The Experts below are selected from a list of 114 Experts worldwide ranked by ideXlab platform
Minoru Tsutsui - One of the best experts on this subject based on the ideXlab platform.
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Detections and Confirmation of Co-seismic Electromagnetic Pulses in the Earth
2020Co-Authors: Minoru TsutsuiAbstract:In order to confirm whether electromagnetic (EM) pulses could be excited or not when Earthquakes occurred, we first began to measure electric noise in an electrically non-conductive borehole of 100 m in depth which was constructed in the campus of Kyoto Sangyo University in 1999. It was found, from the measurements, that many impulsive noises were detected even in the Earth, and was expected that these impulsive noise would be generated in the Earth because their intensity in the Earth is stronger than those detected above the ground [1]. It is considered that these impulsive electric noises would be electric field component of EM pulses. In order to clarify the relation between locations of detected EM pulses and of Earthquake occurrences, we next accomplished a sensor system for determining arrival directions of EM pulses, aiming to find their source locations. At 14:49:56 of January 6, 2004, the new system detected an EM pulse just when an Earthquake occurred at off-shore of Kumano-nada, Mie-prefecture, and simultaneously displayed its arrival direction pointing toward the Earthquake as shown in Fig. 1. From frequency dispersion characteristic curves derived from waveforms of the detected electric and magnetic field components of the EM pulse, we estimated its propagation distance, and found that the source location of the EM pulse was in the epicenter region of the Earthquqake (see Fig.1). The result suggested that the EM pulse had first leaked out of the ground surface of the epicenter region Fig. 1 Source location of Earth-Origin EM pulse detected at of the Earthquake and was propagating 14:49:54, Jan. 6, 2004 when the Earthquake occurred. between the ionosphere and the ground The source location was in the epicenter region. 135.5E
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Three dimensional propagation directions of electromagnetic pulses detected in the Earth
2012 IEEE International Geoscience and Remote Sensing Symposium, 2012Co-Authors: Minoru Tsutsui, Taka Nakatani, Munetoshi KamitaniAbstract:Completing a tri-axial electromagnetic (EM) sensor system used in a narrow borehole, and inserting it into 150 m deep borehole constructed on a seashore, we began to measure three dimensional arrival directions of EM pulses detected in the Earth by means of strict calculation of Poynting vector. Measured arrival directions have shown clear difference in EM environment between on the landside and seaside of the observation point on the seashore. On the landside, many up-propagating lightning EM pulses were detected, which would result from their reflections at deeper layers than the sensor depth after penetrating into the ground. Another is less detections of EM pulses on the seaside, which is due to strong decay of lightning EM pulses penetrated into the sea water. The less detections of lightning EM pulses on the seaside suggests favorable situation for the observation of Earth-Origin EM pulses.
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IGARSS - Three dimensional propagation directions of electromagnetic pulses detected in the Earth
2012 IEEE International Geoscience and Remote Sensing Symposium, 2012Co-Authors: Minoru Tsutsui, Taka Nakatani, Munetoshi KamitaniAbstract:Completing a tri-axial electromagnetic (EM) sensor system used in a narrow borehole, and inserting it into 150 m deep borehole constructed on a seashore, we began to measure three dimensional arrival directions of EM pulses detected in the Earth by means of strict calculation of Poynting vector. Measured arrival directions have shown clear difference in EM environment between on the landside and seaside of the observation point on the seashore. On the landside, many up-propagating lightning EM pulses were detected, which would result from their reflections at deeper layers than the sensor depth after penetrating into the ground. Another is less detections of EM pulses on the seaside, which is due to strong decay of lightning EM pulses penetrated into the sea water. The less detections of lightning EM pulses on the seaside suggests favorable situation for the observation of Earth-Origin EM pulses.
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Method of Pointing Source Locations of Earth-Origin Electromagnetic Pulses as a Precursor of Earthquakes
Ieej Transactions on Fundamentals and Materials, 2009Co-Authors: Minoru TsutsuiAbstract:In order to confirm that Earth-Origin electromagnetic (EM) pulses could be excited by dynamical stress impacts onto Earth crusts, we have been developing a method of pointing source locations of EM pulses on real-time basis, using a highly sensitive direction finding sensor system installed in deep boreholes at geographically different observation sites. Source locations of EM pulses can be determined by intersected points of arrival direction lines obtained at the observation sites. Through test measurements, we found that many detected EM pulses were unnecessary ones radiated from electric power lines on the ground and their related Earth currents. It tells us a most important remark to beware in measurements of natural electromagnetic phenomena. By taking the preventive measures against noise, we obtained a preliminary result of source locations of EM pulses which are concentrated in an area of off-shore of Tou-Nan-Kai where is an area of potential Earthquake occurrences in the future. Through the present developing process, we have proceeded to another stage toward the establishment of an observation network for accurately pointing source locations of Earth-Origin EM pulses on real-time basis.
