Bulletin of Earth Sciences of Thailand https://ph01.tci-thaijo.org/index.php/bestjournal <p><strong>Bulletin of Earth Sciences of Thailand</strong> (BEST) is an international Earth Science journal publishing papers of high quality yearly, in printed and electronic versions, by <a href="http://www.geo.sc.chula.ac.th/en/" target="_blank" rel="noopener">Department of Geology, Faculty of Science, Chulalongkorn University</a>. The journal publishes original research papers that provide novel findings and important contribution to Earth Science community.</p> <p>The journal welcomes outstanding contributions in any domain of Earth Science. Submitted manuscripts must conform to the guidelines given in the <a href="https://ph01.tci-thaijo.org/index.php/bestjournal/about/submissions">Author Guidelines</a>. </p> <p><strong>ISSN 1906-280X</strong> (Print)</p> <p><strong>ISSN 2821-9104</strong> (Online)</p> en-US <p><strong>Copyright</strong> © 2008 Department of Geology, Faculty of Science, Chulalongkorn University. Parts of an article can be photocopied or reproduced without prior written permission from the author(s), but due acknowledgments should be stated or cited accordingly.</p> montri.c@chula.ac.th (Montri Choowong) piyaphong.c@chula.ac.th (Piyaphong Chenrai) Sun, 13 Jul 2025 01:04:58 +0700 OJS 3.3.0.8 http://blogs.law.harvard.edu/tech/rss 60 Susceptibility Investigation of Debris Flow Hazard Using Topographic Index in Phang-nga province, Southern Thailand https://ph01.tci-thaijo.org/index.php/bestjournal/article/view/260999 <p>Phang-nga, a province in Southern Thailand, is highly susceptible to geohazards such as debris flows and flooding, both of which pose significant risks to human life and property. Several topographic factors contribute to the potential for debris flow, including: i) steep mountain slopes and ii) the presence of multiple mountain-front outlets. In this study, the Frequency Ratio (FR) method was used to identify and generate a map of debris flow susceptibility across Phang-nga. Topographic indices related to debris flow activity were analyzed using terrain data obtained from a 30-meter resolution Digital Elevation Model (DEM). The FR was computed by integrating ten parameters that characterize areas prone to debris flow, including: i) slope, ii) elevation, iii) aspect, iv) lithology, v) vegetation cover, vi) land use, vii) topographic wetness index, viii) terrain ruggedness index, ix) rainfall, and x) profile curvature. The findings indicate that debris flow susceptibility in Phang-nga can be categorized into five levels. The high and very high susceptibility classes are concentrated in the valley directions, near the streamlines. The most prevalent class in the region is the moderate susceptibility class. Meanwhile, the eastern and southern parts of Phang-nga have been found to have low and very low susceptibility (Class 1 and Class 2, respectively), located in the direction of the mountain range and areas with lower average rainfall.</p> Santi Pailoplee, Aksara Kulsilrak Copyright (c) 2025 Bulletin of Earth Sciences of Thailand https://creativecommons.org/licenses/by-nc-nd/4.0 https://ph01.tci-thaijo.org/index.php/bestjournal/article/view/260999 Sun, 13 Jul 2025 00:00:00 +0700 A Review of Cetacean Fossils from the Holocene Gulf of Ayutthaya https://ph01.tci-thaijo.org/index.php/bestjournal/article/view/261002 <p>Cetacean fossils from the Thai Lower Central Plains, or what was once the paleo-Gulf of Ayutthaya during the Holocene maximum transgression, despite their potential in the study of sea-level oscillations and their vast discoveries in the past centuries, have only been infrequently reported and lacked compilations, preventing insights into these past Cetacean faunas from being studied in the scientific field. Accordingly, this research aims to review the records of Cetacean fossils from the Holocene Gulf of Ayutthaya, experimentally retrace historical sea level transgressions using these fossils, and lastly, due to the diverse Cetacean record, to compare Holocene Cetacean faunas with present-day faunas of the Gulf of Thailand. Results showed that a total of 17 Cetacean fossil sites had been identified from the Thai Lower Central Plains, all being found in the Bangkok Clay Formation and dating from 1,000 to 6,000 YBP. The most abundant species found was <em>Balaenoptera edeni </em>(<em>n</em> = 7), out of the seven taxa discovered, and a specimen from Bang Khun Thian District, Bangkok is preliminarily reidentified as <em>Ziphius</em> cf. <em>cavirostris</em>, posing a new record of the genus in the Gulf of Thailand. Moreover, these Cetacean fossil localities also allow for an interpretation of the paleo-shoreline, being in line with previous research using different indicators, further solidifying the vast extent of the Holocene Gulf of Ayutthaya. Lastly, almost all of the Cetacean faunas identified are still present in the present-day Gulf of Thailand presenting the possibility that the faunas of the Gulf of Thailand could be descendants of the original population in the paleo-Gulf of Ayutthaya.