Apparent seasonal site position variations are derived from 4.5 years of global continuous GPS time series and explored through the “peering” approach. Peering is a way to depict contributions comparatively well‐known sources garner insight into relatively poorly known contributors. Contributions pole tide effects, ocean loading, atmospheric nontidal oceanic mass, groundwater loading evaluated. Our results show that ∼40% power observed annual vertical in positions can be explained by joint...

We report a “slow thrust slip event” that occurred beneath the Bungo Channel region, southwestern Japan. On Oct. and Dec., 1996, two Hyuganada earthquakes (both M w = 6.7), followed by afterslips, occurred. In addition, crustal movement characterized an extremely slow rise was observed around Channel, about 200 km north from epicenters, continued for 300 days long. Assuming on plate boundary, we estimate its duration surface displacements GPS time series data curve‐fitting, then, determine...

The dual frequency radio signals of the Global Positioning System (GPS) allow measurements total number electrons, called electron content (TEC), along a ray path from GPS satellite to receiver. We have developed new technique construct two-dimensional maps absolute TEC over Japan by using data more than 1000 receivers. A least squares fitting procedure is used remove instrumental biases inherent in and Two-dimensional vertical are derived with time resolution 30 seconds spatial 0.15° ×...

We investigate crustal deformation in southwest Japan over a 3‐year period revealed by permanent dense Global Positioning System (GPS) array. Southwest is part of the Amurian Plate, microplate moving about 10 mm/yr toward east with respect to Eurasian Plate. It overrides Philippine Sea Plate at Nankai Trough and collides northeast arc central Japan. In this paper we first derive GPS site velocities relative stable order isolate signals caused subduction and/or collision. The velocity field...

Two‐dimensional total electron content (TEC) perturbations over Japan are mapped with the Geographical Survey Institute (GSI) GPS network, GEONET (GPS Earth Observation Network). Its spatial resolution is 0.15° latitude × longitude and temporal 30 seconds. TEC observations these high resolutions revealed structures evolutions of traveling ionospheric disturbances (TIDs) in nighttime mid‐latitude ionosphere on July 03, 1997. A preliminary result perturbation mapping indicates that it would be...

GPS time series following the September 25, 2003 (UT) Tokachi‐oki earthquake ( M W ∼ 8.0) reveal significant deformation. We use Network Inversion Filter to invert for spatial and temporal evolution of afterslip in 30 days earthquake. Afterslip is concentrated adjacent coseismic rupture zone, between inferred source regions 1968 1973 Nemuro‐oki earthquakes. The inversion shows a rapid decay slip‐rate with slower deceleration surrounding regions. stress‐velocity paths approximately follow d...

We analyze permanent Global Positioning System (GPS) data obtained over Japan between 1995 and 1997 to estimate the instantaneous interseismic coupling ratio of seismogenic zones due subduction Pacific Philippine Sea plates below Japanese islands. first derive GPS strain rate fields that characterize crustal deformation southern northern invert them determine effective velocity along central Nankai trough on one side Japan‐west Kurile trench other. These “reference free” velocities are close...

[1] Episodic Tremor and Slip (ETS), involving transient deformations accompanied by emergent, low-frequency tremor occurs in subduction zones around the world. ETS events increase shear stress on locked megathrusts may potentially trigger damaging earthquakes. Despite clear association of slip physical relationship between them is unresolved. appears to result from small asperities plate interface due either creep surrounding fault, or increases ahead propagating slow-slip front. Previous...

When the frequency of a low-voltage r-f signal superposed on probe was swept within an adequate range, d-c component electron current due to nonlinearity sheath impedance measured. lt found that resonant increase appeared in at plasma frequency, omega /sub p/ = (4 pi N/sub 0/e/sup 2/m)/sup 1/2/, wh ere 0/ is density. The relation between voltage and corresponding shown. height resonance peak depended not only magnitude voltage, but collision electrons with atoms. (M.C.G.)

We simultaneously estimate 2.5 years of afterslip and viscoelastic relaxation, as well coseismic slip, for the 2011 Tohoku-oki earthquake. Displacements at inland GPS seafloor GPS/Acoustic stations are inverted using Green's functions a model with an upper elastic layer lower substrate. The result shows that is isolated from rupture area possibly asperities historical earthquakes has almost decayed by 10 September 2013, after main shock. inversion also suggests observed landward postseismic...

The strong motion and geodetic data were individually inverted for the source process of 2003 Tokachi-oki, Hokkaido, earthquake with a hypocenter 25 km deep fault plane above subducting Pacific slab. Both results show simple slip distribution single major asperity, but inversion may include trade-off between location rupture time does not have sufficient resolution far slips. We then carred out joint two datasets in order to overcome these weaknesses dataset inversions. resultant still...

