Side Of Gulf Research Articles

Integrating magnetic and stratigraphic data to delineate the subsurface features in and around new Galala City, Northern Galala Plateau, Egypt

ABSTRACTThe Egyptian Government is developing a new city, Galala, above the Northern Galala Plateau, western side of Gulf of Suez between Ain Sukhna and Zafarana. The aim of the study is integrating magnetic and stratigraphic data to delineate the subsurface features beneath the New Galala City, in order to avoid the possible geological hazards. The stratigraphic succession in the study area consists of Precambrian basement complex overlain unconformably by Phanerozoic sequence. The Phanerozoic sequence composed mainly of siliciclastic-dominated rocks superimposed by carbonate-dominated rocks. The carbonate-dominated rocks cover most surface area, whilst the siliciclastic-dominated rocks exposed along eastern and southern foot slope of the Northern Galala Plateau. The observed palaeo-karst surfaces, fissures, caves, sink-holes and fault zones within carbonate rocks may cause some geological hazards in the study area. The total intensity aeromagnetic map was subjected to un-prescribed structural index 3D-Euler Deconvolution (ED), the tilt angle derivative (TDR) and the power spectrum in order to estimate both trends and source depths. The source depths range from 500 m to 4000 m, which result from the Precambrian basement complex. However, the trends of encountered structural elements are mainly NE–SW, NW–SE, NNW–SSE and E–W directions.

Palaeoenvironmental evolution of the ancient harbor of Lechaion (Corinth Gulf, Greece): Were changes driven by human impacts and gradual coastal processes or catastrophic tsunamis?

The Corinth Gulf, Central Greece, is one of the most rapidly widening tectonic rifts on Earth, where large earthquakes with magnitudes of up ~7.0 have been documented not only by instrumental records but also assessed from historical reports extending back to the 5th century BCE. Several of these earthquakes were associated with tsunamis, particularly in the western part of the Gulf. Of particular interest is the ancient harbor of Lechaion in the eastern side of Corinth Gulf. We reexamine the hypothesis that Lechaion was hit by high-energy tsunami waves in the 8th–6th century BCE, 1st–2nd century CE, and during the 6th century CE. On the basis of sedimentological, seismotectonic, archaeological and historical data, completed with field observations, we support that there is no evidence for tsunami impact in Lechaion. Local stratigraphy and environmental changes are rather interpreted by human impacts and gradual coastal processes. Such interpretations confirm that the tsunami potential in the east Corinth Gulf is relatively low.

Long-Period Ground Motion in the Arabian Gulf from Earthquakes in the Zagros Mountains Thrust Belt

The Arabian Gulf is adjacent to the Zagros Mountains, one of the most seismically active regions in the world. We observe that broadband seismic records of Zagros earthquakes recorded on the Arabian side of the Gulf display long-duration surface waves. While shorter periods (<1 s) are attenuated from crossing the deep sediments (>10 km) of the Gulf basin, the long-period energy is enhanced and transmitted efficiently. Consequently, large earthquakes in the Zagros could result in amplified ground motions at long periods (2–10 s) relative to average behavior. Such ground motions are of concern for large engineered structures, such as tall buildings and long bridges with resonant periods in the same period range. Here we present results of investigations of the characteristics of ground motions recorded on the western shore of the Gulf from selected earthquakes in the Zagros Mountains region. Exceptionally, long-duration seismic waves, as compared with standard models, are shown to occur with periods of 2–10 s. This may be due to waveguide effects in the deep sedimentary basin structure of the Arabian Platform. In addition to analyzing recorded ground motion we performed 3D wave propagation simulations using a finite difference method and experimental velocity models of the Gulf, with different shallow sedimentary layers structures. The simulation results confirm our hypothesis that long-period waves with extremely long duration and relatively large amplitudes are caused by the geometry of the basin sedimentary layers and, to some extent, by shallow earthquake depths. Combined effects of basin edge geometry with sharp velocity contrasts and shallow sources (<10 km) on the eastern side of the Arabian Gulf can cause large long-period ground motion on the western side of the Gulf. In contrast, the short-period content of ground motion (<2 s) at long distances is relatively weak. This is mainly due to wave propagation scattering and attenuation in the shallow sedimentary layers of the Gulf basin.

