September 11th Historical Context

• September 11, 2023: exactly 22 years after 9/11 attacks
• Libya Derna dam collapse disaster occurred same date
• Catastrophic scale but shorter media coverage than 9/11

Storm Daniel and Initial Impact

• Once-in-thousand-year storm formed over Mediterranean central Ionian Sea early September 2023
• Moved through Balkans causing damage, then shifted to Libya's Gulf of Sirte September 9th
• Record summer temperatures created unusually warm Mediterranean waters
• Storm evolved into "medicane" (Mediterranean hurricane-like cyclone)
• Made landfall near Benghazi September 10th with 80+ mph winds

Derna Geographic Context

• City of 90,000 people on northeastern Libya coast
• Located in Jebel Akhdar region - rainiest, most forested part of Libya
• Wadi Derna: seasonal river 115km long, starts 800m above sea level
• Narrow valley geography made flash floods frequent historical problem
• Previous major floods: 1942 (German Africa Corps), 1956, 1959, 1968

Dam Construction History (1970s)

• Built 1973-1977 by Yugoslavian company under Gaddafi government
• Two rockfilled dams with clay cores:
  • Albada Dam (closer to city): 45m height, 1.5 million cubic meter capacity
  • Boom and Sore Dam (upstream): 75m height, 22.5 million cubic meter capacity, 220m elevation
• Yugoslavian estimates: 1-in-1,000 year flood = 14 million cubic meters, 1-in-10,000 year = 22.5 million cubic meters
• Recommended third dam upstream never built (would have reduced watershed from 466km to 140km)

Warning Signs and Maintenance Issues

• 1998: Significant cracks and defects detected (25 years after completion)
• 2003: Swiss consultancy concluded Yugoslavian company vastly underestimated flood volumes
• 2007: Turkish company Arsel contracted for maintenance and third dam construction
• Work delayed until 2010, then Libya collapsed into civil war

Libya's Political Chaos (2011-2023)

First Civil War (2011)

• Arab Spring revolts against Gaddafi February 2011
• Derna taken by rebels (National Transitional Council)
• 8-month civil war, NATO intervention
• Gaddafi killed October 2011
• 30,000+ killed, 50,000+ wounded
• Turkish construction company fled, equipment looted
• $2 million allocated 2012-2013 for dam maintenance, never used (possibly embezzled)

Second Civil War (2014-2020)

• 2014: New contract signed with Turkish company
• May 2014: Disputed election split Libya into rival governments
  • Western GNU (UN-recognized, Tripoli-based)
  • Eastern GNS (Tobruk-based, Libyan National Army support)
• Prime Minister Ali Zeidan overthrown, fled to Morocco

ISIS and Al-Qaeda Control of Derna

• October 2014: ISIS seized control of Derna
• June 2015: Al-Qaeda Shura Council revolt against ISIS
• April 2016: Al-Qaeda gained control
• August 2016: Khalifa Haftar's Libyan National Army began siege
• May 2018: House-to-house fighting began
• June 2018: Haftar declared control
• February 2019: Final Al-Qaeda surrender
• 5 years contested control (2014-2019) prevented any dam maintenance

Continued Political Division

• October 2020: Ceasefire after 15,000+ additional deaths
• Turkey backed western GNU with 18,000 Syrian mercenaries
• Eastern territories expelled Turkish companies as potential spies
• Political uncertainty prevented dam maintenance resumption

Storm Daniel Rainfall Data

• September 10-11, 2023: Albida weather station recorded 414.1mm rainfall in 24 hours
• Highest 24-hour measurement ever recorded
• Normal annual rainfall: 280-500mm (entire year's worth in 24 hours)
• Academic debate on frequency:
  • Nature journal (2025): Once-in-thousand-year event
  • Science journal (2025): Once every few decades
• Estimated 100 million cubic meters dumped into Wadi Derna valley
• 5x greater than "once-in-10,000-year" dam capacity

Dam Failure Sequence

Water Accumulation

• 8:00 PM September 10th: Reservoirs began filling
• Midnight: Only halfway full
• 12:30 AM September 11th: Boom and Sore dam reservoir completely full, overtopping began
• 12:50 AM: Albada dam reservoir full, overtopping began
• 2:00 AM: Water level 2m above Boom and Sore dam top

Discharge Capacity Crisis

• Dam maximum discharge: 170 cubic meters per second
• Required discharge: 1,200 cubic meters per second
• 7x greater than design capacity

Collapse Timeline

• 2:40 AM: Boom and Sore dam catastrophically collapsed
• 30 million cubic meters released (equivalent to 30 Empire State Buildings of water)
• 20-minute surge down valley
• 3:00 AM: Surge destroyed Albada dam
• Water hit sleeping city of Derna

Government Response Failures

• September 9th: Curfew imposed, residents ordered to shelter in place
• September 10th: Contradictory evacuation orders for coastline residents
• Mixed messaging concentrated population in disaster path
• Recent violent history reduced trust in government authorities
• 2.5 hours between overtopping and collapse - evacuation window missed

Disaster Impact

Physical Destruction

• 1/4 of entire city obliterated within minutes
• Entire city blocks annihilated, swept to sea
• All bridges crossing Wadi Derna destroyed
• 5 of 7 roads into city destroyed
• City geographically split in half, isolated

Human Casualties

• Death toll estimates: 11,000-24,000 people
• Up to 1/3 of city's 90,000 population killed
• Bodies found 20km away from city
• One survivor rescued 11 nautical miles offshore
• More deaths than entire Second Libyan Civil War (2014-2020)
• Most survivors rendered homeless

Historical Significance

• Deadliest dam collapse disaster of 21st century
• Among deadliest in human history
• Ancient Greek-founded city almost completely destroyed

Causation Analysis

Multiple Compounding Factors

• Faulty original design calculations (1970s)
• Climate change effects (record Mediterranean temperatures)
• 12 years without maintenance (2011-2023)
• Political chaos preventing repairs
• Possible embezzlement of maintenance funds

Academic Research Findings

• Science journal conclusion: Disaster would have been less severe without dams
• Simulations showed dam presence created larger surge
• Without dams: 8x less peak discharge, 67% smaller flood area
• Dam collapse created tsunami-like effect

Legal Consequences

• 12 former Libyan officials arrested and convicted 2024
• Prison sentences: 9-27 years
• Identities not publicly revealed

September 11th Historical Connections

Three September 11th Tragedies

• 2001: 9/11 attacks (US)
• 2012: Benghazi attack (Libya) - 250km from Derna
• 2023: Derna dam collapse (Libya)

Benghazi Attack Details

• September 11, 2012: Ansar al-Sharia militants attacked US diplomatic compound
• 4 American officials killed including Ambassador J. Christopher Stevens
• First US ambassador killed in office in decades
• 8th US ambassador ever killed in office
• 10 separate US government investigations conducted
• No conclusive wrongdoing proven against Obama administration