Solving mysteries in the Earth though space geodesy
Department of Earth and Planetary Sciences, Earth and Planetary Dynamics
Exploration of the shape, rotation, gravity of the Earth and their change in time using mainly satellite data
|Field||Geodesy, Seismology, Upper atmosphere physics, Geodynamics|
|Keyword||Gravity, Crustal deformation, Ionosphere/troposphere, Plate tectonics, Satellite positioning, Lunar/planetary exploration, Space geodetic techniques, Earth rotation|
Introduction of Research
Most researchers in earth sciences focus on particular phenomena, e.g. earthquake, volcanic eruption, atmospheric dynamics, ocean circulation, and try to solve mysteries in those phenomena with various approaches. On the other hand, researchers of space geodesy, like me, have their favorite space techniques and become interested in everything they could study with those techniques regardless of disciplines. For example, GRACE satellites can measure subtle change in the Earth’s gravitational attraction and let us study e.g. glacial mass loss due to global warming, precipitation anomalies induced by climate changes, and gravity changes by megathrust earthquakes. GNSS (e.g. GPS) is the most versatile sensor in geophysics. I use GNSS to measure short-term crustal movements such as coseismic jumps as well as long-term motions reflecting plate tectonics and slow earthquakes. Measurement of ionospheric total electron contents with GNSS offered hot topics, e.g. constraint of the orbits and powers of ballistic missiles, discovery of changes in ionosphere immediately before large earthquakes.
Averaged monthly gravity changes in terms of equivalent water depth obtained by analyzing the GRACE time-variable gravity data. Red and blue indicate the gravity increase and decrease. Change in ionospheric total electron content (TEC) before and after the 2011 Tohoku-oki earthquake (5:46 UT) observed with GNSS satellite data. Positive TEC anomaly started ~40 minutes (left) over the region overlapping with the megathrust fault (right). See Parity 2018 Feb. issue for detail.
Mw dependence of preseismic ionospheric electron enhancements, K. Heki, and Y. Enomoto, J. Geophys. Res. Space Phys., 120, 7006-7020, 2015.
Accelerated Pacific Plate subduction following interplate thrust earthquakes at the Japan Trench, K. Heki and Y. Mitsui, Earth Planet. Sci. Lett., 363, 44-49, 2013.
Seasonal modulation of interseismic strain build-up in Northeastern Japan driven by snow loads, K. Heki, Science, 293, 89-92, 2001.
Silent fault slip following an interplate thrust earthquake at the Japan Trench, Heki, K., S. Miyazaki and H. Tsuji, Nature, 386, 595-597, 1997.
Rotation of the Peruvian Block from palaeomagnetic studies of the Central Andes, Heki, K., Y. Hamano and M. Kono, Nature, 305, 514-516, 1983.
|Self Introduction||No geodesy, no geophysics!|
|Academic background||1979 BSc Univ. Tokyo, Geophysical Inst.|
1984 DSc Univ. Tokyo, Geophysical Inst.
1984-1994 Res. Official, Radio Res. Lab., MPT
1990-1992 Postdoc Univ. Durham (UK)
1994-2001 Assoc. Prof., Earth Rotation Div., Nat. Astr. Obs. Japan
2001-2004 Prof. ibid
2004- Prof. Hokkaido Univ.
|Affiliated academic society||Geodetic Soc. Japan, American Geophys. Union, Seism. Soc. Japan|
|Project||IAG Global Geodetic Observing System|
|Room address||Science Bldg. No.8 8-317|