Nori's research interests

Here, I briefly introduce my research. Through research I aim to gain better understanding of natural and manmade structures by analyzing seismic waves. Although the laterally averaged (i.e., 1D) Earth's seismic-velocity structure has been known accurately since the 1940s, subsurface is heterogeneity in 3D, even 4D, and understanding these heterogeneities is key to understanding Earth dynamics. Among the topics I am interested in predicting ground motion caused by large earthquakes, understanding earthquake source physics, discerning the history of the Earth, anticipating volcanic eruptions, and imaging the distribution of natural resources (e.g., petroleum, mines, geothermal). Seismic waves sample Earth's interior, and hence we can obtain information of the Earth in 3D. Temporally repeating these measurements opens a window into the dynamics of the Earth. To extract such information, I use manmade seismic sources, earthquakes, microseismic, and natural and anthropogenic background noise (aka ambient seismic noise).

Velocity changes caused by large earthquakes

With earthquake data observed between January 1 and May 26, 2011, I find about 5% S-wave velocity reduction in the near surface throughout northeastern Japan.

(Nakata and Snieder, GRL, 2011 and 2012)

One-dimensional seismic interferometry

Near-surface velocity

(Nakata and Snieder, JGR, 2012)

Builidng health monitoring

(Nakata et al., BSSA, 2013, Nakata and Snieder, BSSA, 2014)

Seismic interferometry with traffic noise

(Nakata et al., Geophys, 2011)

High Performance Computing

GPU wave

Elastic wave simulation needs huge computer power especially for three dimensions. By using a graphic processing unit (GPU), we obtain 10 times greater computing speed for computing 3D finite difference than by using CPU.

(Nakata et al., EG, 2011)

High resolution figures

Because we should reduce the size of PDF for our papers, the resolution of figures on the papers is sometimes not enough to use for your presentation. Here, you can download all figures with great resolution (mostly vector figures).