Crossing the mountain pass on the journey to Loui, one sees such magnificent cliffs. I hear the entire mountain is limestone. Looking closely, the left side slopes to the right and the right side to the left, making the whole appear like an anticline structure. This is likely the Paleozoic bedrock underlying the Jurassic to Cretaceous fluvial deposits that form the Korat Plateau. Geological maps show such ancient bedrock outcrops east of the Loei region. In the foreground, colorful balloons—perhaps for tourist hot air balloons—are visible. Here, we transfer to the car sent to pick us up from Loei.

We have lunch here with the teacher who came to pick us up from Luang Prabang and the teachers from Mukdahan who saw us off. The students in uniform seem to have come to help carry our luggage. We are grateful to the Luang Prabang teachers and these students.

After handing over our luggage and belongings, we took a commemorative photo. From left, the figure in the back is my close friend Mr. S. Next is Mr. S, the physics teacher from Luang Prabang. Then is Mr. N, who took care of us in Mukdahan. Holding the souvenirs is Mr. D, the astronomy teacher from Luang Prabang. And on the right is Mr. S, the English teacher from Mukdahan (his wife is a former JICA volunteer from Japan).

We saw more sharp rock peaks. I'd like to survey these mountains someday. While my body still allows it.

Arriving in Luang Prabang, this was a fire lookout tower along the Mekong River, I believe. Northern Thailand's clear skies continued, not a cloud in sight. This was somewhat unfortunate weather for Mr. S, who had mentioned wanting to have students observe clouds at his school.

Immediately, in the astronomy room where the school's seismometer is housed, I explain seismometer maintenance and the software to the students. I'd be delighted if they continue maintaining the seismometer. Incidentally, looking at this science high school's Facebook page, student photos appear everywhere. It's worlds apart from countries like Japan, where photos aren't posted much due to personal information protection. I'm thinking now that the gap with the world might surprisingly exist in such places too. What do you think?

The three-part lecture series on the Myanmar earthquake is the same as the one at Phayao University High School. Since this session is only for science high school students, the explanations are somewhat shorter. Calculations determining the hypocenter distance from S-P time. A key feature is the use of data from IRIS-affiliated observatories and waveforms from two Thai schools where my equipment is installed. A report on this special lecture series about the Myanmar earthquake, including this lab, is scheduled for presentation at JpDU2026 in May.

Here too, we had pre-marked the S-wave locations, ensuring high precision in the source determination. Since this was a large earthquake, estimating the S-wave arrival times was quite challenging. Therefore, for several distant observation points, we had pre-instructed them on the S-wave arrival times. The observation points marked with white circles on the map are those where my seismometers recorded data. For these, the S-wave arrival was clear.

Materials for the morning lecture that day. I had the PowerPoint content printed. Note that there are three parts. These will be introduced in the JpGU presentation.

That afternoon was spent studying ahead of the next day's geology field trip. We learned about the geology of the Korat Plateau and methods for measuring dinosaur footprints.

Students actually walked, measured their stride length, compared it to calculation formulas like waist height, and practiced calculating walking speed from stride length. Each measured their stride with a tape measure.

Now, the evening after the special class concluded without incident. Following a visit several years prior, we were invited once again to a Mekong River sunset cruise. Even though it was my second time, anticipation grew. Just like before, we promptly started drinking beer, our excitement building for the sunset.

About thirty minutes after the boat departed, the sun finally sank into the upper reaches of the Mekong River—an impressive sight. Despite it being a weekday, every seat was quite lively.

Now, enjoy the breathtaking Mekong River sunset cruise. We'll sail along the border, with Thailand on the left and Laos on the right.

Now, here's another classic spot: the old town shopping street in Chiang Khan. Old wooden houses line both sides, making it feel like stepping back in time about 50 years. Here, my good friend S and I each bought a T-shirt featuring local motifs. A bargain at 300 baht.

The decorations have a hint of Chinese cultural influence, but they seem to be traditional items from the Isan region. I recall learning in history that the roots of the Thai people originally lie in southern China.

Now, the next day's field trip. This time, we visited Phuluang Wildlife Sanctuary, a protected area we were seeing for the first time. It's a treasure trove of rare flora and fauna, but it's actually also famous for being the first place in Southeast Asia where magnificent dinosaur footprints were documented. The materials for the day are below. These were used for the preliminary explanation and footprint measurement practice with the students yesterday. http://seagull.stars.ne.jp/2026_Thailand/Loei/Footprint.pdf

Prof. S promptly spotted the weather station. It seems this forest center uses it daily for meteorological observations. I'm a bit concerned it looks a little dirty.

Inside was an analog maximum-minimum thermometer in operation. Is it correct to interpret today's high as 28 degrees and the low as 10 degrees?

There's also a rain gauge. Is it the famous tipping-bucket type?

I was surprised looking at the GPS I brought that day. I thought the car had been driving through the mountains for a long time, but the elevation was actually 1454m. No wonder it felt a bit chilly. However, since we're going hiking now, I'm adjusting by wearing lighter clothes.

