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(1) In an earthquake, huge masses of rock move beneath the earth’s surface and cause the ground to shake. Earthquakes occur constantly around the world. Often, they are too small for people to feel at all. Sometimes, however, earthquakes cause great loss of life and property. Most earthquakes are caused by changes in the earth’s outermost shell, or crust.

(2) The crust is made up of about a dozen rock masses called plates that are constantly moving. In different places, they move apart, collide, or slide past each other. Over time this movement causes great pressure to build up. When the pressure becomes too great, the rock masses suddenly shift along a crack in the crust, called a fault. The shifting rocks release energy in the form of shock waves. The waves spread through the rocks in all directions, causing an earthquake.

(3) A small number of earthquakes have other natural or human causes. The movement of molten rock beneath a volcano can trigger an earthquake. The pressure resulting from holding vast amounts of water behind large dams can cause minor quakes. So can underground nuclear explosions and the digging of mines.

(4) An earthquake may be powerful enough to change the surface of the Earth, thrusting up cliffs and opening huge cracks in the ground. Earthquakes can do great damage to buildings, bridges, railroads, and other structures. The violent shaking during earthquakes often causes other earth movements, such as avalanches. Some quakes that happen in or near oceans cause huge, destructive waves called tsunamis to sweep ashore.

(5) Scientists record the shock waves produced in an earthquake with an instrument called a seismograph. They measure the strength of a quake in different ways. The Richter scale measures earthquakes based on the amount of energy they release. The weakest earthquakes are close to zero on the scale, and the strongest measure about 9. The Mercalli scale measures the amount of destruction caused by an earthquake on a scale of 1 to 12.

(1) Recently Elon Musk, founder of SpaceX made a giant step toward being the first moon tour provider by signing up his first passenger; the Japanese billionaire and entrepreneur Yusaku Maezawa. If all goes according to plan, in 2023, Maezawa will become the first passenger and private astronaut to travel to the Moon. He will also join the elite group of just 2 dozen humans who have been fortunate enough to see Earth's satellite up close.
(2) Maezawa does not plan to take family or friends on this historic excursion. Instead, the former drummer from the punk rock band Switch Style, says, "I would like to invite six to eight artists from around the world to join me on this mission to the Moon. These artists will be asked to create something after they return to Earth, and these masterpieces will inspire the dreamer within all of us." Though the guest list has not been determined, he indicated they would be of the same caliber as geniuses, such as Pablo Picasso, Andy Warhol, Michael Jackson, Coco Chanel, and John Lennon. "These are all artists that I adore, but sadly are no longer with us."
(3) The mission, entitled #dearMoon, will be conducted in a Big Falcon Rocket (BFR). First announced by Musk in 2016, the reusable spacecraft, which is still in the early stages of development, is being designed such that it can be refueled both on Earth and in space. Standing 387 feet tall, its 31 main engines, fueled by liquid oxygen and methane, will provide 5,400 tons of thrust and be capable of carrying a payload of over 100 metric tons to low-Earth orbit.
(4) Though the details of the week-long mission have not been finalised, Musk expects the spacecraft to skim past the lunar surface, fly beyond it, and then pass close to the Moon again before heading back to Earth.