Research for Non-volcanic Deep Tremors by ushig Seismic Array and Electromapetic Active Monitoring

• Project/Area Number: 18340132
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Solid earth and planetary physics
• Research Institution: Shizuoka University
• Principal Investigator: FUJII Naoyuki Shizuoka University, 理学部, Visiting Professor (60011631)
• Co-Investigator(Kenkyū-buntansha): WATANABE Toshiki Nagoya University, 環境学研究科, Associate Professor (50210935) ; KASAHARA Junzo Shizuoka University, 理学部, Visiting Professor (70012953) ; SATOMURA Mikio Shizuoka University, 理学部, Vsiting Professor (50126778) ; KUNITOMO Takahiro Shizuoka University, 理学部, Visiting Associate Professor (40234463) ; SAYANAGI Keizo Tokai University, 理学部, Associate Professor (40332308)
• Project Period (FY): 2006 – 2007
• Project Status: Completed (Fiscal Year 2007)
• Budget Amount: ¥15,010,000 (Direct Cost: ¥13,900,000、Indirect Cost: ¥1,110,000); Fiscal Year 2007: ¥4,810,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥1,110,000); Fiscal Year 2006: ¥10,200,000 (Direct Cost: ¥10,200,000)
• Keywords: Elecromaenetic (EM) ACROSS / Seismic ACROSS / Array Obserbation / Electric Current Dipole / ACROSS:Accurately Controlled. Routinely Operated Signal System

Research Abstract

An essential point of ACROSS (Accurately Controlled Routinely Operated Signal System), is a noise-robust observation system of acquiring the transfer function between a pair of signal source and receiver by means of continuous transmission of very accurately controlled sinusoidal signals of both seismic and electromagnetic waves. At present, two EM transmitters are being operated ; one at Horonobe in Hokkaido with a set of electric dipoles of 180mx10A continuously for more than 2 years, and another at Shizuoka with a larger dipole moment of 600mx20A for long distance transmission. In this report, the recent results obtained by Shizuoka transmission experiments are presented in order to determine the transfer function and to estimate the delay time of signal propagation.
The essential factor for the observation system is to enable us to the acquire the high S/N transfer function data between the source and the receiving site of electromagnetic diffusion waves which are reflected back fro m the depth of-20 km just above the subducting plate boundary beneath the Tokai region. The observation system demanded is consisted
of (a) the accurately controlled signal transmitters with a large dipole moment of-10^6 Am, (b) the accurately synchronized and sensitive sensor array, and (c) such a technology system that makes noise reduction at every aspect of data management. The most important targets of (c) are the spatial noise in the shallow layers and its temporal change originated from the environmental disturbances (e.g. rain falls leading to the change in conductivity distribution).
As the first step of our approach towards realization of the actual monitoring the earthquake and volcanic fields in Tokai region, we have installed a large test transmitter (dipole moment=560mx20A) in Shizuoka University campus to work on the problems (a,b,c). In the trial observation in the frequency range 0.1-20Hz, the S/N of -5 for the transfer functions has been reached by one week stacking of the data acquired at the advanced observation system located up to 20 km from the transmitter. Whereas a number of technical innovations were made and are demanded further as will be shown in the presentation, the results were encouraging and appear as a substantial milestone towards the routine methodology for the active monitoring of our targets. Further we present a prospect towards the monitoring of 'water' in the coming Tokai Earthquake field located deep in the vicinity of contact between the Philippine Sea Plates and Asian Plates in Shizuoka prefecture. ^s a matter of course, we need more powerful transmitters and also an observation network designed specially for our approa.
In contrast to EM ACROSS, in which the signal is diffusion wave with large attenuation and dispersion, seismic ACROSS appears easy to grasp the approach by ray-path concept in geometric optics of wave propagation. In addition, the seismic signal source at Toki has been operated already for almost 5 years continuously to accumulate a large amount of data containing the information on the temporal variation in the deep lithospheres. By analyzing seismic data from several Hi-net stations, we found around the Horai Hi-net station)HOUH) in Aichi prefecture shows fairly good S/N and preliminary studies of small seismic array observations around the HOUH indicate relatively strong later phases are clearly observed with slignificant heterogeneities. One of the latest topics is the start of a new seismic transmitter at morimachi(MRI/JMA) in cooperation with Shizuoka Univ.) just above the expected focal plane of Tokai Earthquake.

