The sideways motion of the fault's branches is caused by the Pacific Ocean's crustal plate moving to the northwest under North America's continental crust.
The most famous example is California's San Andreas Fault, which stretches some 600 miles (1,000 kilometers) from southern California to north of San Francisco. When portions of the Earth's crust moves sideways, the result is a horizontal motion along a "strike-slip" fault.
Here are a list of the various ways Earth can shake. The ground first bends and then snaps-an earthquake-to release energy along faults. Most earthquakes arise along such fault zones. Along the Ring of Fire girding the Pacific Ocean, for example, the seafloor plunges beneath Asia and the Americas, building mountains, feeding volcanoes, and triggering earthquakes. The Earth's crust is made of a jigsaw puzzle of continental and oceanic plates that are constantly ramming each other, sliding past each other, or pulling apart. Learn about the geophysics behind earthquakes, how they are measured, and where the most powerful earthquake ever witnessed occurred. The total loss of life by a factor of 3 or 4.Earthquakes can leave behind incredible devastation, while also creating some of the planet's most magnificent formations. The frequently quoted value of 700 deaths causedīy the earthquake and fire is now believed to underestimate However, was equally severe in many other places along theįault rupture. It spawned in San Francisco, giving it the somewhat misleadingĪppellation of the "San Francisco earthquake". Mind, this earthquake is perhaps remembered most for the fire The most important study of a single earthquake. (1908) report remains the authoritative work, as well as arguably Modern seismic-zonation practice accounts for the differences in seismic hazard posed by varying geologic conditions.Īs a basic reference about the earthquake and the damage itĬaused, geologic observations of the fault rupture and shakingĮffects, and other consequences of the earthquake, the Lawson Areas situated in sediment-filled valleys sustained stronger shaking than nearby bedrock sites, and the strongest shaking occurred in areas where ground reclaimed from San Francisco Bay failed in the earthquake. One important characteristic of the shaking intensity noted in Lawson's (1908) report was the clear correlation of intensity with Of VII to IX paralleled the length of the rupture, extending as far as 80 kilometers inland from the fault trace. The highest Modified Mercalli Intensities (MMI's) Oregon to south of Los Angeles and inland as far as central Nevada. Violent shocks punctuated the strong shaking which lasted some 45 to 60 seconds. The great earthquake broke loose some 20 to 25 seconds later, with an epicenter near San Francisco. Of the earthquake source, which remains today the principalĪt almost precisely 5:12 a.m., local time, a foreshock occurred with sufficient force to be felt widely throughout the Sanįrancisco Bay area. The advent of plate tectonics more than half a century later.Īnalysis of the 1906 displacements and strain in the surroundingĬrust led Reid (1910) to formulate his elastic-rebound theory Large cumulative offset would not be fully appreciated until Indeed, the significance of the fault and recognition of its Large, horizontal displacements and great rupture length. The earthquake confounded contemporary geologists with its San Juan Bautista to the triple junction at Cape Mendocino, Rupturing the northernmostĢ96 miles (477 kilometers) of the San Andreas fault from northwest of Today, its importanceĬomes more from the wealth of scientific knowledge derivedįrom it than from its sheer size. The most significant earthquakes of all time. The California earthquake of Apranks as one of (from Steinbrugge Collection of the UC Berkeley Earthquake Engineering Research San Francisco City Hall after the 1906 Earthquake.
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