Observation of Earth's free oscillation by dense GPS array: After the 2011 Tohoku megathrust earthquake
نویسندگان
چکیده
Day-scale Earth's free oscillation after large earthquakes has been detected by underground instruments such as strainmeters, gravimeters and seismometers, to investigate Earth's internal structure, geodynamics, and source properties of earthquakes. Here we show that Global Positioning System (GPS) can also detect the signals of the Earth's free oscillation. A dense GPS array in Japan (GEONET) recorded the surface deformation following the 2011 Tohoku megathrust earthquake. A simple array analysis over 300 stations reduces local noise in GPS time series. We find that the dense GPS array truly detected both spheroidal and toroidal fundamental modes in three-direction displacement. This new tool has a strong potential to investigate the free oscillations particularly in low-frequency bands.
منابع مشابه
A detailed source model for theMw9.0 Tohoku-Oki earthquake reconciling geodesy, seismology, and tsunami records
The 11 March 2011 Mw9.0 Tohoku-Oki earthquake was recorded by an exceptionally large amount of diverse data offering a unique opportunity to investigate the details of this major megathrust rupture. Many studies have taken advantage of the very dense Japanese onland strong motion, broadband, and continuous GPS networks in this sense. But resolution tests and the variability in the proposed solu...
متن کامل6 Detecting the 2011 M 9 . 0 Tohoku Earthquake with Moment Tensors
The M9 Tohoku earthquake offshore Japan that occurred on May 11, 2011 triggered strong local and regional shaking as well as a large-scale tsunami that caused major damage in both the nearand far-field. The Japanese earthquake and tsunami warning systems were able to detect and locate the earthquake; however information regarding the focal mechanism of the event was unknown until the moment ten...
متن کاملThe Sanriku-Oki low-seismicity region on the northern margin of the great 2011 Tohoku-Oki earthquake rupture
[1] We examine a region of the megathrust fault offshore of northeastern Honshu (38.75°–40.25°N, 141.5°–143.25°E) that we designate as the Sanriku-Oki low-seismicity region (SLSR). The SLSR, located near the northern termination of the 2011 Tohoku-Oki (Mw 9.0) rupture, lacks historical great earthquake ruptures and has relatively low levels of moderate-size (Mj ≥ 5.0) earthquakes, with subregio...
متن کاملStructural heterogeneity in the megathrust zone and mechanism
[1] The great 2011 Tohoku‐oki earthquake (Mw 9.0) and its 339 foreshocks and 5,609 aftershocks (9–27 March 2011) were relocated using a three‐dimensional seismic velocity model and local P and S wave arrival times. The distribution of relocated hypocenters was compared with a tomographic image of the Northeast Japan forearc. The comparison indicates that the rupture nucleation of the largest ev...
متن کاملInversion of high ‐ rate ( 1 sps ) GPS data for rupture process of the 11 March 2011 Tohoku earthquake ( Mw 9 . 1 )
[1] The space‐time fault displacement history of the 11 March 2011 Tohoku (Mw 9.1) megathrust earthquake is obtained by least‐squares inversion of high‐rate (1 sample per second) GPS ground motions recorded in Japan. Complete near‐source time‐varying and static ground motions for periods ≥25 s are fit in the inversion using a normal mode formalism to compute the Green functions. The basic ruptu...
متن کامل