Volcanoes and Earthquakes

1. Volcanoes and Earthquakes Based on Discover God’s Creation, chapter 4-1 & 4-2 By Rebecca Fraker

2. A few notes This is a large slide show. It would be better to show it in several parts. This slide show includes animations, video clips, and links to websites. Be careful where you click! If the pointer is on a link, your computer will try to take you to the website.

3. Part 1: Volcanoes • Volcanoes are formed when magma, the melted rock of Earth’s mantle, pushes up through the crust onto the surface. • Volcanoes form on both land and in the ocean.

4. Parts of a volcano Pipe or tube

5. Parts of a volcano • The vent of a volcano is an opening in Earth’s crust. • From the vent, a tube or pipe serves as a pathway from the mantle to the crust and allows magma to move up and out of the vent.

6. Parts of a volcano • Lava is magma that reaches the surface. Lava can be thin and almost watery or thick like cookie dough.

7. Lava & Magma • As lava cools it crystallizes to form rock. • When it cools quickly, it has a smooth texture such as obsidian. • When it cools slowly the rocks are coarser. • Sometimes gasses create “foamy” lava that cools into rocks called pumice and scoria. obsidian scoria pumice granite

8. Volcanoes • Volcanoes usually form near the boundaries of Earth’s plates. • The Ring of Fire is a region of heavy volcanic activity that surrounds the Pacific Ocean.

9. Eruptions • Volcanoes also differ in the way they erupt. • In some volcanoes the lava flows out of cracks called fissures. These eruptions do not build mountains but form broad, spreading layers of lava. • Other volcanoes build mountains as they erupt. When lava flows out of the vent and cools, a bowl-shaped crater often forms around the vent. • As new material flows over the top, a cone builds up.

10. Kinds of Volcanoes • Three kind of volcanoes form mountains: • Shield volcanoes • Cinder cones • Composite volcanoes

11. Shield Volcanoes • Shield volcanoes are the largest type of volcano. • They are broad with gently sloping sides. • They do not have violent eruptions; lava flows out slowly. • The Mauna Loa volcano, perhaps the largest active volcano on Earth, is a shield volcano.

12. Examples of shield volcanoes: Mauna Loa Volcano in Hawaii

13. Cinder Cones • Cinder cones are the smallest type of volcano, usually less than 1000 feet high. • They form when pieces of lava blow out of a volcano’s vent. • Unlike shield volcanoes, cinder cones have very steep sides. • In 1943, Paricutin, a volcano in Mexico, erupted. • In the first day, a cone of over 130 feet high formed, and within five days it was over 300 feet high. Two years later, this volcano was more than 1300 feet high.

14. Examples ofCinder cones Paricutin in Mexico

15. Composite Volcanoes • Mount St. Helens in the United States is a composite volcano. • These volcanoes have alternating layers of lava and ash. • Lava quietly flows out for a time. • When the lava stops flowing, a plug forms in the vent. In this condition, the volcano may stay inactive for many years.

16. Composite volcanoes • When a composite volcano again becomes active, there is no place for magma and steam to go. • As pressure within the volcano builds, there is an explosion that blows out the plugged vent. • Such eruptions release tremendous power. • The eruption of Mount St. Helens blew away most of the mountain’s north side.

17. Examples of compositevolcanoes Mount St. Helens before eruption And afterwards, in 1982

18. Some products of volcanic eruptions Steam and gases lava Fine ash rocks

19. Famous eruptions • Volcanic eruptions have had a dramatic impact on the Earth’s surface and on the lives of people and cultures. • Following are accounts and pictures of some of the more famous eruptions.

20. Mount Krakatoa • So much pumice was released onto the ocean’s surface from the eruption of Krakatoa in 1883 that sailors were able to walk 2 miles from their ship to the shore on top of the floating pumice! Krakatoa before and after

21. Krakatoa • A volcanic island of Indonesia between Sumatra and Java. A momentous volcanic explosion on Aug. 23, 1883, blew up most of the island and altered the configuration of the strait; it caused a tsunami that killed more than 36,000 people along the nearby coasts of Java and Sumatra. • The explosion is classed as one of the largest volcanic eruptions in modern times; so great was the outpouring of ashes and lava that new islands were formed, and debris was scattered across the Indian Ocean as far as Madagascar. Since then there have been several lesser eruptions.

22. Mt. Vesuvius • POMPEII, MT. VESUVIUS, ITALYIn 79 AD, Mt. Vesuvius erupted an enormous volume of pumice and ash. This material flowed very quickly down the side of the volcano as hot ash flows. The ash flows covered the Roman city of Pompeii in a few hours. Many people were trapped by the hot ash. Almost the entire population of the city was killed.

