折射波地震记录叠加成像方法研究

多次覆盖折射波地震勘探是用来追踪反射波成像质量较差地区的地质构造或用于追踪深层基底形态及研究基岩面的一种勘探方法.基于折射波理论，用折射地震记录中的折射波对地下折射界面进行成像，应用共深度折射面元叠加成像理论方法，给出用共深度折射面元叠加成像技术对地下折射界面进行成像的速度分析与动校正计算方法，提出一种适用于折射波发育探区的共深度折射点叠加成像方法，最后以模型和实际例子说明方法的正确性和实用性.     

黄土坡面细沟侵蚀发生的临界条件

通过玻璃水槽试验和径流冲刷试验，研究了坡面径流的流速分布和坡面细沟侵蚀发生的临界条件。研究表明：径流在坡面上并非是以均匀流形式运动，而是以滚波的形式运动的，同时本文运用能量守恒原理分析了坡面土壤侵蚀率（Dr）与径流能耗（△E）之间的关系，建立了给定土壤条件下坡面土壤侵蚀率估算模型：Dr=0.0026（In△E-2）。结果表明坡面土壤侵蚀的发生具有一定的临界能量条件，当径流能耗大于7.38（J）时坡面开始有细沟侵蚀发生。     

Edge wave and non-trapped modes of the 25 april 1992 Cape Mendocino tsunami

The 25 April 1992 Cape Mendocino earthquake generated a tsunami characterized by both coastal trapped edge wave and non-trapped tsunami modes that propagated north and south along the U.S. West Coast. Both observed and synthetic time series at Crescent City and North Spit are consistent with the zero-order edge wave mode solution for a semi-infinite sloping beach depth profile. Wave amplitudes at Crescent City were about twice that observed at North Spit, in spite of the fact that the source region was three times farther from Crescent City than North Spit. The largest observed amplitude was due to an edge wave which arrived almost three hours after the initial onset of the tsunami; since such waves are highly localized nearshore, this suggests that the enhanced responsiveness at Crescent City is at least partly due to local dynamic processes. Furthermore, the substantially delayed arrival of this wave, which was generated at the southern end of the Cascadia Subduction Zone, has significant implications for hazard mitigation efforts along the entire U.S. West Coast. Specifically, this study demonstrates that slow-moving but very energetic edge wave modes could be generated by future large tsunamigenic earthquakes in the CSZ, and that these might arrive unexpectedly at coastal communities several hours after the initial tsunami waves have subsided.     

Inferred attenuation from site effect-correctedT phases recorded on the island of Hawaii

Coda site amplification factors are used to eliminate the site effect from records of three circum-PacificT phases recorded by the Hawaiian Volcano Observatory (HVO) network on the island of Hawaii. ObservedT-phase amplitudes across the island generally decrease with increasing distance from the conversion point where acoustic waves in the SOFAR channel become seismic waves propagating through the crust. However, the decay of the observedT-phase signal across the island is not regular in regions of dense station coverage, in particular, the Kilauea caldera region. We divide the maximum observedT-phase amplitudes at a given station by the coda site amplification factor obtained for the same station and frequency band (3.0Hz); the distribution of these amplitudes reveals a smooth pattern over the entire island. The distance over which the site effect-correctedT-phase amplitude decreases by one-half, combined with the apparent velocity of propagation ofT phases across the island, allows for an approximate determination of near-surfaceQ over much of the island of Hawaii. We found a region of lowQ in the Kilauea summit area (Q≈30) and east rift zone (Q≈60) with considerably higherQ in the Kaoiki and northern portions of the island (Q≈150 to 200). The lowQ values obtained in the Kilauea summit region and east rift zone are significantly lower than estimates of codaQ in the same region, suggestingT phases may be sampling the earth's near-surface properties.     

热液成矿分带的溶解－沉淀波结构

热液成矿分带是一种输运－反应问题。热液成矿分带基本属于渗滤交代分带性质，它是溶解－沉淀波在可渗透介质中形成和传播的结果。本文应用物理化学流体动力学中的渗滤与溶解－沉淀反应耦合过程理论研究溶解－沉淀波的结构特征，并进一步应用多组分耦合系统动力学中的用于原理揭示其形成的动力学机制，最后提出了一种热流成矿分带理论，对热液成矿分带问题的性质、热液成矿分带的本质和热液成矿分带的结构特征与形成机制提出了新认识。     

NLS EQUATION OF INTERNAL WAVES IN WEAKLY STRATIFIED OCEAN

The NLS (Non-Linear Schr(?)dinger) equation of internal waves in a wekly stratified ocean is der-ived in phase coordnates in terms of the RPM (Reductive Perturbation Method). It was shown thatwhen AB>0 there exist modulation forms of envelope soliton and dn, and tha when AB<0 there arethree modulation forms dark soliton, sn and cn. Only if K~2>B/A(?) . the side-band perturbation is stable,otherwise unstable. For the stable side-band perturbation there ekisis a modulation form of MdV soliton.     

福州地区地壳结构的地震转换波测深研究

地震转换波测深法首次在我国东南沿海的福州地区进行地壳深部构造的探测,得出了该区地壳中的4个主要界面的构造形态图和沿北东方向穿越本区的地壳深部构造剖面图。查明闽江断裂由两条北西向产状较陡的超壳断裂组成,福州断陷盆地的深部上地壳G界面呈条带状下沉,下地壳C、C_1界面和M面及壳内低速层均相对上隆,这一结果为解释本区高地热异常提供了深部依据     

STUDY OF NONLINEAR ROSSBY WAVES IN THE ATMOSPHERE UNDER SEMI-GEOSTROPHIC APPROXIMATION*

Under semi-geostrophic approximation the nonlinear ordinary differential equations are obtained for the motion in the barotropic and baroclinic atmospheres with the effects of zonal shear basic flow and topographic forcing included.Two constraints are acquired of finite-amplitude periodic and solitary waves in the original model with the aid of the phase-plane geometric qualitative theory of a dynamic system defined by the differential equation.The explicit solution of the nonlinear waves is found by means of the approximation method and some significant results are achieved.