Latest news with #seismicActivity
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 .
Yahoo
20-07-2025
- Science
- Yahoo
Study based on machine learning expands Yellowstone earthquake record by 10 times
The Yellowstone Caldera, spanning Wyoming, Idaho, and Montana, is among the most seismically active volcanic regions on Earth. A caldera forms when a volcano erupts, emptying the underlying magma chamber and causing the land above to collapse into a large depression. In a recent breakthrough study, professor Bing Li from Western University, Canada and his team—collaborating with researchers from Universidad Industrial de Santander in Colombia and the United States Geological Survey—used machine learning to go through 15 years of historic earthquake data from Yellowstone. Their advanced methods identified and assigned magnitudes to roughly ten times more seismic events than were previously documented, providing new insights into the ongoing dynamics beneath the Yellowstone Caldera and improving the ability to assess potential volcanic risks. More than half of Yellowstone earthquakes occur in swarms With the new study, the earthquake record for the Yellowstone Caldera has been greatly expanded—now including 86,276 events from 2008 to 2022. This enhanced catalogue offers a much clearer picture of the volcanic and seismic activity in the region, thanks to improved data analysis and systematic review. One important discovery from the study is that over half of these earthquakes occurred as part of earthquake swarms—clusters of small, linked tremors that move and evolve within a confined area over short periods. This insight helps scientists better understand the complex behavior of Yellowstone's underground systems. According to professor Li, earthquake swarms differ from aftershocks in that they consist of clusters of small, interconnected earthquakes that occur over a short period and within a confined area, rather than being a sequence of smaller tremors following a single larger event. Li emphasizes that while each volcano, including Yellowstone, has its unique characteristics, the patterns observed in these swarms offer valuable insights. Understanding these seismic patterns can also help improve safety protocols, provide clearer risk information to the public, and guide the development of geothermal energy by avoiding hazardous zones with high heat flow, Li noted. AI helps uncover hidden earthquakes in historical data Before machine learning was used, experts had to manually inspect earthquake data, which was slow, expensive, and often missed many smaller events. Today, machine learning allows scientists to analyze huge quantities of historical seismic data stored in databases worldwide. The new approach is uncovering many more earthquakes and helping researchers better understand both well-known and hidden seismic regions across the globe. Professor Li points out that manually analyzing vast amounts of seismic data simply isn't feasible or scalable. The latest study also reveals that earthquake swarms beneath the Yellowstone Caldera happen along relatively young, rough fault structures, which differ from the more developed, smoother faults found in places like southern California and areas just outside the caldera—a distinction that helps scientists better understand the unique seismic behavior. The researchers emphasized that equipped with a detailed and reliable catalogue of seismic activity beneath the Yellowstone Caldera, they can now apply advanced statistical methods to identify and examine previously undetected earthquake swarms, allowing for a deeper understanding. The study has been published in the journal Science Advances.
NHK
08-07-2025
- NHK
More than 1,700 tremors hit Tokara island chain, southwestern Japan
More than 1,700 earthquakes strong enough to be felt by humans have struck the Tokara island chain in Kagoshima Prefecture, southwestern Japan. Seismic activity has been intensifying around the islands of Akusekijima and Kodakarajima in the island chain since June 21. Akusekijima has been rocked by a quake with an intensity of lower 6 on the Japanese scale of zero to seven. That is the largest in the recent series of tremors. On Sunday, an intensity of upper 5 was registered twice on Akusekijima, followed by a magnitude 5.1 quake with lower-5 intensity on Monday. Seismic activity continues in the area. As of 4 a.m. on Wednesday, 1,713 quakes with an intensity of 1 or greater had been recorded in the current sequence, including 60 tremors on Monday and 39 on Tuesday. The region experienced a series of quakes in 2021 and 2023, but the latest sequence is by far the most active. The Japan Meteorological Agency is urging caution against possible quakes with an intensity of up to around lower 6 for the time being.
NHK
07-07-2025
- Climate
- NHK
More than 1,600 tremors hit Tokara island chain, southwestern Japan
More than 1,600 earthquakes that can be felt by humans have struck the Tokara island chain in Kagoshima Prefecture, southwestern Japan. Seismic activity has been intensifying around the islands of Akusekijima and Kodakarajima in the island chain since June 21. Akusekijima has been rocked by a quake with an intensity of lower 6 on the Japanese scale of zero to seven. That is the largest in the recent series of tremors. On Sunday, an intensity of upper 5 was registered twice on Akusekijima, followed by a magnitude 5.1 quake with a lower-5 intensity on Monday. As of 4 a.m. on Tuesday, 1,663 quakes with an intensity of 1 or greater had been recorded in the current sequence. The region experienced series of quakes in 2021 and 2023, but the latest is by far the most active. For the time being, the Japan Meteorological Agency is urging caution against possible quakes with an intensity of up to around lower 6.
Yahoo
07-07-2025
- Climate
- Yahoo
Indonesia's Mount Lewotobi Laki Laki volcano erupts, sending ash cloud 11 miles in the air
JAKARTA, Indonesia (AP) — Indonesia's rumbling Mount Lewotobi Laki Laki erupted Monday, sending a column of volcanic materials as high as 18 kilometers (11 miles) into the sky and depositing ash on villages. Indonesia's Geology Agency said in a statement it recorded the volcano unleashing an avalanche of searing gas clouds down its slopes during the eruption. There were no immediate reports of casualties. The country's volcano monitoring agency had increased the volcano's alert status to the highest level after an eruption on June 18, and more than doubled an exclusion zone to a 7-kilometer (4.3-mile) radius since then as eruptions became more frequent. An eruption of Mount Lewotobi Laki Laki in November killed nine people and injured dozens. It also erupted in March. The 1,584-meter (5,197-foot) mountain is a twin volcano with Mount Lewotobi Perempuan in the district of Flores Timur. Indonesia is an archipelago of 270 million people with frequent seismic activity. It has 120 active volcanoes and sits along the 'Ring of Fire,' a horseshoe-shaped series of seismic fault lines encircling the Pacific Basin.
