|UTC time||1995-11-22 04:15:11|
|Local date||November 22, 1995|
|Depth||18 km (11 mi)|
|Areas affected||Egypt, Israel, Jordan |
|Max. intensity||VIII (Severe)|
|Casualties||9–12 dead |
The 1995 Gulf of Aqaba earthquake (also known as Nuweiba earthquake) occurred on November 22 at 06:15 local time (04:15 UTC) and registered 7.3 on the Mw scale. The epicenter was located in the central segment of the Gulf of Aqaba, the narrow body of water that separates Egypt's Sinai Peninsula from the western border of Saudi Arabia. At least 8 people were killed and 30 were injured in the meizoseismal area.
The earthquake occurred along the Dead Sea Transform (DST) fault system, an active tectonic plate boundary with seismicity that is characterized by long-running quiescent periods with occasional large and damaging earthquakes, along with intermittent earthquake swarms. It was the strongest tectonic event in the area for many decades and caused injuries, damage, and deaths throughout the Levant and is also thought to have remotely triggered a series of small to moderate earthquakes 500 kilometers (310 mi) to the north of the epicenter. In the aftermath of the quake, several field investigations set out to determine the extent of any surface faulting, and the distribution of aftershocks was analyzed.
The Gulf of Aqaba is situated along the southern portion of the Dead Sea Transform (DST) fault zone, a 1,000 km (620 mi) transform fault that forms the barrier between the African Plate and the Arabian Plate (Arabian-Nubian Shield). The left-lateral strike-slip fault connects the spreading center that forms the Red Sea in the south with the East Anatolian Fault in Turkey in the north. Although there is much that is not known about the DST, it is accepted that its transform motion began around 12–18 million years ago. Geologist A. M. Quennell, who is credited with first recognizing the movement along the fault in 1958, estimated the total displacement to be 107 kilometers (66 mi) while a similar study that included more regional influences resulted in an estimated slip of 100 kilometers (62 mi). That broader kinematic model translates into a slip rate of 8–10 mm/year for the portion of the fault south of the Dead Sea.
Along the length of the Dead Sea Transform (also known as the Levantine fault) there are several pull-apart basins that have resulted in the formation of the Dead Sea as well as the Gulf of Aqaba. The 180 km (110 mi) gulf comprises three distinct pull-apart basins that were formed by individual segments of the fault and are known as (from north to south) the Elat Deep, Aragonese Deep, and the Dakar Deep. At 25 km (16 mi) wide, the gulf is relatively narrow, but is up to 1,800 meters (5,900 ft) deep, with the nearby mountains near 2,600 meters (8,500 ft) in height. This difference in elevation suggests that the tectonic activity outpaces the erosive processes in the area, but the background seismicity is infrequent and is marked by earthquake swarms.
The earthquake was the largest event to occur on along the DST during the 20th century and was felt up to 600 km (370 mi) away. The period of aftershocks carried on for over a year with many exceeding magnitude 5. Within several hours of the mainshock a number of small earthquakes occurred along the DST 500 km (310 mi) north of the epicenter. Analysis of these earthquakes suggest that they may have been remotely triggered by the Gulf of Aqaba mainshock. Much attention has been given to remotely triggered earthquakes since the 1992 Landers earthquake in southern California.
The Dead Sea fault system runs from the Red Sea north to a triple junction in south-central Turkey and consists of a main fault and several secondary faults. The fault system is at its widest and deepest in the gulf where a transition from proto-oceanic rifting to transform faulting occurs. Moving northward through Lebanon and Syria, where the DST is known as the Yammouneh fault, the trace follows a restraining bend and splits into several strands that include the Serghaya and Rachaya faults. These strands are believed to be the source of the Near East earthquakes of 1759. The increased seismic activity following the Aqaba earthquake was detected by the Syrian National Seismic Network (SNSN) and occurred in the area of the Serghaya and Rachaya faults within a 25 km × 25 km (16 mi × 16 mi) area near the restraining bend in southwest Syria. The SNSN consists of twenty vertical-component seismometers, but only nine instruments recorded the swarm.
