Acta Geophysica Polonica

Earlier reviews on fracture and friction, as well as relevant monographs (e.g., “Theory of Earthquake Premonitory and Fracture Processes” by R. Teisseyre), presented the knowledge accumulated at that time. By putting emphasis on the physics of these phenomena, the present review summarizes the experimental and theoretical advances that have been achieved during the last years. This is preceded, in the description of each phenomenon, by a careful inspection of the problems envisaged in the frame of the earlier aspects. As a first example, we refer to the recent experiments which demonstrate that the cracks cannot accelerate up to the Rayleigh wave speed predicted by classic theories. Secondly, contrary to what had been thought previously, the most recent theoretical models of the crack propagation are intrinsically unstable against Yoffe-like deflections (i.e., deviations of the crack motion from a straight line) at all speeds. Recent laboratory experiments shed light on what happens during individual slip events in stick-slip phenomena (e.g., the frictional force is larger for increasing than for decreasing velocity within individual events due to memory effects). Furthermore, measurements on laboratory scale reveal that the frequency of precursor events increases dramatically just before a major slip event (even when studying the friction between relatively smooth solids like). The latter effect is primarily due to defects (or disorder, in general), which are shown to play a major role in both phenomena investigated.

P. Varotsos

Fracture and friction: A review

断裂与摩擦：综述

R. Cieśliński

Application of arithmetic formulae in determining volume of sea waters inflow into Elbląska Bay-river Elbląg-lake Druzno hydrology system

算术公式在确定埃尔布隆卡湾-埃尔布隆格河-德鲁兹诺湖水文系统海水流入量中的应用

Methods of recording and data analysis that jointly allow to estimate rotation components in the seismic field were applied at two glaciers: the Hans Glacier in the Spitsbergen archipelago behind the North Polar Circle and the Pasterze Glacier in the Austrian Alps. A substantial content of rotation velocity components was found in the data collected at both locations; especially high rotation amplitudes were found in the Hans Glacier. Differences between the results obtained from these two glaciers are shown and briefly discussed.

