Below is my interpretive poster for this earthquake.<\/h2>\n
I plot the seismicity from the past month, with color representing depth and diameter representing magnitude (see legend).<\/p>\n
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- I placed a moment tensor \/ focal mechanism legend on the poster. There is more material from the USGS web sites about moment tensors<\/a> and focal mechanisms<\/a> (the beach ball symbols). Both moment tensors and focal mechanisms are solutions to seismologic data that reveal two possible interpretations for fault orientation and sense of motion. One must use other information, like the regional tectonics, to interpret which of the two possibilities is more likely. The moment tensor shows northeast-southwest compression, perpendicular to the convergence at this plate boundary. Most of the recent seismicity in this region is associated with convergence along the New Britain trench or the South Solomon trench. <\/li>\n
- I also include the shaking intensity contours on the map. These use the Modified Mercalli Intensity Scale (MMI; see the legend on the map). This is based upon a computer model estimate of ground motions, different from the “Did You Feel It?” estimate of ground motions that is actually based on real observations. The MMI is a qualitative measure of shaking intensity. More on the MMI scale can be found here<\/a> and here<\/a>. This is based upon a computer model estimate of ground motions, different from the “Did You Feel It?” estimate of ground motions that is actually based on real observations.<\/li>\n
- I include the slab contours plotted (Hayes et al., 2012<\/a>), which are contours that represent the depth to the subduction zone fault. These are mostly based upon seismicity. The depths of the earthquakes have considerable error and do not all occur along the subduction zone faults, so these slab contours are simply the best estimate for the location of the fault. The hypocentral depth plots this close to the location of the fault as mapped by Hayes et al. (2012).<\/li>\n
- I also include the latitudinal ranges of historic earthquakes in this region (labeled in green).<\/li>\n<\/ul>\n
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- In the upper left corner, I include a time-space diagram from Moernaut et al. (2010)<\/a>.<\/li>\n
- To the right of that space time figure is a plot showing the tsunami recorded at a tide gage 30-40 km to the south of the epicenter. This comes from the Intergovernmental Oceanographic Commission here<\/a>. Here is the NWS National Tsunami Warning Center tsunami announcement.<\/a><\/li>\n
- In the upper right corner I include an inset map from the USGS Seismicity History poster for this region (Rhea et al., 2010). There is one seismicity cross section with its locations plotted on the map. The USGS plot these hypocenters along this cross section and I include that below (with the legend).<\/li>\n
- In the lower left corner are the MMI intensity maps for the three earthquakes listed above: 1960 M 9.5, 2010 M 8.8, and 2016 M 7.6. Note these are at different map scales.<\/li>\n<\/ul>\n
\n![\"\"](\"http:\/\/earthjay.com\/earthquakes\/20161225_chile\/201225_chile_interpretation.jpg\")
<\/a><\/p>\n- \n
- This map shows the MMI contours for the 1960 and 2010 earthquakes in addition to this 2016 earthquake. This helps us visualize the spatial extent for these earthquakes with a large range of magnitudes. Recall that an M 9.5 earthquake releases about 32 times the energy that an M 8.5 earthquake releases. Note how the 1960 and 2010 earthquakes span a region between the Juan Fernandez fracture zone and where the Chile Rise intersects the trench, where the 4 fracture zones (Guamblin, Darwin, Taitao, and Tres Montes) intersect the trench.<\/li>\n<\/ul>\n
\n![\"\"](\"http:\/\/earthjay.com\/earthquakes\/20161225_chile\/201225_chile_interpretation_19602010.jpg\")
<\/a><\/p>\n- \n
- Here is the USGS fault slip model. Note the short rupture length of this earthquake, proportional to the magnitude.<\/li>\n
\n![\"\"](\"http:\/\/earthjay.com\/earthquakes\/20161225_chile\/10007mn3_basemap.png\")
<\/a>\n<\/ul>\n- \n
- Below are some figures from Moreno et al. (2011) that show estimates of locking along the plate interface in this region. I include the figure captions as blockquote.<\/li>\n
- The first figure shows how the region of today’s earthquake is in an area of higher locking.<\/li>\n
\n![\"\"](\"http:\/\/earthjay.com\/earthquakes\/20161225_chile\/moreno_etal_2011_heterogeneous_coupling_south_central_chile_fig_07.PNG\")
