Abstract

The Puerto Rico Strong Motion Program (PRSMP) has 114 strong motion stations and 21 seismically instrumented structures in five (5) countries. This paper explains how the PRSMP has been able to recover from the detrimental effects of Hurricane María to become a more robust, strong motion network in terms of instrumentation with 100% of the data loggers with recent technology, in terms of energy with 48/90 (53%) of the free field stations in the Island with photovoltaic systems, and in terms of communication with 51/90 (57%) transmitting its data real time and developing two data centers. In addition, the southwest Seismic Sequence, with its main event on January 7, 2020, has allowed the increment of strong motion stations and the improvement of its communication in the region that covers from Ponce to Mayagüez.

Abstract

Hurricane María was an extreme atmospheric event that impacted Puerto Rico in 2017. As a result of the passage of hurricane María over the island more than 70,000 landslides were triggered, with the highest density of mass wasting found in the mountainous center of the island. This area is highly susceptible to slope failure given the local soils that form as a result of continuous tropical chemical weathering of the bedrock material. Copious amounts of sediment from these soils were mobilized and transported by the landslide-triggering event. The results of our study reveal the soil types that are most susceptible to mass wasting loss in order to better understand their susceptibility to failure and contribution to sedimentation across the rugged interior of the island. A preliminary analysis of area volume scaling statistics for thousands of landslide sites in the important Lago Dos Bocas basin reveals that Hurricane María likely liberated at least 1.7 million cubic meters of mostly superficial sediment in the lake’s contributing area (not including the Caonillas sub-basin). In an effort to determine the efficiency of the fluvial system to transport these sediments during and after the catastrophic hurricane event, bathymetric surveying was carried out in Lago Dos Bocas, where much of the sediment is hypothesized to have been deposited. This reservoir is a vital piece of infrastructure in the island as it supplies water to the San Juan metropolitan area. Based on the 2021 bathymetric survey and the historical data, the excess sediment deposition to the reservoir related to Hurricane María is estimated at approximately 2.1 million cubic meters. When compared with data from 1999-2010, this volume represents the equivalent of 18 years of background sedimentation. At present, the reservoir capacity loss since construction is at 64%. These analyses are pertinent to understand how the local sediment budget has been affected and to re-calculate the useful life of the reservoir and highlight the vulnerability of Caribbean infrastructure systems, given the forecasted likelihood of increased tropical cyclone activity in the years to come. 

Abstract

This article summarizes the lessons learned from the evaluation of failed concrete utility poles in Puerto Rico as a consequence of Hurricane Maria. Teams were deployed between October 3^rd to 11^th 2017, to cover the west, northwest, south, and east of the island. The evaluation presents sample cases of the failed poles around the island but does not attempt to conduct an inventory. The Puerto Rico building code was being updated based on changes in the International Building Code and the effects of Hurricane Georges. However, many poles made from previous designs are still in service, and many of them failed as a consequence of design deficiencies and improper construction practices. Poles manufactured under the updated codes failed mostly due to foundation issues or structural overload from nearby vegetation impact and the failure of in-line poles, especially wood poles and pre-Georges concrete poles.