[IGSMAIL-6893] Predicted displacements from April 1 earthquake off Iquique, Chile
Jeff Freymueller
jeff.freymueller at gi.alaska.edu
Wed Apr 2 11:22:40 PDT 2014
Author: Jeff Freymueller
I have calculated predicted displacements from yesterday’s earthquake for IGS stations and other CGPS sites that I know about in the area. The predictions use the US Geological Survey (USGS) Finite Fault model version 1 (from Gavin Hayes, USGS National Earthquake Information Center). I used the program ffaultdisp from Sergey Kolesov of Moscow State University, which implements the standard Okada dislocation code. I checked these against the displacements computed by the USGS Coulomb program, and these were slightly different (a few percent). I am not sure why they are different, but I suspect that this is either due to differences in map projection to x-y coordinates, or a slight inconsistency in the definition of the location of the fault in the input format.
Key assumptions and caveats:
1. Near-field displacements may be poorly predicted because the USGS finite fault model, determined from teleseismic data, has limited resolution on the spatial distribution of slip. Near-field GPS sites are extremely sensitive to the details of the slip distribution.
2. Far-field displacements may be biased because the calculation done here assumes a uniform half-space rather than a more realistic spherical layered space.
These displacements should be used as a guide rather than as values that could be used to correct GPS site locations. However, if a substantial displacement is predicted you can expect that a substantial displacement will be observed. The IGS site AREQ did not move very much because the earthquake was located well to the south of this station.
USGS Finite Fault model:
http://earthquake.usgs.gov/earthquakes/eventpage/usc000nzvd#scientific_finite-fault
Web page for ffaultdisp:
http://ocean.phys.msu.ru/projects/ffaultdisp/
Site longitude latitude east north up (displacements in meters)
AREQ -71.493196 -16.465669 -0.00009 0.00038 -0.00418
COLO -67.803979 -22.167384 -0.01241 0.00444 -0.00125
ARE2 -71.493016 -16.465264 -0.00009 0.00038 -0.00418
ARE1 -71.493196 -16.465669 -0.00009 0.00038 -0.00418
UNSA -65.407643 -24.727457 -0.00238 0.00077 -0.00041
COPO -70.338236 -27.384527 0.00026 -0.00023 -0.00094
IQQE -70.131718 -20.273544 -0.56603 0.02360 -0.34515
UEPP -51.408534 -22.119905 -0.00080 -0.00000 0.00013
TUCU -65.230352 -26.843255 -0.00094 0.00027 -0.00046
LCEN -68.602603 -25.326061 -0.00054 -0.00020 -0.00150
LLST -68.520184 -25.165462 -0.00067 -0.00015 -0.00154
JRGN -70.574909 -23.288917 0.00117 -0.00281 -0.00433
PCCL -70.106744 -18.457674 -0.11396 -0.10402 -0.04333
UTUR -67.205542 -22.242005 -0.01068 0.00333 -0.00054
CDLC -69.761524 -22.189636 -0.00450 -0.00107 -0.00707
CLLA -69.35665 -20.954484 -0.08602 0.03197 -0.01687
CTLR -70.096828 -21.964162 -0.00272 -0.00677 -0.00892
QUET -67.343328 -22.198357 -0.01129 0.00361 -0.00065
SRGD -69.347835 -22.871137 -0.00290 0.00003 -0.00427
ATJN -70.136751 -19.300815 -0.30064 -0.13171 -0.14933
CBAA -68.44815 -22.746369 -0.00663 0.00270 -0.00257
