Most powerful earthquakes are called megathrust earthquakes. These happen at subduction zones where one tectonic plate is forced under another. If this happens suddenly, you get a massive earthquake. We understand these subduction zones poorly.
Continue reading “Megathrust earthquake triggers”Climate change axis shift
The Earth’s axis is not static but is always moving. The way water is distributed on Earth’s surface is one factor responsible for the shift.
Continue reading “Climate change axis shift”Mantle generated magnetic field
One of the key tenets of geophysics is that Earth’s liquid outer core has always been the source of the dynamo that generates its magnetic field. Magnetic fields form on Earth and other planets that have liquid, metallic cores, rotate rapidly and maintain conditions that make the convection of heat possible.
Continue reading “Mantle generated magnetic field”Last CO2 level high
The last time CO2 levels were as high as today, in a time called the Pliocene, was some 3 million years ago when sea levels were around 30 feet higher. The Pliocene was a significantly warmer world, likely around 3 degrees warmer than pre-industrial temperatures of the late 1800’s. Much of the Arctic had melted. Heat-trapping carbon dioxide levels hovered around 400 parts per million, or ppm. Today these levels are 418 ppm and relentlessly rising.
Continue reading “Last CO2 level high”Water rich mantle
Oceans on Earth are present as a result of equilibrium between degassing and regassing through the interaction of the Earth’s interior. Because of mantle convection and resultant partial melting and melt transfer, water may circulate deep into the mantle and return through Earth’s surface into the oceans.
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Earth’s collection of interlocking plates is unique in the solar system. Scientists connect it to our planet’s other special features, such as its stable atmosphere, protective magnetic field and the abundance of complex life.
Continue reading “Plate tectonic beginnings”Ice age climate dominos
Throughout the last ice age, the climate changed repeatedly and rapidly where Greenland temperatures rose between 5 and 16 degrees Celsius in decades. The climate system changed like a series of dominos falling in succession. This is the result of a study by a group of researchers from the University of Copenhagen.
Continue reading “Ice age climate dominos”Last deglaciation indicators
The most rapid global sea-level rise event of the last deglaciation, known as Meltwater Pulse 1A (MWP-1A), occurred roughly 14,650 years ago. There is considerable uncertainty regarding the sources of meltwater and the relationship between MWP-1A and the fast-changing climate.
Continue reading “Last deglaciation indicators”Plate tectonic slowdown
In seafloor trenches around the world, slabs of oceanic crust fall slowly into the mantle, while new slabs are formed at mid ocean ridges, where magma emerges at the seams separating tectonic plates. Beginning about 15 million years ago, ocean crust production declined by a third over 10 million years to a slow pace that continues to today.
Continue reading “Plate tectonic slowdown”Recycling of oceanic crust
In plate tectonics, there are three categories of volcanism: ocean ridge, arc and intraplate. While the origins of ocean ridge and arc volcanism are readily explained by plate tectonics, intraplate volcanism (IPV) is not. The dominant hypothesis for the origins of IPV is by mantle plumes from deep within the interior of the earth.
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