Coseismic change and precipitation effect in temporal gravity variation at Inuyama, Japan: A case of the 2004 off the Kii peninsula earthquakes observed with a superconducting gravimeter

Nawa, Kazunari; Suda, Nobuhide; Yamada, Isao; Miyajima, Rikio; Okubo, Shuhei

doi:10.1016/j.jog.2009.01.006

Cited by 19 publications

(15 citation statements)

References 13 publications

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“…pirical models A number of researchers have predicted changes in gravity due to variations in land-water distributions through empirical models, by assuming a simple gravity response to the water plane thickness (e.g., Imanishi et al, 2006;Nawa et al, 2009). However, water flow is governed by nonlinear equations (Eq.…”

Section: Comparison Between the Physical Model And Em-mentioning

confidence: 99%

“…Firstly, the majority of models, including the tank model, assume a linear gravity response to precipitation (e.g., Hanada et al, 1990;Imanishi et al, 2006;Nawa et al, 2009;Lampitelli and Francis, 2010). Since water flow is governed by non-linear equations (as demonstrated in this study), there are limitations in applying linear theory to gravity responses (Kazama et al, 2005).…”

Section: Introductionmentioning

confidence: 99%

“…Many scientists have modeled the effects of land-water distribution on the observed gravity (e.g., Francis et al, 2004;Abe et al, 2006;Boy and Hinderer, 2006;Meurers et al, 2007;Jahr et al, 2009;Leirião et al, 2009;Longuevergne et al, 2009;Nawa et al, 2009;Pfeffer et al, 2011). For example, Hanada et al (1990) found a simple proportional relationship between water level and abCopyright c The Society of Geomagnetism and Earth, Planetary and Space Sciences (SGEPSS); The Seismological Society of Japan; The Volcanological Society of Japan; The Geodetic Society of Japan; The Japanese Society for Planetary Sciences; TERRAPUB.…”

Section: Introductionmentioning

confidence: 99%

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Gravity changes associated with variations in local land-water distributions: Observations and hydrological modeling at Isawa Fan, northern Japan

et al. 2012

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Gravity changes associated with variations in local land-water distributions have been observed at Isawa Fan in northern Japan, and modeled by hydrological equations. We solve the Richards equation numerically for the time variation in the vertical soil moisture distribution, which is then spatially integrated to estimate gravity changes due to the soil moisture distribution. In modeling Isawa Fan, we assume a simple hydrological model: a horizontally homogeneous soil in an infinite half-space. The estimated gravity is consistent with the observed gravity during a 50-day period within about 0.4 µgal root mean square, owing to both observed soil parameter values and the observation building geometry being incorporated into the hydrological model. However, the estimated gravity cannot fully reproduce annual gravity changes observed during a 2-year time frame, because the boundary conditions in the modeling determine only local water distributions and the resultant short-period gravity changes. Instead, the observed gravity over these 2 years can be reproduced within about 1.0 µgal root mean square, if the additional parameters of the annual gravity change (A ac and A as ) and the snowfall effect (A s ) are calculated by the function regression to the observed gravity with the least-squares method. The hydrological modeling techniques presented here can be utilized at all gravity sites in flat areas similar to Isawa Fan, such that hydrological effects in gravity data can be corrected and mass transfers associated with earthquakes and volcanoes can be monitored.

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Section: Comparison Between the Physical Model And Em-mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Gravity changes associated with variations in local land-water distributions: Observations and hydrological modeling at Isawa Fan, northern Japan

et al. 2012

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“…2), belonging to the National Astronomical Observatory of Japan, with the main purpose of detecting possible gravity signals associated with long-term slow slip events occurring beneath the Yaeyama Islands (Heki and Kataoka 2008). This gravimeter had been in operation until 2011 at the Inuyama Observatory of Nagoya University (e.g., Nawa et al 2009). Ikeda et al (2013) described the preparatory work for the gravimeter before its movement to the Ishigakijima Island.…”

