Saša said:
Oxajil said:
Renaissance said:
mkrnhr said:
This tragedy is not clear. If it were a terrorist attack (ISIS/US/Israel or other), then the timing and target can be understood. If it were a "natural" event of meteoric or other nature, then the fact that it is a Russian civilian plane, one month after the beginning of Russian intervention in Syria is confusing. Don't know what the odds are but it could be a 4DSTS kind of a tentrum of some sort. OSIT
I agree the timing, the location and that it was a Russian plane creates a strange picture for a natural event. I've doubted that the US would create an overt terror attack against Russia because they wouldn't want to garner sympathy or more support towards Russia in their fight against terrorism. A manufactured 'accident' as a warning would make sense from their perspective, but so far the details of the crash are a bit befuddling.
Yeah, I see what you guys mean, it is confusing. Then again, during this time there was quite some cometary activity going on in the skies. Perhaps this plane was just at the wrong place at the wrong time.
And maybe (areas close to) warzones are more prone to 'attract' certain natural events.
It somehow doesn't seem so to me (bolded part).
I've been wondering also why Chelyabinsk since it's in Russia and no war there (or war game/agenda as far as we known about it), in addition to Tunguska in 1912 which is basically in the middle of nowhere (and also in Russia). Also, taking historic records into account, that I know of on top of my head, it doesn't really seem very likely that places of "physical" disturbance on Earth "attract" space rocks/comets. It's more like wars and disturbance come as a result of a space visit. Besides, the Cs once said that comets/rocks visit those areas where there is pronounced "orthogonality" to truth and objective reality, while war zones don't seem like that to me (too much suffering and preoccupation with mere surviving for "orthogonality" to be mass imposed).
Just my 2 cents.
Added: It's like the war zones send specific signal to Universe: "It's so much suffering here, we need no more." And the Universe listens...
I have wondered that as well. What is the gravity of this area its history?
ScienceDirect
http://www.sciencedirect.com/science/article/pii/S2090997713000540
Gravity observations at Sinai Peninsula and its geophysical and geodetic applications
4. Methodology
The main objective of the current research is to delineate local and regional geologic subsurface structure and its relation to the tectonic and geodynamic behaviors of the selected region. Three data sets have been used for the current objective. Terrestrial gravity observation has been dedicated to detect local gravity anomaly. Meanwhile, satellite altimetry data have been used to detect the marine regional gravity anomaly. Mass redistribution attributed to the tectonic setting of Sinai has been monitored utilizing temporal gravity variation from grace satellite mission.
4.1. Terrestrial gravity observation
Ground-based gravity data precision requires accurate gravity sensor and precise determination of geographical position. On the current research, the Scintrex CG-5 gravimeter was used to collect the gravity measurements. The meter has a range of 200 mGal and a resolution of 1 μGal. Positioning has been carried out using dual frequency GPS.
Gravity observations are made on a grid with 3- to 4 km-spacing between the gravity stations. The grid has been selected to be possible to well cover the selected region. The grid comprises of 950 points and is illustrated in Fig. 5.
Image 4.1
4.2. Satellite altimetry
In Egypt land and marine geophysical data are inadequate because of rough topography on land and economic reasons of marine observations. The use of satellite altimetry data is of special importance.
The availability of altimeter data from satellite observations, such as data collected by the European Space Agency ERS-1 and data from the US Navy Geosat, has opened new perspectives in the Earth sciences. One of the most important applications of these data is that they provide scientists with an unprecedented view of the Earth’s interior and its gravity field over the marine regions (Sandwell and McAdoo 1990).
The surface of the marine region can be, with some limitations, considered as an equipotential surface of the gravity field, or the so-called geoid surface. The actual geoid surface deviates up to 100 m from the ideal ellipsoid. Deviations of geoid surface obey to a great extent the topography of the marine floor and reflect the tectonic settings and the subsurface structures. Small deviations in the geoid height, which take the form of tiny bumps and dips, can be measured using precise radar mounted on a satellite such as ERS-1 and Geosat.
One of the main applications of collecting gravity data on land is the determination of the geoid height. However, in marine regions the observed geoid can be converted into gravity anomaly or the so-called satellite altimeter gravity. The advantages of this conversion are that it makes it possible to figure out the gravity field over marine regions. In addition, converted gravity anomalies from the precise geoid can enhance the determination of small-scale geological features. The role of satellite altimetry data in geophysics is illustrated in the current study for the Sinai region. These data are evaluated by comparing them with the known tectonic and geologic settings as well as observed land gravity data for the studied region.
On the current study, free air gravity map of Sinai will be used to figure out the gravity anomaly and its relation to its regional tectonic settings.
