#TRANSFORM PLATE BOUNDARY CRACKED#

The lake was created from an extensional step over in the fault, which created a natural depression where water could settle. This line ran through San Andreas Lake, a sag pond. He concluded that the fault must have been the origin of the earthquake. When the location of these offsets were plotted on a map, he noted that they made a near perfect line on top of the fault he previously discovered. He began by surveying and mapping offsets (such as fences or roads that had been sliced in half) along surface ruptures. In the wake of the 1906 San Francisco earthquake, Lawson was tasked with deciphering the origin of the earthquake. The fault was first identified in 1895 by Professor Andrew Lawson of UC Berkeley. Sediment deposited by the Colorado River is preventing the trough from being filled in with sea water from the gulf. In this region (known as the Salton Trough), the plate boundary has been rifting and pulling apart, creating a new mid-ocean ridge that is an extension of the Gulf of California. Here, the plate motion is being reorganized from right-lateral to divergent. In the south, the fault terminates near Bombay Beach, California in the Salton Sea. It has been hypothesized that a major earthquake along the subduction zone could rupture the San Andreas Fault and vice versa. In the north, the fault terminates offshore near Eureka, California at the Mendocino Triple Junction, where three tectonic plates meet. The average slip rate along the entire fault ranges from 20 to 35 mm (0.79 to 1.38 in) per year. Traditionally, for scientific purposes, the fault has been classified into three main segments (northern, central, and southern), each with different characteristics and a different degree of earthquake risk. It forms the tectonic boundary between the Pacific Plate and the North American Plate.

The San Andreas Fault is a continental right-lateral strike-slip transform fault that extends roughly 1,200 kilometers (750 mi) through the Californias. The plates of the Earth's crust are constantly moving at about the same speed as your fingernails grow, so the map of the world will continue to change, but just very, very, very slowly.Plaque showing location of San Andreas Fault in San Mateo County These are known as Transform Faults.Īs the plates scrape past each other, pressure builds up and is released suddenly, causing an earthquake. Plates can also move past each other, like at the San Andreas Fault in the USA, which forms the tectonic boundary between the Pacific Plate and the North American Plate. The Mid-Atlantic Ridge on the floor of the Atlantic Ocean, where the Eurasian and North American Plates are moving apart, is the perfect example of this. These are usually found under oceans.Īs the plate moves apart, magma rises to the surface and cools, forming shallow-sided volcanoes.

This is called a constructive or divergent plate boundary. Where the movements of the currents in the mantle separate, like this, plates move apart. As the Nazca Plate collides with the South American Plate, it's forced underneath it creating the ever-changing Andes Mountains. South America has a great example of a convergent plate boundary. Tall, steep volcanoes can also form as a result of the denser rock melting and the magma being forced up to the surface. The force of this collision is so great that mountains are created.Įarthquakes are very common at this type of boundary as the mountains are pushed upwards by the force of the plates' movement. When the plates collide, the denser plate, usually the oceanic one, is forced underneath the continental plate. This is called a destructive or convergent plate boundary. Where the movement of currents and the mantle converge, like this, plates are pushed together. These plates can be oceanic, meaning they're found mainly under the ocean, or continental, and mainly found under land.Īnd they are moved around, constantly fuelled by energy from the very hot mantle below.

#TRANSFORM PLATE BOUNDARY CRACKED#

If Earth was the size of an egg, the Earth's crust would be as thin as the eggshell.Īnd like an eggshell, the crust has cracked and split into many different pieces called tectonic plates. The mantle is made up of magma, or molten rock.Īnd the crust is this layer of solid rock that we live on. The outer core is also made of iron and nickel but in liquid form. The solid inner core is made of iron and nickel and is as hot as the surface of the sun. Earth is divided into four layers: the inner core, the outer core, the mantle and the crust.

Transform plate boundary