How handsome it is to support the war. Liang Jiahai Road wants Dong Chen to swing through Liang Xiangyang.
(Guangdong Geological Survey Institute, Guangzhou 5 10080)
According to the geological survey in recent years, the ecological environment of the Pearl River Delta Economic Zone: 250,000 geological exploration has made new progress, and we have a new understanding of urbanization trend, human activities in fragile geological environment and abstract information of environmental geological achievements.
Fragile ecological environment, geological environment and geological problems, sustainable urbanization in the process of urbanization in Pan-Pearl River Delta Economic Zone
The Pearl River Delta Economic Zone is located on the southern and central edge of the South China Sea, adjacent to Hong Kong and Macao. Guangdong province is one of China's coastal areas, one of the three most developed and fastest-growing economic units, but also one of the most populous gathering areas. In countries with a large floating population, only a few cities and rural areas are basically integrated, which accelerates the process of rapid urbanization and a series of environmental geological problems have become areas of sustainable development. Socio-economic constraints.
In recent years, the ecological environment organized and implemented by China Geological Survey was organized and implemented by Guangdong Geological Survey Institute under the unified deployment of the Pearl River Delta Economic Zone/KLOC-0: 250,000 geological survey. Based on the project data, this paper summarizes the investigation progress and environmental geology in recent years.
Understand the trend of urbanization and the characteristics of human activities
The objective expression of urbanization trend is the most important material feature, the highest level of socio-economic structure and social form development, and the level of urbanization is the remarkable degree of modernization of a country or region. Since the reform and opening up, the Pearl River Delta Economic Zone has experienced a historic socio-economic leap and soon entered the process of industrialization. The overall level of core groups in Guangzhou, Shenzhen and other cities has risen rapidly, urbanization has developed interactively, rural towns have become towns, county towns and small cities have become metropolises, and large and medium-sized cities have become international. Since 1995, this aspect has reached a mature stage in the vast rural areas, urbanization has basically realized the integration of urban and rural areas, and the degree of urbanization and internationalization has been continuously improved. After more than 20 years of development, the Pearl River Delta Economic Zone is mainly concentrated in two megacities, Guangzhou and Shenzhen, as well as nearly 10 large and medium-sized cities, 20 central cities above the county level and more than 400 towns, and the trend of pan-urbanization is gradually emerging (Figure 1). Whether a mature country with urban connotation is a city in a strict sense is greatly different from the "permanent population" and "registered population", but in this sense, as a whole, the land landscape of this area has formed a metropolitan area and a pan-urban core area. The mature trend continues, extending to the periphery. Non-Pearl River Delta regions will gradually promote the integration with the Pearl River Delta and Delta airlines, and the pan-urban area will continue to expand.
The trend of pan-urbanization makes human activities in this area have obvious regional characteristics.
(1) Ways to increase the number of human activities. From agricultural activities, mining activities, land reclamation, embankment construction, etc.
Figure 1 Thumbnail of Urbanization Mode Extracted from Remote Sensing Image of Pearl River Delta Economic Zone
Description: The pan-dot area has been completed, and the urbanization process of Buddhism, Guangzhou, Dongguan and Shenzhen is clearly visible.
Urban development and economic construction are closely related to all aspects of human activities, and now cover the utilization rate of space resources on the earth's surface.
(2) The influence of human activities and diversity. Different types of human activities may be caused by the same type of eco-environmental geological problems. Such as the area of reclamation? It may lead to siltation in estuaries and ports, degradation of wetlands and coastal mangrove ecosystems, salt tide upwelling, surface water pollution, groundwater pollution and soil pollution caused by mining development and agricultural activities.
(3) Spatial aggregation and diffusion of human activities. In metropolitan areas, human activities are mainly concentrated in regional and social development planning, including Guangzhou (excluding cities with increased Conghua), Dongguan, Shenzhen (including Baoan District of Shenzhen), Foshan (Nanhai District, Chancheng District and Shunde District of Foshan City), Zhongshan City, Jiangmen City (urban area and Xinhui District) and Zhuhai City (including Doumen District). In plain areas, urban construction activities, linear construction such as railways and highways, landfill sites, point construction projects and agricultural activities are the main activities; The environmental resources of mountain-Taiwan Province province, hilly-low mountain building materials, mines and slopes are mainly developed and utilized by human activities in coastal areas; Development and utilization of main resources in reclaimed beaches.
