Visualization of the seismic waves and permanent displacements

Visualization of the seismic waves and permanent displacements Ronni Grapenthin1 The ARIA Team2 Jeffrey Freymueller1 1 Geophysical Institute, Univ. of Alaska Fairbanks 2 SusanOwen, Jet Propulsion Laboratory Angelyn Moore, Jet Propulsion Laboratory Frank Webb, Jet Propulsion Laboratory Mark Simons, Caltech March 28, 2011 logo-gi 1 / 10

Tectonic Setting Paciﬁc plate moves westward and collides with Japan (Okhotsk Plate), subducts underneath this plate interaction drives earthquakes offshore Japan logo-gi Figure: USGS, http://earthquake.usgs.gov/earthquakes/world/japan/031111_M9.0prelim_geodetic_slip.php 2 / 10

BackgroundFor some background on plate mechanics, watch the following videomade available through the Education and Outreach Program ofIRIS (www.iris.edu/educate). logo-gi 3 / 10

Japan GEONET: Dense continuous GPS array started in 1993 by Geospatial Information Authority (GSI) of Japan with about 210 sites) 1995 Kobe earthquake tragedy resulted in intensiﬁed earthquake research see Sagiya (2004) for more details today: more than 1200 continuous GPS stations logo-gi 4 / 10

Permanent deformation measured by GPS 130 135 140 145 ARIA Preliminary Post and Coseismic 45 Displacements from Mw9.0 Sendai-Oki Earthquake 45 40 40 arrows show permanent horizontal displacements red: Mw 9.0 event at 05:46:23 UTC 35 35 blue: mainly Mw 7.9 event near Tokyo at 1m 06:26:12 UTC 1m 30 30 Figure shows horizontal displacements based on ARIA verion 0.3 position estimates for GEONET stations. Coseismic displacement is shown in red, and first 8 hours of postseismic motion is shown in blue, including motion caused by aftershocks. Bars at end of vector show logo-gi 95% error estimate. Solutions courtesy of ARIA team at JPL and Caltech (email aria@jpl.nasa.gov or aria@caltech.edu). All original GEONET RINEX data provided to Caltech by the Geospatial Information Authority (GSI) of Japan. 5 / 10

The displacement ﬁeld at 5:50 UTC is the sum of . . . logo-gi 6 / 10

. . . permanent displacement . . . logo-gi 7 / 10

. . . and seismic waves (watch for those in the video) logo-gi 8 / 10

Preliminary observations from the animation the actual slip of the Mw =9.0 earthquake is captured in frames 05:47:30-05:49:00 body waves (S-wave), causing small displacements, traverse the array at about 8 km/s (this is apparent velocity, not S-wave velocity) surface wave, causing large displacements, travels at about 5 km/s logo-gi 9 / 10

Links Preliminary Geodetic Slip Model of the 2011 M9.0 Tohoku-chiho Taiheiyo-oki Earthquake (USGS): http://earthquake.usgs.gov/earthquakes/world/japan/031111_M9.0prelim_geodetic_slip.php Geohazards Supersite website – preliminary results: http://supersites.earthobservations.org/sendai.php Seismic wave propagation recorded on dense strong-motion seismograph networks in Japan (K-NET/KiK-net): http://outreach.eri.u-tokyo.ac.jp/eqvolc/201103_tohoku/eng/#knet R. Grapenthin, Kinematic GPS solutions: http://gps.alaska.edu/ronni/sendai2011.html logo-gi 10 / 10

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Visualization of the seismic waves and permanent displacements

by Ronni Grapenthin

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