Immediately upon entering the walking trail, a ranger guide explains the flora and fauna. Epiphytic orchids densely cover the trees. Having cultivated Western orchids in my home greenhouse when I was young, this is a sight to make me drool. Numerous types of epiphytic orchids can be observed. I imagine this is due to the high altitude, cloud cover, and the resulting high humidity that is maintained.

However, this day was in the middle of the dry season, completely clear, offering magnificent views. The trail runs along the edge of steep cliffs formed by horizontal rock layers called “kesta” or “mesa,” providing such splendid vistas. When I asked the students if they came often, they said it was their first time coming from school, which surprised me. The town of Loi should be visible in the distance, but I couldn't make it out clearly.

A teacher who poses at the viewpoint, teaching both physics and earth science. He is our host this time. He is a dedicated researcher and has already received the Teacher Award twice. Apparently, this visit came right after he received his second Governor's Award. His specialty is physics, but he also studies geology diligently. At this school, students learn astronomy and geology in their first year of high school, then meteorology in their second year, completing the geology field. I heard all PCSHS schools follow a similar curriculum. Mr. S had received a textbook on meteorology.

This is the walking path just above the cliff near the observatory we visited earlier. Here too, magnificent epiphytic orchids continue to thrive. Unfortunately, it was the dry season, so we didn't hear many birds or see many insects.

Today's lunch was a bento-style meal like this. I had the tamagoyaki rice, but it seems S-san chose a different side dish.

Now, with a clear outcrop visible in the distance, I took a moment to explain the geological formation of this area and the characteristics of its topography. The students listened very attentively. When I mentioned the formation process was similar to the Grand Canyon, they nodded in agreement. The visible steep cliffs appear to be composed of somewhat coarse, hard sandstone, while the gentler slopes seem to be made of finer-grained sandstone and mudstone, more susceptible to weathering. The layers are rhythmically stacked. This is a sight rarely seen in Japan.

Now, gazing at similar kesta (mesa) landforms in the distance, we headed for the dinosaur footprint fossil site. This sanctuary is, of course, within the national park and cannot be entered without a guide. Well, entering on your own would just lead to getting lost anyway.

Surprisingly, such magnificent footprints are still preserved on this plateau. There are no explanations or fences. Without a guide, it was a place you would naturally overlook. However, there was a Japanese research paper on the dinosaur footprint fossils of the Khorat Plateau. I referenced this as teaching material for the students on this trip. https://www.palaeo-soc-japan.jp/public.../100_Kozu_et_al.pdf

Yesterday we conducted a lab exercise to estimate dinosaur size and walking speed from footprints. This is the field verification. Here we are measuring the footprints.

This lab exercise calculates hip height—that is, the dinosaur's body size—from the size of a single footprint. Typically, with three footprints of this type, multiplying the footprint size by 4 gives the hip height. That's about the same height as this student.

Next, we calculated walking speed from stride length. Values came out around 3-4 m/s. While we can't say if this is reasonable, the students seemed convinced, realizing the previous day's calculations were useful with actual footprints. After all, the previous lesson emphasized the importance of seeing the real thing and not being fooled by artificial intelligence.

The white area is where salt is scattered. I never imagined elephants would eat this.

The round holes are apparently marks left by elephant tusks. Amazing, isn't it?

Now, back at the school. This is a distant view of the astronomy classroom where the seismometer is placed. At this school, Mr. T, a young Japanese JICA volunteer, had spent two years and was about to return home after completing his term. I spoke with the young man during my visit last year. I was deeply moved by his passion—he had deliberately quit a development job at a certain famous optics manufacturer to pursue teaching and volunteered for JICA. This time too, despite being busy preparing to return home, he managed to join me for dinner just once with Mr. S. He spoke at length about his upcoming life as a math teacher in Tokyo. https://www.facebook.com/photo/?fbid=1343312431169096&set=pcb.1343312551169084 Here's a photo of him overcome with emotion at the farewell ceremony where students saw him off.

Next, we visited the attached botanical garden, where dinosaur models also stood out, and observed graduate students conducting fieldwork. They seemed to be measuring ground temperatures. When asked, they mentioned specializing in environmental science. Their instructor appeared, and Mr. S promptly exchanged business cards.

Here's a commemorative photo with the students. Although the university is located within the city, its expansive botanical garden features numerous tropical trees, making it an excellent location for environmental research.

We stopped at a cafe near Loei Airport. They had local beer, so I tried some. It was a fruity craft beer. I packed the bottle of Peter Corn as-is into my suitcase to bring back as a souvenir.

Well, after a hectic four-day visit, we're heading back to Bangkok. Loei is convenient because the airport is nearby. This might be my first time boarding from the back on AirAsia. The daytime sun is getting a bit stronger. Many people are wearing short sleeves. However, looking at the horizon, the PM2.5 impact doesn't seem too strong yet.