Earthquakes in the Santa Cruz Mountains: A Boulder Creek Preparedness Guide

The short version

• Secure the heavy stuff. Strap the water heater, anchor tall bookcases and dressers, and take down heavy mirrors and art hanging over beds and couches. A Saturday with straps and museum putty is the highest-value hour here.
• Store water and supplies. One gallon of water per person per day, and more up here, because roads and utilities can stay down for days. Add food, a hand-crank radio, a first-aid kit, medications, and sturdy shoes and gloves by each bed.
• Learn Drop, Cover, and Hold On, and practice it once with the household so the motion is automatic.
• Sign up for alerts. Install MyShake for a few seconds of warning before shaking, and register for CruzAware to get evacuation orders after a quake.
• Older raised-foundation home? Check Earthquake Brace + Bolt eligibility, then have a licensed contractor or structural engineer look at your crawl space.

Ask anyone who was here for Loma Prieta and they'll tell you where they were standing. One of the most famous faults on Earth runs through these mountains, and the 1989 quake started about 15 miles east of here, across the ridge. No one, including the U.S. Geological Survey, can tell you when the next big one will hit, so the useful work isn't worrying about timing. It's the handful of things that make your household safer whenever it comes: secure the heavy stuff, store water and supplies, learn Drop, Cover, and Hold On, and sign up for alerts.

Most of it takes a weekend, and none of it requires you to become a seismologist. We live in earthquake country. That's not a reason to be scared. It's a reason to be ready, the same way we get ready for winter storms and fire season.

The San Andreas Fault Runs Through These Mountains

The San Andreas is not a distant California abstraction up here. The USGS describes the San Andreas Fault Zone as "the main part of the boundary between the Pacific tectonic plate on the west side and the North American plate on the east side." Those two plates grind past each other at a rate the USGS puts at "50 mm/yr (about 2 inches/yr)." That steady motion loads the fault with the strain that earthquakes eventually release.

The stretch nearest us has a name. The USGS calls it the Santa Cruz Mountains section, and says it "stretches 62 km (39 mi) from Los Gatos (near San Jose) to San Juan Bautista, CA and was last ruptured in the famous 1906 San Francisco earthquake." Boulder Creek sits in the mountains just west of that stretch of the fault.

Other mapped faults are closer to home than the well-known Bay Area names. The San Gregorio fault runs offshore, following the coast, and the Zayante-Vergeles fault zone crosses the Santa Cruz Mountains. The Hayward and Calaveras faults run through the wider Bay Area too, which is part of why this region is studied as closely as it is.

One point is worth holding onto: proximity to a fault tells you an earthquake is possible, not that one is imminent. Nobody can predict earthquakes. For the specific hazard at your parcel, the authority is the USGS, not a blog and not a neighbor's hunch. Their earthquake hazards program publishes the maps and forecasts that professionals rely on, and it's the right place to send any question that starts with "how likely is."

What the 1989 Loma Prieta Earthquake Tells Us

Loma Prieta is local history, not ancient history, and it's the clearest picture we have of what a major quake does to this terrain. According to the USGS, "On October 17, 1989, at 5:04 PM (PDT), a magnitude 6.9 earthquake" struck the region. The USGS places the epicenter "near Loma Prieta peak in the Santa Cruz Mountains, approximately 9 miles northeast of Santa Cruz and 60 miles southeast of San Francisco." That peak is in our mountains, roughly 15 miles east of Boulder Creek, across the ridge.

The toll was serious. The USGS records "63 deaths, 3757 injuries, and an estimated $6 billion in property damage," and calls it "the strongest earthquake to hit the San Francisco Bay region since the M 7.9 Great San Francisco earthquake of 1906." Longtime residents remember the collapsed section of the Bay Bridge and the Cypress Street Viaduct in Oakland, but the shaking was felt hardest right here in the mountains, where roads cracked, chimneys came down, and homes shifted on their foundations.

The damage patterns were predictable, and most of them are the kind you can plan around: things falling, water and power cut off, roads blocked, and older houses moving because they weren't bolted down. Every step below addresses one of those.

Secure Your Space and Store Supplies

The Earthquake Country Alliance, a public-private partnership that includes the USGS and California's emergency management agencies, organizes what to do before, during, and after a quake into Seven Steps to Earthquake Safety. The first is "Secure your space." Walk your house and picture it shaking hard for fifteen seconds. What falls?

