Earthquakes in California: The Hidden Threat Beneath Los Angeles

Intro Earthquakes in California: The  Hidden Threat Beneath Los Angeles Just when our videos were drawing attention  to the dangers of seismic regions like New   Madrid and Cascadia, with the cry  of "forget the San Andreas Fault,   the real danger doesn't come from  there!"... here come a couple of   significant earthquakes in California,  even in the heart of Los Angeles,   putting the Big One back in the race as the  "most dangerous upcoming earthquake" contender! As you may recall, just over an  hour after sunset on August 6, 2024,   a sparsely populated strip of farmland  near Bakersfield, Southern California,   was shaken by a magnitude 5.2 earthquake,  followed by hundreds of smaller aftershocks. According to California standards,  this wasn't an unusually severe event.   The state is the second most seismically  active in the United States after Alaska,   with Southern California experiencing an  earthquake on average every three minutes.   While most are too small to be felt, about  15-20 events exceed magnitude 4.0 each year. This recent magnitude 5.2 earthquake is  the strongest to hit Southern California   in the past three years. The epicenter was  about 17 miles (27 km) south of Bakersfield,   California, and people reported feeling the tremor   nearly 90 miles (145 km) away in parts  of Los Angeles and as far as San Diego. Then, at 12:20 PM local time on August 12,  another tremor shook the Los Angeles area   due to a rupture on a small section  of a minor fault independent of the   San Andreas. The resulting magnitude  4.4 earthquake had its epicenter just   four miles (6.4 km) northeast of downtown  and at a depth of about 7 miles (11 km). Given the densely populated area, the tremor was  felt not only throughout the city but also in San   Diego – about 124 miles (200 km) from the  epicenter – and in Orange County, home to the   famous Disneyland amusement park. Despite this,  the tremor did not cause significant damage. From a geological perspective, none of this should  surprise us, given that the area is particularly   seismic: along the entire western coast of  the USA, there is a complex fault system,   The san Andreas Fault the most notable of which is the San  Andreas Fault: a structure about 800   miles (1,280 km) long, 10 miles (16 km) deep,  and made famous by the "Big One," a journalistic   term referring to the much-feared earthquake  that could strike California sooner or later. Specifically, this term refers to a tremor of  at least magnitude 7.0 on the Richter scale:   the last major earthquake associated with  the fault dates back to April 18, 1906,   with a magnitude 8.3 quake that caused destruction  and fires in the city of San Francisco. However, putting the past aside,  can these two tremors really make   us fear that the San Andreas Fault  has started moving? No more Cascadia,   no more New Madrid... Do we have  to deal with the Big One again? But then, are we really sure  that the Big One would mean   the complete destruction of Los Angeles,  San Francisco, and the surrounding areas? Let's try to clarify with this exciting video! “Roll intro” San Andreas Movie and Predictions Have you seen the movie San Andreas, which hit  theaters a few years ago? The latest Hollywood   blockbuster about natural disasters played on the  fears of residents of the US West Coast, offering   a glimpse of what will happen when The Big One,  the predicted mega-earthquake, actually strikes. Well, after hearing about the recent seismic  activity in California, I felt the need to   rewatch the film, especially to immerse myself in  the right context before voicing this new video. As you may recall, the film depicts a  sudden magnitude 9.6 earthquake hitting   California. The long-awaited gigantic  earthquake levels the metropolises   along the infamous San Andreas  Fault. Los Angeles, San Francisco,   and their surroundings are plunged into chaos.  Triggering violent tremors from the depths of   the earth, the disaster sparks fires, power  outages, and the mother of all tsunamis. Setting aside the protagonist's improbable  stunts, it's worth noting that the film   gets at least one thing right: the basic safety  measures an individual should follow during an   earthquake. Throughout the film, the characters  demonstrate that in the event of a tremor,   they should immediately drop to the ground  and hide under sturdy objects. They also   know that if the sea recedes along the  coast, it means a tsunami is coming. Early warning systems also blare along the coast,  urging people to move to higher ground. In short,   watching the film is like participating in a  rudimentary survival course. And that's something. However, there are many other things in  the film that don't add up. For example,   the initial tremors of magnitude 7.0 and 8.0 on  the Richter scale cause much more damage than they   would in reality in a city where most buildings  are constructed with seismic safety standards.  "before moving on, don't forget to subscribe  to our channel if you haven't already ...  make sure to hit the notification bell so  you don't miss out on our daily videos!" We know... directors and screenwriters have  to exaggerate, multiplying the disasters and   their consequences tenfold and  a hundredfold. But in reality,   even the most devastating earthquakes, like the  magnitude 7.9 that hit Nepal in 2015, wouldn't   cause the collapse of most buildings as shown  in the film. And if I mention this earthquake,   which happened many years ago, it's because  a survey by the Nepali Engineers Association   found that only 20 percent of buildings  suffered severe damage from that quake.   About 60 percent of the buildings that  collapsed in the area were made of masonry   and lacked steel structures, construction  methods banned in California since 1933! The film then ventures into science fiction when  the geologist character played by Paul Giamatti   goes on national TV to announce the start of  a "swarm," a series of earthquakes that would   spread from Nevada to San Francisco. According  to his "magnetic earthquake prediction model,"   the geologist also warns Americans that The  Big One will eventually hit San Francisco with   a magnitude of 9.6 and that its impact will  be felt even on the East Coast. Its force,   he says, will be such that "the  ground will literally split open." Sure, seismic swarms are real phenomena:  several earthquakes can indeed occur over   a relatively short period. However,  these types of earthquakes generally   have a fairly low average magnitude and  do not produce a distinguishable main   earthquake. While a swarm might explain the  continuous earthquakes depicted in the film,   they certainly wouldn't be able to  produce individual