Guest Videos: What Is Lightning?

When thunder roars, go indoors! — words of wisdom from James Spann and other meteorologists.

Note that on Earth, lightning is most frequent in equatorial regions.

For almost 40 years–ever since Voyager passed the planet Jupiter–scientists have wondered why lightning is more frequent at Jupiter’s poles. It otherwise seems to work pretty much the same way as terrestrial lightning.

Thanks to data from the Juno mission, they may have figured it out now.

Meanwhile, back on Earth–
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Guest Video: The Salton Sea

A study at the end of June made headlines about earthquake hazard on the San Andreas Fault. The research looked at the area covered by the Salton Sea:

According to news reports, geologists found:

. . . a nearly 15.5-mile-long, sheared zone with two, nearly parallel master faults and hundreds of smaller, rung-like cross faults. . . The discovery . . . reveals the southern tip of the San Andreas Fault changes fairly gradually into the ladder-like Brawley Seismic zone. The structure trends northwest, extending from the well-known main trace of the San Andreas Fault along the Salton Sea’s northeastern shore, to the newly identified East Shoreline Fault Zone on the San Andreas’ opposite edge.

. . .

Future earthquakes in that zone or near the San Andreas Fault could potentially trigger a cascade of earthquakes leading to the overdue major quake scientists expect along the southern San Andreas fault zone . . .

So, perhaps it’s good that the “Riviera” scheme never worked out.

While seismologists scramble over the area to learn more about earthquake hazards, the USGS is monitoring the local volcano situation–which includes five vents discovered in 2013–through the California Volcano Observatory.

Again, not a good place for a resort!

Featured image: 12019, at Pixabay. Public domain.

Popocatepétl: A Dangerous Volcano

People in central Mexico have always felt a strong personal link with Popocatepétl, which they often call Don Goyo.

As we saw last time, when this volcano broke its five-decade silence with a VEI-2 bang in 1994, local people responded with traditional ceremonies; artists were drawn to the event; government officials took emergency measures; and scientists expanded their monitoring networks.

For almost a quarter of a century now, Don Goyo has been on center stage. People have adjusted to it and are moving on with their lives, as people always do after a natural disaster.

But scientists just updated the official hazard map (Spanish) for Popocatépetl, which we’re going to take a look at in this post.

The volcanologists did reassure everybody that there is no sign of any increased or upcoming increase in activity; the volcano is still at a “Yellow, Phase 2” alert level.

Also, to counter popular rumors, they stated in no uncertain terms that Don Goyo is not connected to Guatemala’s Fuego, which recently had a deadly eruption, or to Kilauea, out in Hawaii, with its spectacular lava flows. Each of these three volcanoes has its own plumbing system and exists for different geological reasons.

The problem with Popocatépetl is that, not only in 1994 but also at any point in modern times, this volcano has never shown the levels of violence that the geologic record proves that it is capable of.

And now Don Goyo has 25 million human neighbors, unfamiliar with its historic power and living less than 65 miles (100 km) away from its summit.

Ashfall risk from Popocatépetl

Ashfall risk for Popo

See CENAPRED’s hazard map (Spanish) for details. “Ciudad de México” is Mexico City.

  • The dotted line shows the area that would get at least 4 inches (10 cm) of ash if Don Goyo had another eruption as powerful as one about 14,000 years ago.
  • Red: In a big eruption, this unfortunate area could get lots of volcanic ash (up to yards/meters in depth) as well as a bombardment of rocks up to a foot (30 cm) in size.
  • Orange: Just a little ash would fall here in a small eruption, but up to 3 feet (1 meter) or more in a big one.
  • Yellow: This region isn’t at much risk of ashfall in small eruptions at Popocatepétl, but it could get several inches (dozens of centimeters) in a large eruption.

Seismic sensors, deformation monitoring, and gas/hydrothermal studies can pick up signs of such approaching events, especially the big ones.
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Mount Rainier

This was first published at my other blog on May 3, 2014.

There is a king in the Pacific Northwest, his brow crowned in glittering ice.

Mount Rainier starts to rise only about 25 miles from the Seattle-Tacoma metropolitan area. Today this beautiful Cascades stratovolcano, towering 14,410 feet above Puget Sound, dominates the skyline of towns and cities that sit on material that once made Rainier almost 2000 feet taller.

Flank Collapse

About 5600 years ago, around the time when the ancient Egyptians were getting organized, Mount Rainier’s northeast flank and summit collapsed. It was dramatic even as described by scientists, who say that a cubic mile (4 cubic kilometers) of flank and summit material (now called the Osceola Mudflow):

…washed across Steamboat Prow and Glacier Basin and then ran up to about the 6400-foot level of Goat Island Mountain and Sunrise Ridge. It then descended the White River valley 80 to 150 m (260- 490 ft) deep, spread out over 210 km2 (82 mi2) of Puget Sound Lowland 70-100 km (44-62 mi) from source, and flowed into Puget Sound, moving underwater up to 20 km (12.4 mi) to the present sites of Tacoma and the Seattle suburb of Kent. The contemporaneous phreatic and phreatomagmatic explosive eruptions blew hydrothermal clay and mud northeastward across Sunrise Ridge and spread pumice across an arc from south to northeast of the volcano. The Osceola edifice collapse left a horseshoe-shaped crater open to the northeast at Mount Rainier, much like the open crater formed at Mount St. Helens in 1980.