We use Global Positioning System (GPS) velocity data to model eastern Asian plate kinematics. Out of 15 stations in Korea, Russia, China, and Japan studied here, three sites considered be on the stable interior hypothetical Amurian Plate showed eastward velocities as fast ∼9–10 mm/yr with respect Eurasian Plate. They were stationary relative each other within 1 mm/yr, these vectors together those a few additional used accurately determine instantaneous angular (Euler) vector The predicted...

Temporal change of deformation in northeastern Japan is clarified by continuous Global Positioning System (GPS) observations from 1995 April to 2002 March. The observed GPS velocity approximately parallel the direction plate convergence on east and west boundaries shows post-seismic transient around source regions Mw 7.8 1993 Hokkaido-Nansei-Oki 7.7 1994 Sanriku-Haruka-Oki earthquakes. We interpret as contemporary interplate coupling subducting boundary Pacific Plate collision Amurian Plate....

We investigate an ongoing silent thrust event in the Tokai seismic gap along Suruga‐Nankai Trough, central Japan. Prior to event, continuous GPS data from April 1996 end of 1999 show that this region displaced ∼2 cm/yr northwest relative landward plate. The time series abrupt change rate mid‐June 2000 continues as mid‐2005. model transient deformation, which we refer slow slip caused by on interface between Philippine Sea and Amurian plates. spatial temporal distribution is estimated with...

Surveys by continuous Global Positioning System in and around Japan revealed that the Amurian Plate collides with North American central ∼2 cm/yr. Long‐term crustal deformation seems to be influenced mainly this collision although subduction of oceanic plates governs short‐term elastic over arc. Here we study long‐term field carefully removing signals inferred from a‐priori plate convergence vectors coupling strengths predicted a thermal model. The obtained shows change velocities occurs...

Analysis of Global Positioning System (GPS) data shows transient crustal deformation in the Boso peninsula, central Japan, for about fifty days from October 2002. The southeastward horizontal displacements detected suggest occurrence interplate aseismic slip between Philippine Sea plate and North American plate, six years after a similar event 1996. We estimate an area with moment magnitude ( M w ) 6.6 centered off adjacent to associated seismic activity. Slip evolution 2002 aeismic started...

High‐rate GPS has the potential to recover both dynamic and static displacements accurately. We analyze 1‐Hz data recorded during 2003 Tokachi‐Oki earthquake. The displacement waveforms show good agreement with integrated accelerometer records except for low frequency noise that are inherently present in seismic records. were inverted model spatio‐temporal evolution of fault slip rupture. is found propagate downdip subduction zone largest moment release ∼50 km northwest hypocenter. region...

The F ‐region Radio and Optical measurement of Nighttime TID (FRONT) campaign was conducted to clarify the non‐classical features traveling ionospheric disturbances (TIDs) at mid‐latitudes in May, 1998 August, 1999. A cluster all‐sky CCD cameras a GPS receiver network observed wide area ionosphere over Japan detect spatial structure temporal evolution TIDs. propagation direction nighttime detected during FRONT periods is restricted southwest. time their amplitude indicates that intensified...

The nighttime traveling ionospheric disturbances (TIDs) and the F -region 3-m scale field-aligned irregularities were simultaneously observed with MU radar GEONET, a GPS network, during FRONT (F-region Radio Optical measurement of Nighttime TID) campaign periods in May 1998 August 1999. vertical profile electron density detected by incoherent scatter observation clarified that ionized atmosphere on bottomside F-region was deeply modulated TIDs, which would cause variations 630 nm band...

The March 11, 2011, off the Pacific coast of Tohoku Earthquake is first great subduction zone earthquake to be recorded by a dense, modern network geodetic quality Global Positioning System (GPS) receivers, and hence presents an unprecedented opportunity study evolution fault slip during time periods immediately before, during, after truly earthquake. We utilized sub-daily GPS data constrain distribution in 9 Mw 7.3 foreshock, 50-hour period between coseismic 9.0 mainshock. find that...

This paper reports the first attempt to observe equatorward limit of medium-scale traveling ionospheric disturbances (TIDs) in middle latitudes. The TIDs usually propagate southwestward northern hemisphere. An all-sky cooled-CCD imager measured 630-nm airglow at a southern island Japan, Okinawa (26.9°N, 128.3°E, geomagnetic latitude (MLAT) = 17.0°), during FRONT-2 campaign August 4–15, 1999. were detected mainland Japan (∼21°–36° MLAT) by total electron content (TEC) observations more than...