destructive tremors! Then there's the issue of the tsunami, which  in the film completes the destructive work   of the earthquakes. One thing is certain:  even in the face of a massive earthquake,   a tsunami – even a modest one – will never  occur as a result of a slip on the San Andreas   Fault. The fault is located inland, far from  the coast, whereas for a tsunami to occur,   the earthquake would need to manifest on the  ocean floor or at least very close to the sea. Many of the characteristics of the tsunami  depicted in the film – as you might   Inaccurate Facts About Earthquakes And Tsunamis imagine – were created for dramatic effect  and are inaccurate. For example, a tsunami   would never form a wave of that size in  shallow waters near the coast. Additionally,   tsunami events typically have multiple waves,  and the first one is not always the largest. In short, the film greatly exaggerates  the destructive power of a natural   phenomenon like a fault rupture and  blatantly evokes impossible scenarios,   such as being able to predict the location,  time, and intensity of its occurrence. The first thing to know is that the San Andreas  Fault is not long and deep enough to trigger a   magnitude 9 or higher earthquake like the one  depicted in the film! The largest historical   earthquake triggered on the northern part of the  fault was the magnitude 7.9 earthquake of 1906,   and computer simulations show that the fault  is capable of producing earthquakes up to   a maximum magnitude of 8.3, which  is an event almost a hundred times   weaker than the magnitude 9.6 quake that  devastates San Francisco in the film! Another thing to consider is that  all the most recent earthquakes,   including the magnitude 6.2 quake on August  24 in Napa Valley, have occurred along the   northern and central parts of the fault. In the  southern part, however, no earthquakes of greater   than magnitude 7 have occurred for nearly  300 years. And it is precisely from here,   where much more energy may have accumulated,  that experts predict the arrival of the Big One. The Big one: When? Yes, but when? Well, according to the group  of scientists from the Uniform California   Earthquake Rupture Forecast, there is  a 99.7% probability that an earthquake   of magnitude 6.7 or greater will occur in  California within the next 30 years and a   46% chance that the quake will be greater  than magnitude 7.5. The probabilities are   higher in the south (37%) than in the north  (15%). The Big One has a 67% chance of   hitting the Los Angeles area and a 63%  chance for the San Francisco Bay Area. If the Big One were to hit the area  most likely indicated by studies,   it could destroy Palm Springs and many cities  in the San Bernardino and Riverside regions   of California. The effects could be very  severe for all of Southern California,   including the major metropolises and  densely populated areas of Los Angeles,   Orange County, San Diego, and Tijuana. No need to worry, though... The scenario   seems catastrophic, but there are also those  who argue otherwise. In a study published in   the Bulletin of the Seismological Society of  America, seismologists from San Francisco analyzed   Scientist Analysis based on the past data recorded since 1776 from the first Spanish  missions and those collected by observing fault   displacements. It turns out that between 1690  and 1776, earthquakes with magnitudes between   6.6 and 7.2 occurred, releasing energy similar  to that of 1906. According to the researchers,   the geological characteristics of the San  Francisco area make a scenario of intense   and frequent earthquakes more likely than one  involving a highly destructive earthquake. So, who should we believe? My answer  is: no one who claims to see the future.   A certain amount of trust should only be given to  those who, in the tradition of scientific inquiry,   hypothesize scenarios in terms of probabilities  rather than absolute certainties... but above all,   it is absolutely necessary to have  faith in preventive engineering,   that is, the ability to construct  buildings to seismic standards. However, contrary to what I've done so far, I  want to end our chat by suggesting an additional   danger for California residents... For over a  century, Los Angeles has feared the infamous   Another Danger: Puente Hills San Andreas Fault and focused solely on it. But  its residents may be overlooking a much closer   and even more lethal monster: the Puente Hills  Fault, which could kill more people and cause   much more damage, being located right beneath  the oldest and most vulnerable neighborhoods. A study by the University of Southern California  states that Puente Hills has the potential to   produce "the most costly disaster in U.S.  history." Up to 18,000 people could die,   735,000 could lose their homes, and  up to 100,000 tons (90,718 metric   tons) of debris could be generated. The total  economic loss would amount to $252 billion. The United States Geological Survey  has presented similar projections,   noting that the destructive power of  Puente Hills is five times that of   San Andreas. A magnitude 7.5 earthquake  on the nearby Puente Hills Fault would   cause the same destruction as a magnitude 8.0  earthquake on the more distant San Andreas,   with a magnitude 8.0 earthquake releasing 16  times the energy of a magnitude 7.5 earthquake. According to statistics, the rupture of the  Puente Hills Fault occurs once every 3,000 years. Note for editor: Here's the improved and  translated version of your additional text,   with double units of measurement  added where necessary: The fault, first discovered in 1999,  extends for about 25 miles (40 km)   across the Los Angeles Basin, from downtown  to the southeastern part of the county,   reaching into Orange and San Bernardino counties. The magnitude 6.0 Whittier Narrows earthquake  in October 1987 led to this discovery. This   was followed by the Chino Hills (2008), Pico  Rivera (2010), and La Habra (2014) earthquakes. In 2017, a team of Harvard scientists produced  a report showing an acceleration in the slip   rate along this fault. An increase  that implies that the magnitudes   and/or frequency of earthquakes on this  fault segment are increasing over time. These faults also pose an additional  danger because they are located along   the Los Angeles Basin, where local soil  conditions are prone to liquefaction,   a phenomenon that causes the ground to move  like jelly when shaken. When this phenomenon   occurs under vulnerable buildings and other  structures, the consequences can be catastrophic. Well... guess which fault triggered  the magnitude 4.4 earthquake on August   12? That's right, right under Los  Angeles, on the Puente Hills Fault. Scared? No, you shouldn't be...  everything will be fine...