A water heater that isn't strapped can topple, break a gas line, and cut off a big reservoir of drinkable water all at once. Tall bookcases and dressers can tip onto a bed or a doorway. Heavy mirrors and framed art over the couch become projectiles. Straps, flexible fasteners, and museum putty are cheap, and a Saturday spent anchoring the worst offenders is the highest-value hour in this whole guide.

The third step is to organize disaster supplies, and up here that starts with water. Ready.gov's standard is one gallon per person per day, and because mountain roads and utilities can stay down for days after a big quake, more is better. If you're on a well, the pump won't run without power, so stored water isn't optional.

Keep a few days of non-perishable food, a manual can opener, flashlights, a battery or hand-crank radio, spare batteries, a first-aid kit, any critical medications, and sturdy shoes and work gloves next to each bed for the walk across broken glass in the dark. Our power outage plan for mountain households covers the water, food, and backup-power side in more depth, and most of it applies directly here.

Retrofit and Bracing: Route This to a Pro

Loma Prieta was hard on older houses that weren't fastened to their foundations, and a lot of Boulder Creek's housing stock predates modern seismic standards. A well-established fix exists. The California Residential Mitigation Program, a joint effort of the California Earthquake Authority and state emergency management, runs the Earthquake Brace + Bolt (EBB) program. It describes the retrofit plainly: "the foundation is 'bolted' to the frame of the house, and when there are walls called 'cripple walls' in the crawl space under the house, they are 'braced' with plywood," which helps "prevent the house from sliding or toppling off of its foundation during an earthquake."

The program is limited to "wood-framed, pre-1980 homes with a raised foundation," and when funds are available it offers "up to $3,000 toward a code-compliant seismic retrofit." Income-eligible homeowners may qualify for more.

Two conditions the program's summary pages tend to bury:

• Your ZIP Code has to be eligible. Good news for us: Boulder Creek's 95006 appears on CRMP's current eligible-ZIP list, which is posted with a December 2024 date, and Ben Lomond's 95005 is on it too.
• Registration isn't open year-round. It opens for a limited period each year, and we could not verify a 2026 window, so treat the dates as unknown until you check. Check at earthquakebracebolt.com or call CRMP at (877) 232-4300 to find out whether registration is open and when the next window is.

Whether your specific house is a candidate, and how the work should be done, is a question for a licensed contractor or a structural engineer, not a DIY weekend and not this article. Check your eligibility with the program first, then get a professional's eyes on your crawl space. This is one of the few home projects that can change whether your house is livable after a major quake.

Learn Drop, Cover, and Hold On

When the ground moves, the goal is to avoid being knocked down and avoid being hit by what's falling. The Great ShakeOut, run by the same earthquake-safety partnership, gives the three steps:

• Drop where you are, onto your hands and knees. As the ShakeOut puts it, this "protects you from being knocked down and reduces your chances of being hit by falling or flying objects."
• Cover your head and neck with one arm and hand, crawling under a sturdy table if one is close or next to an interior wall if not.
• Hold on until the shaking stops, gripping your shelter if you're under one and protecting your head and neck if you're not.

If you are in bed when it starts, stay there. Turn face down and cover your head and neck with a pillow.

Skip the old advice about doorways and running outside. Most injuries come from moving during the shaking. If you use a wheelchair, the guidance is to "LOCK your wheels (if applicable)," then cover your head and neck with your arms, a book, or a pillow, and hold on. Practice it once with the kids so the motion is automatic, because a real quake is not the moment to think it through.

After the Shaking Stops

The minutes after a quake are when a lot of the injuries happen. Work through these in order.

• Expect aftershocks. They can come within seconds and can be strong enough to bring down what the first shock loosened. When one starts, Drop, Cover, and Hold On again.
• Check for injuries. Yourself first, then the people with you. Put on the shoes and gloves you staged by the bed before you walk anywhere, because broken glass is the most common post-quake injury.
• Gas and propane. If you smell gas or propane, get everyone out of the building, then call 911 from outside. Do not flip light switches, use a phone, or start a vehicle inside or next to the building. Most of the San Lorenzo Valley runs on propane rather than PG&E natural gas, so the standard "shut off the gas at the meter" advice does not fit many homes here. If you are on propane, the shutoff is the valve on the tank itself, not a meter at the house. Find that valve now, while nothing is wrong, and know which system your house is on. If you do shut off gas or propane, leave it off and have the utility or your propane supplier turn it back on. On PG&E natural gas, call 911 first and then PG&E at 1-800-743-5000.
• Don't tie up 911. Do not call for information, to ask what happened, or to report a power outage. Keep the line open for people who are hurt or trapped. Report an outage to PG&E at 1-800-743-5002 instead.
• Check on neighbors once you are safe, especially older residents and anyone living alone. On these roads, a neighbor is going to reach you before a crew does.
• Watch for CruzAware messages. Evacuation orders after a quake can follow from landslides, damaged roads, or fire, and the county sends them through that system. If the county tells you to leave, leave.

