Kyeong Ja Kim

Late Holocene uplift of beach ridges at Turakirae Head, south Wellington coast, New Zealand

Abstract Holocene terraces at Turakirae Head on the south coast of the North Island, New Zealand, record four recent earthquakes from simultaneous rupture of the Wairarapa Fault and flexure of the Rimutaka Anticline. The lowest tread and riser is the modern marine platform and storm beach that began forming when the area was raised during the Mw 8.2 Wairarapa earthquake of AD 1855 January. The remaining chronology is established by radiocarbon dating, in situ 10Be surface‐exposure dating, and slip‐predictable uplift estimation. Prior to AD 1855, uplifts occurred at 110–430 BC (max. 9.1 m), 2164–3468 BC (6.8 m), and 4660–4970 BC (7.3 m). Earlier uplift of unknown magnitude occurred at c. 7000 BC but went unrecorded because of rapidly rising sea level. Sea level was still rising when the two oldest surviving beach ridges were raised. Uplift at Turakirae Head in AD 1855 varied from 1.5 m at the Wainuiomata River to 6.4 m at the crest of the Rimutaka Anticline. Older beaches also are tilted, with the amount of tilt increasing with age. Coastal uplift at the anticline crest has averaged 3.32 ± 0.17 mm/yr over the past 9000 yr, and has changed little over the past 0.5 m.y. Uplift fits a slip‐predictable model of earthquake occurrence, and is log‐normally distributed with a mean of 7.3 ± 0.7 m. The most frequently occurring uplift is 7.1 ± 0.9 m. Uplift in AD 1855 was not significantly smaller than mean or mode, suggesting that the Turakirae Head sequence records four great earthquakes of at least similar magnitude to that of AD 1855. The mean earthquake recurrence interval is 2194 ± 117 yr; the modal interval is 2122 ± 193 yr. At the crest of the anticline, the coastal platform was cut entirely during the postglacial rise of sea level until shortly before 4660–4970 BC. Away from the crest, however, it may have been partially cut during low sea level of the penultimate glaciation. The open‐ocean radiocarbon reservoir correction (δR) for 10 14C dates of coastal marine shells that died in AD 1855 at Turakirae Head is 3 ± 14cal. yrBP(andnot‐31 ± 13 cal. yr BP, the currently accepted δR for central New Zealand coastal waters).

Orbital forcing of mid-latitude Southern Hemisphere glaciation since 100 ka inferred from cosmogenic nuclide ages of moraine boulders from the Cascade Plateau, southwest New Zealand

Cosmogenic nuclide (Be-10) exposure dating of moraine boulders in the Cascade Valley, southwest New Zealand, reveals three phases of glaciation with similar maximum magnitude since 100 ka. In this area, 8–10 lateral moraines were deposited during the Last Glacial Maximum (LGM) at 22–19 ka, and >15 lateral moraines and three end moraines were deposited during recession after the LGM. Also, three exposure ages of 29–33 ka from pre-LGM deposits may indicate increased weathering and erosion at the onset of the LGM in New Zealand, as has been suggested by other studies. An exposure age of 57.8 ± 2.7 ka from one of the highest moraines, combined with previous studies of cave speleothems, glacial features offset by the Alpine fault, the Vostok dust record, and sediment cores, supports the inference that a significant glacial phase culminated at 66–58 ka. A cluster of five exposure ages from older moraines reveals a glacial phase with at least three advance-retreat cycles at 79.0 ± 3.9 ka. Correlation between the ages of glacial periods and the timing of Southern Hemisphere summer insolation minima suggests that orbital forcing has played a first-order role in regulating glacial extent in New Zealand.

First Results of High Performance Ge Gamma-Ray Spectrometer Onboard Lunar Orbiter SELENE (KAGUYA)

The high precision gamma-ray spectrometer (GRS) is carried on the first Japans large-scaled lunar explorer, SELENE (KAGUYA), successfully launched by the H-IIA rocket on Sep. 14, 2007. The GRS consists of a large Ge crystal as a main detector and massive bismuth germanate crystals and a plastic scintillator as anticoincidence detectors. After a series of initial health check of the GRS, it started a regular observation on December 21, 2007. Energy spectra including many clear peaks of major elements and trace elements on the lunar surface have been measured by the GRS. Global measurement of thorium counting rate on the lunar surface is presented. The region showing the highest count rate of thorium extends from Kepler to Fra Mauro region in the Procellarum. And Apennine Bench and Aristillus region and the northwestern region of Mare Imbrium are high in thorium count rate. Second high count rate region is located in the South Pole-Aitken basin of the farside. Arago and Compton/Belkovich craters are also e...

Theoretical fluxes of gamma rays from the Martian surface

[1] Theoretical fluxes of gamma rays escaping the surface of Mars were calculated. These and other calculated fluxes are needed to model the counting rates in the Mars Odyssey gamma ray spectrometer that are used to determine elemental compositions and other results using these measurements. Cross sections for the formation of gamma rays by both thermal and fast neutrons were compiled and evaluated. These evaluated cross sections were used with neutron fluxes calculated with the Monte Carlo N Particle Extended (MCNPX) code to get gamma ray production rates as a function of depth in the Martian surface. The fluxes of these gamma rays as a function of angle at the Martian surface were then calculated using gamma ray attenuation coefficients.

Experimental cross-sections for the production of 10Be from natural carbon targets with 40.6 to 500 MeV protons

Abstract Cross-sections for the production of 10Be from natural carbon targets were measured for proton energies ranging from 40.6 to 500 MeV. The yield of 10Be in each target was determined using accelerator mass spectrometry. The values of these new cross-sections ranged from 0.164 to 2.75 mb and confirmed previously published data in this energy range.