This small area in southwest Syria situated 500 km north of the Gulf of Aqaba mainshock had almost no activity during the two previous months then, beginning two hours and 47 minutes after the event, a swarm of 21 small earthquakes occurred. The average background seismicity was .5 to 1 events per day preceding November 22, and during the swarm 21 small earthquakes with a peak magnitude of (Md = 3.7) were recorded in three and a half hours. Randa Mohamad (from the Syrian National Seismological Center) and other seismologists determined that the abrupt increase of activity was due to remote earthquake triggering from the Gulf of Aqaba mainshock, and reported the results of their investigation in a journal published by the Seismological Society of America.
The epicenter was located 60 kilometers (37 mi) south of the head of the Gulf of Aqaba where the countries of Egypt, Israel, Jordan, and Saudi Arabia converge. Damage to buildings occurred in the coastal cities of Eilat, Israel and Aqaba, Jordan and a small tsunami was observed by witnesses there. Farther down the coast and closer to the epicenter in the Egyptian city of Nuweiba several well-built, modern, concrete reinforced homes were completely destroyed.
The earthquake's effects were felt as far north as Lebanon and Syria and it was the strongest event in the Jordan Rift Valley since the 1927 Jericho earthquake which was centered near the Dead Sea. The heaviest damage occurred in the resort town of Eilat where seven hotels and 50 other buildings were damaged, and cracks formed in the sidewalks. Fifteen people were treated there for injuries or shock and one man died of a heart attack in Aqaba. In Saudi Arabia two women were reported dead and five deaths were reported in Egypt, with three of them occurring in the gulf resort town of Nuweiba. Eight buildings collapsed in Cairo where, just several years before, the much smaller 1992 Cairo earthquake had a much more destructive impact.One person was killed and two were injured slightly at Al-Bad', Saudi Arabia and damage was reported there as well as the towns of Al-`Ula and Haql.
The Gulf of Aqaba lies between the Sinai Peninsula and the Arabian Peninsula, both mostly desert regions with very few permanent settlements. The seismologists who work with historical events gather macroseismic data from written records from cities that may not have been anywhere near the epicentral area. This can result in the mislocation of events when significant damage was reported in a particular location which were not actually where the earthquake occurred. The records of these events have been influenced by the distribution of the population (where the people were) and this has caused difficulty in creating a complete and accurate index of historical events. Several studies in the 80s and 90s indicate that there were two or possibly three large earthquakes in the region in the last 2000 years with magnitudes estimated to be 6.5–7.0 based on macroseismic data.
The countries surrounding the gulf have been actively monitoring the seismicity there since the 1980s and have found a consistent low level of activity, but a primary characteristic of the activity is that there are multiple sequences of earthquake swarms. Three swarm events, beginning in the north and ending in the south gulf, have been observed beginning in 1983 when more than 1,000 events occurred over a three-month period near the northeastern boundary of the Elat Deep (in the northern gulf) with the largest three events approaching 5 on the Richter magnitude scale. A less pronounced swarm occurred in 1990 with the largest event reaching 4.3 in the central gulf near the Elat Deep and the Arogonese Deep. The last significant swarm happened in 1993 in the southwestern Arogonese Deep (in the southern gulf) with the highest magnitude of 6.1 and more than 300 larger than magnitude 3 in the following weeks.
During several independent field studies cracks and other ground deformations were observed on both the Egyptian and Saudi Arabian sides of the gulf. During a field survey that was done there in 1996, a series of cracks were discovered between 28°35' N and 29°05' N on the Saudi Arabian coast. A field investigation was also done in Egypt in 1996 by seismologist Yann Klinger and others along with the Egyptian Geological Survey and Mining Authority. The most dramatic ground ruptures found were north of Nuweiba along a coastal road.
The countries surrounding the gulf (Egypt, Israel, Jordan, and Saudi Arabia) operate their own seismic networks and during the months that followed the main event, fourteen temporary and permanent stations recorded thousands of aftershocks. Klinger acquired data on approximately 1,000 aftershocks via the European-Mediterranean Seismological Center and the agencies of each country. The data was filtered to include only those aftershocks within 150 km (93 mi) of the epicenter. Data from four stations from the Institute for Petroleum Research and Geophysics of Israel plus seven stations from Jordan's Natural Resource Authority recorded aftershocks in the epicentral area that met the restriction. It was found that the aftershocks were arranged with a north-south alignment over a length of 70 km (43 mi) and that was expected from an earthquake of such magnitude. The group of aftershocks were bunched in two distinct clusters, with one in the north and one further south.
