o Huge meteorite impact. Generated 2-km-high tsunamis that inundated the shores of continents and generated a blast of hot air that set forests on fire. Blast could have ejected so much debris that for months there would have been perpetual night and winter-like cold. o The Chicxulub impactor , also known as the Chicxulub asteroid , was an asteroid 10 to 15 kilometres in diameter which struck the Earth at the end of the Cretaceous , approximately 66 million years ago , creating the Chicxulub crater . o It impacted a few miles from the present-day town of Chicxulub in Mexico , after which the impactor and its crater are named. Because the estimated date of the object's impact and the Cretaceous–Paleogene boundary (K–T boundary) coincide, there is a scientific consensus that its impact was the Cretaceous–Paleogene extinction event which caused the death of most of the planet's non-avian dinosaurs and many other species. o The impactor's crater is just over 177 kilometers in diameter,making it the third largest known impact crater on Earth. Megathrust earthquakes A megathrust earthquake occurs in subduction zones where two crustal plates are colliding. Most subduction zones occur where an oceanic plate is being forced beneath a continental plate. Large sections of the two plates become locked together. Stress in the rocks builds up storing energy in the rocks until they break, creating great earthquakes that are often magnitude 9.0 or higher. Since 1900 there have been five magnitude 9.0 or greater earthquakes. All these events were subduction zone earthquakes.
1960 Great Chilean Earthquake “Valdivia Earthquake” (M w : 9.5) 22 nd of May 1960 The 1960 Chilean earthquakes were a sequence of strong earthquakes that affected Chile between 21 May and 6 June 1960. The first was the 8.1 M w Concepción earthquake , and the strongest was the Valdivia earthquake . The earthquake was a megathrust earthquake resulting from the release of mechanical stress between the subducting Nazca Plate and the South American Plate , on the Peru–Chile Trench . The largest earthquake we’ve ever measured Earthquake-induced tsunamis affected southern Chile, Hawaii, Japan, the Philippines, China, eastern New Zealand , southeast Australia and the Aleutian Islands . Some localized tsunamis severely battered the Chilean coast, with waves up to 25 m (82 ft). The main tsunami crossed the Pacific Ocean and devastated Hilo, Hawaii , killing 61 people. The earthquake triggered numerous landslides , mainly in the steep glacial valleys of the southern Andes . On May 24, 38 hours after the main shock of the 1960 Valdivia earthquake, Cordón Caulle began a rhyodacitic fissure eruption . 1964 Alaska Earthquake “Good Friday Earthquake” (M w : 9.2) 27 th of March 1964 Pacific Plate subducting beneath the North American Plate was the most powerful recorded in North American history, and the second most powerful recorded in world history.
- Fall '09
- Plate Tectonics, Final