Sign Up for Earthquake and Emergency Alerts

Two different systems are worth setting up, and they do different jobs.

The first is earthquake early warning. MyShake is a free app built by UC Berkeley's Seismology Lab in partnership with "USGS ShakeAlert and the California Governor's Office of Emergency Services (Cal OES)." It delivers ShakeAlert-powered notifications and is available in the Apple App Store and on Google Play. The point of ShakeAlert is to give you a few seconds of warning before strong shaking arrives, enough time to Drop, Cover, and Hold On.

Be clear about what it is and isn't. The USGS states plainly that ShakeAlert "is not earthquake prediction." It detects a quake that has already started and races the alert ahead of the shaking. Alerts can also arrive through your phone's Wireless Emergency Alerts and, on many Android phones, through the built-in Android Earthquake Alerts system.

The second is your county's emergency notifications. CruzAware is Santa Cruz County's alert and warning system, and it's how you'll hear about evacuations, road closures, and other emergencies that often follow a major quake. Register at CruzAware.org and choose how you want to be reached: text, phone, email, or app. While you're on the county's Plan and Prepare pages, learn your evacuation zone and grab the household safety checklist, since the same plan serves earthquakes, fires, and storms.

Frequently Asked Questions

Which faults are near Boulder Creek?

The San Andreas is the big one. The USGS identifies a "Santa Cruz Mountains section" running "62 km (39 mi) from Los Gatos (near San Jose) to San Juan Bautista," and Boulder Creek sits in the mountains just west of that stretch. The fault marks the boundary between the Pacific and North American plates. Other mapped faults nearby include the San Gregorio, offshore along the coast, and the Zayante-Vergeles fault zone. We are not going to quote you a distance from your driveway to a fault trace, because that depends on which mapped strand you measure to. For parcel-level answers, use the USGS Quaternary Fault and Fold Database and the California Geological Survey's EQ Zapp mapping tool, which show mapped faults and state-designated fault zones by address.

Was the 1989 Loma Prieta earthquake near here?

Yes. The USGS places the magnitude 6.9 quake's epicenter "near Loma Prieta peak in the Santa Cruz Mountains, approximately 9 miles northeast of Santa Cruz," on October 17, 1989. It caused 63 deaths, thousands of injuries, and about $6 billion in damage, and the shaking hit the mountains hard.

Can anyone predict when the next big earthquake will happen?

No. The USGS is direct that its ShakeAlert system "is not earthquake prediction." No credible source can tell you the date of a future quake. Warning systems like ShakeAlert detect a quake that has already begun and send an alert seconds ahead of the shaking. That's why preparation, not prediction, is where your effort belongs.

What's the single most important thing to do first?

Two things, and both take minutes. Install MyShake and sign up for CruzAware so you get warnings and evacuation notices, then strap your water heater and anchor the tallest furniture in your house. After that, work on water storage and a family Drop, Cover, and Hold On practice.

Is my older Boulder Creek house safe in an earthquake?

That depends on your specific house, and it's a question for a professional. Many older homes on raised foundations can be strengthened by bolting the house to the foundation and bracing the cripple walls, work supported by the Earthquake Brace + Bolt program for qualifying pre-1980 homes. Eligibility is also tied to ZIP Code, and 95006 is on the program's current eligible list, dated December 2024. Registration opens only for a limited period each year, so check earthquakebracebolt.com or call CRMP at (877) 232-4300 to see whether it's open. Then have a licensed contractor or structural engineer assess your crawl space.

Last reviewed July 24, 2026. This guide links to official sources from the U.S. Geological Survey, the Earthquake Country Alliance, the California Residential Mitigation Program, and Santa Cruz County. Parcel-level hazard and property-specific advice come from the USGS, the responsible county agency, and qualified professionals.

Preparedness is one line in a bigger rhythm up here. When the power goes out after a quake, our power outage plan for mountain households takes over, and the Residents guide pulls together utilities, emergency contacts, and county resources in one place. The single best next step: install MyShake and register for CruzAware before you close this page.