Double seismic zone in the North Mariana region revealed by long-term ocean bottom array observation

Hajime Shiobara, Hiroko Sugioka, Kimihiro Mochizuki, Satoko Oki, Toshihiko Kanazawa, Yoshio Fukao, Kiyoshi Suyehiro

研究成果: Article

10 引用 (Scopus)

抄録

A long-term seismic array observation was conducted around the North Mariana island arc using 10 long-term ocean bottom seismometer (LTOBS), which gathered data for one year starting in 2001 October. The purpose of the observation was to research the deep seismic activity and the structure of the Mariana subduction system. By using data from nine of the LTOBS, which covered about 11 months of elapsed time, more than 3000 local events were found through the hypocentre determination with a one-dimensional velocity model. Only 59 of these events were listed in the same period on the US National Earthquake Information Centre's Preliminary Determination of Epicentres (PDE) publication. The hypocentres with small determination errors clearly show a double seismic zone (DSZ) reaching 150 km in depth with two seismic planes separated by about 30 km. The extension of the DSZ's seismic activity remains high until a depth of about 270 km. In the backarc basin, some shallow seismic activities were found as linear foci around the current ridge axis. High seismic activity was also recorded to the north and the west of a large serpentine seamount in the forearc. In addition, a zone almost devoid of earthquakes exists in the upper plane of the DSZ with the low velocity of the P phase (VP) region modelled by an inversion. This region looks like a narrow channel running east to west. A shear wave splitting study of the area indicates a change of splitting direction near the southern edge of this channel. A result of a gravity study also shows negative gravity anomalies in the same area. This region could be a serpentinized forearc mantle with water supplied to it from a seamount that was in the past carried downwards with the subducting Pacific Plate.

元の言語English
ページ(範囲)1455-1469
ページ数15
ジャーナルGeophysical Journal International
183
発行部数3
DOI
出版物ステータスPublished - 2010 12
外部発表Yes

Fingerprint

Seismographs
ocean bottom
seismic zone
Earthquakes
Gravitation
seafloor
ocean bottom seismometer
seamounts
seismographs
Shear waves
Information services
seamount
earthquakes
backarc basin
earthquake
wave splitting
island arcs
Water
gravity anomalies
Pacific plate

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics

これを引用

Double seismic zone in the North Mariana region revealed by long-term ocean bottom array observation. / Shiobara, Hajime; Sugioka, Hiroko; Mochizuki, Kimihiro; Oki, Satoko; Kanazawa, Toshihiko; Fukao, Yoshio; Suyehiro, Kiyoshi.

:: Geophysical Journal International, 巻 183, 番号 3, 12.2010, p. 1455-1469.

研究成果: Article

Shiobara, Hajime ; Sugioka, Hiroko ; Mochizuki, Kimihiro ; Oki, Satoko ; Kanazawa, Toshihiko ; Fukao, Yoshio ; Suyehiro, Kiyoshi. / Double seismic zone in the North Mariana region revealed by long-term ocean bottom array observation. :: Geophysical Journal International. 2010 ; 巻 183, 番号 3. pp. 1455-1469.
@article{88357cc3cc5845118eee356bb6cec1eb,
title = "Double seismic zone in the North Mariana region revealed by long-term ocean bottom array observation",
abstract = "A long-term seismic array observation was conducted around the North Mariana island arc using 10 long-term ocean bottom seismometer (LTOBS), which gathered data for one year starting in 2001 October. The purpose of the observation was to research the deep seismic activity and the structure of the Mariana subduction system. By using data from nine of the LTOBS, which covered about 11 months of elapsed time, more than 3000 local events were found through the hypocentre determination with a one-dimensional velocity model. Only 59 of these events were listed in the same period on the US National Earthquake Information Centre's Preliminary Determination of Epicentres (PDE) publication. The hypocentres with small determination errors clearly show a double seismic zone (DSZ) reaching 150 km in depth with two seismic planes separated by about 30 km. The extension of the DSZ's seismic activity remains high until a depth of about 270 km. In the backarc basin, some shallow seismic activities were found as linear foci around the current ridge axis. High seismic activity was also recorded to the north and the west of a large serpentine seamount in the forearc. In addition, a zone almost devoid of earthquakes exists in the upper plane of the DSZ with the low velocity of the P phase (VP) region modelled by an inversion. This region looks like a narrow channel running east to west. A shear wave splitting study of the area indicates a change of splitting direction near the southern edge of this channel. A result of a gravity study also shows negative gravity anomalies in the same area. This region could be a serpentinized forearc mantle with water supplied to it from a seamount that was in the past carried downwards with the subducting Pacific Plate.",
keywords = "Earthquake source observations, Pacific Oceans, Seismicity and tectonics, Subduction zone processes",
author = "Hajime Shiobara and Hiroko Sugioka and Kimihiro Mochizuki and Satoko Oki and Toshihiko Kanazawa and Yoshio Fukao and Kiyoshi Suyehiro",
year = "2010",
month = "12",
doi = "10.1111/j.1365-246X.2010.04799.x",
language = "English",
volume = "183",
pages = "1455--1469",
journal = "Geophysical Journal International",
issn = "0956-540X",
publisher = "Wiley-Blackwell",
number = "3",

