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Saffer, D. M.; McNeill, Lisa C.; Araki, Eiichiro; Byrne, T. B.; Eguchi, N.; Toczko, S.; Takahashi, Kyoma

doi:10.2204/iodp.pr.319.2009

Cited by 54 publications

(30 citation statements)

References 57 publications

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“…Inset shows detail of Units III-IV at Site C0002. See Saffer et al (2009Saffer et al ( , 2010 for further details of seismic stratigraphy and structure. tiple lines of evidence for margin-normal extension, potentially driven by uplift and tilting of the seaward forearc basin.…”

Section: Preliminary Results Site C0009mentioning

confidence: 99%

“…Data collected from the long offset 'walkaway' VSP experiment will allow remote imaging and resolution of properties of the deeper plate boundary fault system. The first observatory instruments of the NanTroSEIZE experiment were installed during Expedition 319, in the form of a simple instrument package (termed a "smart plug") at Site C0010, where it was designed to monitor pressure and temperature at the shallow megasplay fault Saffer et al, 2009). …”

Section: A B Cmentioning

confidence: 99%

“…See Fig. 6 and Saffer et al (2009Saffer et al ( , 2010 for further geographic information. Contours = estimated slip from 1944 event (0.5 m intervals, increasing inwards; Kikuchi et al, 2003), red box = region of recorded VLFs (Obara and Ito, 2005).…”

Section: Introductionmentioning

confidence: 99%

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IODP Expedition 319, NanTroSEIZE Stage 2: First IODP Riser Drilling Operations and Observatory Installation Towards Understanding Subduction Zone Seismogenesis

McNeill

Saffer

Byrne

et al. 2010

Scientific Drilling

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The Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) is a major drilling project designed to investigate fault mechanics and the seismogenic behavior of subduction zone plate boundaries. Expedition 319 is the first riser drilling operation within scientific ocean drilling. Operations included riser drilling at Site C0009 in the forearc basin above the plate boundary fault, non-riser drilling at Site C0010 across the shallow part of the megasplay fault system-which may slip during plate boundary earthquakes-and initial drilling at Site C0011 (incoming oceanic plate) for Expedition 322. At Site C0009, new methods were tested, including analysis of drill mud cuttings and gas, and in situ measurements of stress, pore pressure, and permeability. These results, in conjunction with earlier drilling, will provide a) the history of forearc basin development (including links to growth of the megasplay fault system and modern prism), b) the first in situ hydrological measurements of the plate boundary hanging wall, and c) integration of in situ stress measurements (orientation and magnitude) across the forearc and with depth. A vertical seismic profile (VSP) experiment provides improved constraints on the deeper structure of the subduction zone. At Site C0010, logging-while-drilling measurements indicate significant changes in fault zone and hanging wall properties over short (<5 km) along-strike distances, suggesting different burial and/or uplift history. The first borehole observatory instruments were installed at Site C0010 to monitor pressure and temperature within the megasplay fault zone, and methods of deployment of more complex observatory instruments were tested for future operations.

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Section: Preliminary Results Site C0009mentioning

confidence: 99%

Section: A B Cmentioning

confidence: 99%

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IODP Expedition 319, NanTroSEIZE Stage 2: First IODP Riser Drilling Operations and Observatory Installation Towards Understanding Subduction Zone Seismogenesis

McNeill

Saffer

Byrne

et al. 2010

Scientific Drilling

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“…Four main lithological units within the basin section were defined at Site C0009, by combining cuttings analysis with logging data [Saffer et al, 2009]. These units correlate broadly with the units identified at nearby Site C0002 [Kinoshita et al, 2009;Saffer et al, 2010].…”

Section: Fore-arc Basin Stratigraphymentioning

confidence: 99%

“…Other strong reflectors may also suggest the presence of gas accumulations in the lowermost basin sediments above the older accretionary prism (Figure 1). Site C0009 was drilled in riser mode, enabling recovery of cuttings and monitoring of mud gas for the first time in IODP history and allowing the newest logging technology to be deployed in the riser hole [Saffer et al, 2009[Saffer et al, , 2010. In particular, the Schlumberger SonicScanner™ wireline logging tool recorded shear wave velocity within the unconsolidated sediments (Figure 2), providing key data needed to quantify gas accumulations.…”

Section: Introductionmentioning

confidence: 99%

Quantification of free gas in the Kumano fore-arc basin detected from borehole physical properties: IODP NanTroSEIZE drilling Site C0009

Doan

Conin

Henry

et al. 2011

Geochem. Geophys. Geosyst.