Section: Introductionmentioning

confidence: 99%

Effects of horizontal acceleration on the superconducting gravimeter CT #036 at Ishigakijima, Japan

Imanishi

Nawa

Tamura

et al. 2018

Earth Planets Space

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In the gravity sensor of a superconducting gravimeter, a superconducting sphere as a test mass is levitated in a magnetic field. Such a sensor is susceptible to applied horizontal as well as vertical acceleration, because the translational degrees of freedom of the mass are not perfectly limited to the vertical direction. In the case of the superconducting gravimeter CT #036 installed at Ishigakijima, Japan, horizontal ground acceleration excited by the movements of a nearby VLBI antenna induces systematic step noise within the gravity recordings. We investigate this effect in terms of the static and dynamic properties of the gravity sensor using data from a collocated seismometer. It is shown that this effect can be effectively modeled by the coupling between the horizontal and vertical components in the gravity sensor. It is also found that the mechanical eigenfrequency for horizontal translation of the levitating sphere is approximately 3 Hz.

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“…A 1 nanoGal sensitivity and a 1 Hz sampling rate make SGs very useful for detecting internal gravity waves inside the earth, and thus for determining the influence of environmental effects on gravity (Ikeda et al 2005). A series of co-seismic gravity perturbations were detected and analyzed using SGs to demonstrate their sensitivity, with results compared with those obtained by seismometers (Imanishi et al 2004;Hwang et al 2009;Kim et al 2009;Nawa et al 2009). The gravity signal of an SG is influenced by many natural events, including free oscillations of the Earth after a strong earthquake (Virtanen 1996;Park et al 2005;Arora et al 2008), seismic background noise (Virtanen 1998), the gravity effects of hydrological phenomena (Virtanen 2000(Virtanen , 2001, and variation in atmospheric mass (Virtanen and Mäkinen 2003;Virtanen 2004).…”

Section: Introductionmentioning

confidence: 99%

An Analysis of Mechanical Constraints when Using Superconducting Gravimeters for Far-Field Pre-Seismic Anomaly Detection

Lan¹,

Yu²,

Hwang³

et al. 2011

Terr. Atmos. Ocean. Sci.

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Pre-seismic gravity anomalies from records obtained at a 1 Hz sampling rate from superconducting gravimeters (SG) around East Asia are analyzed. A comparison of gravity anomalies to the source parameters of associated earthquakes shows that the detection of pre-seismic gravity anomalies is constrained by several mechanical conditions of the seismic fault plane. The constraints of the far-field pre-seismic gravity amplitude perturbation were examined and the critical spatial relationship between the SG station and the epicenter precursory signal for detection was determined. The results show that: (1) the preseismic amplitude perturbation of gravity is inversely proportional to distance; (2) the transfer path from the epicenter to the SG station that crosses a tectonic boundary has a relatively low pre-seismic gravity anomaly amplitude; (3) the pre-seismic gravity perturbation amplitude is also affected by the attitude between the location of an SG station and the strike of the ruptured fault plane. The removal of typhoon effects and the selection of SG stations within a certain intersection angle to the strike of the fault plane are essential for obtaining reliable pre-seismic gravity anomaly results.

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Coseismic change and precipitation effect in temporal gravity variation at Inuyama, Japan: A case of the 2004 off the Kii peninsula earthquakes observed with a superconducting gravimeter

Cited by 19 publications

References 13 publications

Gravity changes associated with variations in local land-water distributions: Observations and hydrological modeling at Isawa Fan, northern Japan

Gravity changes associated with variations in local land-water distributions: Observations and hydrological modeling at Isawa Fan, northern Japan

Effects of horizontal acceleration on the superconducting gravimeter CT #036 at Ishigakijima, Japan

An Analysis of Mechanical Constraints when Using Superconducting Gravimeters for Far-Field Pre-Seismic Anomaly Detection

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