Radio echo sounding survey along the profile of the JARE-.- seismic exploration on the Mizuho Plateau, East Antarctica

380 Report JARE-.- +, -. / Radio echo sounding survey along the profile of the JARE-.- seismic exploration on the Mizuho Plateau, East Antarctica Masamitsu Takada +, Shigeru Toda,, Daisuke Kamiya -, Takeshi Matsushima. and Hiroki Miyamachi /,**- 0,/ ;,**- 2,0 Abstract: A seismic exploration was conducted in the austral summer of,**+,**, by the.-rd Japanese Antarctic Research Expedition (JARE-.-) on the Mizuho Plateau, East Antarctica. We carried out the radio echo sounding survey along the seismic line in order to estimate the distribution of bedrockaltitude. This report describes the outline of the radio echo sounding survey and the obtained result. :.-.-.- +. The.-rd Japanese Antarctic Research Expedition, JARE-.-.+ JARE-.+ SEAL,**+ JARE-.+ S+1 Z,* +2* km,**+: + H+10 + Institute of Seismology and Volcanology, Graduate School of Science, Hokkaido University, Kita-+*, Nishi-2, Kita-ku, Sapporo *0* *2+*., Aichi University of Education, +, Hirosawa, Igaya-cho, Kariya..2 2/.,. - Hakusan Corporation, J-Tower, + +, Nikko-cho, Fuchu-shi, Tokyo +2- **.... Institute of Seismology and Volcanology, Faculty of Sciences, Kyushu University, Shinyama,, Shimabara 2// *2.-. / Department of Earth and Environmental Sciences, Faculty of Science, Kagoshima University, +,+ -/, Kourimoto, Kagoshima 23* **0/. Vol..1, No.-, -2* -3.,,**- Nankyoku Shiryô (Antarctic Record), Vol..1, No.-, -2* -3.,,**-,**- National Institute of Polar Research

JARE-.- 381 + Fig. +. HM HM*., HM+0+.+ Map showing the seismic refraction line (solid line) on the Mizuho Plateau in JARE-.-. The radio echo sounding was carried out along the segment from HM*., to HM+0+. The dashed line indicates the JARE-.+ seismic line along the Mizuho route. +/* km HM : + 1** kg 1,* kg + +0+,**-a GPS Tsutsui et al.,**+,. 0* MHz : + GPS, 0* MHz DC,.V

382 Table +. + Specification of the radio echo sounding survey. Antenna Type Gain - elements Yagi Antenna 14, dbi Receiver Minimum sensitivity ++* dbm Transmitter Frequency Peak power Pulse width Pulse repeat frequency 0* MHz + kw + ms + khz Fig.,., Configuration of the instruments used in the radio echo sounding survey. Max. /** W AC +** V N N SM+*2,**+ +,,0,1. +

JARE-.- 383 -. : + 0* MHz + ms + khz, /* ms,* ns - S N,,/0,. +* +, km 2* m GP-IB CPU: MMX Pentium +00 MHz, : 0. MByte GPS /** m, + HM+0+ HM*., +*3 km S+0 H+10 N, Table,. Log notes schedule of radio echo sounding survey. Date Location Operation distance (km),**,. +.,+,**,. +.,-,**,. +.,.,**,. +.,/,**,. +.,2 HM**+ HM*/1 HM*/1 HM+*1 HM*01 HM*3/ HM*3/ HMl0+ HM*02 HM*., /04,.*4+,-4+ 004,,*40

384 - Fig. -. An example of an observed radio echo. The arrow in the figure shows an echo reflected from the bedrock surface. The vertical axis shows the intensity of the echo. The horizontal axis shows the depth from the ice sheet surface. N,**, +,. N HM**+ HM*.+ - +, +33/ - +1** m +/** m +,.. HM +0+ +* km HM*1/ HM+./..

JARE-.- µ ij'rs @vwxyzy' K 385 ῌ. 89 y ª«HM+0+ 89 DE «89 H6P! ± ²³ 89 y Fig... A continuous chart of the observed radio echo along the profile. The vertical axis indicates the depth from the ice sheet surface. The horizontal axis shows the distance from HM+0+ with the location codes. The arrow in the figure indicates an echo reflected from the bedrock surface. t s v mῌs d m d vtῌ, m +! "# $%! "# &'()*+, -./ n $%! c -0+*2 mῌs v cῌn mῌs, 12345 6 7 +, 89 d ctῌ,n m - 6:;9< =>?@ABC DE FGHI*JK L MKNO6P Q R9 +331 1 S K TUV'WX6P S VYZ [ \]89 ^ _ JK6 `a K bc 8d e a fgh6 ijkkl m n 6P o p2.1qc 'rs n -./ +.12 tu* `a r @vwxyzy DE{ O }t ~ w t s v mῌs t vῌ, m 6 ^_ JK6 Z 2. m 6P S< 6 f JK 6 @vwxyzy tu K 1bc<*u ; Maeno et al., +33. ^_ y 6 Z,*** m 6 y }t S t JKH< y!89 y y * `a e v

386 / HM*1/, Mae +312 Miyamachi et al.,,**-b - 0 - GPS WGS-2. / HM+./ +/** m Fig. /. A distribution chart of the radio echo observed at HM+./. The vertical axis shows the intensity of the echo. The horizontal axis indicates the depth from the ice sheet surface. The inset shows the echo enlarged around a depth of +/** m, where the arrow shows an echo from the bedrock surface.

JARE-.- 387 - Table -. Results of the radio echo sounding survey.

388 - Table -. Continued.

JARE-.- 389 - Table -. Continued.

390 ῒῐ ῌ - ῑῌ Table -. Continued.

JARE-.- 391 - Table -. Continued.

392 - Table -. Continued. 0 HM+0+ WGS-2. Fig. 0. Altitude distributions of the ice sheet surface and the bedrock surface. The altitude is the height from the normal ellipsoid in the WGS-2. system.

JARE-.- 393 HM+0+,**-a HM*1- HM *11 HM+0+ HM*., +.30 m 0 m HM*1/ /. +*3 km HM+0+ HM*., S+0.-.-.-.-.,.- +33/ : -3 02 1-.,**+ : SEAL 10 - +,. Mae, S. (+312): The bedrock topography deduced from multiple rader echoes observed in the Mizuho Plateau, East Antarctica. Nankyoku Shiryô (Antarct. Rec.), 0+,,- -+. Maeno, H., Kamiyama, K., Furukawa, T., Watanabe, O., Naruse, R., Okamoto, K., Suitz, T. and Uratsuka, S. (+33.): Using a mobile radio echo sounder to measure bedrock topography in East Queen Maud Land, Antarctica. Proc. NIPR Symp. Polar Meteorol. Glaciol., 2, +.3 +0*. Muravyev, Y.D. +331 : /3,/1,0,.,**+ :.+./ +*+ +.1.,**-a :.-.1 -, 1+.

394 Miyamachi, H., Toda, S., Matsushima, T., Takada, M., Watanabe, A., Yamashita, M. and Kanao, M. (,**-b): A refraction and wide-angle reflection seismic exploration in JARE-.- on the Mizuho Plateau, East Antarctica. Polar Geosci., +0, +,+. Tsutsui, T., Murakami, H., Miyamachi, H., Toda, S. and Kanao, M. (,**+): P-wave velocity structure of the ice sheet and the shallow crust beneath the Mizuho traverse route, East Antarctica, from seismic refraction analysis. Polar Geosci., +., +3/,++.