Krzysztof P. Teisseyre

Marek Górski

Jerzy Suchcicki

SEISMIC EVENTS AND ROTATION WAVES IN THE HANS GLACIER, SPITSBERGEN, AND THE PASTERZE GLACIER, AUSTRIA

汉斯冰川（斯匹次卑尔根）和帕斯特泽冰川（奥地利）中的地震事件与旋转波

J. JANKOWSKI et al. 350 In Poland there are three major geological units. Western Poland lies on a platform of Paleozoic folding. Eastern Poland is on an old platform of craton-type, extending far eastwards. A relatively young Carpathian arc, folded in the Alpine orogenesis, is situated on the south. On the Paleozoic Platform there is a profound sedimentary Permian Basin (Guterch et al., 1999), up to 20 km thick. The depth of sediments reaches 20 km also in the Carpathians (Ernst et al., 2002). Geomagnetic induction studies have been initiated by the Institute of Geophysics, Polish Academy of Sciences, in the early 1960 s. We collected and interpreted data mainly in the two geotectonic units: the Permian Basin in Central and NW Poland (prolongation of the North German conductivity anomaly) and in the Carpathians where we worked together with Czech colleagues (Jankowski, 1965; Jankowski et al., 1985; 1991). After so many years of field measurements we were convinced that we know geomagnetic induction arrows distribution on the majority of the Polish territory. In many areas, the distribution of induction arrows is very regular, in the sense that the their lengths and directions are not changing rapidly at two neighbouring points; the maximum length of arrows is about 0.5 at the period of about 1800 s. The interpretation models showed that the induction effect is connected with large sedimentary synclines. In both areas under study, the thickness of sedimentary cover exceeds 15 km and its conductance is several thousand Siemens (see the papers cited above). We were not making regular studies of NE Poland because the geometry of contact between the sedimentary cover and the crystalline basement is simple and conductance of the sediments is low. The sediments are rather thin, less than 1 km thick in the eastern part of East European Platform (EEP) in Poland. The dip of the crystalline basement from east to west is about 2 degrees. Basing of these facts we were expecting rather short induction arrows and magnetotelluric curves close to the 1D situation. In the years 1999-2000 we made 19 geomagnetic and magnetotelluric soundings in the area and the results were quite different from our expectations. This paper shows the possible influence of the thin conductive layer situated on the high resistivity basement on the length and azimuth of the induction arrows. 2. MEASUREMENTS In the summer seasons of 1999 and 2000 we collected data from two profiles crossing NE Poland. The locations of measurement sites are shown in Fig. 1. For field measurements we used seven long-period magnetotelluric stations. The magnetometers used were of two types: one with photoelectric conversion – PSM type (Marianiuk, 1977) and the other of fluxgate type made in Lvov (Korepanov et al., 1998). The first instrument has a better resolution (few pT) but it is heavier and more difficult to install. The fluxgate resolution is 0.1 nT. Before measurements, all stations were carefully calibrated at Belsk observatory. A new set of algorithms was developed for optimal determination of frequency responses of these instruments (Marianiuk, 2000; GEOMAGNETIC INDUCTION ARROWS – EFFECT OF THIN LAYER 351 Nowozynski, 2001). Because we were interested in collecting data for long-period variations, we kept every magnetotelluric station on the measurement site for three weeks. The main difficulty was to obtain good quality data with high signal to noise ratio. This is especially difficult for long periods, because Poland has a dense net of electric railway connections. The amplitude of disturbances in magnetic vertical component at a distance of 20 km from the railway line is about 1 nT. The noise in the electric components is as a rule higher, due to electric railway and local human activity. For getting good quality data it is necessary to select the recording place very carefully and wait for a period of comparatively high magnetic activity. To illustrate the quality of our data we show in Fig. 2 an example of simultaneous recordings of all five components. Additionally we made recordings of horizontal components using induction coils which allowed us to construct the MT curve up to 25 Hz. ig. 1. Location of the two induction soundings profiles on the generalised tectonic map of Central Europe (northern profile 1999; southern profile 2000). Jurassic Triassic Palaeozoic and older Inner Carpathian/Alpine units Synand post-orogenic basins Neogene volcanics Outer Carpathians Pieniny Klippen Belt main thrusts 1 1 2 2 3 3 4 4 5 5 10 10 6 6 7 7 8 8 9 9

J. Jankowski

T. Ernst

W. Jóźwiak

Effect of thin near-surface layer on the geomagnetic induction arrows: an example from the East European Platform

薄近地表层对地磁感应箭头的影响：以东欧平台为例

Examples of ice-vibrations recorded in the Hans Glacier (South Spitsbergen) in spring-summer 2002, and in the Pasterze Glacier (Alps) in the fall of 2003 have been analysed. The spectral analysis of the recorded vibrations reveals a relationship between the period of vibrations and the scale of dynamic processes in a given glacier. Predominant frequency of ice-vibrations recorded in the Pasterze Glacier is higher than that of the events in the Hans Glacier, where the scale of dynamic processes in much greater. The presented spectra of the icevibration seismic events display characteristic frequency maxima related to the scale of dynamic processes taking place within a given glacier.

Predominant frequencies in the spectrum of ice-vibration events

冰振动事件频谱中的主频

The paper presents methodologies to quantify sediment sources in order to determine the sediment budget of a river. The methods are applied to assess the morphological state of the heathland River Wuemme. The results emphasize that detailed knowledge of the sediment budget is a prerequisite for the development of successful river restoration strategies.

A. Schulte-Rentrop

K. Koll

J. Aberle

A. Dittrich

Sediment budget of a heathland sand-bed river

荒地砂床河流的沉积物预算

The amplitude spectral ratio of PKPdf and PKPbc phases recorded at Polish stations from some strong deep Kermadec/Fiji earthquakes is used to derive the attenuation at the top of the inner core. The derived mean value of QP is 314±46 (95% confidence level) and the maximum depth of penetration of the PKPdf phase into the inner core is roughly 341 km. The sampled region of the inner core is centered beneath the Kuril Islands and North East of Japan.

