The prehistoric Mt Wilberg rock avalanche, Westland, New Zealand

The Mt Wilberg rock avalanche in Westland, New Zealand occurred before 1300 AD and may have occurred as a consequence of an Alpine fault earthquake in ca. 1220 AD or earlier. Its ∼40 × 10⁶ m³ deposit may have briefly obstructed the Wanganui River, but only about 25% of its surface morphology still survives, on terraces isolated from river erosion. The landslide appears to have moved initially as a block, in a direction controlled by a strong rock mass at the base of the source area, before disintegrating and spreading across terraces, fans, and floodplains. Rock avalanche deposits in Westland have relatively short expected lifetimes in the rugged terrain and high rainfall of the area; hence, the hazard from such events is under-represented by their current remnants.     

VIRGO: Experiment for helioseismology and solar irradiance monitoring

The scientific objective of the VIRGO experiment (Variability of solar IRradiance and Gravity Oscillations) is to determine the characteristics of pressure and internal gravity oscillations by observing irradiance and radiance variations, to measure the solar total and spectral irradiance and to quantify their variability over periods of days to the duration of the mission. With these data helioseismological methods can be used to probe the solar interior. Certain characteristics of convection and its interaction with magnetic fields, related to, for example, activity, will be studied from the results of the irradiance monitoring and from the comparison of amplitudes and phases of the oscillations as manifest in brightness from VIRGO, in velocity from GOLF, and in both velocity and continuum intensity from SOI/MDI. The VIRGO experiment contains two different active-cavity radiometers for monitoring the solar constant, two three-channel sunphotometers (SPM) for the measurement of the spectral irradiance at 402, 500 and 862 nm, and a low-resolution imager (LOI) with 12 pixels, for the measurement of the radiance distribution over the solar disk at 500 um. In this paper the scientific objectives of VIRGO are presented, the instruments and the data acquisition and control system are described in detail, and their measured performance is given.died 13 October 1994     

2021年5月22日青海玛多MS 7. 4地震地表破裂带及发震构造

2021年5月22日2时4分,青海省果洛藏族自治州玛多县发生了MS 7.4级强烈地震,震中位于巴颜喀拉地块北部边界东昆仑断裂带以南约70 km左右(34.59°N,98.34°E),震源深度17 km.震后的野外现场考察表明,这次地震在海拔4200～4600 m的高原面上形成了一系列由张裂隙、张剪裂隙、剪切裂隙、挤压鼓包和裂陷等多类型破裂雁行状组合而成的复杂同震地表变形带,总体表现为左行走滑运动性质,局部略带正断分量.该破裂带主要沿东昆仑断裂带南部的江错断裂分布,整体呈N105°E走向,全长约151 km.根据破裂带的走向变化和阶区特征,可将其分为四段:西段、中西段、中东段和东段.其中西段分叉为南、北两支,北支破裂走向N112°E,呈不连续分布,长约18 km,南支走向N94°E,呈连续性分布,长约25 km,最大左行位错约2.9 m;中西段全长约52 km,主要由约22 km长、呈N109°E走向的连续分布的地表破裂与稍北分布约30 km长、不连续分布的两支破裂组合而成,最大左行位错约1.9 m;中东段为总体呈N104°E走向的不连续地表破裂,全长约51 km,其中包含长约20 km的破裂空区;东段分叉为北、中、南三支,北支为走向N84°E、长约23 km的连续性破裂,最大左行位错约1.8 m,中间一支为N110°E走向、长约14 km的不连续破裂,南支则表现为零星破裂及系列滑塌,走向N120°E,长约6 km.这种两端发育较大规模分叉的"扫帚"状同震地表破裂在青藏高原已发生的走滑型地震中尚未报道过.这次地震的发震断裂为江错断裂,该断裂向西延伸可与2001年东昆仑MS 8.1地震的发震断层昆仑山口断裂相接,表明昆仑山口-江错断裂带与北部东昆仑断裂带中东部的托索湖-玛沁断裂挤压弯曲段共同构成了巴颜喀拉地块北部的宽阔边缘断裂带,并与南部的玉树-甘孜-鲜水河断裂带协同运动,共同调节着巴颜喀拉地块向东的运动和形变.由于东昆仑断裂带东部的玛沁—玛曲段是历史地震空区,因此可能是未来强震发生的区段.同时需要考虑到近20多年以来,巴颜喀拉地块周缘的强震活动具有跳跃性特征.因此,在未来的强震危险性评价中,应重点关注巴颜喀拉地块北边界带中东段玛沁—玛曲段和南部边界带鲜水河断裂带等的强震活动性及危险性.     

The transition region and coronal explorer

The Transition Region and Coronal Explorer (TRACE) satellite, launched 2 April 1998, is a NASA Small Explorer (SMEX) that images the solar photosphere, transition region and corona with unprecedented spatial resolution and temporal continuity. To provide continuous coverage of solar phenomena, TRACE is located in a sun-synchronous polar orbit. The ∼700 Mbytes of data which are collected daily are made available for unrestricted use within a few days of observation. The instrument features a 30-cm Cassegrain telescope with a field of view of 8.5×.5 arc min and a spatial resolution of 1 arc sec (0.5 arc sec pixels). TRACE contains multilayer optics and a lumogen-coated CCD detector to record three EUV wavelengths and several UV wavelengths. It observes plasmas at selected temperatures from 6000 K to 10 MK with a typical temporal resolution of less than 1 min.