Nuclear Planetology: Especially Concerning the Moon and Mars

To approach basic scientific questions on the origin and evolution of planetary bodies such as planets, their satellites and asteroids, one needs data on their chemical composition. The measurements of gamma-rays, X-rays and neutrons emitted from their surface materials provide information on abundances of major elements and naturally radioactive gamma-ray emitters. Neutron spectroscopy can provide sensitive maps of hydrogen- and carbon-containing compounds, even if buried, and can uniquely identify layers of carbon-dioxide frost. Nuclear spectroscopy, as a means of compositional analysis, has been applied via orbital and lander spacecraft to extraterrestrial planetary bodies: the Moon, Venus, Mars, Mercury and asteroids. The knowledge of their chemical abundances, especially concerning the Moon and Mars, has greatly increased in recent years. This paper describes the principle of nuclear spectroscopy, nuclear planetary instruments carried on planetary missions so far, and the nature of observational results and findings of the Moon and Mars, recently obtained by nuclear spectroscopy.

Germanium Gamma-Ray Spectrometer on SELENE (KAGUYA)

The Japanese lunar explorer SELENE was launched from Tanegashima Space Center on September 14, 2007. It consists of a main orbiter KAGUYA at 100 km altitude and two daughter satellites (relay satellite OKINA and VRAD satellite OUNA) with 14 scientific instruments. The high precision gamma-ray spectrometer (GRS) on KAGUYA measures 200 keV–12 MeV gamma rays to determine the elemental composition of the lunar surface. The GRS is composed of a large Ge crystal as a main detector and massive bismuth germinate (BGO) crystals and a plastic scintillator as anticoincidence detectors. The Ge detector is cooled by a Stirling cryocooler below 90 K during the observation. After successful launch of the spacecraft and initial checkouts, the GRS started the nominal observation on December 21, 2007, and the temperatures and counting rates of the GRS were confirmed to be stable. Energy spectra of gamma rays with a good energy resolution are being obtained over the lunar surface, which will allow us to make global maps of ...

Development of an x-ray generator using a pyroelectric crystal for x-ray fluorescence analysis on planetary landing missions

The chemical element abundance on planetary surface is essential for planetary science. We have been developing an active X-ray spectrometer (AXS), which is an in-situ chemical element analyzer based on the X-ray florescence analysis for future planetary landing missions. The AXS consists of an X-ray detector and multiple X-ray sources. Although a pyroelectric X-ray generator is promising for the AXS as an X-ray source, the raise of emission X-ray intensity is necessary for short-time and precise determination of elemental composition. Also, in order to enhance the detection efficiency of light major elements such as Mg, Al, and Si, we have tested the low energy X-ray emission by changing the target material. In this study, the X-ray emission calculation at the target by Monte Carlo simulation and the X-ray emission experiments were carried out. More than 106 cps of the time-averaged X-ray emission rate was achieved in maximum using a LiTaO3 crystal with 4 mm thickness and Cu target with 10 um thickness. The performance of pyroelectric X-ray generator is presented in this paper.

Multi-purpose wide-angle vision system for remote control of planetary exploring rover

Wide-Angle Fovea Vision Sensor (WAFVS) system was designed and developed being inspired from advantages of the human eyes functions. This system is characterized by its space-variant data acquisition property, i.e., the WAFVS captures a 120-degree wide-angle input image in which its resolution (or magnification) changes like the human visual acuity. As well-known, the human visual acuity is the highest at its central field of view (FOV) and decreases rapidly towards its peripheral FOV. Thus, using the WAFVS, we can observe a target in detail by its central field of view while observing the whole of environment by its wide field of view. In addition, by controlling a view direction of the WAFVS, this WAFVS system gets visual information from the environment more in detail by smaller data amount. Hence, the WAFVS achieves a better performance of data transmission and data storage. One of severe problems in remote control of rovers, UAVs, and satellites is of a pay-load. In this point of view, the authors think that the WAFVS is suitable for the planetary exploring rover because it was originally developed for multi-purpose use of a single vision sensor. This paper describes the multi-purpose use of the WAFVS system, i.e., the following tasks: (1) observing the environment displayed to the operator for the remote navigation of the rover, (2) recording images of important scenes by changing a view direction of the WAFVS, and (3) monitoring if the instruments on the rover work well or not. Moreover, this paper experiments and discusses on how to display images to the operator when an eye-tracking device is applied as a target coordinate input device. Accuracy index, i.e., a measurement error of a target, is defined in order to evaluate performance of a combination among the vision sensor, the coordinate input device and the image display method.

Basic studies on x-ray fluorescence analysis for active x-ray spectrometer on SELENE-2

An active X-ray spectrometer (AXS) is now being developed as a payload candidate for the rover on SELENE-2, the next Japanese lunar exploration mission. The AXS will determine the chemical compositions of lunar rocks and regolith around the landing site. The surface of lunar rock samples will be ground using a rock abrasion tool. Thus, fundamental studies on the X-ray fluorescence analysis for lunar rocks and regolith are required to design and develop the AXS. In this study, we have investigated the X-ray fluorescence analysis in order to evaluate the effects of surface roughness of samples and the angle of incident and emergent X-rays. It was found that the fluorescent X-ray yield for low energy X-rays, i.e. the light elements, decreases at rough surface samples. This effect of surface roughness becomes small for smooth surface samples. It was also found that the fluorescent X-ray yield depends on the incident angle, which is attributed to the fact that the X-ray fluorescence occurs closer to the sample surface at larger incident angles. Since the emergent X-rays are affected by the detection geometry and surface roughness, the incident angle effect also depends on the above conditions.