(4) The intensity of human activities is firm. Especially after the reform and opening up, the intensity has been increasing, and human activities have been carried out since 1990. In table 1, the three stages listed in table 2 reflect the increasing trend of human activities. As a result of the large-scale expansion of urban construction in the process of urbanization in the eastern economic zone interpreted by remote sensing, 1990 increased by 8.6%, and increased to 14.8% in 2000.
Double; Cultivated land decreased from 19% in 1990 to 13.6% in 2000 (Table 3). With the signing of the "9 +2" Pan-Pearl River Delta regional cooperation framework agreement, the pace of urban development in this region will be further accelerated. According to the statistical planning area of towns and villages, in 20 10, it will exceed this area and urban area 1.0× 104 square kilometers, accounting for non-agricultural construction land 1.5× 104 square kilometers (accounting for the total land area of the whole region? 1/3 or more), then more than 70% of the ground in this area will be used for construction. It can be predicted that the scale of human engineering activities will be unprecedented in the next few years or even decades.
Table 3 1990 and 2000 NDVI index partition value comparison table
NDVI value of partition type, as a percentage of total area (%), and as a percentage of total area in 1990 and 2000 (%).
-1 to -0.5 Water body (river, lake and sea) 24.3 24.438+0
8.6 1.5 0.4.8-0 urban architecture
0-0.5 Crops, cultivated land and cultivation 19.4 13.6
0.5? Bamboo forest 0.75, shrub (plant) 25.4 24.9
0.75 to 1 forest (plant) 22.3 22.6
(5) Gradually orderly human activities. The disorder of human activities will be alleviated. The so-called obstacle refers to human activities, because blindly ignoring the consequences of lack of guidance and supervision of the ecological geological environment is an ecological situation and environmental geological problem that may lead to variation and derivation. With high-level education, strengthening formal laws and regulations to improve people's awareness of environmental protection, and the development of related technologies, human activities will have standards, so as to curb disorderly activities to a certain extent. However, a large number of planned human activities still need to fully consider the possible consequences.
2 vulnerability of geological environment: from a geological point of view, environmental geological problems
Human activities are intrinsic to external factors such as raw material development, environmental geological problems, and geological environment fragility. Understanding the vulnerability of geological environment is undoubtedly helpful to the study of environmental geological problems. The vulnerability of the geological environment in the Pearl River Delta Economic Zone is mainly reflected in the following aspects.
2. 1 residual soil in bedrock area is well developed.
The area of bedrock in this area accounts for about 60% of the total land area, of which the main magmatic intrusive rocks (granite) account for about one third. Development of residual soil in weathered bedrock area of strong rock. Granite contains high content of unstable minerals such as feldspar and mica (usually about 70%), and the thickness of residual soil is usually larger (>: 20m) and less than 5m. Besides the mountain height, the weathered residual hill of coastal islands-Taiwan Province Province has become the main soil erosion area, and metamorphic rocks and volcanic eruption rocks are mostly mixed breccia debris residual soil with average clay thickness.
2.2 Quaternary loose sedimentary soft soil is generally developed.
Widely distributed in Quaternary loose sediments in the Pearl River Delta Economic Zone. What is the distribution area? Land area accounts for 2/5 of alluvial, alluvial, alluvial ocean and red sea area, which is a genetic curve. Alluvial deposits, alluvial deposits and alluvial deposits in river valleys and river terraces are mainly distributed at the edge of the delta, and the thickness is generally less than10m. The terrace alluvial peat 14C is usually of binary structure, and the lower part is fine sand or silty clay sand mixed with coarse sand and gravel, with an age of 7580 170. Scouring marine sediments and marine striations are widely distributed in delta plains and coastal areas, mainly occurring in the plains of the interaction between bay sediments and coastal rivers during the late Holocene transgression. The average thickness is 25. 1 m, and the maximum thickness is 63.6 m. The upstream area is mainly yellowish gray or grayish brown silty clay, and the downstream area is mostly dark gray silty soil and silt.