23. Pompeii and Mt. Vesuvius • Pompeii is undoubtedly one of the world's best known archaeological sites. Its fame comes from its dramatic destruction and extraordinary preservation as a result of an eruption of Mount Vesuvius. • On February 5, A.D. 62, Pompeii was at the epicenter of a severe earthquake that caused considerable structural damage to buildings and the infrastructure of the city. It is clear that the process of repair and redevelopment was slow and extensive.

24. Pompeii • On August 20, A.D. 79, Pompeii was rocked by more earth tremors. Springs in the area dried up. • The ancient Pompeiians did not recognize that these were signs of the imminent eruption of Vesuvius. Therefore when the volcano went off between noon and 1pm on August 24, it caught everyone by surprise. • According to Pliny the Younger, a 12-mile high cloud of ash and rock was thrown into the air, blocking out the sun.

25. By chance, the wind was blowing from the northwest, so when the volcanic matter began to fall, it was blown in the direction of Pompeii, Herculaneum and other sites to the southeast. • The eruption produced total darkness, as well as electrical discharges from atmospheric disturbances. • Ash, pumice, and rock fell, initially with a low density. This piled up in streets, on rooftops, and fell in through every open space such as windows. • Some roofs collapsed under its weight and falling debris may also have caused injury.

26. This phase of the eruption continued for the rest of the day. People wandered around in darkness, pushing their way through pumice and debris, which was piling up. Some may have tried to escape, while others decided to wait it out. Surely no one had experienced such a catastrophe before so they did not know what to expect from it. • Shortly after midnight, ground surges of magma and volcanic mud began as well as pyroclastic surges, avalanches of noxious gases and ash rushing from the cone of Vesuvius with terrific force at over 100 kilometers an hour Pompeii

27. Herculaneum, which was situated at the base of Vesuvius, was hit with a surge and entombed in volcanic mud. Several pyroclastic surges roared toward Pompeii but were stopped from doing too much damage by the northern city wall right behind our city block. At about 7:30 am, enough pumice stones and debris had piled up that a pyroclastic surge finally rolled up over the top of the city wall, shearing off any buildings that were not already buried by volcanic matter. All people still present in the city died instantly. • Thousands of people died within the city during the eruption. Many more were probably killed in the surrounding landscape as they tried to flee, but little archaeological work has been done on Pompeii's hinterland. A powdery deposit followed the most destructive surge and when the eruption finally ceased late on August 25, only the largest structures in the city such as the Amphitheater and the Grand Palaestra were probably identifiable.

28. Pompeii and Herculaneum were to remain buried for around 1,700 years. Survivors of the eruption must have decided that rebuilding on the site was out of the question, but some researchers claim that there were signs that for a time people lived in the ruins, and a fishing community probably existed at the mouth of the nearby river Sarno. • During the later Roman period, and into the Middle Ages, Pompeii was forgotten. In March 1748, a surveying engineer, was sent by King Charles III of Spain with a mission to supply the Spanish court with ancient statues and other treasures. He learned that at the place called La Cività (what the people of the country called this area) objects of antiquity had been found. The excavations at Pompeii have continued ever since.

29. Mosaics, pottery, and casts of people buried in the Mt. Vesuvius eruption about 80 years after Jesus’ crucifiction.

30. CRATER LAKE, OREGONCrater Lake erupted about 7770 years ago. It was a gigantic eruption of ash flows. So much material erupted that the top of this volcano collapsed. • This formed a great hole where the top of the volcano had been. The hole was gradually filled with water from rainfall and melting snow. A new eruption in the middle of the lake formed a tiny cinder cone volcano, now called Wizard Island.

31. PARICUTIN, MEXICOA cinder cone grew to a height of more than 1500 feet. It first began in a cornfield in 1943. The volcano grew and erupted a lot of lava, eventually covering more than 10 square miles. It frightened farmers, but enough warning was given for most of the local population to escape without harm.

32. Mt. Pelée on Martinique • The island of Martinique lies in the Caribbean Archipelago between the Atlantic Ocean and the Caribbean Sea. Mt. Pelée, located on the northern side of the island, proved to be the deadliest volcano of the 20th century.

33. Mt. Pelée • Three days before the eruption, the rim of the volcano crater collapsed, sending scalding water down the nearby River Blanche. Collecting debris along the way, the mudflow buried everything in its path before reaching the sea. • The impact created a nearly ten-foot-high (three-meter-high) tsunami, flooding the low-lying areas around St. Pierre.

