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.


Advertisements

Guest Videos: Landslides (and the Lituya Bay Megatsunami)


There have been lethal landslides lately in the Caribbean and Rwanda.

Fortunately no one was injured in a Chinese landslide that was caught on video.

A geologist blogs about that here.

Here in Corvallis there are plenty of homes on steep slopes, just as there are in Portland, north of us, where the first part of this video was filmed:

Over 4,000 people died in landslides last year.

Probably the worst landslides recently were those in China, in 2017 —

— and in the US state of Washington in 2014:

Lituya Bay

Landslides that happen in or around water, of course, cause a big splash. People often perish as a result, because there is no warning before it happens.

This occurred near Newfoundland in 1929, and it also happened in Alaska’s Lituya Bay one night, causing a 1,720-foot-high tsunami–that these two people rode.

That holds the record for the biggest wave ever.

Here is more information about landslides from US Geological Survery.


Featured image: USGS


Kirishimayama Volcano Group


 

For most of us, the words “Japan” and “volcano” summon up an image of Mt. Fuji, near Tokyo. But this country has many more volcanoes, some of them not as simple in appearance as Fuji-san.

Take Mount Kirishima, for instance. It is a study in contrasts.

6398836675_760a3fc4f2_z

Not least because it rises out of townlands and has a lot of vents. (Jun Seita, CC BY 2.0)

On the one hand, Kirishima frequently erupts; on the other, it’s a great place for a walk through the park.

A violent history

Starting some 600,000 years ago, huge caldera-forming eruptions began here, at the head of Kagoshima Bay on the island of Kyushu. Ever since then, volcanic events have been explosive in nature (not showing much runny “Hawaiian-style” lava).

About 330,000 years ago the style changed to building stratovolcanoes instead of big holes in the ground (which is what a caldera is, basically). Ever since, this complex volcano has built more than 25 relatively small peaks and cones. Two vents are currently erupting: Shinmoedake and Ioyama.

Occasionally magma interacts with ground water, forming a maar with the resulting steam-driven eruption.

The park

Here is someone’s video of a walk up three volcanoes in the area; the first two–Takachiho (crowned with a legendary spear, per Wikipedia) and Karakuni–are part of the Kirishima center; the last one, beautiful Kaimon, belongs to the Ata caldera underneath Kagoshima Bay.

That certainly looks peaceful. Volcanoes sculpt some of the most beautiful landscapes in the world. But as you can see, a lot of people live near Mount Kirishima.

This volcanic group is slowly becoming more active and its magma rate is increasing. Volcanologists are watching Kirishimayama closely to better understand how it works so they can most accurately predict its future course.


Featured image: NASA Earth Observatory.



Sources:

Global Volcanism Program. 2018. Kirishimayama.

Nagaoka, S., & Okuno, M. 2011. Tephrochronology and eruptive history of Kirishima volcano in southern Japan. Quaternary International, 246(1-2): 260-269.


The Fourth US Natural Disaster Ongoing This Weekend: Wildfires


Heads up, if you live in the Southwest or parts of the central and western US. Severe weather, floods, and blizzards aren’t the only natural disasters happening today.

https://platform.twitter.com/widgets.js

I didn’t know when I scheduled a post on wildfires for this coming week that Oklahoma was burning. It is.

Last year, around this time, it was Kansas.


Featured image: Firefighters at a 2006 Oklahoma wildfire. Bob McMillan, FEMA. Public domain


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.


Guest Video: Cascades Volcanoes


We have looked at some of these volcanoes before, but this video presents an in-depth look at the situation in the Pacific Northwest, as seen in the 1990s.

Updates/More information:

A 2015 study on Mount Unzen and its effects on the Shimabara Peninsula.

CENAPRED’s monitoring page for Popo. (Spanish) Yes, the “smoking mountain” is still doing its thing today. Webcams de Mexico also has a good Popocatepétl page. (Spanish)

Pierce County’s Mount Rainier page.

Some volcano observatories:


Featured image: NASA


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. http://www.march.afrc.af.mil/News/Photos/igphoto/2000266910/