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[1] The Kumano fore-arc basin overlies the Nankai accretionary prism, formed by the subduction of the Philippine Sea Plate beneath the Eurasian plate offshore the Kii Peninsula, SW Honshu, Japan. Seismic surveys and boreholes within the framework of the Nankai Trough Seismogenic Zone Experiment (NanTroSEIZE) project show evidence of gas hydrates and free gas within the basin. Here we use high-quality borehole sonic data from Integrated Oceanic Drilling Program (IODP) Site C0009 to quantify the free gas distribution in the landward part of the basin. The Brie theory is used to quantify gas content from sonic logs, which are calibrated from laboratory measurements on drill cores. First, we show that the sonic data are Copyright 2011 by the American Geophysical Union 1 of 12 mainly sensitive to the fluid phase filling the intergranular pores (effective porosity), rather than to the total porosity that includes water bound to clay minerals. We then compare the effective porosity to lithodensityderived porosity that acts as a proxy for total porosity. The combination of these two data sets also allows assessment of clay mineralogy of the sediments. Second, we compute free gas saturation and find a gasrich interval that is restricted to a lithological unit characterized by a high abundance of wood fragments and lignite. This unit, at the base of the fore-arc basin, is a hydrocarbon source that should be taken into account in models explaining gas distribution and the formation of the bottom-simulating reflector within the Kumano fore-arc basin.

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Interplate seismicity at the CRISP drilling site: The 2002 Mw 6.4 Osa Earthquake at the southeastern end of the Middle America Trench

Arroyo

Grevemeyer

Ranero

et al. 2014

Geochem Geophys Geosyst

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We investigate potential relations between variations in seafloor relief and age of the incoming plate and interplate seismicity. Westward from Osa Peninsula in Costa Rica, a major change in the character of the incoming Cocos Plate is displayed by abrupt lateral variations in seafloor depth and thermal structure. Here a Mw 6.4 thrust earthquake was followed by three aftershock clusters in June 2002. Initial relocations indicate that the main shock occurred fairly trenchward of most large earthquakes along the Middle America Trench off central Costa Rica. The earthquake sequence occurred while a temporary network of OBH and land stations 80 km to the northwest were deployed. By adding readings from permanent local stations, we obtain uncommon P wave coverage of a large subduction zone earthquake. We relocate this catalog using a nonlinear probabilistic approach within both, a 1-D and a 3-D P wave velocity models. The main shock occurred 25 km from the trench and probably along the plate interface at 5-10 km depth. We analyze teleseismic data to further constrain the rupture process of the main shock. The best depth estimates indicate that most of the seismic energy was radiated at shallow depth below the continental slope, supporting the nucleation of the Osa earthquake at 6 km depth. The location and depth coincide with the plate boundary imaged in prestack depth-migrated reflection lines shot near the nucleation area. Aftershocks propagated downdip to the area of a 1999 Mw 6.9 sequence and partially overlapped it. The results indicate that underthrusting of the young and buoyant Cocos Ridge has created conditions for interplate seismogenesis shallower and closer to the trench axis than elsewhere along the central Costa Rica margin.

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Cited by 54 publications

References 57 publications

IODP Expedition 319, NanTroSEIZE Stage 2: First IODP Riser Drilling Operations and Observatory Installation Towards Understanding Subduction Zone Seismogenesis

IODP Expedition 319, NanTroSEIZE Stage 2: First IODP Riser Drilling Operations and Observatory Installation Towards Understanding Subduction Zone Seismogenesis

Quantification of free gas in the Kumano fore-arc basin detected from borehole physical properties: IODP NanTroSEIZE drilling Site C0009

Interplate seismicity at the CRISP drilling site: The 2002 Mw 6.4 Osa Earthquake at the southeastern end of the Middle America Trench

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