34. Mt. Pelée • Mt. Pelée erupted at 7:50 a.m. on May 8, 1902. A giant black plume darkened the sky, while a pyroclastic flow—a superheated cloud of hot ash, toxic gases, and magma fragments—raced down the volcano's sides at hurricane-force speeds. • Within minutes, the city of St. Pierre had been destroyed, its 30,000 inhabitants dead.

35. Mt. Pelée • One of only two survivors, 25-year-old Louis-Auguste Cyparis was in jail when the volcano erupted the morning of May 8, 1902. Cyparis had been moved to solitary confinement in an underground cell. The thickness of the walls and absence of windows sheltered him from the most deadly effects of the eruption, but Cyparis was severely burned by hot air and ash. In great pain, he managed to survive trapped in the cell for four days until scientists exploring the ruins rescued him.

36. Some resources http://volcano.und.nodak.edu/vwdocs/current_volcs/current.htmlInformation on currently erupting volcanoes around the world, with links to each site.http://www.geo.mtu.edu/volcanoes/Michigan Technological University - volcano sites from around the world.http://vulcan.wr.usgs.gov/home.htmlThe US Geological Survey Cascades Volcano Observatory. Excellent information on US volcanoes, as well as plate tectonics and geologic hazards.

37. Part 2: Earthquakes and Tsunamis • Earthquakes are shock waves resulting from movements in Earth’s crust. They have occurred throughout the history of the world. • Scientists estimate that worldwide, over 800,000 earthquakes occur each year. • Most earthquakes are too small to be felt, but they can be detected by special equipment.

38. Where do earthquakes take place? • Earthquakes often happen near boundaries of plates and at faults, or cracks in the plates. • As the plates move, pressure builds up in the rocks along the fault. • If movement stops, the energy remains stored in the rocks. • If movement continues, the rocks can no longer hold their position and suddenly they slip past each other. • To illustrate this, try bending a small branch you have taken from a bush or tree. It will bend so long, and then snap.

39. Faults • Only one side of a fault moves. The moving plate can either push up, slip down, or move horizontally. • There are three kinds of faults: • Normal faults • Thrust faults • Strike-slip faults (transform faults)

40. Normal Faults • The moving plate slips below the stationary plate. • The fault that runs through the Rift Valley of Africa is an example of a normal fault.

41. Thrust Faults • The moving plate moves up and over the stationary plate. Chief Mountain in Montana is an example of a thrust fault.

42. Thrust faults

43. Strike-Slip Faults • The moving plate slides past the stationary plate. The San Andreas fault in California is a strike-slip fault.

44. Strike-Slip faults

45. Focus and Epicenter • The point where the actual slip happens is the focus of the earthquake. It is usually deep within the earth. • Energy waves travel out in all directions from the focus.

46. Focus and Epicenter • The epicenter of an earthquake is the point on the surface of the grounddirectly above the focus. • If you were standing at this point, you would be the first to feel the earthquake.

47. Earthquakes Today • Today we have more than 4,000 seismograph stations in the world that record 12,000 to 14,000 earthquakes per year—that’s about 35 a day!

48. Some earthquakes • Here are some earthquakes that have caused great loss of life and great damage: • China, 1920, 7.6, 180,000 • China, 1976, 7.6, 250,000 • Japan, 1923, 8.3, 140,000 • Peru, 1970, 7.7, 70,000 • Mexico, 1985, 8.1, 10,000 • Afghanistan, 1998, 6.9, 5,000

49. San Francisco Earthquake • "San Francisco and Oakland are becoming as Sodom and Gomorrah, and the Lord will visit them. Not far hence they will suffer under His judgments."--Ms 30, 1903. Ellen G. White

50. Other quotes: • On April 16, 1906, two days before the San Francisco earthquake, Mrs. White said that, • “While at Loma Linda, California, April 16, 1906, there passed before me a most wonderful representation. During a vision of the night, I stood on an eminence, from which I could see houses shaken like a reed in the wind. Buildings, great and small, were falling to the ground. Pleasure resorts, theaters, hotels, and the homes of the wealthy were shaken and shattered. Many lives were blotted out of existence, and the air was filled with the shrieks of the injured and the terrified. The destroying angels of God were at work. One touch, and buildings, so thoroughly constructed that men regarded them as secure against every danger, quickly became heaps of rubbish. There was no assurance of safety in any place. I did not feel in any special peril, but the awfulness of the scenes that passed before me I cannot find words to describe. It seemed that the forbearance of God was exhausted and that the Judgment day had come. “ (Testimonies, Vol. 9, pp. 92-93) • Two days later, on April 18, 1906, a devastating earthquake struck San Francisco