M. Ivan

P. Wiejacz

Inner core attenuation observed at Polish broadband stations

波兰宽带台站观测到的内核衰减

Monitoring of recent crustal deformation was carried out using GPS observations to detect the present-day styles and rates of extension, as well as riftmargin deformation along the extent of the Red Sea rift. For studying the crustal deformation along the Red Sea Region and Gulf of Aden, 12 geodetic stations were established to cover some areas in Egypt and Yemen. The GPS measurements were carried out in April 2000 and November 2001. Analysis of the first and second campaigns of GPS measurements indicates that the magnitude of movements together with the strain parameters is small, but the magnitude of displacement may reach up to 20 mm in some points close to the Red Sea, such as those in Hodeidah (Yemen) and Dahab (Egypt). Moreover, the direction of movement on these points is opposite to each other. Such results are in harmony with the general trend of the tectonics in the Red Sea region. Separate analyses of GPS measurements on geodetic points in Yemen relative to each other show a rate of displacement of about 3 mm. The direction of movement on Sana’a is SW and on Aden is NE.

K. Sakr

S.M. Abdel-Monem

H. Khalil

S. Mahmoud

Z. Hamimi

A. Al-Aydrus

A. Al Subbary

A. Al-Kottbah

A. Al-Gabary

M. A. Al-Wosabi

I. El Ganad

A STUDY OF CRUSTAL DEFORMATION ALONG THE RED SEA REGION USING GEODETIC AND SEISMIC DATA FROM EGYPT AND YEMEN

利用埃及和也门地区大地测量和地震数据对红海地区地壳形变的研究

Global Seismic Hazard Assessment Program (GSHAP) has classified the Indian peninsula into several seismogenic zones. Considering the seismotectonic setting of the Sikkim Himalaya, sources 2, 3, 4, 5, 25, 26, 27 and 86 may be critical in contributing to the seismic hazard of the region. These seismogenic zones have been classified as Himalayan source (25, 86), extension of Tibetan plateau (26, 27), Burmese arc subduction zone (4, 5), Shillong plateau (3) and the Indian Shield region (2). The probabilistic seismic hazard assessment of the region necessitated prediction of Maximum Credible Earthquake magnitude for each source with 10% probability of exceedance in 50 years. Considering the widespread damages caused in the state capital of Sikkim due to the recent earthquakes of 1934 (Mw = 8) and 1988 (Mw = 7.2) a 50-year prediction seemed to be reasonable. Gutenberg–Richter (b-value) approach and Gumbel’s method of extreme value statistics have been used in the present analysis for the prediction of Maximum Credible Earthquake magnitude, results of both being comparable to each other. The maximum credible earthquake magnitude as predicted by both the methods are above 6 except for zone 26, the highest being in the Burmese arc with a magnitude of 8.5 by Gutenberg–Richter approach and a magnitude of 7.7 by Gumbel’s method

M. Vyas

S.K. Nath

I. Pal

P. Sengupta

W.K. Mohanty

GSHAP revisited for the prediction of maximum credible earthquake in the Sikkim region, India

印度锡金地区最大可信地震预测的GSHAP再探讨

Instrumental and macroseismic data of a sequence of local earthquakes re-corded in 1995 in the Western Carpathians (the region of Podhale, northernmost part of the Pieniny Klippen Belt) have been analysed. The earthquakes occurring in the area of the Orawa–Nowy Targ depression are the evidence that tectonic faults in this area are still seismically active. An earthquake of M = 4.1 was re-corded there in November 2004.

Barbara Guterch

Hanna Lewandowska-Marciniak

Janusz Niewiadomski

Earthquakes recorded in Poland along the Pieniny Klippen Belt, Western Carpathians

波兰记录的沿西喀尔巴阡山脉皮耶尼尼克利彭带的地震

Publication Information	Publisher: Polska Akademia Nauk，Publishing cycle: ，Journal Type: journal，Open Access Journals: No
Basic data	Year of publication: 1978，Proportion of original research papers: ，Self Citation Rate:， Gold OA Rate:

Acta Geophysica Polonica

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