Latest news with #seismologists
Yahoo
an hour ago
- Science
- Yahoo
Why the Tsunami from Russia's Earthquake Wasn't as Large as Feared
Russia's magnitude 8.8 earthquake spawned serious tsunami warnings, but waves have been moderate so far. Here's the geological reason why Why the Tsunami from Russia's Earthquake Wasn't as Large as Feared The moment seismologists got word that a magnitude 8.8 earthquake had struck near Russia's Kamchatka Peninsula, they felt an acute sense of anxiety. This location—where the Pacific plate is plunging below an arm of the North American plate and in the vicinity of the Eurasian plate—can produce widespread, highly destructive tsunamis. It did just that in 1952, when a magnitude 9.0 quake effortlessly washed away a nearby Russian town while also causing extensive damage in far-off Hawaii. When the seafloor next to Kamchatka violently buckled at 11:24 A.M. local time on Wednesday (7:24 P.M. EDT on Tuesday), everything seemed primed for a dangerous tsunami. Early forecasts by scientists (correctly) predicted that several countries around the Pacific Ocean would be inundated to some degree. Millions of people were evacuated from coastal Japan, and many in Hawaii were ordered to seek higher ground. People across swaths of Central and South America were also advised to flee from the receding ocean. And as an initial smaller tsunami formed on the northern Japanese island of Hokkaido, there was some preliminary concern that waves could reach a height of nearly 10 feet. But for the most part (at the time of writing), plenty of countries in the firing line didn't get hit by an extremely lethal wall of water. It appears that waves of just more than four feet hit Japan and Hawaii—two locations that have now significantly downgraded their tsunami alerts and rescinded some evacuation notices. One tourist in Hawaii told BBC News that 'the disaster we were expecting did not come.' Parts of California have seen water up to eight feet but without considerable damage. [Sign up for Today in Science, a free daily newsletter] READ MORE: Tsunami Warnings Issued after Magnitude 8.8 Earthquake Strikes off Russian Coast This raises a key question: Considering that the Kamchatka oceanic megaquake had a magnitude of 8.8—one of the most powerful ever recorded—why wasn't the resulting tsunami more devastating? The answer, in short, is this: the specific fault that ruptured produced pretty much exactly the tsunami it was capable of making, even if we intuitively feel like the effect should have been worse. 'First, it's important to recognize that the issuance of any warning at all is a success story,' says Diego Melgar, an earthquake and tsunami scientist at the University of Oregon. A tsunami doesn't have to be 30 feet tall to cause intense destruction and death; even a relatively modest one can wash people and structures away with ease. So far, it looks like there won't be a high number of casualties—and that's in part because 'the warnings went out, and they were effective,' Melgar says: people got out of danger. It's also fair to say that, for Kamchatka and its surroundings, there actually was some localized destruction. The earthquake itself severely shook the eastern Russian city of Petropavlovsk-Kamchatsky and did scattered damage to buildings there. And tsunami waves reached heights of up to 16 feet in Severo-Kurilsk, a town in the northern Kuril Islands just south of Kamchatka. Houses and sections of a port have been wrecked or swept out to sea. READ MORE: Russia's 8.8 Earthquake Is One of the Strongest Ever Recorded The way each nation issues a tsunami warning differs slightly. But in general, if a tsunami is very likely incoming and is thought to be potentially dangerous, an evacuation order for those on the afflicted coastline is issued. When such alerts go out, some tsunami-wave-height estimates are often given, but these numbers are initially difficult to nail down. One reason is because, when a tsunami-making quake happens, 'the tsunami energy is not distributed symmetrically,' says Amilcar Carrera-Cevallos, an independent earthquake scientist. A tsunami does not move outward in all directions with the same momentum because faults don't rupture in a neat linear break. Nor does the seafloor movement happen smoothly and in one direction. 'Initial warnings are based only on the estimated size and location of the source, but this alone doesn't determine how much water is displaced or where waves will concentrate,' Melgar says. 