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98411
From: ryan, [DNS_Address]
Subject: SoCal is seeing more quakes in 2024 than it has in 20 years
URL: https://www.sfgate.com/bayarea/article/socal-earthquake-activity-2024-19656461.php
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Southern California is seeing more quakes in 2024 than it has in 20 years By Amy Graff, Senior News EditorAug 14, 2024 A 4.4 magnitude earthquake hit near South Pasadena, Calif., on Monday, Aug. 12. USGS The earth has woken up in Southern California. After a 20-year quiet period, the region is seeing an uptick in earthquakes, with the magnitude 4.4 temblor that jolted Los Angeles on Monday a part of this trend. Despite the rattling of knickknacks and nerves, however, experts say this is normal. Since 1932, Southern California has recorded on average about 10 to 12 sequences of earthquakes with at least one quake of magnitude 4.0 and above a year. The past 20 years didn’t follow this long-term trend, however: The average dropped to about five such sequences a year, Lucy Jones, a geophysicist and researcher at Caltech, wrote in a message on X and told KTLA-TV. This year saw another shift. Since the start of 2024, the region has recorded 13 sequences with quakes of magnitude 4.0 and above. “So lots of variability but 2024 is closer to normal than the quiet of the last 2 decades,” Jones wrote. Stephen DeLong, supervisory research geologist in the USGS Earthquake Science Center, told SFGATE the recent increase in activity is a random occurrence and not an indication that the fault is behaving abnormally. “I wouldn’t read into this,” he said. “Risk is the same as it has been with lots of active faults and the potential for much larger earthquakes.” “This is really normal behavior,” he added. “You’re going to have some variability in these earthquakes.” While the recent heightened activity doesn’t increase the odds of Southern California getting hit with a large, damaging earthquake — like a magnitude 6.0 or above — the region is still at risk because it hasn’t seen a significant shaker in a long time, and faults are holding stress, DeLong said. “The stress builds up, and the stress continues to build until it’s released,” DeLong said. Small earthquakes don’t help prevent the big earthquakes from happening, which is a common assumption. “It would take hundreds and hundreds of little earthquakes to release the amount of stress that’s released in a big one.” The southern section of the San Andreas fault that runs just east of Los Angeles has not seen a big quake since the 1857 magnitude 7.9 Fort Tejon earthquake, which did not cause widespread property damage because Southern California had little development and a small population at the time. “It’s probably the highest hazard fault” in the state, DeLong said. “The largest on the San Andreas could be a 7.0 and above. People need to be prepared to have their homes safe and have food and water set aside.” He added that damage and deaths would be likely with a quake of this size. “Los Angeles tends to have good engineering, but older buildings will be vulnerable to this kind of shaking,” he said. The recent magnitude 4.4 earthquake, with an epicenter near South Pasadena just northeast of Downtown LA, hit on the Puente Hills thrust fault system. “The Puente Hills thrust fault probably hasn’t had a [big] earthquake in hundreds of years … and that fault is a high risk, as it runs right under Los Angeles,” DeLong said. Jones told the Los Angeles Times that the Puente Hills fault “is actually our most dangerous fault” due to its proximity to a highly populated area. Monday’s quake did not cause significant damage, but it did provide a reminder that California is earthquake country, and residents should be prepared. In Los Angeles, “there are a lot of faults … that have a high probability of having a large, damaging earthquake in the next 30 years,” DeLong said. “We don’t know that it will occur in five years or 30 years, but a large earthquake will occur.” |
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[98416]
98416
From: LaMan, [DNS_Address]
Subject: Was showing kid
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The 30 day USGS map and especially Japan, now we all felt that 3.9 Elsinore quake. Us long range map watchers know when somethings up. Big time. |
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