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California: Two Dozen Quakes A Day Not Unusual For Golden State
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The Nimitz Freeway through Oakland pancaked with the top deck collapsing onto the lower deck and killing 43 people during the 1989 Loma Prieta Earthquake.

A few years back on the way to Monterey with some teen visitors from North Dakota, they were astounded to see a mileage sign as we were crossing Pacheco Pass on Highway 152 that listed “Hollister”.

They incorrectly assumed we were a few miles from the inspiration — or birthplace — of the Abercrombie and Fitch clothing line “Hollister” that was wildly popular at the time.

They asked to make a quick side trip, and we did.

I didn’t want to spoil the fun so we soon arrived in Hollister during the quick detour off our route. They were expecting a surf city given that is the mythical story A&F created when they rolled out their Hollister line that — according to Piper Jaffray financial services — was one of the top five teen clothing brands globally based on 2019 sales.

Imagine their surprise when we ended up driving through the county seat of San Benito that is very much a dusty agricultural town of 35,000 more than 30 miles inland from the Pacific Ocean. Instead of finding the streets filled with surfer dudes we passed a number of farm workers.

I further deflated their bubble when I informed them Hollister wasn’t even a coastal city in Southern California as their marketing hype alludes to. Instead it was a company founded in Ohio that — according to A&F — pulled the name Hollister out of thin air. When they threatened to sue Hollister merchants in 2009 to prevent them from selling T-shirts with their city’s name on it, they claimed they were stunned to find a city that actually was named Hollister. Obviously they didn’t visit very many salad bars given Hollister is part of the Salinas Valley, the unchallenged lettuce capital of the world.

What I missed the opportunity to do was brag on Hollister of being the Earthquake Capital of the World given it is in the heart of the most earthquake prone county in California — San Benito.

There are other places that contend they are the Earthquake Capital of California. They are Parkfield in Monterey County and Coalinga in Fresno County.

Parkfield, a hamlet of 18 souls with a rustic dining spot dubbed the Parkfield Cafe that has an old-fashioned water tower on the grounds that carries the slogan “Be here when it happens”, claims the title based on the fact on an average of every 22 years they are hit with an earthquake 6.0 or higher on the Richter scale.

Quakes at 6.0 to 6.9 occur 100 to 150 times a year worldwide. In built-up areas they cause moderate damage to buildings. The shaking at the epicenter is violent.

Coalinga, a 123 mile trip from Manteca via Interstate 5, has 11,000 residents. Based on data from the United States Geological Survey (USGS) they have had 3,762 quakes since 1931 within 30 miles of Coalinga. There is a 98.64 percent chance of a 5.0 or higher quake occurring in the area within the next 50 years. The most recent quake was Jan. 12 near San Lucas at 1.5 on the Richter scale with its epicenter 8.6 miles below the surface.

Parkfield is not large enough of a population center to have aggregate quake data.

Hollister on the other hand is. The city has had 8,527 quakes since 1931 within 30 miles of the city. Compare that to 337 for San Francisco and 256 for Los Angeles.

Hollister has a 99.99 percent chance of being impacted from a 5.0 or higher quake over the next 50 years.

Hollister, by the way, also experienced other activity that has shaken the community. In 1947 what was to become an annual motorcycle rally ended in the death of one participant. It was the inspiration for what many consider was the first movie depicting an outlaw biker gang, “The Wild One”. The 1953 movie sent the career of an up and coming actor playing the lead character Johnny Strabler into orbit. The actor was the brooding Marlon Brando.

Both Hollister and Parkfield are near the most active segment of the infamous San Andreas Fault.

By comparison, Manteca, Turlock, and Oakdale are on the low side for being within 30 miles of an epicenter of an earthquake at any given time. Manteca since 1931 has had less nearby “shakers” than San Francisco but more than Los Angeles. As such Manteca is considered as a very high risk earthquake area. Turlock and Oakdale are considered simply as high risk.

The number of quakes within 30 miles since 1931 for the three 209 communities includes 337 for Manteca, 82 for Turlock, and 34 for Oakdale. Manteca has an 86.39 percent chance within the next 50 years being within 30 miles of a 5.0 or higher quake. Turlock is at 73.49 percent and Oakdale at 54.43 percent.

