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Earthquake hits off the coast of northern Chile

on Sat, 04/05/2014 - 17:33
On April 1st, 2014 at 8:46 p.m. local time (UTC-03:00) an 8.2-magnitude earthquake struck off the northern coast of Chile, 95 kilometers west of the city of Iquique. According to Chilean authorities and press agencies, at least six people died due to the earthquake and around 900,000 people were evacuated because of a tsunami alert issued by the Chilean government. As expected, a series of aftershocks followed the natural event and eventually a high risk for infrastructure and service damages and human life. During the next eights hours after the earthquake, 29 aftershocks with magnitude in the range of 4.4 - 6.2 on the Richter scale were registered by the Earthquake Hazards Program of the US Geological Survey.
A tectonic analysis from the US Geological Survey stated:
Historical records indicate a 8.8-magnitude earthquake occurred within the Iquique gap in 1877, which was preceded immediately to the north by an M 8.8 earthquake in 1868.
A recent increase in seismicity rates has occurred in the vicinity of the April 1 earthquake. An M6.7 earthquake with similar faulting mechanism occurred on March 16, 2014 and was followed by 60+ earthquake of M4+ and 26 earthquakes of M5+. The March 16 earthquake was also followed by three M6.2 events on March 17, March 22, and March 23. The spatial distribution of seismicity following the March 16 event migrated spatially to the north through time, starting near 20oS and moving to ~19.5oS. The initial location of the April 1 earthquake places the event near the northern end of this seismic sequence. Other recent large plate boundary ruptures bound the possible rupture area of the April 1 event, including the 2001 M 8.4 Peru earthquake adjacent to the south coast of Peru to the north, and the 2007 M 7.7 Tocopilla, Chile and 1995 M 8.1 Antofagasta, Chile earthquakes to the south. Other nearby events along the plate boundary interface include an M 7.4 in 1967 as well as an M 7.7 in 2005 in the deeper portion of the subduction zone beneath inland Chile.
Data and metadata related to seismic activity worldwide are provided by the U.S. Geology Survey (USGS), especifically the Spreadsheet Applications page. Data can be download in several file formats, different time periods and magnitudes. Based on these data [plain text csv format] a visualization to explore the seismic activity produced by the earthquake M8.2 - 95km Northwest Iquique, Chile was designed. It serves to provide comprehensive and reliable information about this natural event to the general public. See the screenshot bellow, taken from the interactive visualization on Saturady, April 5th, 2014, four days after the M8.2 earthquake, Iquique, Chile.
The interactive data visualization is also available by clicking on the screenshot.
At the moment this blog post was written, a total of 108 aftershocks with magnitude greater that 2.5 have occured (109 including the M8.2 earthquake on April 1st, 2014), all in a range of 3.9 - 8.2 magnitude and six of them were significant (magnitude greater than 6.0).  On April 2, 2014 at 11:43PM (UTC-03:00) local time in Chile, a 7.2-magnitude aftershock hits Iquique generating more damages over urban infrastructure, including cut in the electricity service, and producing cracks on streets and roads, and distructions of houses in Iquique. Many people abandoned there homes going to high places for fear to a tsunami and injuries.
The Pan American Organization (PAHO/WHO) reported that the health services network in Iquique is operating normally with the exception of the Regional Hospital, which suffered damages that are being evaluated. Chile has declared a catastrophe zone for the Arica – Parinacota and Tarapacá regions in order to expedite both damage assessment and the national and local responses.
The visualization allows you to see in a map the geographical location of the earthquake and aftershocks. and in a timeline chart the time every event occurred. The list of quakes shows information about every event in chronological order, from most recent at the top to the oldest. These threee visuals are dynamically linked, so a selection on one of them will highlight the selected objects in the others. The interactive data visualization allows you to interact with the dashboards by hovering the mouse over any chart objtect to get additional information or by click-and-drag to select and highlight specific events.
I will update the data at least twice a day while the seismicity rate is high (It is expected to be high for at least next two weeks). 
I hope readers find it useful and informative. As always, your point of view, recommendations and suggestions are welcome. Add your comment or drop me an email using contact.

P.S. The visualization of this article was selected by Tableau Public as Visualization of the Day on April 4th, 2014.

Tableau Public Visualization of the Day, April 4th, 2014

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