The Guishan Island volcano is wearing a vest? We still recognize you!

Guishan Island (English name Kueishantao or Guishan Island), also known as Guishan Island, is a volcanic island formed by the eruption of an underwater volcano. It was originally a volcano located on the seabed in the northeastern waters of Taiwan Province. Later, it rose above the sea level due to regional plate tectonic movement and magmatic activity. The island is located in the sea area about 12 kilometers east of Yilan County, Taiwan Province, my country (near 122° east longitude and 24° north latitude). Administratively, it belongs to Toucheng Town, Yilan County, Taiwan Province, China. It is located at the intersection of the southern end of the Philippine Sea Plate subducting to the Eurasian Plate, the western section of the Ryukyu Island Arc and the southern part of the Okinawa Trough. Looking down at the entire Guishan Island, it is like an agate inlaid in the vast blue sea, making my country's sea borders more beautiful. The part exposed to the sea is dotted with green vegetation, like wearing a fashionable green vest. There are two round peaks on the island. The outline of the small peak on the east side is like a turtle's head, and the outline of the large peak on the west side is like a turtle's tail, so it is named "Guishan Island". Looking at Guishan Island from Yilan County, it looks like a turtle's head is looking up and its tail is swinging left and right. The volcanic rocks and gravels around the island float and sink with the tide, just like the claws of a turtle swimming. Therefore, the locals also call it "Guishan Island with smoke and tail". Compared with the high-end atmosphere of Changbai Mountain Tianchi Volcano against the blue sky and white clouds, the Guishan Island volcano under the clear sky is more charming with the strange clouds formed by the abnormal heat in the volcanic area. These two volcanoes show the beauty and charm of China's active volcanoes in different styles!

Location map of Guishan Island volcano in Yilan County, Taiwan Province (left and middle images, from GF-2 Earth observation images) and bird's-eye view of Guishan Island volcano (right image, from GF-2 Earth observation images)

Side view of the Guishan Island volcano in Yilan County, Taiwan Province (left and middle pictures, pictures from the Internet) and the Changbai Mountain Tianchi large active volcano in Antu County, Jilin Province (right picture, original picture)

There are about 68 submarine volcanoes in the waters between Yilan County, Taiwan Province and Guishan Island. Only the main part of the Guishan Island volcano is located below the sea surface, with a small part exposed above the sea surface. The exposed part of the Guishan Island volcano is about 3.1 kilometers long from east to west, about 1.6 kilometers wide from north to south, with a coastline of about 9 kilometers and an area of ​​about 2.8 square kilometers. In addition, there are at least 10 submarine volcanoes distributed in the sea near the Guishan Island volcano. Among them, the submarine volcano about 70 kilometers northeast of Pengjia Islet still had small-scale eruptions in 1916 and 1927.

The main rock type of the Guishan Island volcano exposed above the sea surface is pyroxene andesite, which belongs to the same andesitic volcanic rock type as the andesitic lava formed by the eruption of the large active volcano Mount Fuji in Japan, and is in sharp contrast to the basaltic volcanic rocks formed by the Italian Stromboli volcano and Mount Etna on the western edge of the Eurasian continent. The latest thermoluminescence dating results of the pyroclastic rocks in the Guishan Island volcanic area show that the volcano was formed about 7,000 years ago, indicating that the Guishan Island volcano is one of the volcanoes in my country that has erupted since the Holocene.

Andesitic lava from the large active volcano Mount Fuji on Honshu Island, Japan (left, source: Internet), basaltic pumice from the large active volcano Stromboli in Italy, and basaltic lava from the large active volcano Etna (middle and right, original images)

