong Motion Network has grow since 1970's from seven (7) free field strong motion stations and one instrumented building with analog accelerographs to sixty-six (66) strong motion stations and two instrumented buildings with digital accelerographs.