M 8.2 earthquake in northern Chile

Alright. Lets hope not many people are harmed as a result of this earthquake and likely large tsunami. We all know what to do. Drop, duck, cover, and hold on. Run to high ground. Stay there.
Check back here for updates throughout the night. I am posting information about the tsunami here.
Here is an earthquake that ruptures today in the region of a recent swarm of earthquakes in the northern Chile subduction zone. This is the USGS web page for this earthquake.
Here is the USGS web page for a large aftershock (M 6.2).
Here is a great animation from IRIS that shows the tectonics and seismology associated with this earthquake.

This is a great animation of the seismic waves travelling through the transportable array.

This is the early moment tensor (Mww), which shows a pure thrust/reverse slip.

Here is a map showing the region with earthquakes from the last 30 days. The largest dot is today’s great earthquake.

This map is zoomed into the region of the swarm and mainshock. The earthquakes that ruptured prior to the megathrust earthquake may be now considered generally foreshocks. The colored lines represent the depth of the subduction zone fault shown in km. The two main red depth contours are 20 and 40 km respectively.

Here is a map put together by the Belfast Telegraph.

This is a map that shows instrumental and historic earthquake rupture regions. This figure from Chlieh et al. (2011) shows the slip models (earthquake slip in meters) and earthquake slip regions for pre-seimologic (prior to seismometers) earthquakes in grey. The swarm of earthquakes from this March are in the northern region of the 1877 M 8.8 subduction zone earthquake.

Here is an estimate of ground shaking intensity, with contours offshore and the fault slip region plotted at 21:00 PST:

This is the seismograph from the HSU seismometer, thanks to HSU Department of Geology facebook page.

This map shows a large M 6.2 aftershock right near the coastline. Lets hope people are safe from all these earthquakes. There is also a M 5.5 further south.

Here is the USGS PAGER page. These plots are generated by overlaying shaking intensity with estimates of population and infrastructure. These overlays are “multiplied” to predict what number of fatalities and amount of economic losses might be (in a probabilistic way). These are just models, but do help international and national efforts that may need to be arisen. Most earthquakes that I have shown these PAGER plots for have had low exposure, but this M 8.2 earthquake has possibly affected up to or over 100 fatalities and up to a hundred to hundreds of millions of USD.

This is an interesting plot, showing the coupling ratio. 0 means that the fault is not locked, or is slipping aseismically. 1 means that the fault is completely locked. The darker the map, the higher their estimate of % locking. This is from Metois et al., 2013.

This is the fault slip model just generated by the USGS. The red star represents the hypocenter and the red squares represent regions of higher slip. Notice how the region of highest slip is not collocated with the hypocenter.

This is the source time function, which tells us how much energy is released over time. This is generated by integrating the energy amplitudes from the seismic waves generated by the earthquake. If we were to go coring in a month, we would possibly find a turbidite with two main pulses.

6 thoughts on “M 8.2 earthquake in northern Chile

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