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31.
The NW–SE-trending Dinar fault is an active normal fault upon which the 1 October 1995 earthquake ( M = 6.1) occurred. The 1995 earthquake resulted in a c. 10-km-long surface rupture with the south side down-thrown by 50 cm. Investigations of two trench sites perpendicular to the 1995 rupture suggest at least two prior large earthquakes in historical times. Radiocarbon dates and historical records constrain the age of events between 1500 bc and ad 53, event 2 possibly coinciding with the earthquake that damaged Dinar (the ancient city of Apamea Kibotos) in c. 80 bc and event 1 around 1500 bc. Surface displacements determined for events 1 and 2, compared to the 1995 surface faulting, indicate that M > 6.8 earthquakes were associated with each rupture. Using the total displacement in trenches, a slip rate of about 1 mm yr−1 can be estimated for the Dinar fault. Observations suggest that the return period for large earthquakes in the Dinar area is about 1500–2000 years. 相似文献
32.
Lars P. Dyrud Kelly Denney Julio Urbina Diego Janches Erhan Kudeki Steve Franke 《Earth, Moon, and Planets》2004,95(1-4):89-100
In this paper, we use radar observations from a 50 MHz radar stationed near Salinas, Puerto Rico, to study the variability
of specular as well as non-specular meteor trails in the E-region ionosphere. The observations were made from 18:00 to 08:00 h
AST over various days in 1998 and 1999 during the Coqui II Campaign [Urbina et al., 2000, Geophys. Rev. Lett. 27, 2853–2856]. The radar system had two sub-arrays, both produced beams pointed to the north in the magnetic meridian plane,
perpendicular to the magnetic field, at an elevation angle of approximately 41 degrees.
The Coqui II radar is sensitive to at least two types of echoes from meteor trails: (1) Specular reflections from trails oriented
perpendicular to the radar beam, and (2) scattering, or, non-specular reflections, from trails deposited with arbitrary orientations.
We examine and compare the diurnal and seasonal variability of echoes from specular and non-specular returns observed with
the Coqui II radar. We also compare these results with meteor head echo observations made with the Arecibo 430 MHz radar.
We use common region observations of these three types of meteor echoes to show that the diurnal and seasonal variability
of specular trails, non-specular trails, and head echoes are not equivalent. The implications of these results on global meteor
mass flux estimates obtained from specular meteor observations remains to be examined. 相似文献
33.
Hydrogeology of karst aquifer systems in SW Turkey and an assessment of water quality and contamination problems 总被引：1，自引：0，他引：1
Aysen Davraz Remzi Karaguzel Iskender Soyaslan Erhan Sener Fatma Seyman Sehnaz Sener 《Environmental Geology》2009,58(5):973-988
The aim of this research is to determine the relationship between groundwater flow and water quality of different ground and
surface water basins in the southwest Turkey. In addition, groundwater vulnerability is assessed taking into consideration
groundwater flow and quality. The autochthonous Beydaglari limestone is the major karstic aquifer in the region. According
to the groundwater level map of alluvium aquifers in the basins, groundwater discharge toward the carbonate aquifer is direct
and indirect. The hydrogeological connection between ground and surface water basins occurs via the karstic aquifer located
at the bottom of the alluvium bottom. In Egirdir lake, water also discharges in the karstic aquifer via karstic sinkholes
at the western border of the lake. In the research area, general groundwater discharge is toward the Mediterranean Sea by
means of autochthonous carbonate system, according to hydrogeological investigations, research of lineament and hydraulic
conductivities. This result is supported by the locations of lineaments and shore springs discharging from the limestone.
In addition, spreading of contaminants via karstic aquifer to great distance has been clearly identified. 相似文献
34.
Evidence of right‐lateral offsets associated with the 1912 earthquake (Mw 7.4) along the North Anatolian Fault (Gaziköy–Saros segment) allow us to survey (using DGPS) the co‐seismic and cumulative slip distribution. The damage distribution and surface breaks related with the earthquake show an elongated zone of maximum intensity (X MSK) parallel to the fault rupture on land but this may extend offshore to the north‐east and south‐west. Detailed mapping of the fault using topographic maps and aerial photographs indicates the existence of pull‐apart basins and pressure ridges. At several localities, the average 1912 offset along strike is 3.5–4 m and cumulative slip is 2–6 times that of individual movement. The fault rupture geometry and slip distribution suggest the existence of three subsegments with a combined total length of 110–120 km, a fault length and maximum slip similar to those of the 1999 Izmit earthquake. The amount of slip at the north‐easternmost section and in the coastal region of the Sea of Marmara reaches an average 4 m, thereby implying the offshore extension of the 1912 rupture. The results suggest that the 1912 event generated up to 150 km of surface faulting, which would imply a Mw 7.2–7.4 earthquake and which, added with rupture lengths of the 1999 earthquakes, help to constrain the remaining seismic gap in the Sea of Marmara. 相似文献