From Kamchatka

 

Shown above are the water levels as recorded at the Point Reyes tide gauge on 30 July 2025.  The blue line represents the predicted tide levels.  The red line shows the recorded levels with marked fluctuations,  both higher and lower than the predicted levels, revealing the effects of the Kamchatka tsunami.

 

I posted about the Tonga tsunami back in 2022, so you might have seen a graph like this before.  The basic idea is that the tsunami is a series of water level fluctuations that can continue for hours or days.  The duration of the fluctuations surprised me during the Tohoku tsunami in 2011, but I was ready for them in 2022, and again this time.

 

You can see that most of these water level deviations are less than 1 foot (with an exception at ~3 a.m.).  But the water levels rise and fall very quickly (hence the steep, jagged line).

 

What does this look like in the field?  I've learned that it's easiest to see these tsunami-influenced water levels in Bodega Harbor because the elevation change is so gradual.  It's fairly straightforward to see the water levels rising and falling as the water flows across the mudflats.

 

I only had about an hour this morning, but I took a series of photos between 9-10 a.m. to document the tsunami.  This is a little tricky to describe, but here's the basic scenario of what I captured (below).  It's important to compare the water levels in each photo, especially along the left side of the image. 

 

First photo, 9:02 a.m.  Note the water level on the left side of the photo and where it is relative to the wooden post/sign.
 

 

 

Second photo, 9:25 a.m.  The water has flooded in from the left side and spread across the tidal flats to the right of the sign.  Importantly, low tide was at 9:28 a.m. this morning, so the tide should have been dropping, but the water was rising quickly:

 

 

Third photo, 9:30 a.m.  Only 5 minutes later, the water levels have now dropped back almost to the left of the sign again.  (They should have been rising after the low tide.)

 

 

 

Fourth photo, 9:52 a.m.  About 20 minutes later, the water starts to rise for a second time.  It's spreading to the right of the sign again:

 

 

 

Fifth and sixth photos, 9:58 a.m. and 10:08 a.m.  Although the tide should be coming in at this point, the water levels are dropping again.  They are receding to the left of the sign:

 

 

 

 

 

 

Seventh and eighth photos, 10:12 a.m. and 10:16 a.m.  Only four minutes later, the water levels are rising for a third time within a 75-minute period:

 

 

 

 

 

 

I think the area in the green box below shows the period when I took these photos:

 

 

It'll be interesting to see how long the water level fluctuations continue.  You can check the Point Reyes tide gauge yourself here.

 

Amazing to see how these waves cross the entire Pacific Ocean basin!  

 

P.S.  I'm thankful to NOAA for maintaining these tide gauges and helping us understand this phenomenon.

 

Morning warning?

  

Red sky in the morning, sailors take warning?

Whew, it was an intense day with a tsunami warning issued after an earthquake near Cape Mendocino.  The tsunami warning covered a large swath of the West Coast from Florence, Oregon, to Davenport, California.

The only surge measurement I've heard about so far was 9 cm at Arena Cove (near Point Arena) at 11:45 a.m.

This brought back memories of the Tōhoku tsunami in 2011 and the Tonga tsunami in 2022.  I posted a few photos and some info in 2022, so if you'd like to review that post, see "Tsunami surges" on 16 January 2022.

Tsunami surges

To document evidence of the tsunami yesterday, I took a few photos from the shoreline of Bodega Harbor.  Below I'll share a short time series, but before I do that I wanted to explain what you'll be seeing.  

I learned a lot from seeing the Tohoku tsunami in 2011.  It's easier to think about these effects not as one larger wave, but instead as a series of water level changes.  The water surges above the predicted tide height and then recedes below the predicted tide height, and this happens over and over and over again.  (In 2011 the effects were visible for at least 7 days.)  These changes in water level happen relatively quickly – e.g., rather than taking 6 hours to go from high tide to low tide, during the tsunami events we've experienced in 2011 and 2022 some of the water levels changed from the equivalent of high tide to low tide within 30 minutes!