}

TY - JOUR

T1 - Double seismic zone in the North Mariana region revealed by long-term ocean bottom array observation

AU - Shiobara, Hajime

AU - Sugioka, Hiroko

AU - Mochizuki, Kimihiro

AU - Oki, Satoko

AU - Kanazawa, Toshihiko

AU - Fukao, Yoshio

AU - Suyehiro, Kiyoshi

PY - 2010/12

Y1 - 2010/12

N2 - A long-term seismic array observation was conducted around the North Mariana island arc using 10 long-term ocean bottom seismometer (LTOBS), which gathered data for one year starting in 2001 October. The purpose of the observation was to research the deep seismic activity and the structure of the Mariana subduction system. By using data from nine of the LTOBS, which covered about 11 months of elapsed time, more than 3000 local events were found through the hypocentre determination with a one-dimensional velocity model. Only 59 of these events were listed in the same period on the US National Earthquake Information Centre's Preliminary Determination of Epicentres (PDE) publication. The hypocentres with small determination errors clearly show a double seismic zone (DSZ) reaching 150 km in depth with two seismic planes separated by about 30 km. The extension of the DSZ's seismic activity remains high until a depth of about 270 km. In the backarc basin, some shallow seismic activities were found as linear foci around the current ridge axis. High seismic activity was also recorded to the north and the west of a large serpentine seamount in the forearc. In addition, a zone almost devoid of earthquakes exists in the upper plane of the DSZ with the low velocity of the P phase (VP) region modelled by an inversion. This region looks like a narrow channel running east to west. A shear wave splitting study of the area indicates a change of splitting direction near the southern edge of this channel. A result of a gravity study also shows negative gravity anomalies in the same area. This region could be a serpentinized forearc mantle with water supplied to it from a seamount that was in the past carried downwards with the subducting Pacific Plate.

AB - A long-term seismic array observation was conducted around the North Mariana island arc using 10 long-term ocean bottom seismometer (LTOBS), which gathered data for one year starting in 2001 October. The purpose of the observation was to research the deep seismic activity and the structure of the Mariana subduction system. By using data from nine of the LTOBS, which covered about 11 months of elapsed time, more than 3000 local events were found through the hypocentre determination with a one-dimensional velocity model. Only 59 of these events were listed in the same period on the US National Earthquake Information Centre's Preliminary Determination of Epicentres (PDE) publication. The hypocentres with small determination errors clearly show a double seismic zone (DSZ) reaching 150 km in depth with two seismic planes separated by about 30 km. The extension of the DSZ's seismic activity remains high until a depth of about 270 km. In the backarc basin, some shallow seismic activities were found as linear foci around the current ridge axis. High seismic activity was also recorded to the north and the west of a large serpentine seamount in the forearc. In addition, a zone almost devoid of earthquakes exists in the upper plane of the DSZ with the low velocity of the P phase (VP) region modelled by an inversion. This region looks like a narrow channel running east to west. A shear wave splitting study of the area indicates a change of splitting direction near the southern edge of this channel. A result of a gravity study also shows negative gravity anomalies in the same area. This region could be a serpentinized forearc mantle with water supplied to it from a seamount that was in the past carried downwards with the subducting Pacific Plate.

KW - Earthquake source observations

KW - Pacific Oceans

KW - Seismicity and tectonics

KW - Subduction zone processes

UR - http://www.scopus.com/inward/record.url?scp=78449257828&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=78449257828&partnerID=8YFLogxK

U2 - 10.1111/j.1365-246X.2010.04799.x

DO - 10.1111/j.1365-246X.2010.04799.x

M3 - Article

AN - SCOPUS:78449257828

VL - 183

SP - 1455

EP - 1469

JO - Geophysical Journal International

JF - Geophysical Journal International

SN - 0956-540X

IS - 3

ER -