Pixel Tracker

Monday, February 18 , 2019, 1:22 am | Fair 48º

 
 
 
 

Santa Barbara May Be at Greater Risk of a Major Earthquake and Tsunami, But It’s the Ventura Fault

Recent studies point to evidence of regional hazards, but wary officials cite community’s attention to tsunami readiness

A tsunami hazard zone sign at the Santa Barbara Harbor is part of the city’s readiness preparations. A recent geological study stated that the Ventura Fault, which passes under downtown Ventura and continues into the Santa Barbara Channel, connects with other faults in the area — a network that could cause larger earthquakes than previously thought, and have tsunami implications for coastal cities. Click to view larger
A tsunami hazard zone sign at the Santa Barbara Harbor is part of the city’s readiness preparations. A recent geological study stated that the Ventura Fault, which passes under downtown Ventura and continues into the Santa Barbara Channel, connects with other faults in the area — a network that could cause larger earthquakes than previously thought, and have tsunami implications for coastal cities. (Lara Cooper / Noozhawk photo)

Recent studies that have linked the Ventura Fault to a network of nearby geological fault lines could have major earthquake and tsunami implications for Santa Barbara County’s coastal areas, including the possibility of a higher magnitude quake than previously thought likely.

The fault line that runs underneath downtown Ventura and then northwest through the Santa Barbara Channel adjacent to offshore Carpinteria and Santa Barbara is connected to other fault lines in the area, according to a paper published last year in the Bulletin of the Seismological Society of America.

The study states that the Ventura Fault connects with other regional faults, including the San Cayetano and Red Mountain faults. If the faults slipped at the same time, the impact could result in an earthquake with a magnitude as large as 8.

“Because of local geography and geology, such events would be associated with significant ground-shaking amplification and regional tsunamis,” the paper states.

The paper says the last earthquake of such size struck what is now Ventura about 800 years ago.

UC Santa Barbara seismologist Jamie Steidl broke down some of the studies’ findings for Noozhawk, noting that the data suggest the South Coast could be at risk of large earthquakes that might rupture the length of the Santa Barbara Channel and “potentially generate a significant tsunami.”

Steidl said that the seismological community has known about the local hazard, and has always agreed that significant quakes are possible in the area.

What has changed is the length of the fault that is needed — and, thus, the magnitude of the earthquake — to support the new data that suggest there could be an uplift of 15 feet or more during a single quake, he said.

“Santa Barbara has recently been certified as tsunami-ready,” he said. “Hence the signs that denote tsunami evacuation routes, which if this new data is correct, might come in handy.”

Steidl said the evidence indicates there have been four of these type events in the last 10,000 years.

“I think that the more likely event is a magnitude 6 to 6.5 event under Santa Barbara or Ventura on this same fault system,” he said, close to what was experienced in the 1925 Santa Barbara earthquake and, more recently, in the 1994 Northridge earthquake.

That magnitude can cause a significant disruption to normal life, Steidl said, but he added that area residents should be ready at all times to face an earthquake.

“We need to be prepared regardless of if it’s a M6 event or a M8 event,” he said.

“The main differences between these two sizes of earthquakes is just the length of the fault that is rupturing, and thus the number of affected cities and people.”

An earthquake’s size is determined by measuring the energy released by the quake and assigning a magnitude number to quantify it.

Steidl said a larger earthquake could mean the potential for a larger tsunami, while a smaller quake would make a tsunami more focused in a smaller area.

Rick Wilson, of the California Geological Survey’s tsunami program, told Noozhawk that the tsunami inundation maps won’t be changed yet.

“The report on the Ventura Fault came out about a year ago, and we did do preliminary tsunami modeling that incorporated the data it contained to ensure our maps are useful,” he said, adding that no changes to the inundation maps are planned currently.

“Of course, our primary concern is the safety of coastal communities,” he said. “If additional new information becomes available, we certainly can incorporate that into our maps.”

Yolanda McGlinchey, manager of the City of Santa Barbara’s emergency services office, said the city got its tsunami maps in 2009 and officially became a “tsunami-ready” community in 2011.

At the time, California Geological Survey officials conducted a walk-through of the coastal area, she said.

Being “tsunami-ready” means that a plan is in place about how to best evacuate Santa Barbara’s waterfront area. The city also worked with several agencies to create the evacuation plan, including the California Highway Patrol, county agencies and the American Red Cross Santa Barbara County.

McGlinchey said the city gets a chance to practice a large-scale “evacuation” every Fourth of July, when tens of thousands of people descend on the waterfront area for the fireworks show — and then leave all at once when it’s over.

The National Weather Service maintains offshore buoys that measure sea rise and fall, which generate estimate times of when wave action would reach the area, McGlinchey said, giving people warning time to evacuate.

She said Santa Barbara’s community plan will be updated again in 2016.

Noozhawk staff writer Lara Cooper can be reached at .(JavaScript must be enabled to view this email address). Follow Noozhawk on Twitter: @noozhawk, @NoozhawkNews and @NoozhawkBiz. Connect with Noozhawk on Facebook.

Talk to Us!

Please take Noozhawk's audience survey to help us understand what you expect — and want — from us. It'll take you just a few minutes. Thank you!

Get Started >

Support Noozhawk Today

You are an important ally in our mission to deliver clear, objective, high-quality professional news reporting for Santa Barbara, Goleta and the rest of Santa Barbara County. Join the Hawks Club today to help keep Noozhawk soaring.

We offer four membership levels: $5 a month, $10 a month, $25 a month or $1 a week. Payments can be made using a credit card, Apple Pay or Google Pay, or click here for information on recurring credit-card payments and a mailing address for checks.

Thank you for your vital support.

Become a Noozhawk Supporter

First name
Last name
Email
Select your monthly membership
Or choose an annual membership
×

Payment Information

Membership Subscription

You are enrolling in . Thank you for joining the Hawks Club.

Payment Method

Pay by Credit Card:

Mastercard, Visa, American Express, Discover
One click only, please!

Pay with Apple Pay or Google Pay:

Noozhawk partners with Stripe to provide secure invoicing and payments processing.
You may cancel your membership at any time by sending an email to .(JavaScript must be enabled to view this email address).

  • Ask
  • Vote
  • Investigate
  • Answer

Noozhawk Asks: What’s Your Question?

Welcome to Noozhawk Asks, a new feature in which you ask the questions, you help decide what Noozhawk investigates, and you work with us to find the answers.

Here’s how it works: You share your questions with us in the nearby box. In some cases, we may work with you to find the answers. In others, we may ask you to vote on your top choices to help us narrow the scope. And we’ll be regularly asking you for your feedback on a specific issue or topic.

We also expect to work together with the reader who asked the winning questions to find the answer together. Noozhawk’s objective is to come at questions from a place of curiosity and openness, and we believe a transparent collaboration is the key to achieve it.

The results of our investigation will be published here in this Noozhawk Asks section. Once or twice a month, we plan to do a review of what was asked and answered.

Thanks for asking!

Click Here to Get Started >

Reader Comments

Noozhawk is no longer accepting reader comments on our articles. Click here for the announcement. Readers are instead invited to submit letters to the editor by emailing them to [email protected]. Please provide your full name and community, as well as contact information for verification purposes only.