CHMZ -69.194167 -19.668538 -0.16085 -0.03077 -0.02309
CJNT -67.760575 -23.027491 -0.00589 0.00228 -0.00151
MCLA -70.247502 -22.745815 0.00043 -0.00415 -0.00592
PTRE -69.574329 -18.194288 -0.06083 -0.05008 -0.01251
VLZL -69.964689 -23.117231 -0.00021 -0.00225 -0.00462
CGTC -70.068966 -20.177126 -0.58761 -0.04091 -0.32742
CMPN -70.685824 -29.028204 0.00023 -0.00010 -0.00062
AREV -71.492796 -16.465516 -0.00009 0.00038 -0.00418
SCRZ -63.159674 -17.796791 -0.00527 -0.00134 0.00075
SOCM -68.295165 -24.454613 -0.00142 0.00020 -0.00172
CHAC -58.959693 -27.420439 -0.00088 0.00021 -0.00001
CUIB -56.069867 -15.555262 -0.00130 -0.00035 0.00023
PPTE -51.408534 -22.119903 -0.00080 -0.00000 0.00013
YCBA -63.679985 -22.017103 -0.00509 0.00062 0.00045
CATA -65.774121 -28.470984 -0.00043 0.00006 -0.00047
AREQ -71.493196 -16.465669 -0.00009 0.00038 -0.00418
COLO -67.803979 -22.167384 -0.01241 0.00444 -0.00125
ARE2 -71.493016 -16.465264 -0.00009 0.00038 -0.00418
ARE1 -71.493196 -16.465669 -0.00009 0.00038 -0.00418
UNSA -65.407643 -24.727457 -0.00238 0.00077 -0.00041
COPO -70.338236 -27.384527 0.00026 -0.00023 -0.00094
IQQE -70.131718 -20.273544 -0.56603 0.02360 -0.34515
UEPP -51.408534 -22.119905 -0.00080 -0.00000 0.00013
TUCU -65.230352 -26.843255 -0.00094 0.00027 -0.00046
LCEN -68.602603 -25.326061 -0.00054 -0.00020 -0.00150
LLST -68.520184 -25.165462 -0.00067 -0.00015 -0.00154
JRGN -70.574909 -23.288917 0.00117 -0.00281 -0.00433
PCCL -70.106744 -18.457674 -0.11396 -0.10402 -0.04333
UTUR -67.205542 -22.242005 -0.01068 0.00333 -0.00054
CDLC -69.761524 -22.189636 -0.00450 -0.00107 -0.00707
CLLA -69.35665 -20.954484 -0.08602 0.03197 -0.01687
CTLR -70.096828 -21.964162 -0.00272 -0.00677 -0.00892
QUET -67.343328 -22.198357 -0.01129 0.00361 -0.00065
SRGD -69.347835 -22.871137 -0.00290 0.00003 -0.00427
ATJN -70.136751 -19.300815 -0.30064 -0.13171 -0.14933
CBAA -68.44815 -22.746369 -0.00663 0.00270 -0.00257
CHMZ -69.194167 -19.668538 -0.16085 -0.03077 -0.02309
CJNT -67.760575 -23.027491 -0.00589 0.00228 -0.00151
MCLA -70.247502 -22.745815 0.00043 -0.00415 -0.00592
PTRE -69.574329 -18.194288 -0.06083 -0.05008 -0.01251
VLZL -69.964689 -23.117231 -0.00021 -0.00225 -0.00462
CGTC -70.068966 -20.177126 -0.58761 -0.04091 -0.32742
CMPN -70.685824 -29.028204 0.00023 -0.00010 -0.00062
AREV -71.492796 -16.465516 -0.00009 0.00038 -0.00418
SCRZ -63.159674 -17.796791 -0.00527 -0.00134 0.00075
SOCM -68.295165 -24.454613 -0.00142 0.00020 -0.00172
CHAC -58.959693 -27.420439 -0.00088 0.00021 -0.00001
CUIB -56.069867 -15.555262 -0.00130 -0.00035 0.00023
PPTE -51.408534 -22.119903 -0.00080 -0.00000 0.00013
YCBA -63.679985 -22.017103 -0.00509 0.00062 0.00045
CATA -65.774121 -28.470984 -0.00043 0.00006 -0.00047
Dr. Jeffrey T. Freymueller Office: 907-474-7286
Geophysical Institute Cell: 907-378-7556
University of Alaska, Fairbanks Home: 907-479-3550
Fairbanks, AK 99775-7320 email: jeff.freymueller at gi.alaska.edu
URL: http://www.gps.alaska.edu/jeff/jeff.html
Download Alaska GPS data: ftp://gps.alaska.edu/pub/gpsdata/
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