fault lines and tectonic shifts
Imagine two giant plates, called tectonic plates, floating on Earth's surface. These are constantly moving at a very slow rate measured in centimeters per year. They interact in various ways, rubbing against each other, colliding, or even pulling apart. Jamaica sits precisely where two of these plates, the Gonâve microplate and the Caribbean Plate, meet. Over millions of years, this continuous movement has fractured Jamaica's crust into distinct blocks, much like a puzzle breaking apart.
However, the sideways movement of these blocks isn't the only force at play. When the blocks encounter resistance or obstacles, they can no longer move sideways so they are forcefully pushed upwards. This upward movement is responsible for the formation of mountains and the overall elevation of the island. This is how Jamaica emerged from the ocean, and the process continues to this day, as evidenced by a slow but steady rise of the Blue Mountains.
These fractures in the Earth's crust are called faults, and they are the primary locations for earthquakes. In Jamaica, most seismic activity occurs along these faults, particularly the Plantain Garden and Blue Mountains faults. While there are also faults in central Jamaica, they are not as active.
The video above explains the process and the tectonic impact to Jamaica.
By early 1692, Port Royal was home to 6,500 people and 2,000 buildings. When the estimated magnitude 7.5 earthquake struck, ground shaking and liquefaction caused two-thirds of the town to sink into the sea. Approximately 2,000 people were killed immediately, many entombed in sand that liquefied then solidified. An additional 3,000 deaths followed from injuries and disease. Port Royal was described then as "one of the wickedest places on Earth" and "the most important English city of the New World." For more on the devastation, see Port Royal.
In 1907, a magnitude 6.5 earthquake struck Kingston. Over 80% of buildings in the business and harbor districts were destroyed due to intense shaking and liquefaction. In the harbor, seiches (standing waves) inundated the shoreline, and tsunamis reached 2 meters in height on northern shores. This event caused between 800 and 1,000 fatalities. Since then, Kingston has grown to over 1 million people, highlighting the critical need for earthquake-resistant infrastructure.
