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| Harrat Rahat | |
|---|---|
| Name | Harrat Rahat |
| Location | Hejaz, Saudi Arabia |
| Type | Volcanic field, lava field |
| Last eruption | 1256 CE |
Harrat Rahat Harrat Rahat is a large basaltic volcanic field in the Hejaz region of Saudi Arabia, situated near Medina, Red Sea, and the Najd plateau. The field forms part of the Arabian Plate margin and lies within the broader Arabian Plate tectonic setting, adjacent to the Gulf of Aqaba and the Dead Sea Transform. It is one of several Harrats in the western Arabian Peninsula, comparable to Harrat Khaybar and Harrat Rahat-region neighbors such as Harrat Khaybar and Harrat Lunayyir.
The volcanic field occupies much of the western Hejaz near the historic city of Medina and extends toward the Red Sea Rift and the Asir Mountains, intersecting routes between Mecca, Ta'if, and the port of Jeddah. Harrat Rahat sits on late Proterozoic to Phanerozoic basement rocks affected by the Pan-African orogeny and the Madinah Complex, with overlays of Mesozoic sedimentary successions. Regional tectonics are influenced by the Red Sea rifting, the Gulf of Aqaba transform fault system, and intraplate stresses related to the African Plate–Arabian Plate interactions. Morphologically the field comprises numerous cinder cones, shield volcanoes, and extensive ʻaʻā and pahoehoe lava flows typical of basaltic volcanism, forming a broad lava field that merges with neighboring volcanic provinces such as Harrat Khaybar and Harrat Lunayyir.
The volcanic history includes product emplacement during the Neogene and Quaternary with multiple eruptive episodes recorded by radiometric dating and stratigraphic correlation to events such as the Holocene volcanic sequence in the western Arabian Shield. Historical activity includes a well-documented eruption in 1256 CE that produced lava flows reaching the outskirts of Medina; this event is correlated with chronicles from contemporaneous travelers and records tied to the Mamluk Sultanate era. Geochronological studies link earlier episodes to regional magmatic pulses contemporaneous with activity at Harrat Khaybar, Harrat Khaybar eruptions, and younger vents active during late Holocene times similar to eruptions in Iceland and the Ethiopian Rift. Seismic swarms and ground deformation detected in modern times near Medina and Yanbu indicate the field remains potentially active, analogous to unrest observed at Campi Flegrei and Mount Etna.
Lavas are dominantly olivine-phyric to porphyritic basalts and basaltic andesites bearing minerals such as olivine, clinopyroxene, and plagioclase, comparable to compositions analyzed from Harrat Khaybar and Harrat Khaybar-region basalts. Geochemical signatures show enrichment in incompatible elements and isotopic ratios linking mantle source heterogeneity akin to mantle domains sampled beneath the Red Sea and Afro-Arabian mantle plume hypotheses. Eruption products form ʻaʻā, pahoehoe, scoria, spatter cones, and tephra deposits with textures similar to those described at Kīlauea, Mauna Loa, and Mount Cameroon. Petrological studies utilize techniques from institutions like the Smithsonian Institution and universities such as King Saud University and Imperial College London to characterize melt evolution, fractional crystallization, and crustal assimilation processes.
Hazards include effusive lava inundation, localized tephra fallout, ground fissuring, volcanic gas emissions, and induced seismicity that threaten urban areas such as Medina, infrastructure on highways connecting Mecca and Jeddah, and heritage sites under the custodianship of regional authorities. Potential impacts mirror those observed during lava flow crises at Iceland and urban-adjacent eruptions at Mount Etna, requiring civil protection coordination among agencies like the Saudi Geological Survey and municipal authorities of Medina Province. Monitoring employs seismic networks, InSAR ground deformation from satellites such as Sentinel-1 and TerraSAR-X, gas sampling comparable to protocols at Sakurajima, and geothermal gradient surveys; early warning frameworks draw on models developed after events at Lusaka-regional responses and best practices from the USGS and Global Volcanism Program.
The region encompasses historical trade corridors linking Mecca, Medina, Medinah, and Red Sea ports including Yanbu and Jeddah, with archaeological sites reflecting occupation during the Pre-Islamic and Islamic Golden Age periods. Traditional land use includes pastoralism by communities historically associated with clans of the Hejaz and irrigated agriculture in oases serviced from wells and wadis, with modern expansion driven by urban growth in Medina and infrastructure projects under initiatives like Saudi Vision 2030. Cultural and religious sites, heritage properties, and pilgrimage routes intersect the lava field, requiring integrated land-use planning with conservation authorities such as the Saudi Commission for Tourism and National Heritage.
Ecological communities on the lava field are characterized by desert-adapted flora and fauna, with plant assemblages comparable to those of the Asir and Najd bioregions including shrubs and xerophytic species observed near Wadi Al-Aqiq and oasis habitats. Faunal elements include reptiles and avifauna recorded in surveys by organizations like IUCN and regional universities, with habitat pressures from urban encroachment and grazing. Conservation efforts engage entities such as the Saudi Wildlife Authority and international partners to protect unique habitats and archaeological landscapes, integrating strategies similar to those implemented in Negev and Sinai volcanic terrains to balance development, pilgrimage traffic, and biodiversity preservation.
Category:Volcanoes of Saudi Arabia Category:Volcanic fields