Mount St. Helens composite image by Ewen Roberts

Mount St. Helens composite image by Ewen Roberts.

Geologists believe that this collapse happened because the rock had been weakened by the circulation of hot, acidic water inside the volcanic structure. Over time, through many eruptions, Rainier built itself back up into the majestic but dangerous structure everyone today knows and loves.

The USGS says it has seen no change in the pattern and expects Rainier to continue growing, erupting and collapsing.

Volcanic Hazards

Today, about 80,000 people are at risk from a potential mudflow, also known as a lahar, from Mount Rainier, say experts at the United States Geological Survey (PDF). This could be triggered by the sort of volcanic activity that the USGS monitoring network would pick up, but it might also happen without warning as another flank collapse. Such a collapse, say the geologists, could reach Orting, Washington, in as little as 40 minutes.

For this urgent need, an acoustic network now surrounds Rainier. Pierce County, Washington, also is developing a specific volcanic hazard plan (PDF) for Mount Rainier.

No one wants to live in fear when there is so much beauty and wonder about this monarch of the Cascades. Having recognized its dangers, people are working to minimize them so that everybody can continue to enjoy this beautiful mountain.. This requires a lot of work but, as shown in Jayson Yogi’s video of a 2011 Rainier summit climb via the Emmons Glacier, difficult struggles have their own special rewards.

Update, July 17, 2014: “Detailed imaging of Mount Rainier shows subduction zone in glorious detail.” Scott Johnson, Ars Technica.

Front Page Image of Mount Rainier is by Michael Lehenbauer.


Mount Rainier,” United States Geological Survey: Volcano Hazards Program.

“Mount Rainier – Living Safely With A Volcano In Your Back Yard.” (PDF) USGS Fact Sheet 2008-3062

Timeline — B.C.” Air War College: Contents of 12,000 Year Timeline.

“Volcanoes of the Cascades: Their Rise and Their Risks.” Richard L. Hill. Globe Pequot Press, Guilford, Connecticut. 2004.

Guest Video: Early Earthquake Warning Systems

You may have heard of earthquake warning systems. Here is how one of them works.

In that example, people in Palm Springs and along the line of the spreading rupture are out of luck, but the system definitely helps communities farther away.

Early warnings have saved many lives in Mexico, but there are limitations to what any early warning system can do.

False alarms are inevitable. Another problem is that earthquakes are unpredictable and little is known about why they occur. Seismologists, for example, wonder why Mexico experienced three major earthquakes in six months.

And local media report that the sirens are stressing people out to the point where some even hear them when they are not in operation.

A seemingly good solution to reduce anxiety would be to set your phone/alarm system to only register large-amplitude ground movement. Unfortunately, according to a recent study, early earthquake warnings work best for relatively small seismic waves.
Humanity has come a long way since a large earthquake in 1556 killed over 800,000 Chinese people, but there is still quite a way to go.

Featured Image: Andy Maguire. CC BY 2.0.

Kick-’em-Jenny Volcano on Orange Alert

Update: On March 22, UWISRC lowered the alert level to yellow, but the 1.5-kilometer exclusion zone is still in place.

Update, March 15: UWI seismic experts note that the number of quakes at the volcano is dropping. However, Kick-‘Em-Jenny has done that before and then gone on to an eruption, so they are keeping the level at orange for now.

No, seriously, that’s the name of this underwater Caribbean volcano. Here’s a post I did on it at the Clear Sight blog in 2015.

The University of the West Indies Seismic Research Centre has raised the alert level to orange again and has set up an exclusion zone. More details are available in this UPI story.

Per the Kick-’em-Jenny Global Volcanism Program page, the exact details of the current increase in activity are unspecified. A combined British/UWISRC research team recently studied the volcano.

Featured image: Lyn Topinka, USGS, via Wikimedia.

Guest Videos: Finding Megaquakes Before They Happen

On March 8, a two-month seafloor-drilling expedition set off to investigate the underwater megathrust fault that most threatens New Zealand’s North Island–the Hikurangi subduction zone.

The South Island is also at risk from its own big fault zone:

Information obtained from these investigations will help geoscientists all over the world improve their understanding of subduction zones and the deadly megathrust earthquakes they spawn.

Sometimes it is also possible to get 3D studies of a subduction zone.

The Hikurangi zone researchers also want data that will help them understand slow-slip quakes and their relationship to the damaging “fast” earthquakes that we’re all familiar with.

Featured image: US Air Force/Technical Sergeant Daniel St. Pierre.

Guest Video: Quicksand

I have never wandered into this nasty stuff but had always thought you can “swim” your way out of it.

Apparently it’s not that simple.

Note that they’re doing this while the tide is out. What if it were coming back in and he was all alone?

Scary thought. So is the fact that this quicksand looks exactly like the solid mud.

Bottom line: ALWAYS pay attention to your surroundings, and if you see warning signs, heed them.

On a reassuring note, reportedly wet quicksand isn’t a bottomless pit. So you might not not sink in all the way.

Per Wikipedia, density differences are a factor, too.

Featured image: Urban Dispute, CC BY-ND 2.0.