Laboratory experiment of electrical resistivity measurement under in situ pressure and temperature conditions is essential to precisely interpret the DC resistivity and electro-magnetic survey and logging data. We constructed a resistivity measurement system under confining and pore pressure control, and examined the pressure dependence of electrical resistivity of rocks. Electrical resistivity of four sandstone and two igneous rock samples saturated with 35 g/L NaCl solution were measured under different effective pressure conditions (maximum 80 MPa with pore pressure of 1 MPa). We also estimated geometric change of pore space by measuring the drained pore water volume under confining pressure. The result showed that pore water in all the samples were drained with increasing pressure, and at the same time resistivity were increased. Resistivity changes of sandstone samples were highly correlated with changes of pore water volume, which directly indicates the strong relationship between resistivity increase and closure of pore space under pressure condition. Pressure dependence of resistivity was different among the rock types. Rapid increase of resistivity at low confining pressure (～10 MPa) might be caused by closure of microcracks in igneous rocks. Resistivity changes of sandstone samples possibly depended on the shape and size distribution of pores, and their deformation characteristics.

The Japan Agency for Marine-Earth Science and Technology (JAMSTEC) has deployed m-TRITON buoys at three sites in the eastern tropical Indian Ocean since 2006 as a part of the Research Moored Array for African-Asian-Australian Monsoon Analysis and Prediction (RAMA) which plays a major role in Indian Ocean Observing System. In recent years, due to increasing mooring period and serious damages by frequent vandalism, the data return rate of real time data had declined to less than 60％; furthermore, in the worst case, that of internally recorded data dropped about 50％. For the improvement of data return rate, we developed wire rope armored with Technora^® sheet and underwater sensor clamp to reduce entanglement of fishing gear to reduce vandalism damage. As a result, data return rate of each under-water sensor was improved to 90％. For meteorological sensors, data return rate of each sensor is still less than 90％, nevertheless improved anti vandalism countermeasures.

March 2017

From April, 2017, the Editorial Committee of JAMSTEC Report of Research and Development (JAMSTEC-R) will introduce a new category for paper submission named ''Data Paper'', in addition to ''Original Paper'', ''Report'' and ''Review'', for a publication on JAMSTEC-R. Data Paper is defined as a paper that describes data contents, acquisition methods, data formats, and access information pertaining to published data including observation data, measurement data, analysis data or results of computer simulation, etc. but NOT includes analysis, interpretation or scientific conclusions of such data. On JAMSTEC-R, Data Paper pertaining to electronic data obtained / created by JAMSTEC members who are engaged in a scientific research or technical development, or obtained by using surveying equipment / research facilities, etc., of JAMSTEC will be provided.

Upon publication on JAMSTEC-R, metadata of the data concerned will be published on JAMSTEC-R Data Repository. Thus, readers access Data Paper as a portal and then will be able to track the path to data that they want to refer to.

Prior to the official start, we had asked Dr. Junko Yoshimitsu and Dr. Masayuki Obayashi to submit the first Data Paper as a trial aiming to clarify the problems that may be lurking in the editing process and to show what ''Data Paper'' is like. In this volume of JAMSTEC-R, you can see the trial Data Paper that had been adopted after peer review process.

I hope that the introduction of ''Data Paper'' promotes disclosure of data and motivates researchers and technologists to generate new data and consequently contributes to ''open science''

Daisuke Suetsugu

Chief Editor

JAMSTEC-R Editorial Committee

Japan Agency for Marine-Earth Science and Technology (JAMSTEC)

We have constructed a seismic travel time database as an aid to research on the interior structure of the Earth. We measured various types of travel times from seismic waveform data collected by stations around the world, including broadband ocean bottom seismometers (BBOBSs). We measured absolute arrival times of various seismic phases by manual picking of the phase onset, differential travel times of P waves between two stations, and differential travel times between PP and P waves. The differential travel times were measured using waveform cross-correlation method. So far, we have measured more than 80,000 travel times. These data have been used to improve the spatial resolution of our tomography model, particularly in regions of poor seismic ray path coverage such as the Pacific Ocean. The database is continuing to develop and is publically available at our own web site; we welcome anyone to use the data for further research.

Complete data set is available via site:
http://www.godac.jamstec.go.jp/catalog/jamstec-r_repository/metadataDisp/JAMSTEC-R_24DP01?lang=en