As of Sunday, Jan. 24, the most recent quake within 30 miles of Manteca was on Jan. 3. It was 1.5 on the Richter scale. It happened within six miles of Livermore and centered 1.8 miles below the surface. For Turlock the most recent shaker was Nov. 1, 2020 some 10.2 miles from Patterson; an estimated 11.9 miles below the surface.

Oakdale’s most recent quake was on March 11, 2019 some 1.41 miles from Columbia. That quake was centered 1.5 miles underground.

The closest fault to Manteca is 10 miles to the west and south. The Vernalis Fault is considered one of the 500 most active faults out of the 15,700 that crisscross California. However due to its relatively low seismic activity you don’t hear much about it.

The Vernalis Fault starts near Dairy Road south of Highway 132 in Stanislaus County. It heads north skirting the San Joaquin River near Durham Ferry Road and the Airport Way bridge. It passes beneath the San Joaquin River Club and parallels Kasson Road passing Deuel Vocational Institute prison and ending just short of the Old River between Tracy and River Islands at Lathrop.

If you haven’t figured it out by now, California has earthquakes every day. Most, however, are only detectable by a seismograph.

Based on USGS data, on Jan. 24 there were 21 quakes in California, 162 during the previous seven days, 839 during the previous 30 days, and 11,460 during the previous 365 days.

The Richter scale used to measure the intensity of earthquakes can be as misleading as the scale used to measure flood.

For example, one might think a 100-year flood is an event that happens on average every 100 years. It actually represents an event that has a 1 in 100 chance of occurring in any given year.

As for the Richter scale, a tenth of a move to the scale is not a tenth of a degree of increase in an earthquake’s intensity. Every 0.2 movement on the scale represents a doubling of a quake’s intensity at its epicenter.

In terms of impact and destruction, the following is a quick rundown of the Richter scale:

* 1.0 to 1.9: These are micro quakes that are rarely felt but can be recorded by seismographs. Several million are estimated to occur globally each year.

* 2.0 to 2.9: Some people will slightly feel them. There is no damage to buildings. There are more than a million every year.

* 3.0 to 3.9: They are often felt by people. However, they rarely cause damage. Shaking of indoor objects will occur. There are more than 100,000 a year.

* 4.0 to 4.9: These are considered light quakes. Indoor objects shake and rattling noises occur. Felt by most people indoors while they are felt slightly outdoors. Normally causes zero to minimal damage. Items may fall off shelves or knocked over. Between 10,000 and 15,000 occur yearly.

* 5.0 to 5.9: They are felt by everyone and are considered moderate quakes. They can cause damage to poorly constructed buildings. Other buildings experience slight or no damage. There are 1,000 to 1,500 annually.

* 6.0 to 6.9: Damage can occur to a moderate number of well-built buildings. Those that are poorly constructed can receive extensive damage. They are felt hundreds of miles from the epicenter. They are considered string quakes. There are 100 to 150 a year.

* 7.0 to 7.9: Damage occurs to most buildings in what is a major quake. Some buildings will partially or completely collapse. There are 10 to 20 a year.

* 8.0 to 8.9: Structures are likely to be destroyed and can cause moderate to heavy damage to earthquake resistant buildings. Widespread damage. One a year is the usual frequency.

* 9.0 or greater: This is a great quake that causes extensive permanent changes in ground topography. There is — or almost is — total destruction. There is heavy damage and extensive shaking at locations distant from the epicenter. One can occur every 10 to 50 years.

Of course, the damage depends on the location. A strong quake in the middle of Nevada will cause little or no damage compared to a strong shaker in Los Angeles.

The strongest earthquake ever rated in California was Fort Tejon on Jan. 9, 1857 in Southern California. There were two deaths in the quake that was at 7.9 on the Richter scale.

No. 2 was the most destructive — the April 18, 1906 quake that struck San Francisco killing 3,000 people and displacing 225,000.

The largest big quake recently was on July 5, 2019 in Ridgecrest-Trona. It was preceded by a 6.4 pre shock. The main quake was 7.1. There were no deaths.