'To forecast impacts accurately, scientists need to know how much the fault slipped, over what area and how close to the trench the slip occurred.' And that information is usually gleaned one or two hours after the tsunami has appeared. A tsunami like today's is tracked by a network of deep-ocean pressure sensors, which helps scientists update their forecasts in real time. But 'the network is sparse. It doesn't always catch the full complexity of wave energy radiating across the basin,' Melgar notes. This means it gives scientists only a partial understanding of the ocean-wide tsunami. Another issue is that a tsunami's wave height when the wave reaches the shore is influenced by the shape and height (technically called the bathymetry) of the seafloor it's passing over. Tsunamis are also hindered, or helped, by the shape and nature of the coastline they slam into. 'Features like bays can amplify wave heights; tsunami waves can also be diffracted (bent) around islands,' says Stephen Hicks, an earthquake scientist at University College London. It may also be tempting to compare today's magnitude 8.8 quake with the 2011 magnitude 9.1 quake that struck off eastern Japan, triggering a tsunami with a maximum wave height of 130 feet—one that killed more than 15,000 people. The 2004 magnitude 9.1 earthquake and tsunami in the Indian Ocean—which claimed the lives of more than 280,000 people across a vast area—may also come to mind. That's understandable, but today's magnitude 8.8 quake was not quite powerful as one might think. The magnitude scale for earthquakes is not linear; in other words, a small increase in magnitude equals a huge jump in energy unleashed. According to the U.S. Geological Survey, a magnitude 9.1 quake (like the 2011 Japanese example) is nearly three times stronger than today's. The 2004 and 2011 cataclysms 'were actually quite a lot larger than this event,' says Judith Hubbard, an earthquake scientist at Cornell University. They were simply more capable of pushing a giant volume of water across the ocean than today's temblor. Not knowing the exact height of an incoming tsunami at multiple locations all around the Pacific, though, is a secondary concern. What matters most is that the tsunami warnings went out to those in harm's way quickly and accurately conveyed the times at which the tsunamis would arrive at each coastline. 'The current strategy of preventative evacuation does a good job of saving lives,' Hubbard says.
Sky News
15 hours ago
- Science
- Sky News
'Monster' earthquake in Russia was one that some seismologists were anticipating
As earthquakes go, this was a monster. At 8.8 on the magnitude scale, it's up there with the most powerful ever recorded. It's also one some seismologists were anticipating. The quake, in Russia's Far East, occurred on a fault line running along the Kuril-Kamchatka Trench - a scar on the seabed caused by the Pacific tectonic plate diving beneath the North American and Okhotsk plates. Called a subduction zone, it's one of a series around the Pacific's notorious "Ring of Fire". The friction from shifting plates fuels volcanoes but is also notorious for causing "megathrust" earthquakes and resulting tsunamis. The last major earthquake on the Kamchatka peninsula was in 1952, just 30km (18 miles) from this latest quake's epicentre. The US Geological Survey estimates that six metres-worth of tectonic movement had built up along the Kuril Kamchatka trench since then. A series of "foreshocks," including a 7.4 magnitude earthquake on the 20th of July, suggested those seven decades of stress were being transferred along the fault, indicating a major quake near the 1952 epicentre may have been imminent. But the moment an earthquake strikes is always impossible to predict, so too is the size or spread of a resulting tsunami. A massive earthquake, doesn't always correspond to a massive tsunami. 0:39 A host of factors, including the amount of movement on the sea floor, the area over which the movement spreads, and the depth of the ocean above, all play a role. From the limited information so far, even in areas close to the epicentre, the tsunami wave was sustained, but nowhere near as large as the one that struck Japan in 2011. The 9.1 magnitude earthquake that caused the Tohoku tsunami generated a wave nearly 40 metres high in places. The combined impacts of the earthquake and tsunami claimed nearly 20,000 lives. According to the Kremlin, no fatalities have been reported in Russia so far. 1:05 It's a very sparsely populated area, meaning casualties will almost certainly be lower than in comparable-sized quakes in Japan and Indonesia. It's also possible that the foreshocks that preceded the Kamchatka quake may have helped save lives. Following the 20 July earthquake in Kamchatka, local tsunami alerts warned people to head to higher ground. When this latest quake struck, with more than 10 times more power than the last, people may have acted even before the warnings came.
