Modified Mercalli intensity scale in the context of "Seismic magnitude scales"

On 26 December 2004, at 07:58:53 local time (UTC+7), a M_w 9.2–9.3 earthquake struck with an epicenter off the west coast of Aceh in northern Sumatra, Indonesia. The undersea megathrust earthquake, known in the scientific community as the Sumatra–Andaman earthquake, was caused by a rupture along the fault between the Burma plate and the Indian plate, and reached a Mercalli intensity of IX in some areas.

The earthquake caused a massive tsunami with waves up to 30 m (100 ft) high, known as the Boxing Day Tsunami after the Boxing Day holiday, or as the Asian Tsunami, which devastated communities along the surrounding coasts of the Indian Ocean, killing an estimated 227,898 people in 14 countries, especially in Aceh (Indonesia), Sri Lanka, Tamil Nadu (India), and Khao Lak (Thailand). The direct result was severe disruption to living conditions and commerce in coastal provinces of these and other surrounding countries. It is the deadliest tsunami in history, the deadliest natural disaster of the 21st century, and one of the deadliest natural disasters in recorded history. It is also the worst natural disaster in the history of Indonesia, the Maldives, Sri Lanka and Thailand.

On 6 February 2023, at 04:17:35 TRT (01:17:35 UTC), a moment magnitude (M_w ) 7.8 earthquake struck southern and central Turkey and northern and western Syria. The epicenter was 37 km (23 mi) west–northwest of Gaziantep. This strike-slip shock achieved a Mercalli intensity of XII (Extreme) around the epicenter and in Antakya. It was followed by a M_w 7.7 earthquake, at 13:24:49 TRT (10:24:49 UTC). This earthquake was centered 95 km (59 mi) north-northwest from the first. There was widespread severe damage and tens of thousands of fatalities.

The M_w 7.8 earthquake is the largest to strike Turkey since the 1939 Erzincan earthquake of the same magnitude, and jointly the second-largest in the country, after larger estimates for the 1668 North Anatolia earthquake. It is also one of the strongest earthquakes ever recorded in the Levant. It was felt as far as Egypt and the Black Sea coast of Turkey. There were more than 30,000 aftershocks in the three months that followed. The seismic sequence was the result of shallow strike-slip faulting along segments of the Dead Sea Transform, East Anatolian and Sürgü–Çardak faults.