How do you survive a lahar?

Lahars: How to Not Become Part of the Mudflow

Okay, let’s talk about lahars. These aren’t your average mud puddles; we’re talking about volcanic mudflows that pack the punch of wet concrete and can move faster than you might think – up to 30 kilometers per hour! Imagine a wall of mud, rocks, and debris roaring down a river valley, capable of wiping out everything in its path. Sounds terrifying, right? It is. But knowing what you’re up against and how to react can seriously boost your survival odds.

So, what exactly is a lahar? Basically, it’s a slurry of volcanic ash, rocks, and water. Think of it as a super-charged mudslide on steroids. What sets one off? Well, a few things. Often, it’s heavy rainfall washing away loose volcanic debris. Imagine a recent eruption leaving behind tons of ash – then a downpour hits. Boom, lahar time! Melting snow and ice during an eruption can do the same thing. And sometimes, the eruption itself just blasts water out, creating a lahar directly. The scary part? Lahars aren’t picky; they can happen during an eruption, but also months, even years, after the volcano’s gone quiet.

The 1985 Nevado del Ruiz eruption in Colombia is a stark reminder of how deadly these things can be. The town of Armero was practically erased by a lahar, and over 20,000 people perished. It was a tragedy that highlighted just how crucial it is to understand and prepare for these events.

Spotting the Danger Signs

Being able to recognize the signs that a lahar might be headed your way is absolutely critical. Here’s what to listen and look for:

• That Rumbling Sound: Imagine a freight train barreling down the tracks. That’s what a lahar can sound like as it barrels down a valley. If you hear that coming from upstream, pay attention.
• Water Gone Wild: Keep an eye on any nearby streams or rivers. Are the water levels rising rapidly? Does the water look different, maybe muddier or carrying debris? That’s a red flag.
• Listen Up: A roaring sound coming from upvalley.
• Feeling the Ground Shake: A vibration in the ground.

Getting Ready: Your Lahar Action Plan

If you live anywhere near a volcano – especially in a valley or floodplain – preparation is your best friend. Here’s how to get ahead of the game:

• Know Your Risk: Are you actually in a lahar hazard zone? Find out! Check with your local emergency management agency or geological survey.
• Plan Your Escape: Figure out your evacuation routes now. Where will you go to reach higher ground? Talk it over with your family so everyone knows the plan.
• Grab-and-Go Kit: Pack an emergency kit with the essentials. Think water, non-perishable food, a flashlight, a radio, and extra batteries. And don’t forget those N95 masks and eye protection – volcanic ash is nasty stuff.
• Stay Plugged In: Keep tabs on official news sources. NOAA weather radio, local TV and radio, and alerts from emergency management agencies are your lifeline. Sign up for alerts from the USGS Volcano Notification Service.
• Know the Signals: Familiarize yourself with your community’s warning systems. Sirens, for example. What do they mean? What should you do when you hear them?

When It Hits the Fan: During a Lahar

Okay, the warning sirens are blaring, or you’ve spotted the signs. What do you do right now?

• Get Out! Don’t wait around to see the lahar. If you get a warning or see the signs, evacuate immediately to higher ground. Time is of the essence.
• Head for the Hills: Aim for the highest ground you can reach, ideally at least 50 feet above the valley floor.
• Stick to the Plan: Follow those evacuation routes you planned out. Know where the designated safe zones are.
• Keep Listening: Keep monitoring those official news sources for updates and instructions.
• No High Ground? If you’re caught outdoors and can’t get to high ground, try to find a sturdy building and get to the upper floors.
• Keep Moving: Whether walking or driving, do not stop to look . Keep moving to allow others to evacuate.

After the Lahar: Staying Safe

Even after the lahar has passed, you’re not out of the woods yet.

• Stay Away: Lahar deposits can stay hot and unstable for months. Don’t go near affected areas until the authorities say it’s safe.
• More Could Be Coming: Remember, lahars can happen again, especially if there’s more heavy rain. Stay vigilant.
• Watch Out for Hazards: Be on the lookout for damaged buildings, broken power lines, and contaminated water.

Local Hotspots

Some areas are just naturally more at risk. Take the Puyallup River valley in Washington state, for example. Towns like Orting, Sumner, and Puyallup are built on old lahar deposits, which means they’re in the danger zone. And Mount Rainier? Well, with all that glacial ice and those steep slopes, it’s considered one of the most hazardous volcanoes in the U.S. because of its lahar potential.

The Bottom Line

Surviving a lahar is all about being informed, being prepared, and acting fast. Know the risks, recognize the warning signs, make a plan, and stay alert. It could save your life.