Latest news with #MomentMagnitudeScale
Daily Record
22-05-2025
- Climate
- Daily Record
How severe is a magnitude-6 earthquake as Crete given tsunami warning
The earthquake struck off the coast of Crete in Greece this morning, with a magnitude of 6.1. A tsunami warning has been issued after an earthquake struck off the coast of Crete in Greece in the early hours of Thursday morning, May 22. The shock was felt extensively across islands throughout the Aegean Sea. The epicentre of the quake was in the sea 58 kilometres north-northeast of Elounda. According to the US Geological Survey, the epicentre was 69 kilometres deep. It comes after a similar 6.1-magnitude earthquake struck last week near the island of Kasos. This latest tremor struck the north of Crete at 6.19am local time (3.19am GMT) today, and holidaymakers are being warned to stay alert. The Greek government has urged tourists to 'move away from the coast and reach a higher place' in case a tsunami follows the 6.1-magnitude quake. The European-Mediterranean Seismological Centre (EMSC) issued an official tsunami warning, telling the people of Greece, Turkey, Italy, France and Portugal to go to their local authorities for updates. But as the Crete earthquake makes headlines, questions are being raised on just how severe this tremor was. So, how serious is a 6-magnitude earthquake? Here's everything you need to know. How are earthquakes measured? BBC Bitesize explains that until recently, earthquakes were measured via a system called the Richter scale. The Richter scale measures an earthquake's magnitude, in other words, how powerful the tremor is. Magnitude is measured using a machine called a seismometer which produces a seismograph, and the Richter scale indicates how powerful the quake is on a scale of 1-10. The scale is logarithmic, meaning that an earthquake measuring magnitude 5 is ten times more powerful than an earthquake measuring 4. Earthquakes measuring 1-2 on the scale happen regularly, and they are so small that people cannot usually feel them. Earthquakes measuring upwards of 7 are less frequent but very powerful, and can cause serious destruction. Today, the magnitude of a quake is more commonly measured through the Moment Magnitude Scale - a method that uses the same logarithmic scale as Richter, but which more accurately measures the strength of larger earthquakes. How serious is a magnitude 6 earthquake and can it cause a tsunami? According to Michigan Tech, earthquakes with a magnitude of 6.1 to 6.9 "may cause a lot of damage in very populated areas". They also estimate that the planet sees around 100 earthquakes in this category per year. While a tsunami warning has been issued following the two recent 6.1-magnitute quakes near Crete, USGS explains that tremors with a magnitude less than 6.5 are unlikely to trigger a tsunami. To put this recent earthquake into context, the largest quake ever recorded was in Chile in 1960, which measured 9.5 on the Richter scale, and killed well over 1,000 people. Join the Daily Record WhatsApp community! Get the latest news sent straight to your messages by joining our WhatsApp community today. You'll receive daily updates on breaking news as well as the top headlines across Scotland. No one will be able to see who is signed up and no one can send messages except the Daily Record team. All you have to do is click here if you're on mobile, select 'Join Community' and you're in! If you're on a desktop, simply scan the QR code above with your phone and click 'Join Community'. We also treat our community members to special offers, promotions, and adverts from us and our partners. If you don't like our community, you can check out any time you like. To leave our community click on the name at the top of your screen and choose 'exit group'.
Al Jazeera
31-03-2025
- General
- Al Jazeera
What caused the powerful Myanmar earthquake?
Myanmar has been hit by a magnitude 7.7 earthquake, which also affected neighbouring Thailand, its tremors felt as far afield as Cambodia and India. Much of the devastation caused by Friday's quake appeared to be in Myanmar's ancient capital of Mandalay, close to the epicentre in the Sagaing region, where buildings toppled and infrastructure buckled. More than 140 people were killed in the country, according to state media. Myanmar has been struck by several quakes since a magnitude 7.3 earthquake in the southern city of Bago in 1930, which killed at least 550 people, according to a United Nations seismic risk assessment. So, what makes this Southeast Asian country, which has been blighted by nearly four years of civil war, so vulnerable to earthquakes and how big was this one? First of all, a quick explanation of what an earthquake actually is. The Earth is made up of three parts: a molten, mostly metallic core at the centre, surrounded by a hot, nearly solid layer of rock called the mantle, with a jigsaw-like crust on the outside that is made up of constantly shifting tectonic plates. This movement of the plates on the slippery mantle, at different speeds and in different directions, causes energy to build up. The release of this energy causes the intense shaking of the planet's surface that we call an earthquake. When the energy is released below the ocean, it creates a series of huge waves known as a tsunami. Aftershocks are triggered 'because of changes to stress in the Earth from the main shock,' according to Will Yeck, a seismologist with the US Geological Survey (USGS). Myanmar's location between two tectonic plates – the India and Eurasia plates – places it at particular risk of earthquakes. The boundary between the two plates is called the Saigang Fault. Experts describe it as a long, straight line running approximately 1,200km (745 miles) from north to south through cities such as Mandalay and Yangon, placing millions of people at risk. According to the USGS, the Myanmar earthquake occurred because the India and Eurasia plates were rubbing sideways against each other, a motion described as 'strike-slip faulting'. Dr Rebecca Bell, a tectonics expert at Imperial College London, cited by the London-based Science Media Centre, compared the boundary between the two plates to the famous San Andreas Fault in California, which caused the deadly Northridge earthquake in 1994. 