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Caldera: Crater Formed by Volcanic Collapse or Explosion. Caldera demonstration: This video shows a teaching activity that clearly demonstrates how a caldera is formed.

Caldera: Crater Formed by Volcanic Collapse or Explosion

It can be difficult to explain or draw how a caldera forms. This table-top model is a great demonstration. Teachers can do this activity with their students, or simply show the video in class using computer projection. Dina Venezky and Stephen Wessells, 2010, Caldera Demonstration Model: U.S. Geological Survey Open-File Report 2010-1173. Explosive Eruptions at Kilauea: Many of Kilauea's pre-1924 explosive eruptions that produced significant ash deposits probably happened when the volcano's summit crater was so deep that its floor was below the water table, letting groundwater seep in to form a lake. Eruptions of ash and pumice: The cataclysmic eruption started from a vent on the northeast side of the volcano as a towering column of ash, with pyroclastic flows spreading to the northeast. Brochure for new flats in Golders Green, 1933. Earth's tectonic plates have doubled their speed. By Jeff Hecht (Image: Alex Mustard/ SO MUCH for slowing down as you age.

Earth's tectonic plates have doubled their speed

Earth’s tectonic plates are moving faster now than at any point in the last 2 billion years, according to the latest study of plate movements. But the result is controversial, since previous work seemed to show the opposite. Pacific Northwest Seismic Network. Plate tectonics describes the motions of the 15 to 20 large rigid and brittle tectonic plates into which the Earth's outermost layer (called the "lithosphere") is broken.

Pacific Northwest Seismic Network

It does a good job at explaining the distribution of most of Earth's earthquakes, mountains and other geological features, and a particularly good job at explaining features on the ocean floor. However, it is challenged to explain the details of the older rocks on the continents, and the occurrence of deformation an earthquakes off of plate boundaries. Beyond merely describing current plate motions, Plate Tectonics provides an overarching framework that connects many elements of Earth science.

Plate tectonics is a relatively young scientific theory that needed the advancement of observational and computing technology in the 1950s and 1960s to become fully elaborated. This animation shows, in a very exaggerated way, the sorts of movements Plate Tectonics implies. Italy earthquake: Death toll reaches 247 amid rescue efforts. The death toll in the Italian earthquake stands at 241 as rescuers continue efforts to find survivors.

Italy earthquake: Death toll reaches 247 amid rescue efforts

Dozens of people are believed trapped in ruined Amatrice, Accumoli and Pescara del Tronto, in mountainous central Italy. There have been hundreds of aftershocks since the quake struck, hampering relief efforts and damaging already unstable buildings. More than 4,300 rescuers are using heavy machinery and their bare hands. Rescuers have advised journalists and bystanders to leave Amatrice urgently, as "the town is crumbling", the BBC's Jenny Hill says. Another powerful aftershock struck the town on Thursday afternoon, sending a huge dust cloud into the air.

Many of the earthquake's victims were children, the health minister said, and there were warnings the toll could rise further. The heaviest death toll was in Amatrice - 184, officials said. The Geological Society. What are the active volcanoes in Hawaii and what is their status? There are five active volcanoes in Hawaii.

What are the active volcanoes in Hawaii and what is their status?

They are: Loihi Kilauea Mauna Loa Hualalai Haleakala Kilauea is considered one of the worlds most frequently active volcanoes. If you just look at the number of Kilauea eruptions recorded since Europeans arrived, there have been 62 eruptions in 245 years, which comes out to 1 eruption every 3.95 years. However, this completely ignores the fact that some of the eruptions lasted a long time.

Mauna Loa is an active volcano and is due for an eruption. Haleakala began growing on the ocean floor roughly 1-2 million years ago. Hualalai is an active volcano. Lo’ihi means “long one”, a reference to its elongate shape. Sources of Information: Lockwood, J.P., and Lipman, P.W., 1987, Holocene eruptive history of Mauna Loa volcano, in Decker, R.W. Scientists find our planet's inner core has ANOTHER core of its own.

While there's no prehistoric land hidden at the centre of our planet, as author Jules Verne imagined, the Earth's core may not at all be like what scientists have led us to believe.

Scientists find our planet's inner core has ANOTHER core of its own

Geologists have discovered that the Earth's inner core - previously thought to be a solid lump of iron - may in fact have its own even smaller core within it. Using the seismic waves that reverberate across the planet after earthquakes, researchers have been able to gain new insight into what lies at the centre of our world. Researchers have found that the Earth's inner core has an interior structure of its own made of iron crystals that point in different directions, as can be seen marked by the blue lines in the diagram above The findings could mean that our understanding of Earth's interior, and its history, will need to be rewritten.

Volcano Eruption Update on Hawaii Island.