The distribution area of soft soil is nearly 8000 square kilometers, accounting for about 1-5 of the land area of this area, and the delta plain area with the densest cities is the most widely distributed area of soft soil. The area of soft soil accounts for 82.25% of the total area of economic soft soil distribution. From the Pearl River Delta, the increase of the thickness of soft soil at the top and the increase of the degree of consolidation worsen, which leads to the lithologic stage of the flood plain strata in the estuary area and enters the opposite of muddy soil and muddy soil. According to borehole data, 14C dating and sporopollen analysis, the delta soft soil can be roughly divided into three levels in the vertical direction. Sin occurred three times in the delta region from late Pleistocene to Holocene, corresponding to the sedimentary age, thickness, water content, liquid limit, liquid index, void ratio of new soft soil and the mechanical properties and strength of older people. With the increase of compression coefficient, it becomes smaller. Natural dynamic action, human activities and the influence of soft soil are all prone to land subsidence and harm to ground engineering and buildings.
In addition, in the delta river network area, the distribution area of easily liquefied sand bodies in Donghe River is 2 1.3 million square kilometers, the depth is generally 1.5 ~1.2.8m, and the thickness is1.5? 10.5m, standard penetration, from 2.3 to 7.4. Saturated loose silt, silty sand and silty sand are subjected to dynamic loads (earthquake, piling, blasting and mechanical vibration), which are easy to liquefy and destroy ground projects and buildings.
Table 4 Quality characteristics of physical and mechanical properties of soft soil in Pearl River Delta
Physical and mechanical properties (average value) of the main characteristics of the thickness and depth of the roof silt layer during deposition.
The average maximum value is W0 WL IL E0 A 1-2 ES?
%%-MPa-1 MPa
The first layer of late Holocene shell fragments is 0.0? 5.0 1.5? 2 1.9 9.5 42.7 60.2 45.7 1.89 1.66 1.44 2.45 6.90
On the modern Holocene, the second layer of oyster shell often contains fine sand 2.620.81.51.1.06.037+0.30080.000080008805
The third layer of late Pleistocene marine shell fragments, floodplain facies rotten wood 5.3? 24.0 0.6`7.9 3.7 20.4 42.3 38.6 1.26 1. 18 0.75 5.0 1 13.79
2.3 neotectonic movement is active
The neotectonic movement was active, and it was inherited from Late Cretaceous to Tertiary. According to Guangdong NE-NNE deep fault zone, Lianhua Mountain, Zijin-Boluo fault zone, Donghe fault zone, Enping-Xinfeng deep fault zone, Wuchuan-Shen Si fault zone, east-west Gaoyao-Huili deep fault zone, northwest-Xijiang fault zone and Zhuhai-Xinda fault zone intersect [4]. Gaoyao fault, enping city-Taicang fault, Jinji-he cheng fault, Guangzhou-Gulao fault, Guangkangzang fault, Shenzhen fault, Pinghai fault, Tanghu fault, Chishi-Shatian fault, Xijiang fault, Shajiao fault and Yamen fault are still positive. For example, according to the monitoring data, from the fault activity of the fault to 1973 to 1979, and from 26.5 mm to 4.4 mm, the annual average event occurrence rate, the maximum change of the height difference of the Shougouling fault in Guangzhou (Hangzhou-Tibet) is 3.34 mm, and the horizontal pit section of the Xijiang fault is 2.38 mm1in June. 0.35mm/year.
2.4 carbonate karst development
The area of carbonate rocks around Zhaoqing-Kaiping City, enping city, Longgang District, Shenzhen, Aipi Town, Danshui Town, Zengcheng City, and Chuanfu Lake is 1474 square kilometers, but most of them are covered by Quaternary loose sediments. Carbonate rocks are mainly exported to Laurel-Luodong Formation of Ordovician, Tianziling Formation of Devonian, Quanwan Formation-Tianziling Formation of Carboniferous County, Shixiazi Formation (CS), Shuiziqiao Formation, Ziqiaodapu Formation-Dapu Formation, Hutian Formation (CH) and Shitianzi Formation of Hutian Formation of Qixia Formation of Permian, in which Tianziling limestone is the most karst. Taking the wide flowerpot land as an example, the thickness of Quaternary loose sediments is generally 10? The 25m surface layer is bonded with soil foundation (local silt), and the bottom of sand or gravel layer is often in contact with limestone. The strong karst development area is located at -20? -80m elevation part. The regional and geological structures with hidden karst hydrogeological conditions are very beneficial to the formation of land subsidence.