</p> Saranpat Ouilapan, Parisa Nimnate, Cholawit Thongcharoenchaikit, Kantanat Trakunweerayut Copyright (c) 2025 Bulletin of Earth Sciences of Thailand https://creativecommons.org/licenses/by-nc-nd/4.0 https://ph01.tci-thaijo.org/index.php/bestjournal/article/view/261002 Sun, 13 Jul 2025 00:00:00 +0700 Relationship Between Hotspot and Geography-Meteorology Factors in Thailand and Neighboring Countries https://ph01.tci-thaijo.org/index.php/bestjournal/article/view/261540 <p>Air pollution is a critical issue in many countries and has become a significant problem in Southeast Asia. Wildfires, agricultural burning, and biomass burning are major sources of pollution emissions. This study aims to analyze hotspot activity and examine the relationship between hotspots and geographic-meteorological factors in Thailand and neighboring countries. MODIS hotspot data were analyzed using the frequency-magnitude distribution (FMD) and geography-meteorology factors. The results indicate that areas with high hotspot activity were mainly found in northeastern to eastern Cambodia and northern Laos. Additionally, northern Laos and some pockets in Myanmar showed high hotspot intensity, capable of generating a maximum Fire Radiative Power (FRP)<br>&gt;1,000 MW. The return periods for 8, 20, 40, and 120 MW were found to be 0.05, 0.1, 0.5, and 1 year, respectively. In the next 50 years, parts of Thailand, Myanmar, and Cambodia will have a 0–60% probability of experiencing 120 MW fires. Fires are more frequent at low elevations, on gentle slopes, and across all aspects (excluding flat areas). Moreover, higher elevations, steeper slopes, and southern aspects tend to experience more high-intensity fires. It can be inferred that fire intensity is not primarily influenced by temperature, precipitation, or relative humidity. Instead, other factors, such as fuel availability and human activities, may play a more significant role.</p> Santi Pailoplee, Thanchanok Ngernted Copyright (c) 2025 Bulletin of Earth Sciences of Thailand https://creativecommons.org/licenses/by-nc-nd/4.0 https://ph01.tci-thaijo.org/index.php/bestjournal/article/view/261540 Sun, 13 Jul 2025 00:00:00 +0700 Half century of meander evolution from the Mun River, Surin Province, northeastern Thailand https://ph01.tci-thaijo.org/index.php/bestjournal/article/view/259729 <p>The Mun River, a major tributary of the Mekong River, exhibits a dynamic meandering pattern within its catchment basin. This study reveals a half century of geomorphological changes of the Mun River in Surin province based on geomorphological parameters. Satellite images from 1973 to 2023 were analyzed together with subsurface surveys. The identified landforms alongside the floodplain of the Mun River include paleo-channels, oxbow lakes, and meander scars. To quantify geomorphological changes, four geomorphic metrics were employed: channel width (W), channel length (L), sinuosity index (SI), and radius of curvature (RC). Significant variations in channel width were observed, primarily due to bank erosion and long-term sedimentation in the river. The channel length and sinuosity index have shown a decreasing trend, indicating frequent cut-off process. Erosion rates were found to be higher in the lower reaches, where the river is actively migrating and bending. The upper and middle reaches have experienced past cut-offs and channel patterns were likely stabilized. RC began to decrease after 1990 possibly by increasing river bank protection and settlement expansion.</p> Montri Choowong Copyright (c) 2025 Bulletin of Earth Sciences of Thailand https://creativecommons.org/licenses/by-nc-nd/4.0 https://ph01.tci-thaijo.org/index.php/bestjournal/article/view/259729 Sun, 13 Jul 2025 00:00:00 +0700 Classification of Granitic Rocks Using Stained Rock and µ-XRF Analysis: Comparison with Lithogeochemical Data https://ph01.tci-thaijo.org/index.php/bestjournal/article/view/260729 <p>Classification of granitic rocks are various methods by several researchers in order to limitation of grain size, texture and alteration of the rocks.&nbsp; The research aims to present the sufficient technique for fine-grained and slightly alteration rock. Modal analysis of three stained rock samples classifies them as alkali feldspar granite, while mineral composition analysis using µ-XRF also classifies them as alkali feldspar granite, with both methods yielding closely comparable mineral percentages. However, classification based on geochemical data differentiates the samples as monzogranite and syenogranite, revealing significant variations in K-feldspar and plagioclase content. This discrepancy is likely influenced by feldspar solid solutions between albite and orthoclase, as well as differences in grain size and alteration. Additionally, µ-XRF element mapping of Al, Ca, Na, K, and Si provides insights into the morphology and crystallography of quartz, plagioclase, and K-feldspar, enhancing the understanding of mineral composition and paragenesis. This study proposes µ-XRF as a valuable method for improving rock classification accuracy under these constraints. While petrography and modal analysis remain fundamental, µ-XRF serves as a complementary technique, particularly for samples with similar limitations. The findings demonstrate that µ-XRF enhances the accuracy and reliability of granitic rock classification, especially for rocks with variable grain sizes.</p> Nannapat Kummoo, Ladda Tangwattananukul, Mayuko Fukuyama Copyright (c) 2025 Bulletin of Earth Sciences of Thailand https://creativecommons.org/licenses/by-nc-nd/4.0 https://ph01.tci-thaijo.org/index.php/bestjournal/article/view/260729 Sun, 13 Jul 2025 00:00:00 +0700