The New Madrid fault system was responsible for the 1811–1812 New Madrid earthquakes and has the potential to produce large earthquakes in the future. Since 1812, frequent smaller earthquakes have been recorded in the area.
Earthquakes that occur in the New Madrid seismic zone potentially threaten parts of seven American states: Illinois, Missouri, Arkansas, Kentucky, Tennessee, and to a lesser extent Mississippi and Indiana.
The 150-mile (240 km)-long seismic zone, which extends into five states, stretches southward from Cairo, Illinois; through Hayti, Caruthersville, and New Madrid in Missouri; through Blytheville into Marked Tree in Arkansas. It also covers a part of West Tennessee near Reelfoot Lake, extending southeast into Dyersburg. It is southwest of the Wabash Valley seismic zone.
The zone had four of the largest earthquakes in recorded North American history, with moment magnitudes estimated to be as large as 7 or greater, all occurring within a 3-month period between December 1811 and February 1812. Many of the published accounts describe the cumulative effects of all the earthquakes, known as the New Madrid Sequence, so finding the individual effects of each quake can be difficult. Magnitude estimates and epicenters are based on interpretations of historical accounts and may vary.
In a report filed in November 2008, the U.S. Federal Emergency Management Agency warns that a serious earthquake in the NMSZ could result in "the highest economic losses due to a natural disaster in the United States," further predicting "widespread and catastrophic" damage across Alabama, Arkansas, Illinois, Indiana, Kansas, Kentucky, Mississippi, Missouri, Oklahoma, Texas, and particularly Tennessee, where a 7.7 magnitude quake would cause damage to tens of thousands of structures affecting water distribution, transportation systems, and other vital infrastructure.[24] The earthquake is expected to result in many thousands of fatalities, with more than 4,000 of the fatalities expected in Memphis alone.
Roughly every 11 years, at the height of the solar cycle, the Sun’s magnetic poles flip — on Earth, that’d be like the North and South Poles swapping places every decade — and the Sun transitions from sluggish to active and stormy. During this period, known as solar maximum, the Sun blazes with bright flares and other solar eruptions. In this video, our solar telescopes show how the Sun transitions from minimum to maximum during the solar cycle.
The Sun is made up of plasma, or electrically charged gas. The electrically charged gas can affect magnetic field lines, causing the lines to twist, turn, and tangle up as the plasma moves. These magnetic snarls prevent heat from flowing to the surface, creating darker, cooler regions — the sunspots. They are often around 6,000 degrees Fahrenheit while the rest of the photosphere is around 10,000 degrees Fahrenheit.
Active regions are areas on the Sun where strong magnetic field lines extend into the solar atmosphere. Because of this, scientists often find sunspots in the same area as active regions. Solar eruptions, like solar flares and coronal mass ejections, typically burst from these active regions. Scientists study the regions where activity occurs because those storms can impact spacecraft, astronauts, and infrastructure on Eart
The total number of sunspots on the Sun varies throughout the solar cycle. As the Sun moves through its natural cycle, in which its activity rises and falls roughly every 11 years, sunspots rise and fall in number, too. NASA and NOAA track sunspots to determine, and predict, the progress of the solar cycle — and ultimately, solar activity. Solar minimum is characterized by a low number of sunspots, while solar maximum is marked by many sunspots. Solar Cycle 25, the 25th solar cycle since scientists started tracking them, began in 2019.
Unlike the stable geographic north pole, the magnetic north pole has been known to wander since its first measurement in 1831, slowly drifting from the Canadian Arctic towards Siberia. However, starting in the 1990s, this drift has accelerated significantly, increasing from a historical pace of 0-15 km per year to an astonishing speed of 50-60 km per year.
Satellite data (including those from ESA's Swarm mission) show the north magnetic pole moving rapidly towards Siberia due to two magnetic blobs at Earth's outer core edge. Fluctuations in molten material flow cause changes in magnetic strength, leading to its ongoing drift for decades.
Like its northern counterpart, the south magnetic pole also experiences constant shifts due to changes in Earth's magnetic field. It moves north-westward at a rate of approximately 10 to 15 kilometres per year and is currently about 2,860 kilometres away from the actual Geographic South Pole. Unlike the north magnetic pole, the south magnetic pole's movement did not experience a significant increase in speed during the mid-1990s.
Over the past two centuries, the global average strength of Earth's magnetic field has decreased by approximately 9%. An intriguing phenomenon called the South Atlantic Anomaly emerged between Africa and South America, characterised by a significant reduction in magnetic intensity. This anomaly has indirectly led to temporary disruptions in satellites known as 'Single Event Upsets' due to their exposure to strong radiation in this region.
Auroras are captivating natural light displays that occur on Earth when the solar wind, a stream of charged particles emitted by the Sun, interacts with our planet's magnetic field. This interaction creates an array of colours in the polar night skies. When high-energy particles from the solar wind collide with gases in the atmosphere, they elevate the energy levels of atoms and particles. As these atoms and particles return to their normal energy states, they emit vibrant and colourful light, which we observe as the mesmerising auroras.