2.5 Vulnerability of soft rock engineering
Cretaceous-Tertiary red beds, Jurassic Gaoyao-Sanshui-Guangzhou-Dongguan, Enping-Kaiping, Huizhou, Boluoyang Village, Huiyang, Huidong-Baipenzhu and other places are all distributed. Carboniferous coal-bearing strata often contain mudstone, sandy mudstone, shale, carbonaceous shale, coal, gypsum, salt rock and soft rock with relatively low mechanical strength. These easily weathered rocks are exposed and often swell. The softening coefficient is 0.26 ~ 0.5, and the saturated compressive strength is 0. 1.4? 1.2 MPa, gypsum and salt rock are easy to produce long-term groundwater dissolution pores and ditches. If these stones are selected as the foundation bearing layer, buildings are prone to geological disasters such as engineering foundation sliding, uneven deformation, landslides along weak slopes in mountainous areas and engineering construction sites, so this kind of rock stratum is an unfavorable construction project.
3 environmental geological problems: classification reasons and socio-economic impact
In the process of urbanization, population agglomeration, industrial agglomeration, economic growth, social production and lifestyle have changed, but there are also large-scale resource consumption, spatial agglomeration patterns, and the formation process of urban landscape pattern that destroys natural landscape. With the development of social economy and urbanization, on the one hand, influenced by the fragile factors of geological environment, on the other hand, driven by human economic-engineering activities, environmental geological problems will inevitably arise. The environmental geological problems of the Pearl River Delta Economic Zone and the sustainable development of social economy are mainly soft foundation settlement, coastal ports, rivers, estuaries siltation, urban floods, water and soil pollution, lack of hidden karst collapse in different degrees, natural soil erosion, man-made soil erosion and collapse, landslides, mudslides, water shortage and stable structures, which can be divided into three environmental geological types: local main genetic types and secondary natural combinations.
3. 1 Main environmental geological problems of this machine
Structural stability 3. 1. 1
Structural stability of small amplitude, high frequency and dense group earthquakes in Pearl River Delta Economic Zone. Regional earthquakes occur at the intersection of active fault zones and are often distributed in groups. Earthquakes along the NE active fault zone. It is mainly a felt earthquake that occurred after the 1970 earthquake in modern history, mostly distributed in the western and southern coastal areas of the Pearl River Estuary such as Enping-Taishan-Doumen-Shenzhen, Guangzhou, Shunde, Zhongshan, Xinhui, Taishan, Zhaoqing and Sihui. Judging from the earthquake history, there were 2 15 earthquakes and 13 destructive earthquakes in this area, of which 4.75 was above. Since the instrument recording began at 1970, there have been 2 12 earthquakes of magnitude 2.0 or above in this area, with an average annual frequency of 7/3 earthquakes of 59 and 4 (the 4 earthquakes are not more than 5 respectively).
3. 1.2 Resource water shortage
The shortage of water resources in the coastal areas and islands on the east coast of Huidong Pinghai-Huiyang Xia Yong-Daya Bay-Shenzhen Pearl River Estuary is outstanding. Urban water supply mainly depends on the long-distance dispatching of Dongjiang water to solve the problems such as the lack of local surface water and underground water sources, centralized water supply in cities, changes in quantity and quality of water resources and other reasons leading to drought or upstream pollution, and the water supply problem will become more serious. Shenzhen has become a serious water shortage city in China among the seven major cities in the world.
3. 1.3 Debris Flow
All areas occurred in 36 small debris flows in 1 1, and these debris flows were most likely to occur in Jurassic lava (JKN, Little JKB) and the mountains and steep slopes of Lianhua Mountain in Huidong-coastal mountainous areas. Volcanic eruption rock distribution area, low mountains and hills, steep terrain (usually on hillsides and slopes >; 30) Joints and fissures affected by weathering of rock structure, residual soil has obvious connection with weathered rocks, and most of them are cohesive soil with loose gravel structure. In the rainy season, the clay minerals of residual soil swell and soften when meeting water, which is beneficial to water collection conditions and the soil slides down the weathered rocks and steep slopes to form debris flows, but the weathered rocks are thin, the water collection area is small and the landslides are small. The residents are nearby, and the engineering construction near the mountain is very harmful, which not only destroys the landscape affected by woodland and debris flow, but also directly threatens people's life safety and property and becomes the main factor of danger. Ground instability and regional ecological environment construction in Wucun 1997, Huadu District, Guangzhou, a two-story building at the foot of the mountain was destroyed by debris flow, and all the construction and household use 10 were killed.
