Article,
High-frequency rupture properties of the Mw 9.0 off the Pacific coast of Tohoku Earthquake
Earth, Planets, and Space, (July 2011)
DOI: 10.5047/eps.2011.07.009
Abstract
The devastating Mw 9.0 earthquake on March 11, 2011 is one of the
most complex earthquakes of all the recent large events. Its source
region is compact for an earthquake of this size, but it has highly
variable amount of energy release from different segments. These
conditions prevent conventional back-projection analysis to reveal
the details of the rupture process. We incorporate a new metric to
assess coherency as a part of back-projection analysis to ensure
identification of these weak features. The main features obtained
with this new back-projection approach are consistent with previous
back-projection results, with strongest energy release downdip and
close to the epicentral location. The main rupture propagation is
along strike, in southwestern direction giving rise to the length
extent of the earthquake. The new coherency function also allows
us to investigate rupture characteristics at the beginning of the
earthquake, resolving initial updip propagation from the epicentral
location. Furthermore, some of very weak energy in the stacks are
identified with high coherency. These additional source regions extend
the area of the earthquake farther south and north than the region
that has been imaged by other back-projection studies.