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Spatial Distribution of Source Locations of Earth-Origin Electromagnetic Pulses Excited before Earthquakes
Ieej Transactions on Fundamentals and Materials, 2006Co-Authors: Minoru Tsutsui, Takeshi MaenishiAbstract:In order to find a possibility of Earth-Origin electromagnetic (EM) pulses as a precursor of Earthquakes, we attempted to obtain spatial distributions of source locations of many EM pulses detected two days before Earthquakes. In this paper, we first introduce the procedure for obtaining their source locations, which consists of determinations of exact arrival directions of the EM pulses, estimations of their propagation distances and identifications of their source locations. In deriving a spatial distribution of their locations, we found that the EM pulse sources had been drifting during the period of about 6 hours. The area of the spatial distribution of their source locations was rather small but far from the Earthquake epicenter. The spatial difference between the EM pulse source locations and the Earthquake epicenter is discussed from view points of conditions for excitations and propagations of EM pulses.
Nicholas Barnett-moore - One of the best experts on this subject based on the ideXlab platform.
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The deep Earth Origin of the Iceland plume and its effects on regional surface uplift and subsidence
Solid Earth, 2016Co-Authors: Nicholas Barnett-moore, Rakib Hassan, Nicolas Flament, Dietmar MüllerAbstract:Abstract. The present-day seismic structure of the mantle under the North Atlantic Ocean indicates that the Iceland hotspot represents the surface expression of a deep mantle plume, which is thought to have erupted in the North Atlantic domain during the Palaeocene. The spatial and temporal evolution of the plume since its eruption is still highly debated, and little is known about its deep mantle history. Here, we use palaeogeographically constrained global mantle flow models to investigate the evolution of deep Earth flow beneath the North Atlantic since the Jurassic. The models show that over the last ∼ 100 Myr a remarkably stable pattern of convergent flow has prevailed in the lowermost mantle near the tip of the African Large Low-Shear Velocity Province (LLSVP), making it an ideal plume nucleation site. We extract model dynamic topography representative of a plume beneath the North Atlantic region since eruption at ∼ 60 Ma to present day and compare its evolution to available offshore geological and geophysical observations across the region. This comparison confirms that a widespread episode of Palaeocene transient uplift followed by early Eocene anomalous subsidence can be explained by the mantle-driven effects of a plume head ∼ 2500 km in diameter, arriving beneath central eastern Greenland during the Palaeocene. The location of the model plume eruption beneath eastern Greenland is compatible with several previous models. The predicted dynamic topography is within a few hundred metres of Palaeocene anomalous subsidence derived from well data. This is to be expected given the current limitations involved in modelling the evolution of Earth's mantle flow in 3-D, particularly its interactions with the base of a heterogeneous lithosphere as well as short-wavelength advective upper mantle flow, not captured in the presented global models.
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The deep Earth Origin of the Iceland plume and its effects on regional surface uplift and subsidence
2016Co-Authors: Nicholas Barnett-moore, Rakib Hassan, Nicolas Flament, R. D. MüllerAbstract:Abstract. The present-day seismic structure of the mantle under the North Atlantic indicates that the Iceland hotspot represents the surface expression of a deep mantle plume, which is thought to have erupted in the North Atlantic during the Paleocene. The spatial and temporal evolution of the plume since its eruption is still highly debated, and little is known about its deep mantle history. Here, a paleogeographically constrained global mantle flow model is used to investigate the evolution of deep Earth flow and surface dynamic topography in the North Atlantic since the Jurassic. The model shows that over the last ~ 100 Myr a remarkably stable pattern of convergent flow has prevailed in the lowermost mantle near the tip of the African Large Low-Shear Velocity Province (LLSVP), making it an ideal plume nucleation site. The present-day location of the model plume is ~ 10° southeast from the inferred present-day location of the Iceland plume. We apply a constant surface rotation to the model through time, derived from correcting for this offset at present-day. A comparison between the rotated model dynamic topography evolution and available offshore geological and geophysical observations across the region confirms that a widespread episode of Paleocene transient uplift followed by early Eocene anomalous subsidence can be explained by the mantle-driven effects of a plume head ~ 2000 km in diameter, arriving beneath central western Greenland during the Paleocene. The rotated model plume eruption location beneath Western Greenland is compatible with previous models. The mantle flow model underestimates the magnitude of observed anomalous subsidence during the Paleocene in some parts of the North Atlantic by as much as several hundred meters, which we attribute to upper mantle convection processes, not captured by the model.
Munetoshi Kamitani - One of the best experts on this subject based on the ideXlab platform.
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Three dimensional propagation directions of electromagnetic pulses detected in the Earth
2012 IEEE International Geoscience and Remote Sensing Symposium, 2012Co-Authors: Minoru Tsutsui, Taka Nakatani, Munetoshi KamitaniAbstract:Completing a tri-axial electromagnetic (EM) sensor system used in a narrow borehole, and inserting it into 150 m deep borehole constructed on a seashore, we began to measure three dimensional arrival directions of EM pulses detected in the Earth by means of strict calculation of Poynting vector. Measured arrival directions have shown clear difference in EM environment between on the landside and seaside of the observation point on the seashore. On the landside, many up-propagating lightning EM pulses were detected, which would result from their reflections at deeper layers than the sensor depth after penetrating into the ground. Another is less detections of EM pulses on the seaside, which is due to strong decay of lightning EM pulses penetrated into the sea water. The less detections of lightning EM pulses on the seaside suggests favorable situation for the observation of Earth-Origin EM pulses.
