Easter Microplate facts for kids
Quick facts for kids Easter Microplate |
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Easter microplate (from GeoMapApp) with rough plate boundaries.
Four spreading sections make up the eastern border. The west section comes from the north side down in a southwest manner, until it breaks off and becomes the southwest section. Triple junctions on north and south ends are not well defined. |
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| Type | Micro |
| Coordinates | 25°00′S 114°00′W / 25.000°S 114.000°W |
| Approximate area | 160000 |
| Movement1 | East |
| Speed1 | 50 to 140 millimetres (2.0 to 5.5 in)/yr |
| Features | Bordering: Pacific Plate (west) Nazca Plate (east) |
| 1Relative to the African Plate | |
The Easter Plate is a small piece of the Earth's outer shell, called a microplate. It's located in the middle of the Pacific Ocean, west of Easter Island and off the coast of South America. This microplate sits between two much larger plates: the Nazca Plate to its east and the Pacific Plate to its west. Scientists discovered it by studying where earthquakes happen, which showed a different boundary than they first thought. The Easter Plate is quite young, only about 5.25 million years old, and it's known for having some of the fastest Seafloor spreading rates in the world, moving between 50 to 140 millimeters (2 to 5.5 inches) per year.
Contents
How the Easter Plate is Shaped
Scientists have studied the Easter Plate since the 1970s. They used special surveys to map its shape and how it moves. These studies showed that the Easter Plate is unusually shallow. It is surrounded by areas where new seafloor is created (called spreading centers) and areas where plates slide past each other (called transform boundaries). At its northern and southern tips, there are "triple junctions," which are points where three plate boundaries meet.
Eastern Border
Along the eastern side of the Easter Plate, there are several spreading centers. These are places where the Earth's crust is pulling apart, and new material rises up to form new seafloor. Some parts of this eastern border are like deep valleys, reaching depths of about 6,000 meters (20,000 feet). This spreading is happening very quickly, with the rifts (cracks) growing northward at about 150 millimeters (6 inches) per year.
Northern Border
The northern edge of the Easter Plate has wide ridges that are taller than 1 kilometer (0.6 miles). These ridges are connected to steeper slopes to the south. The very eastern part of this border has plates sliding past each other. The western end of the northern border is a triple junction where the Pacific, Nazca, and Easter plates meet. This area has unusual earthquakes, which might mean there's another spreading area nearby. A deep valley, about 3,700 meters (12,100 feet) deep, runs along this northern boundary. It connects to an even deeper hole, about 5,300 meters (17,400 feet) deep, called the "Pito Deep."
Western Border
The western side of the Easter Plate is split into two main parts. The western section has two spreading areas that run from north to south. Here, the seafloor is spreading quickly, between 120 to 140 millimeters (4.7 to 5.5 inches) per year. These spreading areas are linked by faults where the plates slide past each other. The southwest part of the plate has a slower spreading center, moving at 50 to 90 millimeters (2 to 3.5 inches) per year. This section runs northwest to southeast and connects to the southern transform boundary.
Southern Border
Like the northern border, the southern end of the Easter Plate also has a triple junction, but scientists are still gathering data to confirm it. A single fault line runs from west to east along this border. This area is very rugged and shallow, and it experiences a lot of earthquake activity.
How the Easter Plate Formed
In 1995, scientists used different types of data, including magnetic and gravity surveys, to understand how the Easter microplate formed. They came up with a two-stage model for its development.
Stage 1: 5.25 to 2.25 Million Years Ago
About 5.25 million years ago, the boundary between the Pacific and Nazca plates was not fully connected. The Easter microplate started to grow longer from north to south during this time. The eastern spreading rift began to extend northward until it reached about 2.25 million years ago. At the same time, the western rift was growing southward, breaking into segments connected by faults. Throughout its history, the entire Easter microplate has been slowly rotating counter-clockwise, about 15 degrees every million years.
Stage 2: 2.25 Million Years Ago to Today
During this period, the Easter microplate grew more in its east-west direction. It stopped growing longer from north to south because the eastern rift stopped extending northward. The eastern rift continued to spread, but it didn't move further north. The western rift kept changing, and then the southwest rift began to open up and spread eastward. This spreading continued until the southern triple junction we see today was created.
What Might Happen Next
Scientists have one main idea about what will happen to the Easter microplate in the future. They believe that because the spreading rates are slowing down at the southwest rift and the northern end of the east rift, these spreading activities will eventually stop. If this happens, the entire microplate might transfer from being part of the Nazca Plate to becoming part of the Pacific Plate. This has happened in other areas where similar plate movements have been studied.
Why the Easter Plate Moves
Forces That Push It
The pulling apart of the Nazca and Pacific plates creates a force that makes the Easter microplate rotate. Scientists believe two main types of forces are at work: shear and tension. Shear forces happen along the north and south edges, which explains why there are compressions (squeezing) at the northern end of the plate. Tension forces happen at the east and west spreading rifts, where the plate is being pulled apart.
Because the spreading rates are so fast along these boundaries, the Easter microplate has a thin lithosphere (the Earth's rigid outer layer). The pulling forces across the east and west rifts are strong enough to make the microplate rotate. As the spreading rates slow down towards the north, the lithosphere is thought to get thicker there. In those areas, shear forces also play a role in driving the plate's movement.
Forces That Resist It
About 20% of the forces acting on the Easter microplate come from something called "mantle basal drag." This is the resistance that the soft, flowing asthenosphere (the layer below the lithosphere) applies to the rigid lithosphere floating on top of it.
The other 80% of the resisting forces come from the Easter microplate's own rotation. As the microplate turns, it meets resistance at its north and south ends, especially where there are no rifts to help the plate adjust. Both pulling and squeezing forces contribute to this resistance. However, the squeezing forces along the ends of the rifts have a bigger impact. These squeezing forces are what create the elevated (raised) regions around the "Pito Deep."
See also
In Spanish: Placa de Pascua para niños