An earthquake is the shaking of the surface of the Earth resulting from a sudden release of energy in the Earth's lithosphere that creates seismic waves. Earthquakes can range in size from those that are so weak that they cannot be felt to those violent enough to propel objects and people into the air, and wreak destruction across entire cities. The seismicity, or seismic activity, of an area is the frequency, type, and size of earthquakes experienced over a period of time. The word tremor is also used for non-earthquake seismic rumbling.
The Gulf of Aqaba or Gulf of Eilat is a large gulf at the northern tip of the Red Sea, east of the Sinai Peninsula and west of the Arabian Peninsula. Its coastline is divided among four countries: Egypt, Israel, Jordan, and Saudi Arabia.
An earthquake swarm is a sequence of seismic events occurring in a local area within a relatively short period of time. The length of time used to define the swarm itself varies, but may be of the order of days, months, or even years. Such an energy release is different from what happens commonly when a major earthquake (mainshock) is followed by a series of aftershocks: in earthquake swarms, no single earthquake in the sequence is obviously the mainshock. In particular, a cluster of aftershocks occurring after a mainshock is not a swarm.
The 2005 Qeshm earthquake occurred on November 27 at 13:52 IRST on the sparsely populated Qeshm Island off Southern Iran, killing 13 people and devastating 13 villages. It was Iran's second major earthquake of 2005, following that at Zarand in February. The epicenter was about 1,500 kilometers (930 mi) south of Tehran, close to Iran's southern borders. Initial measurements showed that the earthquake registered about 6.0 on the moment magnitude scale, although that was reduced to 5.8 after further analysis. More than 400 minor aftershocks followed the main quake, 36 of which were greater than magnitude 2.5. The earthquake occurred in a remote area during the middle of the day, limiting the number of fatalities. Iranian relief efforts were effective and largely adequate, leading the country to decline offers of support from other nations and UNICEF.
The Dead Sea Transform (DST) fault system, also sometimes referred to as the Dead Sea Rift, is a series of faults that run from the Maras Triple Junction to the northern end of the Red Sea Rift. The fault system forms the transform boundary between the African Plate to the west and the Arabian Plate to the east. It is a zone of left lateral displacement, signifying the relative motions of the two plates. Both plates are moving in a general north-northeast direction, but the Arabian Plate is moving faster, resulting in the observed left lateral motions along the fault of approximately 107 km. A component of extension is also present in the southern part of the transform, which has contributed to a series of depressions, or pull-apart basins, forming the Gulf of Aqaba, Dead Sea, Sea of Galilee, and Hula basins.
The Dasht-e Bayaz and Ferdows earthquakes occurred in Dashte Bayaz, Kakhk and Ferdows, Iran in late August and early September 1968. The mainshock measured 7.4 on the moment magnitude scale and had a maximum perceived intensity of X (Extreme) on the Mercalli intensity scale. Damage was heavy in the affected areas with thousands of lives lost in the first event and many hundreds more in the second strong event.
The 1202 Syria earthquake struck at about dawn on 20 May 1202 with an epicenter in southwestern Syria. Up to 1,100,000 deaths have been associated with this earthquake, although other estimates are much smaller. It was felt over a very wide area, from Sicily to Mesopotamia and Anatolia to upper Egypt, mostly affecting the Ayyubid Sultanate and the Kingdom of Jerusalem. The cities of Tyre, Acre and Nablus were heavily damaged. A magnitude of Ms = 7.6 has been estimated with damage up to XI on the Mercalli intensity scale.
The 1984 Morgan Hill earthquake occurred on April 24 at 1:15 p.m. local time in the Santa Clara Valley of Northern California. The shock had a moment magnitude of 6.2 and a maximum Mercalli intensity of VIII (Severe). The epicenter was located near Mount Hamilton in the Diablo Range of the California Coast Ranges. Nearby communities sustained serious damage with financial losses of at least US$7.5 million.
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The 1982 North Yemen earthquake hit near the city of Dhamar, North Yemen on December 13. Measuring 6.2 on the moment magnitude scale, with a maximum perceived intensity of VIII (Severe) on the Mercalli intensity scale, as many as 2,800 people were killed and another 1,500 injured. The shock occurred within several hundred kilometers of a plate boundary in a geologically complex region that includes active volcanoes and seafloor spreading ridges. Yemen has a history of destructive earthquakes, though this was the first instrumentally recorded event to be detected on global seismograph networks.