Research Products

• [Journal Article] Development of ACROSS(Accurately Controlled, Routinely Operated, Signal System)to realize constant monitoring the invisible Earth's interiors by means of stationary coherent elastic and electromagnetic waves, (2007)
  • Author(s): Kumazawa, M., T. Kunitomo, T. Nakajima, K. Turuga, Y. Hasada, H. Nagao, H. Matsumoto, J. Kasahara, N. Fujii, and N. Shigeta,
  • Journal Title: JAEA-Research, 2007-033 Pages: 1-155
  • Description: 「研究成果報告書概要(和文)」より
  • Peer Reviewed
• [Journal Article] Development of ACROSS (Accurately Controlled, Routinely Operated, Signal System) to realize constant monitoring the invisible Earth's interiors by means of stationary coherent elastic and electromagnetic waves (2007)
  • Author(s): Kumazawa. M., T. Kunitomo., T. Nakaiima., K.Turuga, Y. Hasada, H. Nagao, H. Matsumoto, J. Kasahara., N. Fuiii., N. Shigeta
  • Journal Title: JAEA-Research vol.2007-033(Reviewed) Pages: 1-155
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Recent Progress in Electromagnetic and Seismic ACROSS in Tokai Region (2007)
  • Author(s): Nakajima T., N. Fujii, K. Sayanagi, T. Nagao, T. Kunitomo, Y. Hasada, M. Satomura, T. Masuda, M. Kumazawa
  • Journal Title: Proc. of Bilateral Seminar Italy-Japan on Electro-magnetics in Seismic and Volcanic Areas, (K.Hattori and L.Terlesca, eds.) 1 Pages: 109-116
• [Journal Article] Development of ACROSS (Accurately Controlled, RoutinelOperated, Signal System) to realize constant monitoring theinvisible Earth's interiors by means of stationary coherentelastic and electromagnetic waves (2007)
  • Author(s): Kumazawa M., T. Kunitomo, T. Nakajima, K. Turuga, Y. Hasada, H. Nagao, H. Matsumoto, J. Kasahara, N. Fujii, N. Shigeta
  • Journal Title: JAEA-Research 2007-033 Pages: 1-155
• [Journal Article] Seismic study Qn off-axis oceanic core complexes in the Pareceera backarc basin (2007)
  • Author(s): Ohara Y., Okino K., Nishizawa A., Kasahara J.
  • Journal Title: Island Arc 16 Pages: 348-360
• [Journal Article] Variation in crustal structure along the Kyushu-Palau ridge atJ15-21°N on the Philippine Sea pate based on the Philippine Se late based on seismic refraction profiles (2007)
  • Author(s): Nishizawa A., K. Kaneda, Y. Katagiri, J. Kasahara
  • Journal Title: Earch Planet Space 59
• [Journal Article] プレート境界型地震監視計画(EARS:Exploration of asperities-reflectors system)-総論- (2007)
  • Author(s): 笠原 順三, 鶴我 佳代子
  • Journal Title: 月刊地球 29 Pages: 355-363
• [Journal Article] Recent Progress in Electromagnetic and Seismic ACROSS in Tokai. Region, (2007)
  • Author(s): Nakajima, T., N. Fujii, K. Sayanagi, T. Nagao, T. Kunitomo, Y. Hasada, M. Satomura, T. Masuda, and M. Kumazawa,
  • Journal Title: Proc. of Bilateral Seminar Italy-Japan on Electro-magnetics in Seismic and Volcanic Areas, (K. Hattori and L. Terlesca, eds.), 1 Pages: 109-116
• [Journal Article] Development of ACROSS (Accurately Controlled, Routinely Operated, Signal System) to realize constant monitoring the invisibleEarth's interiors by means of stationary coherent elastic and electromagnetic waves, (2007)