4.3. Temporal gravity variation (Grace)
Temporal gravity variation was computed from the Gravity Recovery and Climate Experiment (GRACE) of Sinai to determine important mass redistribution zones and shed more light on its geodynamics pattern in relation to its seismological activities.
Gravity field variations as derived from the monthly GRACE solutions result from the integral effect of mass variations in the atmosphere, hydrosphere and geosphere. These effects include oceanic, atmospheric and hydrological mass movements and those caused by dynamics in Earth’s interior. In addition, residual signals from insufficient pre-processing may be present.
Geodynamic processes such as changes in Earth’s topography or mass distribution as a result of lithospheric plate interactions (collision, subduction, rifting), postglacial rebound, mantle convection, earthquakes, sedimentation and erosion, should also contribute to temporal variations of the Earth gravity field.
Several studies have been devoted to quantitative estimates of the contribution of regional geodynamic processes to temporal variations of Earth’s gravity field. Velicogna and Wahr, 2002 addressed the effect of postglacial rebound and the possibility of recovering mantle viscosity profiles using satellite data, and concluded that GRACE data could significantly contribute to solve this problem. In a very recent paper, Sun and Okubo, 2004 compared the GRACE target accuracy to degree amplitude spectra for co-seismic deformations resulting from the 1964 and 2002 Alaska, and 2003 Hokkaido earthquakes. They concluded that co-seismic deformations for an earthquake with a seismic magnitude above 7.5 could be detected by GRACE.
The main objective of this study is to estimate any mass variations attributed to the active tectonics in and around Sinai Peninsula from the GRACE data.
5. Results
5.1. Terrestrial gravity data
Adjustment of gravity observations has been carried out using Geosoft (Oasis montaj, 1998). The resulted Bouguer anomaly map of the studied region is given in Fig. 6. The most remarkable gravity anomaly of the region is seen as a high gravity anomaly of the order of about 854 mGal in the southern and central parts, and has a minimum of about 768 mGal in the Western and Eastern parts of the study area. Central high gravity anomaly can be due to the dense basement section attributed to the El-Tih Plateau.
The boundary tectonic elements, Gulf of Aqaba on the east and Gulf of Suez on the west can be seen as significant low gravity anomaly. These negative anomalies estimate the extension of Sinai along these tectonic zones.
The triple junction of the Red sea is represent by high gravity anomaly explains the elongation of the Red sea.
The general trends of the field are NW-SE and NE-SW and in addition E-W trend. Also, most of the steep gradients have alternating negative and positive anomalies at the north eastern and south western parts of the map, respectively. This indicates that the area is structurally controlled by tectonics having major axis in the NW-SE and NE-SW directions and the Syrian Arc structure influence on the gravitational field trend in E-W direction. The south western part has anomalies with definite polarities and is characterized by irregular contouring pattern, with negative value, different sizes and shapes and from moderate to high gradients, while the central part has high positive value with different sizes and shapes and high gradients. On the other hand, the north eastern part of map reveals steep gradients has alternating negative and positive anomalies. The source of the anomaly may be due to an uplifted block of the denser crystalline rocks.
Skipping down
5.2. Satellite altimetry data
Figure 9. Free-air gravity map of Sinai Area.
The free air gravity anomaly map of Sinai (Fig. 9) is generally characterized by negative free air gravity anomalies, with average values of about 0 to −26 mGal in the land margin areas and a consistent gravity low from −28 to −35 mGal of the axial depression. A Y-shaped region of very low values of a minimum −183 mGal is found near the junction of the Red Sea with the Suez and Aqaba Gulfs.
•The main obtained gravity features at the satellite free air gravity map correlate well with regional feature of ground-based gravity observed map. This means that, the dominant gravity source is a regional feature rather than local structure on the area.
•Ground-based gravity observed map evaluates well satellite-based map.
•The general tectonic pattern of the Gulf of Suez can be seen as two different gravity anomalies. This indicates that, the Gulf of Suez was separated into two zones of different geodynamic behaviors.
•Triple junction consists of complicated gravity sources; represent the multiple tectonic features’ effect on the area.
•The transform dead sea fault can be seen as negative anomaly with a rotation altitude explains the relative movement between African and Arabian plates.
•Gulf of Suez shows less gravity anomaly than Gulf of Aqaba, reflecting its les activities. However, Gulf of Suez shows more complicated tectonics.
• Regional gravity patterns of Sinai appears as positive gravity anomaly in the eastern part represented in the Arabian plate, African plate to the west and Eurasian plate to the north.
More @ the link above
Sinai
michael steinbacher
Published on May 4, 2015
