Chapter 1
Presentation of the case study
Chapter 2
Area under study and organization of water sanitation systems
Chapter 3
Description of the local water and sanitation system
Chapter 4
Seismic hazard
Chapter 5
Vulnerability matrixes
Chapter 6
The 22 April 1991 earthquake in the La Estrella Valley, Limón
Chapter 7
Proposed method for the vulnerability of system mains and pipes to seimic hazards
Chapter 8
Mitigation and emergency plan
Chapter 9

Case Study: The 22 April 1991 Earthquake in Limón, Costa Rica (PAHO, 1996)

On 22 April 1991, a 7.4 magnitude earthquake hit Costa Rica's Atlantic region and caused severe damage to Limón City's sanitation infrastructure. The earthquake cut off the supply of water from the Banano River basin, which provided the Costa Rican Aqueducts and Sewerage Institute (AyA) with 71% of the drinking water used by Limón residents, companies and institutions. This disaster forced AyA to carry out a series of emergency measures over several months to satisfy the demand for water and temporarily rehabilitate the affected systems before eventually replacing part of the infrastructure after securing external funding.

The objectives of the case study were to analyze the characteristics of the event, the water and sanitation system infrastructure in place, and the area's capacity to apply the disaster mitigation guidelines developed by PAHO/WHO for such systems. The initial vulnerability assessment and determination of the mitigation measures required was made based on the information available before the earthquake. In this way, the vulnerability assessment was later compared to the actual situation on the ground in order to evaluate the accuracy of the methodology employed.

The analysis was based on the guidelines produced by PAHO/WHO's Pan American Center for Sanitary Engineering and Environmental Sciences (PAHO/CEPIS) and included in the publication Natural Disaster Mitigation in Drinking Water and Sewerage Systems - Guidelines for Vulnerability Analysis (PAHO, 1998), which is available in English.