Research

Main Research Interests
Seismic sources - imaging and characterisation:

Multi-scale imaging of earthquake source rupture using coherent interferometry, kinematic fault slip inversion and aftershock analysis

Detection, location and characterization of seismic sources: application of array methods at local and regional scales for characterizing and monitoring seismic activity associated to earthquakes, slow-slip events (i.e., tectonic tremors, low-frequency earthquake) and micro seismicity



Research Projects:

  1. Detection, location and characterisation of multi-scale seismic energy sources using array-based methods
    In collaboration with Claudio Satriano, Pascal Bernard, Jean-Pierre Violate (IPGP, France) and Kazushige Obara (ERI, University of Tokyo):

    Main targets:
    • Development of array-based method for detection, location and characterization of multi-scale seismic energy release associated to the deformation processes.
    • Application to the analysis of seismic energy release of regular and slow earthquakes associated to the deformation processes of active subduction zones in Shikoku, South Western Japan, Central and Northern Chile.

    General description:
    Statistical analysis of seismic energy release, spanning a wide range of space and time scales, as well as phenomena, (e.g., earthquakes, seismic repeaters, low and very low-frequency earthquakes, tectonic tremors) can provide original insides to the problem of understanding the dynamics of active deformation and the mechanisms of generation and rupturing of large subduction earthquakes.
    We are working on developing a new methodology exploiting the frequency selective coherence of the wave-field at dense seismic arrays and local antennas that would provide a stable and reliable detection, separation, and location of distributed non-stationary seismic sources. The methodology consist of: (1) a signal processing scheme yielding a simplified representation of a seismic signal by an adaptive time-frequency characterization of its statistical properties (higher-order statistics); (2) a detection and location algorithm based on back projection of stacked local cross-correlations of the simplified signals.

    The new approach is being developed and tested on the Shikoku region in Japan, - an exceptional field laboratory, due to its high seismic activity comprising a wide variety of phenomena observed by the dense Hi-net seismic network operated by NIED. We evaluate the capability and potential of the proposed methodology to detect, locate and characterize the energy release associated to possibly overlapping seismic radiation from earthquakes and low-frequency tectonic tremors.
    As a further application we aim to perform a blind source detection using the data from the International Maule Aftershock Deployment (IMAD) in Central Chile.

    We are also looking into testing our method on the data sets other that those of interest in "traditional" seismology, such as: microseismic events associated to the mining or fracturing activities; seismic signals associated to volcanic activity, and landslides.


  2. Research during PhD study at ERI, Univ. of Tokyo (adviser Kazuki Koketsu, co-adviser Hiroe Miyake):
    Thesis title: The Origin of Near-Fault Ground Motion Pulses and Their Significance for Seismic Design.

  3. Main Research Topics:
    Earthquake Rupture Process (kinematic source modeling)
    Ground Motion Simulation (Empirical Green's Function Method)
    Extreme Ground Motions
    Rupture Directivity Effect


  4. Fast source process estimation for significant earthquakes worldwide
    Contribution to outreach activity at ERI

    Preliminary model of 2011 Tohoku earthquake
    http://www.eri.u-tokyo.ac.jp/PREV_HP/outreach/2010/03/201003_centralchile/
    http://taro.eri.u-tokyo.ac.jp/saigai/20100112eq/20100112.html
    http://taro.eri.u-tokyo.ac.jp/saigai/20090809eq/20090809.html
    http://taro.eri.u-tokyo.ac.jp/saigai/20090715eq/20090715.html
    http://taro.eri.u-tokyo.ac.jp/saigai/20090319eq/20090319.html
    http://taro.eri.u-tokyo.ac.jp/saigai/20090103eq/20090103.html
    http://taro.eri.u-tokyo.ac.jp/saigai/20081116eq/20081116.html