Structure of central and southern Mexico from velocity and attenuation tomography

The 3D Vp, Vp/Vs, P‐ and S‐wave attenuation structure of the Cocos subduction zone in Mexico is imaged using earthquakes recorded by two temporary seismic arrays and local stations. Direct P wave arrivals on vertical components and direct S wave arrivals on transverse components from local earthquakes are used for velocity imaging. Relative delay times for P and PKP phases from teleseismic events are also used to obtain a deeper velocity structure beneath the southern seismic array. Using a spectral‐decay method, we calculate a path attenuation operatort* for each P and S waveform from local events, and then invert for 3D spatial variations in attenuation (Qp−1 and Qs−1). Inversion results reveal a low‐attenuation and high‐velocity Cocos slab. The slab dip angle increases from almost flat in central Mexico near Mexico City to about 30° in southern Mexico near the Isthmus of Tehuantepec. High attenuation and low velocity in the crust beneath the Trans‐Mexico Volcanic Belt correlate with low resistivity, and are probably related to dehydration of the slab and melting processes. The most pronounced high‐attenuation, low‐Vpand high‐Vp/Vsanomaly is found in the crust beneath the Veracruz Basin. A high‐velocity structure dipping into the mantle from the side of Gulf of Mexico coincides with a discontinuity from a receiver functions study, and provides an evidence for the collision between the Yucatán Block and Mexico in the Miocene.

Ground Penetrating Radar (GPR) Investigations for Architectural Heritage Preservation: The Case of Habib Sakakini Palace, Cairo, Egypt

A comprehensive Ground Penetration Radar (GPR) investigations and hazard assessment for the rehabilitation and strengthening of Habib Sakakini’s Palace in Cairo is presented herein, which is considered one of the most significant architectural heritage sites in Egypt. The palace located on an ancient water pond at the eastern side of Egyptian gulf besiding Sultan Bebris Al-Bondoqdary mosque is a place also called “Prince Qraja al-Turkumany pond”. That pond had been filled down by Habib Sakakini at 1892 to construct his famous palace in 1897. The integrated geophysical survey of the palace allowed the identification of several targets of potential archaeological and geotechnical engineering interest buried in fill and silty clay in the depth range between 100 - 700 cm. the methodological development focused on Multi-Fold (MF) Ground Penetrating Radar (GPR) imaging and subsurface characterization based on integrated velocity and attenuation analysis. Eight hundred sqm of Ground penetration Radar (GPR) profiling have been conducted to monitor the subsurface conditions. 600 meters are made in the surrounding area of the Palace and 200 sqm at the basement. The aim is to monitor the soil conditions beneath and around the Palace and to identify potential geological discontinuities, or the presence of faults and cavities. A suitable single and dual antenna are used (500 - 100 MHZ) is used to penetrate the desired depth of 7 meters (ASTM D6432). The GPR is used also detect the water table. At the building basement the GPR is used to identify the foundation thickness and soil-basement interface. As well as the inspection of cracks in some supporting columns, piers and masonry walls. The GPR also was used to investigate the floors and ceilings conditions and structural mapping. The results were validated by the geotechnical and structural surveys. All these results together with the seismic hazard analysis will be used for the complete analysis of the palace in the framework of the rehabilitation and strengthening works foreseen in a second stage.

Prey-switching and Diet of the Great Cormorant During the Breeding Season in the Gulf of Finland

The diet of the Great Cormorant (Phalacrororax carbo) was studied on the Finnish side of Gulf of Finland, Baltic Sea, by collecting regurgitated fish in a colony. Most abundant species of fish were Viviparous Blenny (Zoarces viviparus), Roach (Rutilus rutilus) and Perch (Perca fluviatilis), most of which are economically unimportant. Cormorants switched their diet during the breeding season. Before young were hatched, cormorants ate mainly Roach and Perch; when young were less than 25 days, old they ate mainly small Viviparous Blennies. Later, adults provided larger Roach and Perch for their young. The results suggest that several fish-sampling visits are needed to record the food captured by cormorants during the breeding season. Few samples restricted in time may bias the composition of fish species and size of the fish in diet.