3. 1.4 Natural soil erosion
Patchy distribution is the granite residual soil with sparse vegetation in the most widely distributed natural soil erosion area, which has the greatest negative impact on the distribution of granite (including islands) in hills and southwest coastal areas of Taiwan Province Province, Huidong County, Conghua City, Huadu District, Taishan City and Jiangmen City. Area? Natural soil erosion area? 630 square kilometers, accounting for? It accounts for 43% of the total soil erosion area.
3.2 minor major environmental geological problems
3.2. 1 shelter evil and accommodate evil.
In the Pearl River Delta region, more than 6,000 small-scale and scattered towns and two heavily polluting enterprises generally lack effective sewage treatment facilities, and a large amount of sewage is discharged into rivers. At present, the annual wastewater discharge exceeds 20 108 tons, and industrial solid waste 180× 104 tons and garbage 300× 104 tons are generated every year. The rivers around the city are polluted to varying degrees, and the rivers around the city are seriously polluted. The water bodies and sediments polluted by toxic and harmful heavy metals in the Pearl River water network and the entrance area, especially the harm caused by persistent organochlorine pesticides, polycyclic aromatic hydrocarbons, polychlorinated biphenyls (PCBs) and other organic substances to ecological and environmental safety, have sounded the alarm. According to the geological survey results of Guangdong Geological Survey, the research results of soil environmental quality in the Pearl River Delta show that the region has been polluted in a large area, and the main toxic heavy metals are harmful elements such as cadmium, mercury, arsenic, copper, fluorine and sulfur. The influence of soil pollution and toxic elements is worrying. Zhang et al. confirmed the existence of organochlorine pesticides and polycyclic aromatic hydrocarbons pollution in soil. Guangdong Geological Environment Monitoring Station completed the evaluation report of groundwater resources and discussed the non-organic pollution of groundwater. Academician Fu Jiamo wrote an article about the existence of persistent organic pollutants in the environment and the problems that caused environmental pollution. A paper published by the Ministry of Earth Sciences and China Academy of Sciences published a large number of data on soil and water pollution in the Pearl River Delta.
In the pilot investigation and evaluation of groundwater pollution, 35 kinds of organic pollutants were found in groundwater in the Pearl River Delta in 2005, including 9 kinds of halogenated hydrocarbons, 8 kinds of monocyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons, organochlorine 1 1 pesticides, ketones and phthalates.
A large number of facts such as soil and water pollution, water resources, land resources and biological resources have undergone qualitative changes, which can be used to reduce the direct threat to the living environment and the harm to human health, as well as the impact on social economy and sustainable economic development.
be short of water
The surface water resources are limited, and the soil and water are polluted. Although the per capita water resources are 14580 cubic meters, which is much higher than the national average of 2500 cubic meters, it meets the drinking water quality standards. Coupled with the root cause of salt tide, the impact of the superposition of sewage charges is mainly the salt content of groundwater. 1 Salt water makes Guangzhou (including Panyu Nansha Development Zone), Dongguan, Foshan (including Shunde District and Nanhai District), Pearl River Estuary and Zhuhai in Zhongshan Metropolitan Area seriously short of water ②.
3.2.3 Man-made soil erosion
Humans? 840,000 square meters, soil erosion area? 57% of the total area of soil erosion. Human erosion is mostly spots. In urban development or urban dense areas, the main erosion types near human construction sites are mostly used in construction sites and lack of vegetation protection. In Shenzhen, Dongguan, Zhongshan and other places, the slopes and steep slopes of construction sites (including traffic engineering and construction and development websites) have strong human activities and developed economies. The largest distribution area. In addition, soil erosion caused by local mining operations is serious.
With the occurrence of man-made soil erosion, the pressure of silt and shallow rivers, ponds and reservoirs increases, floods occur frequently and crops fail. For example, the river 5 kilometers away from Shangde Kaolin Mine in Wuxi is a place with serious sediment deposition. A large area of fertile land was flooded and the river was blocked (6 meters thick). In Kengkou village, more than a dozen houses were buried. Destroyed for more than 20 hours, the whole village was forcibly relocated 10 meter. The kaolin mine in Shizui Village, Aotou Town, Conghua City caused the downstream river to deposit about 3 to 5 meters thick, and the farmland on both sides of the river was buried for several kilometers.
