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...