Volcanoes, Earthquakes & Tectonics Quiz — 7 Free Questions

Question 1

What is the name for the process, proposed by Harry Hess around 1960, in which new ocean floor is created at mid-ocean ridges as magma wells up, then moves outward in both directions like a pair of conveyor belts, carrying the continents with it?

Question 2

What is the name for the original 1935 measure of earthquake size, devised in California, that assigns a single number from the amplitude of the waves on a seismogram, adjusted for distance, with each whole step meaning about 32 times more energy released?

Question 3

What is the name for the sharp 60-degree kink, about 47 million years old, in the long chain of volcanoes and drowned seamounts running north-west from Hawaii across the Pacific floor?

Question 4

What is the name for the smallest and simplest kind of volcano, a steep conical hill of loose cinders and ash piled around a single vent, usually built in one short eruption and rarely more than a few hundred metres high?

Question 5

What is the name for the huge, roughly circular basin, often kilometres across, that forms when a volcano empties its magma chamber so fast in a giant eruption that the summit collapses into the void left behind?

Question 6

Which Indonesian volcanic eruption, the largest in recorded history at explosivity 7, blasted so much sulfurous haze into the stratosphere that global temperatures fell and 1816 became known across the Northern Hemisphere as 'the year without a summer'?

Question 7

What is the name for the type of seismic wave that travels along the Earth's outer skin rather than through its interior, arrives last because it is the slowest, and yet usually causes the most destruction because it carries the strongest, longest-lasting shaking?

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About Volcanoes, Earthquakes & Tectonics

The ground feels solid, but its outer shell is cracked into a dozen slabs that drift a few centimetres a year, and almost every earthquake, volcano and mountain range on Earth is a by-product of their slow collisions. This quiz tells that story in eighty questions. Each one describes a concept, a feature, an instrument, a famous disaster or one of the scientists who worked it out, and asks you to name it from four choices, then explains what it is, how it works, and the history or the surprise attached to it. No formulae and no map-reading are needed: every answer is a single name, and the descriptions are written to stand on their own.

The first pack builds the framework of plate tectonics: continental drift and the ridicule it met; Pangaea; the plates themselves and the rigid and soft layers they ride on; the crust, mantle and core; the boundary called the Moho; seafloor spreading and the magnetic stripes that proved it; subduction, mid-ocean ridges and ocean trenches; the Ring of Fire; hotspots; and the mantle convection that helps drive the whole system. It also clears up common muddles: that the plates are not the same as the continents, that magma and lava are one melt with two names, and that 'continental drift' was the discredited early guess while 'plate tectonics' is the working theory that replaced it.

The second pack goes into volcanoes and earthquakes in detail. On volcanoes: the shield, composite and cinder-cone shapes and the caldera collapse; the lava types pahoehoe and aa and the tubes they build; the hazards, pyroclastic flows, lahars, tephra and eruption columns; the explosivity index; fumaroles and geysers; why silica and gas content decide whether a volcano oozes or explodes; flood basalts and supervolcanoes; and the eruptions of Vesuvius, Krakatoa and Mount St Helens. On earthquakes: the focus and epicentre; normal, reverse and strike-slip faults; the San Andreas and elastic rebound; the P, S and surface waves; the seismometer; the Richter, moment magnitude and Mercalli scales; liquefaction, tsunamis and aftershocks; and mountain building, rift valleys and island arcs.

The third pack is history and people: Wegener, Tuzo Wilson, Inge Lehmann and Marie Tharp; the Lisbon, San Francisco, Valdivia, Indian Ocean, Tohoku and New Madrid earthquakes; the Tambora and Pelee eruptions; the Siberian Traps and the Great Dying; and the tectonic settings of Yellowstone, the Hawaiian-Emperor bend, the East African Rift and the Himalayas. Photographs are used only where they do not simply reveal the answer, so a lava flow, a seismogram or an offset fence may appear, but a portrait or a recognisable peak will not. Every figure has been checked against reliable sources, and the wording is kept plain.