Yahoo
22-07-2025
- Science
- Yahoo
In world first, CCTV captures supershear velocity earthquake
Yahoo is using AI to generate takeaways from this article. This means the info may not always match what's in the article. Reporting mistakes helps us improve the experience. Yahoo is using AI to generate takeaways from this article. This means the info may not always match what's in the article. Reporting mistakes helps us improve the experience. Yahoo is using AI to generate takeaways from this article. This means the info may not always match what's in the article. Reporting mistakes helps us improve the experience. Generate Key Takeaways Earthquakes are violent events that alter the face of the planet. In many cases, those changes occur beneath the surface and only gradually become visible over thousands of years. Occasionally, however, an earthquake's effects aren't just felt—they're seen. It's even rarer to actually capture one of those moments on camera, but according to seismologists at Japan's Kyoto University, the footage highlights the first-known video of a strike-slip fault. Their analysis, published in The Seismic Record, has led to new findings based on real-time visual evidence of tectonic motion. The magnitude 7.7 event took place on March 28 along the Sagaing Fault with an epicenter near Myanmar's second-largest city, Mandalay. Although the initial rupture process lasted barely 80 seconds, it and numerous aftershocks were ultimately responsible for 5,456 confirmed deaths and over 11,000 injuries. Later evaluations indicated the quake was the second deadliest in modern history, as well as the most powerful to hit Myanmar in over a century. According to a separate group's paper published in the same journal, the southern portion of the rupture occurred at an astonishing 3.7 miles per second—fast enough to qualify as 'supershear velocity.' Amid the catastrophe, an outdoor CCTV camera about 74.5 miles south of the epicenter recorded a visceral illustration of its power. Over just a few moments, what at first looks like a single chunk of the ground appears to suddenly divide and horizontally shift past one another in opposite directions. Completely by accident, the camera recorded a direct look of a strike-slip fault, something previously analyzed by remote seismic instruments. To researchers at Kyoto University, the clip wasn't just a jaw-dropping scene—it was an opportunity to study a strike-slip fault using visual data. Geologists analyzed the brief video frame-by-frame to learn about the fault shift. Credit: KyotoU / Jesse Kearse 'We did not anticipate that this video record would provide such a rich variety of detailed observations,' corresponding author and geologist Jesse Kearse said in a statement. 'Such kinematic data is critical for advancing our understanding of earthquake source physics.' Kearse and colleagues utilized a technique called pixel cross-correlation to analyze the fault movement on a frame-by-frame basis. Their findings showed the fault slipped horizontally by 8.2 feet in only 1.3 seconds, with a maximum speed of about 10.5 feet per second. While the movement matched experts' existing knowledge of strike-slip ruptures, the short duration and speed were new developments. 'The brief duration of motion confirms a pulse-like rupture, characterized by a concentrated burst of slip propagating along the fault, much like a ripple traveling down a rug when flicked from one end,' Kearse explained. Additional examinations also proved that the slip path was slightly curved, confirming previous observations recorded elsewhere in the world. This means subtly curving strike-slips instead of totally linear ones may be the rule, not the exception. 'Overall, these observations establish a new benchmark for understanding dynamic rupture processes,' the study's authors wrote, adding that the video offers real-time confirmation of curved slip paths while helping 'deepen our understanding of the physical mechanisms that control rapid fault slip during large earthquakes.' Such discoveries may also help seismologists, geologists, and urban planners design more resilient architecture to ensure that when major earthquakes inevitably occur, their damage is minimized as much as possible.
Gizmodo
21-07-2025
- Science
- Gizmodo
Myanmar's Devastating Earthquake in March Split the Earth at ‘Supershear Velocity'
On March 28, Myanmar was rocked by a 7.8 magnitude earthquake that claimed over 5,000 lives and caused damage even in neighboring countries. In a study published July 10 in The Seismic Record, seismologists confirmed previous research indicating that the southern part of the large earthquake's rupture, or fracture, took place at astounding speeds of up to between 3.1 and 3.7 miles per second (5 to 6 kilometers per second)—at supershear velocity. This likely played a role in the earthquake's devastating impact. When an earthquake strikes, the first seismic waves to propagate from the epicenter are P waves, fast-moving waves that compress their way through all kinds of material but do not cause a lot of damage. Then come the S waves, or shear waves, which are slower but cause highly destructive perpendicular motion. Simply put, when parts of an earthquake's fault rupture at supershear velocity, it means that the speed of the break along a particular stretch of the rupture was faster than the speed of its S waves. In moderate earthquakes, rupture velocities are usually between 50 and 85% of S-wave velocity. Myanmar's earthquake occurred along the Sagaing Fault, which runs north-south through Myanmar. The fault is strike-slip, meaning two tectonic plates slide horizontally against each other. The Sagaing Fault's strike-slip movement in March was clearly captured in potentially first-of-its-kind footage showcasing an expanse of land suddenly moving forward relative to the viewer. The natural disaster saw around 298.3 miles (480 km) of the Sagaing Fault rupture or 'slip,' which is extremely long for a strike-slip rupture of this magnitude, according to the seismologists. By studying seismic and satellite imagery, they determined that the rupture had 'large slip of up to 7 m [23 feet] extending ∼85 km [52.8 miles] north of the epicenter near Mandalay, with patchy slip of 1–6 m [3.3–19.7 feet] distributed along ∼395 km [245.4 miles] to the south, with about 2 m [6.6 ft] near the capital Nay Pyi Taw.' A seismic station near Nay Pyi Taw registered ground motion data that were 'immediately convincing of supershear rupture given the time between the weak, dilational P wave first arrival and the arrival of large shear offset of the fault' at the station, UC Santa Cruz's Thorne Lay said in a Seismological Society of America statement. An offset is the ground displacement that occurs along a fault during an earthquake. 