2011-09-30

Ionospheric electron enhancement preceding the 2011 Tohoku-Oki earthquake

A new paper by K. Heki in GRL seems to confirm what could become a tool for large earthquake prediction:

I reproduce the abstract of the paper:
The 2011 March 11 Tohoku‐Oki earthquake (Mw 9.0) caused vast damages to the country. Large events beneath dense observation networks could bring breakthroughs to seismology and geodynamics, and here I report one such finding. The Japanese dense network of Global Positioning System (GPS) detected clear precursory positive anomaly of ionospheric total electron content (TEC) around the focal region. It started ∼40 minutes before the earthquake and reached nearly ten percent of the background TEC. It lasted until atmospheric waves arrived at the ionosphere. Similar preseismic TEC anomalies, with amplitudes dependent on magnitudes, were seen in the 2010 Chile earthquake (Mw 8 .8), and possibly in the 2004 Sumatra‐Andaman (Mw 9.2) and the 1994 Hokkaido‐Toho‐Oki (Mw 8.3) earthquakes, but not in smaller earthquakes.

Reference: Heki, K. (2011), Ionospheric electron enhancement preceding the 2011 Tohoku‐Oki earthquake, Geophys. Res. Lett., 38, L17312, doi:10.1029/2011GL047908.

PD: Check this paper questioning the results by Heki.

2011-09-28

Video of ground motion during Tohoku's earthquake in Japan

Impressive video of the ground motions during Japan's earthquake. Horizontal motion in blue (left panel) and vertical component in red (right). The movie shows the displacements due to the M9.0 and M7.9 earthquakes in Japan on March 11, 2011 (data, no model!). Each dot/arrow represents a continuous high precision GPS station of which more than 1200 are distributed throughout Japan. According to the author (Grapenthin, Alaska Univ.), this is an absolutely unique instrumentation density found nowhere else on the world.


You can distinguish body and surface waves, dynamic slip, and static displacements. Further details and higher resolution video for download at:http://gps.alaska.edu/ronni/sendai2011.html

Also have a look at this other post where you have a video of the release of stress through time.

Visualization: R. Grapenthin, Geophysical Institute, Univ. Alaska Fairbanks.
Data: preliminary GPS positioning solutions provided by ARIA/HPL/Caltech (ftp://sideshow.jpl.nasa.gov/pub/usrs/ARIA). All original GEONET RINEX data were provided to Caltech by the Geospatial Information Authority (GSI) of Japan.


Original scientific paper:
Grapenthin, Ronni; Freymueller, Jeffrey T.
The dynamics of a seismic wave field: Animation and analysis of kinematic GPS data recorded during the 2011 Tohoku-oki earthquake, Japan.
Geophys. Res. Lett., Vol. 38, No. 18, L18308
http://dx.doi.org/10.1029/2011GL048405
22 September 2011