<\/a><\/p>\n\na) Optimal distribution of locking rate in the plate interface. Predicted interseismic velocities and GPS vectors corrected by the postseismic signals are shown by green and blue arrows, respectively. b) Tradeoff curve for a broad range of the smoothing parameter (\u03b2). The optimal value for \u03b2 is 0.0095 located at the inflection of the curve.\n<\/p><\/blockquote>\n
- This second figure shows the moment released during historic earthquakes and the moment accumulated due to seismogenic locking along the megathrust.<\/li>\n
\n![\"\"](\"http:\/\/earthjay.com\/earthquakes\/20161225_chile\/moreno_etal_2011_heterogeneous_coupling_south_central_chile_fig_08.PNG\")
<\/a><\/p>\n\na) Latitudinal distribution of the coseismic moment (Mc) released by the 1960 Valdivia (Moreno et al., 2009) (red line) and 2010 Maule (Tong et al., 2010) (blue line) earthquakes, and of accumulated deficit of moment (Md) due to interseismic locking of the plate interface 50 (orange line) and 300 (gray line) years after the 1960 earthquake, respectively. The range of errors of the Md rate is depicted by dashed lines. High rate of Md was found in the earthquake rupture boundary, where slip deficit accumulated since 1835 seems to be not completely released by the 2010 Maule earthquake. b) Schematic map showing the deformation processes that control the observed deformation in the southern Andes and the similarity between coseismic and locking patches. Blue and red contours denote the coseismic slip for the 2010 Maule (Tong et al., 2010) and 1960 Valdivia (Moreno et al., 2009) earthquakes, respectively. Patches with locking degree over 0.75 are shown by brown shaded areas. The 1960 earthquake (red star) nucleated in the segment boundary, area that appears to be highly locked at present. The 2011 Mw 7.1 aftershock (gray) may indicate that stress has been transmitted to the southern limit of the Arauco peninsula.\n<\/p><\/blockquote>\n<\/ul>\n
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- Here is the space-time diagram from Moernaut et al., 2010<\/a>. I include their figure caption below in blockquote.<\/li>\n
\n![\"\"](\"http:\/\/earthjay.com\/earthquakes\/20161104_chile\/moernaut_etal_2010_fig_1_space_time.JPG\")
<\/a><\/p>\n\nFig.: Setting and historical earthquakes in South-Central Chile. Data derived from Barrientos (2007); Campos et al. (2002); Melnick et al.(2009)\n<\/p><\/blockquote>\n<\/ul>\n
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- The September 2015 earthquake series<\/a> inspired me to compile some information on the historic tsunami in this region. Here is my report on those tsunami<\/a>. Below I present my figure and an animation that compares these three tsunami from 1960, 2010, and 2014.<\/li>\n
- These three maps use the same color scale. There is not yet a map with this scale for the 2015 tsunami, so we cannot yet make the comparison. <\/li>\n
\n![\"\"](\"http:\/\/earthjay.com\/earthquakes\/20150916_chile\/tsunami_wave_height_comparison_96ppi.jpg\")
<\/a>
\nHere is an animation of these three tsunami from the US NWS Pacific Tsunami Warning Center (PTWC)<\/a>. This is the YouTube link<\/a>.
\n - These three maps use the same color scale. There is not yet a map with this scale for the 2015 tsunami, so we cannot yet make the comparison. <\/li>\n
- The September 2015 earthquake series<\/a> inspired me to compile some information on the historic tsunami in this region. Here is my report on those tsunami<\/a>. Below I present my figure and an animation that compares these three tsunami from 1960, 2010, and 2014.<\/li>\n
- This second figure shows the moment released during historic earthquakes and the moment accumulated due to seismogenic locking along the megathrust.<\/li>\n
- Here is the USGS fault slip model. Note the short rupture length of this earthquake, proportional to the magnitude.<\/li>\n
- To the right of that space time figure is a plot showing the tsunami recorded at a tide gage 30-40 km to the south of the epicenter. This comes from the Intergovernmental Oceanographic Commission here<\/a>. Here is the NWS National Tsunami Warning Center tsunami announcement.<\/a><\/li>\n
I include some inset figures in the poster.<\/h2>\n
- I also include the shaking intensity contours on the map. These use the Modified Mercalli Intensity Scale (MMI; see the legend on the map). This is based upon a computer model estimate of ground motions, different from the “Did You Feel It?” estimate of ground motions that is actually based on real observations. The MMI is a qualitative measure of shaking intensity. More on the MMI scale can be found here<\/a> and here<\/a>. This is based upon a computer model estimate of ground motions, different from the “Did You Feel It?” estimate of ground motions that is actually based on real observations.<\/li>\n