3.3 Primary environment and secondary geological problems
3.3. 1 soft foundation settlement
The formation time of plain soft soil thickness near the Pearl River Estuary is short, which is the key part of soft foundation settlement. The distribution of soft soil foundation is concentrated in Panyu District, Guangzhou, east and southwest of Zhongshan North Road, Zhuhai, and the thickness of soft soil layer is more than 20 m. There are obvious areas in ancient and modern African development zones such as Hengmen Town, Minzhong Town, Nansha Economic and Technological Development Zone, West District of Zhuhai City and Xinhui District of Jiangmen City. Settlement of soft foundation. The soft foundation treatment of expressway in Zhuhai Avenue, New Expressway, Guangfo Expressway, Guangzhou-Zhuhai Expressway, Zhongshan, Zhuhai, Panyu District and Guangzhou City also has obvious settlement. The comprehensive analysis of survey data shows that soft soil foundation is prone to settlement disaster.
According to the survey data, the cumulative amount is generally 0.3? The settlement of 1.7 m in this area ended in 2003. Compared with 1994, the average annual settlement of Zhuhai Avenue 10 year is 0.37m, and the maximum settlement is 0.73m.. At present, Jinwan golf ball has solved the maximum cumulative settlement of 2.97 meters on the ground with the maximum cumulative settlement. The thickness of soft soil exceeds 30 meters, and the average siltation is? The rate exceeds 0. 1? 0.3 M/A group.
It was built in the newly deposited soft soil engineering construction, and most of it was distributed in different degrees due to the settlement of soft soil foundation. Some low-rise buildings that directly construct soft soil crust are often soft soil areas and high-rise buildings with inclined cracks in the bearing layer of ground bedrock, which are often suspended in autumn. Subgrade displacement, uneven settlement at the junction of road and bridge, pavement cracking and other phenomena occur in waves of roads and pavements. The settlement of soft foundation in industrial and civil construction projects seriously affects the normal use of dike water conservancy and hydropower projects, underground water supply-power supply network infrastructure, or uneven road surface, which can not play a normal role. This not only caused hundreds of millions of dollars in economic losses in the southern coastal areas, but also caused some businesses and houses to be neglected, which seriously affected the investment environment.
3.3.2 Coastal changes come from ports, rivers, entrance siltation and urban floods.
Before the Tang Dynasty, the average speed of coastline advancing toward the sea was less than 10.2M/A, which was about 15m/A in the Tang and Song Dynasties and about 20 M/A in the Song, Ming and Hou Dynasties. Large-scale human economic engineering activities, so 120 years of abnormal changes in the coast, with Hengmen, Denglongsha to Pingsha Farm Wanqingsha the most obvious. 1883 to the early 1980s, the average nappe rate of Wanqingsha and Denglangsha into the sea was 63.3 M/A 12 1.7 m/. In the 1960s? In 1970s, during the period of "grain as the key link" and the reform and opening-up in 1980s and 1990s, large-scale land reclamation activities rapidly promoted China's presence in the South China Sea, especially the Pearl River port line (Table 5). What is the transgression area of this area? 6 19.23 square kilometers, a large number of Pearl River estuary waters increased by 552.95 square kilometers. The construction area of coastal cities is 4.625 square kilometers, which has rapidly expanded from 1986 in 2000 to 5 1.585 square kilometers. Breeding across 23rd Bay, Panyu District and Zhongshan City has been recovered from Baiteng Lake 1 1 Bay in Doumen District, Zhuhai City. The bureau led Niwan Gate to close Sanzao Island in Zhuhai, and Qinheng Island has been fragmented with other inland islands.
Table 5 The sea passage rate of Humen crossing the coastline of Longsha Pingsha Farm, a doorman (unit: m/)
Notes for lots 1973 to 1990 and 1990 to 2002.
Wanqingsha 5 14.7 29 1.6 Southeast direction
Southeast of Longxue Island 303.9 583.3
Southeast of Hengmen Island 225.5 527.8
Longsha 250.0 770.8 propulsion direction southeast.
4 conclusion