'The straight nature means earthquakes can rupture over large areas – and the larger the area of the fault that slips, the larger the earthquake,' she was quoted as saying. The strength of the earthquake is measured on the Moment Magnitude Scale, which largely replaced the famous Richter scale in the 1970s. Friday's quake of 7.7 was considered powerful, unleashing chaos in Myanmar and Thailand. In Thailand's capital, Bangkok, a 33-storey high-rise that was still under construction crumbled, killing at least eight and trapping dozens of construction workers under the rubble. In Myanmar's Mandalay, buildings were toppled, the royal palace was damaged, and the road-and-rail Ava Bridge collapsed. There was also damage in the modern capital, Naypyidaw, and the former capital, Yangon. State media said at least 144 people had been killed across the country. The USGS estimates that nearly 800,000 people in Myanmar may have been within the zone of the most violent shaking, with the death toll expected to rise sharply over the coming days. The earthquake took place at a relatively shallow depth – just 10km (six miles) deep. Dr Ian Watkinson, from the Department of Earth Sciences at Royal Holloway, University of London, was cited by the Science Media Centre as saying that shallow earthquakes can create a lot of damage, given that 'the seismic energy is not dissipated much by the time it reaches the surface'. While some regions of the world along active fault lines, including California and Japan, have building codes designed to withstand earthquakes, the infrastructure in the region hit by Friday's quake is less well equipped. As Watkinson puts it, Myanmar has gone through 'rapid urbanisation', with 'a boom in high-rise buildings constructed from reinforced concrete'. He believes Friday's earthquake could create levels of destruction comparable to the 2023 magnitude 7.8 quake in southern Turkiye, where many buildings collapsed after years of unregulated construction.
BBC News
28-03-2025
- Climate
- BBC News
Myanmar earthquake: What we know
A huge earthquake has hit central magnitude-7.7 tremor was felt elsewhere, including in Thailand and south-west are feared dead, although it is difficult to obtain accurate is what we know so far. Where did the earthquake strike? The earthquake's epicentre was located 16km (10 miles) north-west of Myanmar's city Sagaing, at a depth of 10km (16 miles), the US Geological Survey (USGS) is near the city of Mandalay, Myanmar's second-largest city with a population of about 1.5 million people, and about 100km north of the capital Nay Pyi Taw. Live: Follow the latest on the Myanmar earthquakeWatch: Moment Bangkok high-rise under construction collapsesEyewitnesses describe horror in quake's aftermath In pictures: Damaged buildings and buckled roads Which areas were affected? In Myanmar, there are reports of roads buckling in the capital in addition to damage to buildings across the country. Strong tremors were also felt elsewhere, including in Thailand and south-west construction workers are missing after an unfinished high-rise building collapsed hundreds of miles away from the epicentre, in the Thai capital Bangkok.A video also showed a rooftop pool in Bangkok spilling over the sides of a swaying building. How deadly was it? It may be a while before official casualty figures become known, but a member of a rescue team based in Mandalay has told the BBC that the number of deaths there "is at least in the hundreds"."That's all we can say right now because the rescue efforts are ongoing," they added. What causes earthquakes? The Earth's crust is made up of separate bits, called plates, that nestle alongside each plates often try to move but are prevented by the friction of rubbing up against an adjoining one. But sometimes the pressure builds until one plate suddenly jerks across, causing the surface to move. They are measured on a scale called the Moment Magnitude Scale (Mw). This has replaced the better known Richter scale, now considered outdated and less number attributed to an earthquake represents a combination of the distance the fault line has moved and the force that moved it.A tremor of 2.5 or less usually cannot be felt, but can be detected by instruments. Quakes of up to five are felt and cause minor damage. The Myanmar earthquake at 7.7 is classified as major and usually causes serious damage, as it has in this above 8.0 causes catastrophic damage and can totally destroy communities at its centre. How does this compare with other large earthquakes? On 26 December 2004, one of the largest earthquakes ever recorded struck off the coast of Indonesia, triggering a tsunami that swept away entire communities around the Indian 9.1 magnitude quake killed about 228,000 earthquake - off the coast of Japan in 2011 - registered as magnitude 9 and caused widespread damage on the land, and caused a tsunami. It led to a major accident at the Fukushima nuclear plant along the largest ever earthquake registered 9.5, and was recorded in Chile in 1960.
