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Chile earthquake: 8.3-magnitude quake strikes off coast

on Thu, 09/17/2015 - 16:32

A powerful 8.3-magnitude earthquake struck off Chile's coast on Wednesday September 16, 2015. The quake's epicenter was located 46 kilometers west of Illapel and it occurred at 7:54 p.m. local time (6:54 p.m. ET), 25 kilometers depth.

This data visualization aims to facilitate data exploration on Chile's quakes ocurrence both in space and time. The USGS Earthquake Hazards Program, National Earthquake Hazards Reduction Program (NEHRP), which monitor and report earthquakes, assess earthquake impacts and hazards, and research the causes and effects of earthquakes was used as data source for this visualization. Data set in csv format for 2.5 and higher magnitude quakes is available online here.  

What is an Eartquake?

According to US Geological Survey, an earthquake (also known as a quake, tremor or temblor) is the perceptible shaking of the surface of the Earth, which can be violent enough to destroy major buildings, roads, and kill thousands of people. The severity of the shaking can range from barely felt to violent enough to toss people around. Earthquakes result from the sudden release of energy in the Earth's crust that creates seismic waves. The seismicity, seismism or seismic activity of an area refers to the frequency, type and size of earthquakes experienced over a period of time.

Magnitude measures the energy released at the source of the earthquake as determined from measurements on seismographs. The magnitude scale most commonly in use now is called the moment magnitude scale. Moment is a physical quantity proportional to the slip on the fault times the area of the fault surface that slips; it is related to the total energy released in the earhquake. The moment magnitude provides an estimate of earthquake size that is valid over the complete range of magnitudes.Charles F. Richter, a California seismologist, introduced the concept of earthquake magnitude in the 1930's.

Earthquakes with magnitude of about 2.0 or less are usually called microearthquakes; they are not commonly felt by people and are generally recorded only on local seismographs. Events with magnitudes of about 4.5 or greater - there are several thousand such shocks annually - are strong enough to be recorded by sensitive seismographs all over the world. Great earthquakes, such as this 8.3-magnitude earthquake in Chile, September 16th, 2015, have magnitudes of 8.0 or higher. 

Intensity measures the strength of shaking produced by the earthquake at a certain location. Intensity is determined from effects on people, human structures, and the natural environment. An earthquake can produce shaking of many different intensities. The Modified Mercalli Intensity Scale is used in the US.

More detailed information about erathquake can be found here.

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Earthquake Hits off the Coast of Northern Chile, April 1st 2014

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