The observation and research data of the Guishan Island volcano in Taiwan Province show that there are many submarine hydrothermal vents such as Baiquan vent and Huangquan vent in the volcanic area. The volcanic gas ejected is mainly water vapor, and also includes acidic gases such as CO2, H2S, SO2, and HCl. The temperature of the ejected hydrothermal fluid is as high as 116°C. The chimney-shaped hydrothermal deposits formed on the seabed are about 0.5-6 meters high and about 1 meter in diameter. The intensity of volcanic gas ejection is slightly inferior to that of the Campi Flegrei superactive volcano in Naples, Italy, but stronger than the large active volcano Vesuvius in Italy and the large active volcano Tianchi in Changbai Mountain, Jilin Province. The earthquake monitoring data in the area show that the density of seismic activity in the volcanic area and nearby areas is large and relatively strong. The earthquakes that occur are mainly shallow-source earthquakes, and the focal depth is generally less than 60 kilometers (data from the Institute of Volcanology, China Earthquake Administration and Fujian Provincial Earthquake Administration). The regional GPS crustal deformation data show that there are obvious anomalies in the GPS velocity field in the volcanic area, and the overall situation is in a tensile tectonic stress environment. Current geophysical exploration data also show that there is a magma chamber within the upper crust at the bottom of the Guishan Island volcanic area. The above fully demonstrates that the Guishan Island volcano is one of the active volcanoes with potential eruption risks in Taiwan Province of my country.

The submarine hydrothermal diffusion area of ​​the Guishan Island volcanic area in Yilan County, Taiwan Province (left picture, from the Internet), the degassing vents of Campi Flegrei volcano in Italy, the degassing vents at the top of Vesuvius volcano in Italy, and the degassing vents in the cone area of ​​Tianchi volcano in Changbai Mountain, Jilin Province (second from the left, second from the right, and first from the right, all original pictures)

The highest point of the volcano on Guishan Island is about 398 meters above sea level, making it the second highest mountain on Taiwan's outlying islands. There are two lakes, Guiwei Lake and Guishou Lake, in the north and west of the island respectively. The hot springs, sea caves, sulfur vents and other features on the island have created a unique volcanic landscape. The fusion of geothermal anomalies in the volcanic area and the regional tropical marine climate has created a scene where the sky over the volcanic area is often shrouded in mist, making it look like a hat, just like a "divine turtle wearing a hat". The north and south sides of the island are constantly surging due to the sea tide, and the gravel carried by the tide has formed a narrow and long gravel beach. As the seasons change, the gravel beach will also move north and south with the tide, just like a "spiritual turtle swinging its tail".

The head of Guishan Island is one of the main parts of the volcanic cone. There are still sulfur fumaroles spewing volcanic gases. On the clear blue sea near the island, you can see patches of slightly turbid milky white seawater constantly gushing upwards. This is because the acidic hydrothermal fluid ejected from the submarine hot springs in the volcanic area mixes with seawater to form submarine hydrothermal fluids. The submarine hydrothermal fluids flow upward and erupt, eventually forming a "hydrothermal chimney". This landscape is also called the "Yin Yang Sea" by the locals. Submarine hydrothermal activity is the process of energy and material exchange between the lithosphere and the ocean. It is common in submarine active volcanoes and active volcanoes at the edge of plates, such as the Campi Flegrei super active volcano in Italy and the large active volcano Stromboli in Italy. There are submarine hydrothermal activities. Research on submarine hydrothermal activity requires the use of advanced technical methods and sampling equipment. Submarine hot spring sampling is an important monitoring method to unveil the mystery of the "hydrothermal chimney".

On-site sampling map of the submarine hot springs in the Campi Flegrei super active volcano area in Italy, and on-site sampling map of the submarine hot springs in the Stromboli large active volcano and volcanic area in Italy (both original maps)

From Guishan Island, you can see the vastness of the Pacific Ocean to the east, and the prosperity of Yilan County to the west. You can also watch the sunrise and sunset. The island has steep cliffs, hot springs, mountains, sea caves, lakes and other volcanic landscapes. In the nearby sea area, you can see the marine ecological landscape with abundant creatures such as whales and dolphins. It can be said to be beautiful! If you choose to check in, please check the following four safety tips for sea travel!

1. Choose safe means of transportation , understand and comply with relevant safety signs and regulations

When going out to sea, please be sure to choose a regular carrier with a reasonable quotation, beware of low-price traps, and do not take unlicensed, overloaded, or risky sea transportation. Check the weather conditions of the destination, the sea area you will stay in, the sea area you will pass through, etc. in advance. If there is bad weather such as typhoons, strong winds, big waves, dense fog, etc., you should decisively cancel the trip.