Marine Geophysical Studies of Western Margins of Luzon, Philippines: ABSTRACT

Multichannel seismic reflection, gravity, and magnetic measurements were made during a reconnaissance study of the western margin of Luzon, between 15 and 19°N. Sixteen lines were run to investigate the along-strike variations in the nature of the accretionary prism and the style and intensity of deformation in the fore-arc region (West Luzon Trough). End_Page 970------------------------------ There is an along-strike difference in the degree of deformation observed landward of the trench slope break. Subduction of the east-west-trending South China basin relict spreading center at the Manila Trench near 16°N appears to roughly define the boundary between two contrasting tectonic regimes of the margin. South of this boundary, deposition of terrigenous sediments in the fore-arc region has occurred in a relatively quiet tectonic setting. In contrast, north of the boundary, the sediments of the fore-arch region have been disturbed by ubiquitous faulting. Some of the faulting is probably associated with the offshore extensions of splays of the Philippine fault system. Furthermore, anticlinal folds, consistent in character and trend, are found both onshore and offshore alon Lingayen Gulf near 16 and 17°N and probably formed in response to a common stress field. MCS records reveal a basement ridge, trending northward from the western side of Lingayen Gulf, which we interpret as the likely offshore expression of the Zambales ophiolite exposed on land to the south. We are attempting to reconstruct the tectonic evolution of this fore-arc region by extrapolating the limited stratigraphic information from onshore wells and outcrops onto the observed offshore seismic stratigraphy. End_of_Article - Last_Page 971------------

Lars Sonck: From the Roots

IN THE LATE I8OOS, Finland began to emerge from foreign political domination toward national independence. From the mid-twelfth century, when Sweden first laid claims to the land lying on the eastern side of the Gulf of Bothnia, until the relatively recent transfer of title to Russia in 1809, the land occupied by a people of Fenno-Ugric stock had been subjected to strong, if not mandatory, cultural influences. A native Finnish literature had developed belatedly in the early part of the nineteenth century, when Elias L*nnroth collected and transcribed the Kalevala, the national epic poem, which up to that time had been transmitted orally. But it was late in the century before Finnish nationalism in the arts could rise above the increased efforts

The Southwestern Frontier of Eskimo Culture

In a recent summary of our knowledge of Eskimo archaeology in Siberia (Chard 1955b) the present writer cited a reference to the existence of remains of underground houses on the west side of Anadyr Gulf, and inferred from this a possible extension of prehistoric Eskimo culture in this area considerably to the west of its presently known range. One of these rumored sites has now been investigated, with highly interesting results (Okladnikov and Naryshkin 1955). The culture revealed was not the classic Eskimo found at all other coastal sites around the Chukchi Peninsula, but instead is a blend of Eskimo with a distinctly different complex whose affinities lie far to the south on the shores of the Okhotsk Sea.

NOTES ON THE WUNAMBAL LANGUAGE

WUNAMBAL belongs to the Northern Kimberley family of languages, and is spoken to the north of the Prince Regent River, Kimberley Division of Western Australia.1 The Worora tribe occupies the country as far north as Mt. Trafalgar ; thence Wunambal country takes in the area remaining between Scott Strait and the Prince Regent River, stretching inland about to the King Edward River, though with dialectic variations ; northwards it merges into Gambre along the east side of Admiralty Gulf, and there are dialectic variations also about Cape Voltaire Peninsula and the southern shore of the Gulf, called Ilwanda or Julwanda. The accompanying map makes the general lay-out of the territory clear. The system of orthography used is the same as in the preceding articles mentioned in footnote i.