Risk Assessment for Umm Qais Archaeological Site as a Case Study
• Umm Qais in Risk • Risks are threating the site values • Aims of the study A. B. C. D. Identifying risks Measuring their magnitude Calculating occurring probabilities Suggesting controlling strategies
Part One: Identifying Risks
Main Risks in Umm Qais
Risk Category Natural Risks Human Risk
• Under this category we identified the following risks.
1. Stone deterioration due to Salt crystallization, Still water, Wind Blowing, Biological agents (algae), Basalt Exfoliation, defects in stone composition. 2. Heavy Rain 3. Earthquake 4. Animals in the site (Grazing cows) 5. Rodents holes.
Stone used at Umm Qais Limestone Basalt
• Limestone is a sedimentary rock composed primarily of calcium carbonate (CaCO3) in the form of the mineral calcite. • Limestone is either Organic or Chemical • Organic : forms from the accumulation of shell, coral, algal and fecal debris. • Chemical : formed by the precipitation of calcium carbonate from lake or ocean water.
• Definition :a dark-colored, fine-grained, igneous rock composed mainly of plagioclase and pyroxene minerals. It most commonly forms as an extrusive rock, such as a lava flow, but can also form in small intrusive bodies, such as an igneous dike or a thin sill. • Basalt is the most abundant bedrock on the earth.
Stone deterioration forms at Umm Qais
Limestone deterioration forms
1. 2. 3. 4. 5. 6. Pitting Cracking Material loss Salt crystallization Salt fluorescence Biological colonization
• Definition : point like shallow cavities, generally cylindrical or conical shape and not interconnected. • Can be biogencally or chemically induced specially in carbonate stone. • mostly due to localize corrosive attack on the stone component.
• Definition : individual fissure clearly visible by naked eye, resulting from separation of one part from another. • Cracking may be due to weathering, flaws in the stone, static problems, rusting dowels, too hard repointing mortar, Vibrations caused by earth tremors, fire, frost may also induce cracking.
3- Material loss (Missing parts)
• Empty space, obviously located in the place of some formerly existing stone part. Protruding and particularly exposed parts (edges, corners..) are typical locations for material loss resulting in missing parts.
5- Salt efflorescence
6- Biological colonization
• Definition : colonization by plants or microorganisims such as algae, Fungi and lichens, it includes also the influence by other organisms such as animals nesting on and in stone. • Mostly algae are found because the condition needed to grow is available (humidity and sun).
Basalt weathering forms
1. 2. 3. 4. 5. 6. 7. Exfoliation Material loss Mineral weathering Microbiological colonization Crust formation Salt crystalization Basalt Spheroidal Weathering
• Natural formation of fracture or rock peeling due to release of pressure upon reaching the surface. • Mostly occur on rock surface.
Basalt Spheroidal Weathering
• Lead to
Still water Running water
Problems of still water
1. Fallen roofs : due to the weight of watershed mainly appears on the of the rooms of the ottoman village. 2. Vegetation mainly in small pools happens due to the lake of water drainage.
1. Fallen Roofs
• Continuous presence of water resulted in the dense growth of grass
Problems of Running water
– Stone deterioration.
1. Past earthquake in the area. 2. Current evidences on past earthquakes in the site. 3. Possibility of future earthquake.
1. Past earthquakes
• Last catastrophic earthquake was in AD 749 according to several historical records.
• According to the World Health Organization, Jordan seismic hazard distribution map of Jordan, Umm Qais...
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