Before boarding, on board or near the sea, please check safety signs, such as escape signs, emergency equipment signs, life-saving signs, etc. Also, please check shore safety signs, such as no swimming, no playing in the water, beware of falling into the water, etc. These safety signs will remind you to pay attention to safety. Also, make sure you understand and comply with all safety regulations for sea travel. Before departure, please be sure to learn more about the safety equipment on board or near the sea.

Ferry terminal and regular and qualified sailing ships (all original pictures)

Some safety signs at the ferry terminal (left, original image) and some shore safety signs (right, sourced from the Internet)

2. Follow common sense when riding a boat and be familiar with safety and rescue equipment

Get on and off the ship in an orderly queue, do not crowd, scramble, or play to avoid accidental injuries or falling into the water. On board, familiarize yourself with the ship's environment as soon as possible, such as the infirmary, toilet, restaurant and other important functional areas. Do not play and chase on the bow, deck and other places to avoid unexpected safety accidents. Before boarding, be sure to be familiar with and understand how to use fire emergency equipment and life-saving equipment, such as fire extinguishers, life buoys, life jackets, etc. Knowing the correct use of these equipment can help you save yourself and each other in an emergency at sea.

3. Travel project selection and personal safety

If you are traveling to Taiwan, you must prepare the relevant application materials for independent travel to Taiwan before departure. You can choose to join a regular and qualified tour group or hire a local tour guide with a good reputation. If you sign a formal travel contract, pay more attention to the scope and requirements of compensation for safety accidents in the contract. In case of emergency, stay calm and find staff or call the police for help in time.

When participating in marine activities, you should understand your own water ability and physical condition, and choose activities according to your actual situation. You should be familiar with the safety factor and excitement level of marine activities, be cautious when participating in water sports such as diving, and be sure to wear a life jacket during the activities and follow the guidance of professionals. Tourists who are elderly or have heart disease, high blood pressure, etc. should not take risks. Minors must be accompanied by their parents when participating in water activities.

4. Prevent marine risks

When participating in marine tourism projects, you should always pay attention to the weather and sea conditions, strictly abide by the severe weather warnings and reminders, and in case of severe weather such as strong winds and waves, typhoons, or red warning flags on the beach, you should follow the warnings and reminders, and never risk going out to sea or engaging in water projects. Before going out to sea, you must be alert to marine risks such as catastrophic waves and rip currents. If you receive a catastrophic wave warning, you should immediately leave the coast and evacuate to a safe place for refuge. At the same time, pay attention to tidal changes to avoid being trapped on reefs and unable to return to shore. Try not to stay and play on the reefs. The moss on the reefs is slippery, and there are many undercurrents nearby. When the tide is high, the sea water can easily flood the retreat, causing unexpected safety accidents.

Offshore navigation marks and maritime emergency rescue ships (all pictures are original)

A real-time picture of the high tide in the Bay of Naples, Italy; a weather map of the Dajinmen and Xiaojinmen islands in Quanzhou City, Fujian Province, on the eve of the typhoon; and a weather map of Gulangyu Island in Xiamen City, Fujian Province, on the eve of the typhoon (all pictures are original)

In short, safety comes first when traveling at sea. By understanding and following these emergency safety tips, your sea travel experience will be both enjoyable and safe! ‌‌

This issue of science popularization ends! Friends, see you next time!

References in this issue:

[1] Chen Yugao, Wu Wenxiong, Liu Conggui, et al. Thermoluminescence dating of Guishan Island[J]. Nuclear Technology, 1999, 22, 10.

[2] Song Yujia, Pan Xiaodong, Gu Guohui, et al. Analysis of the possibility of a magnitude 7.3 earthquake in the waters of Hualien County, Taiwan and its triggering of volcanic activity[J]. Advances in Earthquake Science, 2024, 54(4), 292-298.

[3] Lu Donghua. Research on shallow seismicity model in Taiwan[D]. Institute of Geophysics, China Earthquake Administration, Master's thesis, 2023.

[4] Zhang Haiyan. Hydrothermal gas composition and element diffusion distribution in Guishan Island and Green Island, Taiwan[D]. Zhejiang University, Master's thesis, 2013.

