STUDY ON PALEOEARTHQUAKES ALONG THE JINGHE SECTION OF BOLOKENU-AQIKEKUDUKE FAULT

The Bolokenu-Aqikekuduk fault zone(B-A Fault)is a 1 000km long right-lateral strike-slip active fault in the Tianshan Mountains. Its late Quaternary activity characteristics are helpful to understand the role of active strike-slip faults in regional compressional strain distribution and orogenic processes in the continental compression environment, as well as seismic hazard assessment. In this paper, research on the paleoearthquakes is carried out by remote sensing image interpretation, field investigation, trench excavation and Quaternary dating in the Jinghe section of B-A Fault. In this paper, two trenches were excavated on in the pluvial fans of Fan2b in the bulge and Fan3a in the fault scarp. The markers such as different strata, cracks and colluvial wedges in the trenches are identified and the age of sedimentation is determined by means of OSL dating for different strata. Four most recent paleoearthquakes on the B-A Fault are revealed in trench TC1 and three most recent paleoearthquakes are revealed in trench TC2. Only the latest event was constrained by the OSL age among the three events revealed in the trench TC2. Therefore, when establishing the recurrence of the paleoearthquakes, we mainly rely on the paleoearthquake events in trench TC1, which are labeled E1-E4 from oldest to youngest, and their dates are constrained to the following time ranges: E1(19.4±2.5)~(19.0±2.5)ka BP, E2(18.6±1.4)~(17.3±1.4)ka BP, E3(12.2±1.2)~(6.6±0.8)ka BP, and E4 6.9~6.2ka BP, respectively. The earthquake recurrence intervals are(1.2±0.5)ka, (8.7±3.0)ka and(2.8±3)ka, respectively. According to the sedimentation rate of the stratum, it can be judged that there is a sedimentary discontinuity between the paleoearthquakes E2 and E3, and the paleoearthquake events between E2 and E3 may not be recorded by the stratum. Ignoring the sedimentary discontinuous strata and the earthquakes occurring during the sedimentary discontinuity, the earthquake recurrence interval of the Jinghe section of B-A Fault is ~1~3ka. This is consistent with the earthquake recurrence interval(~2ka)calculated from the slip rate and the minimum displacement. The elapsed time of the latest paleoearthquake recorded in the trench is ~6.9~6.2ka BP. The magnitude of the latest event defined by the single event displacement on the fault is ~M_W7.4, and a longer earthquake elapsed time indicates the higher seismic risk of the B-A Fault.     

三分量磁饱和式磁力仪

本文概述了为青藏科考大地电磁测深工作研制的三分量磁饱和式磁力仪的原理、性能、用途和野外使用情况。 仪器的技术指标为:分辨率0.2伽（亻马）;灵敏度100毫伏/伽（亻马）;温度系数l伽（亻马）/℃;记录频带0-1.0赫兹;耗电量18瓦。 在青藏高原的地球物理考察中,用本仪器先后在藏南、藏北五个点进行了连续数月的野外地磁测量。从工作情况看,仪器工作正常,记录了一次完整的磁暴,为研究青藏高原地壳与上地幔的电性结构提供了一批有意义的资料。     

对流层平流层气溶胶粒子的形态和化学组成

分析研究了１９９３年和１９９４年的８月、９月在香河地区上空采集的单个气溶胶粒子的形态及化学元素和化合物的组成。结果表明：１９９３年,在对流层大气中的气溶胶颗粒经常出现不规则形的粒子,可能是土壤粒子;而在平流层大气中的颗粒以具有“卫星”结构的硫酸粒子为主;硫酸铵粒子则经常出现在对流层的中、下部。香河地区上空颗粒物的化学元素组成比较复杂,单一化学元素组成的粒子较少,粒子主要含有Ｓｉ,Ｆｅ,Ａｌ和Ｓ等元素。气溶胶的化合物有硫酸盐、硅酸盐、硝酸盐和磷酸盐等     

四川盆地干旱动态评估指标的研究

在仔细分析干旱灾害物理成因基础上,围绕定量化和实时化这一核心,根据土壤水分盈亏原理,建立了具有清晰的物理意义的干旱动态评估指标。经检验,该方法符合实际,简便可行。     

全球稻谷主产国遥感估产可行性研究

利用NOAA气象卫星的序列资料,对全球稻谷遥感估产的可行性进行了探讨。并以泰国、美国、越南为例,分别对NDVI植被指数与产量进行相关分析,取得良好的应用效果。此外,还应用数理统计方法对全球稻谷的历史产量进行数学模拟,达到较高的拟合精度。     

玉林地区秋旱气候特征分析及防御对策

利用玉林地区５个测站１９５８～１９９６年降雨量资料,统计分析了玉林地区秋旱天气的气候规律,并在此基础上,提出秋旱的防御对策,为做好秋旱预报、减少秋旱灾害给农业生产造成的损失提供可靠的依据。     

一些常见铀矿物的红外吸收光谱特征

作者对我国产出的41种常见的铀矿物进行了红外光谱分析,并收集了国外已有资料,综合了10类53种铀矿物的红外吸收光谱特征。     

Seven-frequency VLBI Observations of the GHz-Peaked-Spectrum Source OQ 208

We present quasi-simultaneous VLBI images of the GHz-Peaked-Spectrum radio source OQ 208 obtained with the Very Long Baseline Array at 1.4,1.7,2.3,5.0,8.4,15.4GHz and the European VLBI Network at 6.7 GHz.The low frequency(1.4,1.7 and 2.3GHz)ob- servations reveal a weak and extended steep-spectrum component at about 30mas away at position angle-110°,which may be a remnant emission.The radio structure of OQ 208 con- sists of two mini-lobes at 5.0,6.7,8.4 and 15.4 GHz.Our spectral analysis further confirms that the southwest lobe undergoes free-free absorption and finds that the free-free absorption is stronger in the inner region.By fitting the 8.4 GHz images from 1994 to 2005,we obtain a separation speed of 0.031±0.006 mas yr~(-1)between the two mini-lobes.This indicates a jet proper motion of 0.105±0.020 c and a kinematic age of 219±42 yr for the radio source.     

Shapes and Pole Orientations of Asteroids (360) Carlova and (209) Dido

Several light-curves of asteroid (360) Carlova and (209) Dido in different epochs were analyzed to determine shapes and pole orientations by means of AM-method and least squares method. New values of a/b, b/c, λ _p and β _p for asteroid (360) Carlova were obtained, which are 1.52°, 1.5°, 120 ± 6° and 66 ± 7°, respectively. We report a first determination of the parameters of (209) Dido which are 1.3°, 1.1°, 221 ± 6° and 37 ± 3°, respectively.