The 1986 Chalfant Valley earthquake struck southern Mono County near Bishop and Chalfant, California at 07:42:28 Pacific Daylight Time on July 21. With a moment magnitude of 6.2 and a maximum Mercalli intensity of VI (Strong), the shock injured two people and caused property damage estimated at $2.7 million in the affected areas. There was a significant foreshock and aftershock sequence that included a few moderate events, and was the last in a series of three earthquakes that affected southern California and the northern Owens Valley in July 1986.
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The 1992 Cairo earthquake occurred at 15:09 local time on 12 October, with an epicenter near Dahshur, 35 km (22 mi) south of Cairo. The earthquake had a magnitude of either 5.8 or 5.9, but was unusually destructive for its size, causing 545 deaths, injuring 6,512 and making 50,000 people homeless. It was the most damaging seismic event to affect Cairo since 1847.
The 1872 North Cascades earthquake occurred at 9:40 p.m. local time on December 14 in central Washington state. A maximum Mercalli intensity of VIII (Severe) was assessed for several locations, though less intense shaking was observed at many other locations in Washington, Oregon, and British Columbia. Some of these intermediate outlying areas reported V (Moderate) to VII shaking, but intensities as high as IV (Light) were reported as far distant as Idaho and Montana. Due to the remote location of the mainshock and a series of strong aftershocks, damage to man made structures was limited to a few cabins close to the areas of the highest intensity.
The 1979 Imperial Valley earthquake occurred at 16:16 Pacific Daylight Time on 15 October just south of the Mexico–United States border. It affected Imperial Valley in Southern California and Mexicali Valley in northern Baja California. The earthquake had a relatively shallow hypocenter and caused property damage in the United States estimated at US$30 million. The irrigation systems in the Imperial Valley were badly affected, but no deaths occurred. It was the largest earthquake to occur in the contiguous United States since the 1971 San Fernando earthquake eight years earlier.
The 1956 Chim earthquake was a destructive multiple-shock event that occurred on March 16 in Lebanon along a strand of the Dead Sea Transform (DST) fault system. The epicenter was located in the south of Lebanon in the Chouf District. Six thousand homes were destroyed and another 17,000 were damaged. The number of persons killed was 136.
The 2013 Bushehr earthquake occurred with a moment magnitude of 6.3 on April 9 in Iran. The shock's epicenter was in the province of Bushehr, near the city of Khvormuj and the towns of Kaki and Shonbeh. At least 37 people were killed, mostly from the town of Shonbeh and villages of Shonbeh-Tasuj district, and an estimated 850 people were injured.
The 1068 Near East earthquake, or more likely two succesive events in adjacent parts of the same region, occurred on the morning of 18 March and on 29 May, 1068 in the Near East, and are often amalgamated by contemporary sources. The first event had its epicentre somewhere in the northwestern part of the Arabian Peninsula around Tabuk, while the second had its worse effect on the city of Ramla in Palestine, some 500 km farther northwest.
The 1969 Sharm El Sheikh earthquake occurred on March 31 off the southern Sinai peninsula in northeastern Egypt. The epicenter was located near Shadwan island, southwest of the city of Sharm El Sheikh, at the confluence of the Red Sea and the Gulf of Suez. This normal-slip shock measured 6.6 on the moment magnitude scale, had a maximum reported intensity of VII on the Mercalli intensity scale, and was responsible for several deaths and injuries.
The 1979 Coyote Lake earthquake occurred at 10:05:24 local time on August 6 with a moment magnitude of 5.7 and a maximum Mercalli Intensity of VII. The shock occurred on the Calaveras Fault near Coyote Lake in Santa Clara County, California and resulted in a number of injuries, including some that required hospitalization. Most of the $500,000 in damage that was caused was non-structural, but several businesses were closed for repairs. Data from numerous strong motion instruments was used to determine the type, depth, and extent of slip. A non-destructive aftershock sequence that lasted throughout the remainder of the month was of interest to seismologists, especially with regard to fault creep, and following the event local governments evaluated their response to the incident.