Earquakes and Tremors in Nicaragua

EXECUTIVE SUMMARY

Managua, the capital city of Nicaragua, is the country's political, commercial, and industrial center. However, the city is prone to frequent earthquakes and tremors due its very close proximity to the convergent plate boundary occurring only a few kilometres off the coast of Nicaragua: the Cocos plate slowly being subducted under the Caribbean plate (“Historic Earthquake”, 1972). This movement caused significant destruction to Managua in 1931, 1968 and 1972 when earthquakes of magnitudes 5.6, 4.5 and 6.2 on the Richter scale, respectively, rocked the capital city (“Historic Earthquake”, 1972).

One of most destructive earthquakes recorded above the equator in the western hemisphere was the earthquake of December 23, 1972 which struck Managua. The economic losses associated with this earthquake were very significant as 80% of the buildings in Managua were severely damaged and a shocking 10,000 deaths were declared (“Earthquake wreaks devastation in Nicaragua”, 1973). This loss was primarily attributed to several factors: strong seismic shaking due to the shallow focus of the earthquake, permanent ground displacement due to surface faulting, type of materials used to construct buildings, and other secondary factors.

Even though earthquakes and tremors occur frequently in Managua, the city was unprepared for the earthquake of 1972. No risk assessments had ever been performed for earthquake related damages even though it was known that earthquakes were frequent in Managua. In addition to this, the city did not have any warning systems in place or any practices in place to reduce the severity of the damage caused.

BACKGROUND

Managua, the capital city of Nicaragua, is located along the southern coast of Nicaragua at approximately 12°8′11″N 86°15′5″W as shown in Figure 2 (“Latitude and Longitude” 2014).

Tectonically, Managua sits on the southern boundary of the Caribbean plate, close to the boundary with the Cocos plate (“Historic Earthquake”, 1972). The convergent plate boundary movement of the Cocos plate in a north-eastwardly direction is slowly being subducted under the Caribbean plate at a rate of approximately 3 inches per year (Gunn, 2008). In addition, the Cocos and Caribbean plates are two of several plates forming the Ring of Fire: an area in the Pacific Ocean responsible for ninety percent of the total seismic and volcanic activity recorded each year (“Ring of Fire” 2012). The close proximity of Managua to the Cocos-Caribbean subduction zone along the Ring of Fire is known to be the cause of the frequent volcanic and seismic activity experienced by Managua.