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IGARSS - Three dimensional propagation directions of electromagnetic pulses detected in the Earth
2012 IEEE International Geoscience and Remote Sensing Symposium, 2012Co-Authors: Minoru Tsutsui, Taka Nakatani, Munetoshi KamitaniAbstract:Completing a tri-axial electromagnetic (EM) sensor system used in a narrow borehole, and inserting it into 150 m deep borehole constructed on a seashore, we began to measure three dimensional arrival directions of EM pulses detected in the Earth by means of strict calculation of Poynting vector. Measured arrival directions have shown clear difference in EM environment between on the landside and seaside of the observation point on the seashore. On the landside, many up-propagating lightning EM pulses were detected, which would result from their reflections at deeper layers than the sensor depth after penetrating into the ground. Another is less detections of EM pulses on the seaside, which is due to strong decay of lightning EM pulses penetrated into the sea water. The less detections of lightning EM pulses on the seaside suggests favorable situation for the observation of Earth-Origin EM pulses.
R. D. Müller - One of the best experts on this subject based on the ideXlab platform.
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The deep Earth Origin of the Iceland plume and its effects on regional surface uplift and subsidence
2016Co-Authors: Nicholas Barnett-moore, Rakib Hassan, Nicolas Flament, R. D. MüllerAbstract:Abstract. The present-day seismic structure of the mantle under the North Atlantic indicates that the Iceland hotspot represents the surface expression of a deep mantle plume, which is thought to have erupted in the North Atlantic during the Paleocene. The spatial and temporal evolution of the plume since its eruption is still highly debated, and little is known about its deep mantle history. Here, a paleogeographically constrained global mantle flow model is used to investigate the evolution of deep Earth flow and surface dynamic topography in the North Atlantic since the Jurassic. The model shows that over the last ~ 100 Myr a remarkably stable pattern of convergent flow has prevailed in the lowermost mantle near the tip of the African Large Low-Shear Velocity Province (LLSVP), making it an ideal plume nucleation site. The present-day location of the model plume is ~ 10° southeast from the inferred present-day location of the Iceland plume. We apply a constant surface rotation to the model through time, derived from correcting for this offset at present-day. A comparison between the rotated model dynamic topography evolution and available offshore geological and geophysical observations across the region confirms that a widespread episode of Paleocene transient uplift followed by early Eocene anomalous subsidence can be explained by the mantle-driven effects of a plume head ~ 2000 km in diameter, arriving beneath central western Greenland during the Paleocene. The rotated model plume eruption location beneath Western Greenland is compatible with previous models. The mantle flow model underestimates the magnitude of observed anomalous subsidence during the Paleocene in some parts of the North Atlantic by as much as several hundred meters, which we attribute to upper mantle convection processes, not captured by the model.
Dietmar Müller - One of the best experts on this subject based on the ideXlab platform.
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The deep Earth Origin of the Iceland plume and its effects on regional surface uplift and subsidence
Solid Earth, 2016Co-Authors: Nicholas Barnett-moore, Rakib Hassan, Nicolas Flament, Dietmar MüllerAbstract:Abstract. The present-day seismic structure of the mantle under the North Atlantic Ocean indicates that the Iceland hotspot represents the surface expression of a deep mantle plume, which is thought to have erupted in the North Atlantic domain during the Palaeocene. The spatial and temporal evolution of the plume since its eruption is still highly debated, and little is known about its deep mantle history. Here, we use palaeogeographically constrained global mantle flow models to investigate the evolution of deep Earth flow beneath the North Atlantic since the Jurassic. The models show that over the last ∼ 100 Myr a remarkably stable pattern of convergent flow has prevailed in the lowermost mantle near the tip of the African Large Low-Shear Velocity Province (LLSVP), making it an ideal plume nucleation site. We extract model dynamic topography representative of a plume beneath the North Atlantic region since eruption at ∼ 60 Ma to present day and compare its evolution to available offshore geological and geophysical observations across the region. This comparison confirms that a widespread episode of Palaeocene transient uplift followed by early Eocene anomalous subsidence can be explained by the mantle-driven effects of a plume head ∼ 2500 km in diameter, arriving beneath central eastern Greenland during the Palaeocene. The location of the model plume eruption beneath eastern Greenland is compatible with several previous models. The predicted dynamic topography is within a few hundred metres of Palaeocene anomalous subsidence derived from well data. This is to be expected given the current limitations involved in modelling the evolution of Earth's mantle flow in 3-D, particularly its interactions with the base of a heterogeneous lithosphere as well as short-wavelength advective upper mantle flow, not captured in the presented global models.
