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‘The Bulge’ is back: USGS scientists detect renewed uplift near South Sister volcano

Satellite radar interferogram spanning June 19, 2020, to August 13, 2021, and showing the ground motion in the direction of the satellite.  The maximum uplift, indicated by the red color, is about 2.2 centimeters (0.85 inches), and it is located to the west of South Sister.  The HUSB continuous GPS site is marked by the large black dot.  Earthquakes that occurred during the time period spanned by the interferogram are indicated by small black dots
U.S. Geological Survey
Satellite radar interferogram spanning June 19, 2020, to August 13, 2021, and showing the ground motion in the direction of the satellite. The maximum uplift, indicated by the red color, is about 2.2 centimeters (0.85 inches), and it is located to the west of South Sister. The HUSB continuous GPS site is marked by the large black dot. Earthquakes that occurred during the time period spanned by the interferogram are indicated by small black dots

SISTERS, Ore. (KTVZ) -- Some two decades after first drawing widespread attention, a small (but detectable by satellite) uplift near the South Sister volcano is making news once again, with a quicker rate of rising ground than seen for years, accompanied by some small but noticeable, shallow earthquakes. But an eruption, geologists assure, is not in the cards any time soon.

Here's the U.S. Geological Survey's news release, issued Monday, of the latest activity:

Using satellite imagery and sophisticated GPS instruments, Cascades Volcano Observatory geophysicists have detected a subtle increase in the rate of uplift of the ground surface about 3 miles (5 km) west of South Sister volcano, Oregon. Episodes of increased uplift have been observed in this area before, and the volcano’s alert level and color code remain at NORMAL / GREEN.

Data from satellite radar images show an uplift of about 0.9 inches or 2.2 cm (about the width of an adult’s thumb) occurred between the summer of 2020 and August 2021 across an area 12-mile (20-km) in diameter. GPS data from a volcano monitoring station near the center of uplift measured at least 0.2 inches (0.5 cm) of uplift since August 2021.

Additionally, seismologists observed brief bursts of small earthquakes in October 2021, December 2021, and January 2022. Most of these shallow earthquakes are too small to locate precisely; those located are inside the uplifted area. 

Uplift occurred in the same general region in the mid-1990s. During the 25 years between 1995 and 2020, the area rose approximately 12 inches or 30 cm (the height of a 2-liter soda bottle) at its center. Although the current uplift rate is slower than the maximum rate measured in 1999-2000, it is distinctly faster than the rate observed for several years before 2020. 

The uplift is attributed to small pulses of magma accumulating at roughly 4 miles (7 km) below the ground surface. While any magmatic intrusion could eventually lead to a volcanic eruption, an eruption would likely be preceded by detectable and more vigorous earthquakes, ground movement (deformation), and geochemical changes. In general, as magma moves upward during an intrusion, it causes continued or accelerated uplift, fractures rock to generate swarms of earthquakes, and releases significant amounts of volcanic gases, such as carbon dioxide. We do not detect any of these signs currently.

CVO scientists will closely monitor data in the coming months and issue further updates as warranted. 

Read the complete Information Statement that was released January 31, 2022.

KTVZ news sources

Comments

27 Comments

    1. No, it’s COVID’s fault. It’s the new strain called VOLCANIA. Better hurry and get the 1635 jabs for it and wear the new N95000 mask!😂

  1. Time for a state of emergency declaration. Luckily we all have masks and are preconditioned to wearing them. I suspect climate change has something to do with the recent uplift.

        1. Hey Soze, NEWSFLASH Maga Boomer is correct. The poles move all the time and as the magnetic field moves the weather trends follow. But of coarse none of this matters to the Liberal True Believers and the Tin Hat Global Warming Society.

  2. The recent eruption down by New Zealand that erased an island, covered the pacific coastline in tsunamis and produced a shockwave that circled the planet 5 times was also deemed inactive by American geologists who were studying the volcano for years prior to the event. So there’s that.

    1. Mt. St. Helens was also inactive for over 150 years before she erupted in 1980. Nobody is claiming South Sister is dormant. That’s why there are monitors on most of the Cascade volcanoes and quite a few currently on Newberry.

  3. South Sister is the #7 most dangerous volcano in the U.S. out of more than 150 and an eruption is highly likely. No way the USGS or anybody else can predict where or when. This report is irresponsible. Recent report said that one of the top 10 is almost certainly to erupt ‘in our lifetimes’. Mt St Helens and Mt. Hood, along with Mt. Shasta are near the top of the list. I am not trying to be an alarmist, but we should not ignore the possibility. Not that there is much we can do about it. It is like the Cascadia Subduction earthquake. Everybody knows it will happen sometime in the next few centuries, and it will kill ten’s if not 100’s of thousands of Oregonians. But, preparations for it are minimal, because real preparation would cost more than our annual budget.

    1. Why is this report irresponsible? To ignore what is happening all around us in this highly active geologic area we live in would be irresponsible. And you forgot to mention Newberry, when the trees in the caldera start dying it will be time for La Pine and Sunriver to get nervous.

  4. Wow, one person who actually knows what they’re talking about (flashsteve) and a bunch of unemployed volcanologists and climatologists with too much time on their hands. What a font of wisdom this thread is.

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