  • Author(s): Kumazawa, M., T. Kunitomo, T. Nakajima, K. Turuga, Y. Hasada, H. Nagao, H. Matsumoto, J. Kasahara, N. Fujii, and N. Shigeta,
  • Journal Title: JAEA-Research, 2007-033 Pages: 1-155
• [Journal Article] Seismic study on off-axis oceanic core complexes in the Parece Vela backarc basin, (2007)
  • Author(s): Ohara, Y., Okino, K., Nishizawa, A., and Kasahara, J.,
  • Journal Title: Island Arc 16 Pages: 348-360
• [Journal Article] Variation in crustal structure along the Kyushu-Palau ridge at 15-21°N on the Philippine Sea pate based on the Philippine Seaplate based on seismic refraction profiles (2007)
  • Author(s): Nishizawa, A., K. Kaneda, Y. Katagiri and J. Kasahara,
  • Journal Title: Earth Planet Space, 59
• [Journal Article] プレート境界型地震監視計画(EARS: Exploration of asperities-reflectors system)-総論- (2007)
  • Author(s): 笠原順三、鶴我佳代子
  • Journal Title: 月刊地球 29 Pages: 355-363
• [Journal Article] Time Lapse Approach in the Study of Earthquake Generation -Geophysical Exploration of Asperities-Reflectors System(EARS)for Interplate Earthquake Generation along a Subducting Oceanic Plate, (2006)
  • Author(s): Kasahara, J., K. Tsuruga, H. Mikada, K. Yamaoka, and N. Fujii
  • Journal Title: BUTSURI-TANSA, 59・6 Pages: 525-537
  • NAID: 10020126056
  • Description: 「研究成果報告書概要(和文)」より
  • Peer Reviewed
• [Journal Article] 非アスペリティのマッピングから地殻内部の常時監視へ (2006)
  • Author(s): 鶴我佳代子・笠原順三・三ケ方均・山岡耕春・藤井直之
  • Journal Title: 地学雑誌 115・1 Pages: 51-71
  • NAID: 10025675160
  • Description: 「研究成果報告書概要(和文)」より
  • Peer Reviewed
• [Journal Article] Time Lapse Approach in the Study of Earthquake Generation -Geophysical Exploration of Asperities-Reflectors System (EARS) for Interplate Earthquake Generation along a Subducting Oceanic Plate (2006)
  • Author(s): Kasahara. J. K. Tsuruga, H. Mikada, K. Yamaoka, N. Fuiii
  • Journal Title: BUTSURI-TANSA vol.59, no.6(Reviewed) Pages: 525-537
  • NAID: 10020126056
  • Description: 「研究成果報告書概要(欧文)」より
• [Journal Article] Towards Continuous Monitoring of Earth's Interior from Mapping of Non-Asperity Area, (Japanese with English abstract & figure captions) (2006)
  • Author(s): Tsuruga, K., J. Kasahara. H. Mikada, K. Yamaoka, N. Fuiii
  • Journal Title: Journal of Geology vol.115, no.1(Reviewed) Pages: 51-71
  • Description: 「研究成果報告書概要(欧文)」より
• [Presentation] Recent Progress in Electromagnetic ACROSS in Tokai Region, (2007)
  • Author(s): T. Nakajima, *N. Fujii, K. Sayanagi T. Nagao, T. Kunitomo, Y. Hasada, M. Satomura, T. Masuda, and M. Kumazawa
  • Organizer: AGU2007 Fall Meeting(American Geophysical Union),
  • Place of Presentation: San Francisco, USA.
  • Description: 「研究成果報告書概要(和文)」より
• [Presentation] Recent Progress in Electromagnetic ACROSS in Tokai Region (2007)
  • Author(s): T. Nakaiima., * N. Fuiii., K. Sayanaei, T. Nagao, T. Kunitomo., Y. Hasada., M. Satomura., T. Masuda, M. Kumazawa
  • Organizer: AGU2007 Fall Meeting (American Geophysical Union)
  • Place of Presentation: San Francisco, USA
  • Description: 「研究成果報告書概要(欧文)」より