So if the estimate for the Bodega Bay area was for the water level to change by 1.5 feet, then the water level would surge 1.5 feet above the predicted tide height and then recede 1.5 feet below the predicted tide height, and then the flow direction would change and the water would come in again and then go out again.  (In general, the water level deviations are greatest within the first day and then get smaller during the following days.)

Because waves in this area are large (often in the 5-8 foot range), it's actually harder to see the effects of a 1.5 foot water level change on the outer coast.  (Although there can be dangerous surges on sandy beaches.)  But the effects of the tsunami are much easier to see in Bodega Harbor during low tides because you can see the water flooding over the tidal flats and then receding and then flooding in again.  I'll admit, after spending most of my life around tides, it has felt somewhat surreal to me to see this happening!

So here's a time series of photos taken from the same site along Westshore Road.  There is a pink arrow pointing to a clump of algae for a visual landmark to judge the height of the water.  (Note that in these images the water flows in from the left and then recedes to the left.)

The first image was taken at 1:02 p.m. when the water level was relatively high:

 

Then the water receded and was very low within 15 minutes, the time of the second image at 1:17 p.m.:

 

Then suddenly the water started surging back in and it returned to the relatively high level within 7 minutes, by 1:24 p.m.:

After that the water receded again and stayed out for while (but it eventually came back in ~2:30 p.m. after I had left):

 

 

To make this a little easier to visualize, I've also annotated the water level graph from the tide gauge at Point Reyes.  The red line shows all of the water level changes above and below the predicted tide height associated with the tsunami.  I've put in pink arrows at the times that match the photos shown above:

 

 

Amazing to see the effects of the Tonga tsunami reaching Bodega Bay, ~5200 miles (8500 km) away.

P.S.  You can click on the images above and then move through the images faster to see the water level receding, flooding, and receding again.

Thinking about Tonga

 

 

Thinking about the people in Tonga today (15 January 2022).  There were tsunami pulses in Bodega Harbor throughout the day and higher than predicted waves along the outer coast.

 

P.S.  You can see the effects of the tsunami on local water levels on this NOAA web page showing data from the Point Reyes tide gauge.

 

Let's Move!

Remember last night's mystery anemones (see post from 11 March 2016)?

Well, we have a clue to their origin. 

Jim Carlton astutely inquired about whether there were any markings on the cap.

Eric searched more thoroughly today, and found a faded word on the top of the black cap:

 

When Eric searched for the word "KURE" on the Internet, he discovered that Kure is a port town in Japan (near Hiroshima).

And then he started searching for KURE products.  Here's what he found:

 

Lots of black plastic caps!  KURE is a company that makes cleaning products and lubricants — see their website here. (Note that their slogan is, "Let's Move!"  It appears that the mystery anemones took their slogan literally!).

The fact that the anemones were growing in a KURE product cap makes us think that they might have originated in Japan rather than the Indo-Pacific.  We'll continue to follow up on the identity of the mystery anemones.

Beamed across

Here's something interesting that washed up on Doran Beach:

 

Although it's hard to tell, this beam was about 7 feet long.

Can you see those holes in the end of it?  Do you know what kind of animal made the holes?

Here's a view of some of the smaller holes on the top of the beam:

 

The holes belong to "shipworms" — indicating that the beam was at sea for a while.  Shipworms are actually not worms at all, but rather are marine bivalves — small clams that tunnel through submerged wood.

I decided to share pictures of this beam and the shipworm holes because it might have an unusual origin.  Jim let me know that it's possible this is a piece of debris from the Japanese tsunami in 2011.  He's been involved with the Japanese Tsunami Marine Debris project, and there are characteristics of this beam that indicate a possible origin from the Tohoku coast of Honshu.  (An expert is working on identifying the shipworms — they might be a species from the Western Pacific called Psiloteredo.)

It's unknown when the beam washed up at Doran, or how it made its way across the Pacific Ocean, but it's amazing to think about such a long-distance journey.

 

P.S.  If you'd like to read a little more about shipworms, there's a Wikipedia article here.

P.P.S.  For more information about the Japanese Tsunami Marine Debris program, visit NOAA's web site.