'That was unusually clear and convincing evidence for supershear rupture relative to other long strike-slip events that I have worked on.' The Sun Might Be Influencing Earthquakes, Scientists Say Lay and his colleagues suggest that the supershear velocity, as well as the rupture's strong directivity (the piling up of S waves in the direction of the fault line as the rupture spreads) toward the south, might have caused the earthquake's widespread damage. While the Sagaing Fault frequently causes large earthquakes, the one in March involved a stretch of the fault between the cities of Mandalay and Nay Pyi Taw that has been quiet since 1912. 'Longer histories and better understanding of fault segmentation and geometry are needed to have any guidance for future event activity, but I would not expect the central area to fail again before a long period of rebuilding strain energy,' Lay added. While it is impossible to predict earthquakes with any kind of precision, earthquake early-warning (EEW) systems provide last-minute but still crucial warnings of incoming seismic events by sending out electronic alerts that travel faster than seismic waves. While many seismic regions don't have the necessary infrastructure for such systems, the smartphone-based Android Earthquake Alerts (AEA) system has recently proved to be as efficient as traditional seismic networks.
RNZ News
20-07-2025
- Science
- RNZ News
First video of Earth's surface lurching sideways in earthquake offers new insights
Analysis - During the devastating magnitude 7.7 Myanmar earthquake on March 28 this year, a CCTV camera captured the moment the plate boundary moved, providing the first direct visual evidence of plate tectonics in action. Tectonic plate boundaries are where chunks of Earth's crust slide past each other - not smoothly, but in sudden, violent ruptures. The footage shows Earth's surface lurching sideways, like a gigantic conveyor belt switched on for just a second, as the fault slips. What we're seeing is the propagation of a large earthquake rupture - the primary mechanism that accommodates plate boundary motion at Earth's surface. These shear fractures travel at several kilometres per second, making them notoriously difficult to observe. Workers wearing hazmat suit spray disinfectant to sterilise the rubble of a collapsed building in Mandalay on April 2, 2025, five days after a major earthquake struck central Myanmar. Photo: AFP These rare events, separated by centuries, have shaped our planet's surface over millions of years, creating features such as Aotearoa New Zealand's Alpine Fault and the Southern Alps. Until now, seismologists have relied on distant seismic instruments to infer how faults rupture during large earthquakes. This video sheds new light on the process that radiates seismic energy and causes the ground to shake. In our new study, we analysed the video frame by frame. We used a technique called pixel cross-correlation to reveal that the fault slipped 2.5 metres sideways over a duration of just 1.3 seconds, with a maximum speed of 3.2 metres per second. The total sideways movement in this earthquake is typical of strike-slip fault ruptures, which move the land sideways (in contrast to faults that move land up and down). But the short duration is a major discovery. The timing of when a fault starts and stops slipping is especially difficult to measure from distant recordings, because the seismic signal becomes smeared as it travels through Earth. In this case, the short duration of motion reveals a pulse-like rupture - a concentrated burst of slip that propagates along the fault like a ripple travels down a rug when it's flicked from one end. Capturing this kind of detail is fundamental to understanding how earthquakes work, and it helps us better anticipate the ground shaking likely to occur in future large events. Our analysis also revealed something more subtle about the way the fault moved. We found the slip didn't follow a straight path. Instead it curved. This subtle curvature mirrors patterns we've observed previously at fault outcrops. Called "slickenlines", these geological scratch marks on the fault record the direction of slip. Our work shows the slickenlines we see on outcrops are curved in a manner similar to the curvature seen in the CCTV footage. Based on our video analysis, we can be certain that curved slip occurs, giving credence to our interpretations based on geological observations. In our earlier research, we used computer models to show that curved slickenlines could emerge naturally when an earthquake propagates in a particular direction. The Myanmar rupture, which is known to have travelled north to south, matches the direction predicted by our models. This alignment is important. It gives us confidence in using geological evidence to determine the rupture direction of past earthquakes, such as the curved slickenlines left behind after the New Zealand Alpine Fault's 1717 earthquake. This first glimpse of a fault in motion shows the potential for video to become a powerful new tool in seismology. With more strategic deployments, future earthquakes could be documented with similar detail, offering further insight into the dynamics of fault rupture, potentially revolutionising our understanding of earthquake physics. This story originally appeared in The Conversation .