[5] Li Haiyan, Shao Zhigang, Ma Hongsheng, et al. Analysis of the movement characteristics of the Huadong Longitudinal Valley Fault in eastern Taiwan, China based on deformation observation[J]. Earth Science Frontiers, 2018, 1, 240-251.

[6] Long Xiaogang. Finite element method simulation study on the characteristics of the current crust deformation field and its dynamic causes in the Taiwan collision zone[D]. Institute of Crustal Stress, China Earthquake Administration, Master's thesis, 2015.

[7] Wu Xiaolong. Research on the characteristics of current crustal deformation in the arc-continent collision zone of Taiwan Island and its adjacent areas[D]. Chang'an University, PhD thesis, 2017.

[8] Pan Xiaodong, Xu Zhitao, Li Mengmeng, et al. Multiple natural disasters and ecological security evaluation report on the construction of Changbai Mountain's whole-region tourism transportation system[R]. Jilin Provincial Seismological Bureau, 2022.

[9] Li Zhongwei, Xu Zhitao, Yan Donghan, et al. Project report on active fault exploration in the Siping section of the Yitong-Shulan fault in the northern extension of the Tanlu fault zone based on high-resolution remote sensing interpretation technology[R]. Jilin Provincial Seismological Bureau, 2020.

[10] Xu ZT, Ye, XQ, Pan, XD, et al. Geochemistry of apatites from preshield and postshield basalts and their petrogenetic implications: A case study of the Naitoushan basalt and Heishigou dike in the Changbaishan Tianchi volcano, NE China[J]. Mineralogy and Petrology, 2024. Doi: org/10.1007/s00710-024-00863-4.

[11] Xu, ZT, Sun, LY, Ye, XQ, et al. U–Pb geochronology and geochemistry of dikes in the Changbaishan Tianchi volcanic field (NE China) and their relations with the coeval Jingbohu and Longgang monogenetic volcanic fields. International Geology Review, 2023, 66 (3), 814-831.

[12] Ye, XQ, Sun, LY, Xu ZT, et al. Geochemistry and zircon U–Pb dating of Early Jurassic syenogranite in the Kaoshan area, southern part of the Zhangguangcai Range, NE China, and tectonic implications. Geological Journal, 2021, 57(1), 440-461.

[13] Xu, ZT, Sun, JG, Han, JL, et al. Geochronology, geochemistry, and Pb–Hf isotopes of mineralization-related magmatism in the Dongyang gold deposit, Fujian Province, Southeastern China[J]. Canadian Journal of Earth Sciences, 2020, 57(5), 553-574.

Author of this issue: Li Mengmeng, Engineer of Jilin Seismological Bureau, Institute of Volcanology, China Earthquake Administration

Xu Zhitao, Institute of Volcanology, China Earthquake Administration, Jilin Province Earthquake Bureau, PhD

Ye Xiqing, Engineer, Institute of Volcanology, China Earthquake Administration, Jilin Province Earthquake Administration

Sun Liying, Assistant Engineer, Jilin Earthquake Station, Jilin Province Earthquake Bureau

Francesco R. PhD, University of Naples Federico II, Vesuvius Observatory, Naples, Italy

Li Haiyan, PhD, Fujian Seismological Bureau

Sveva·R·M PhD, University of Florence, Vesuvius Observatory, Naples, Italy

Zhang Xin Guangdong Provincial Earthquake Administration PhD, University of Science and Technology of China

Song Yujia, Assistant Engineer, Institute of Volcanology, China Earthquake Administration, Jilin Province Earthquake Bureau

Xu Yueren, Researcher at the Institute of Forecasting, China Earthquake Administration

Doctor of Jilin Seismological Station and Jilin Provincial Seismological Bureau

Li Zhongwei, Senior Engineer, Jilin Earthquake Disaster Risk Prevention and Control Center, Jilin Province Earthquake Bureau

Yan Donghan, Engineer, Jilin Province Earthquake Disaster Risk Prevention and Control Center, Jilin Province Earthquake Administration

Ren Fangyu, Jilin Earthquake Station, Jilin Province Earthquake Bureau, Assistant Engineer

Ito Eri, Researcher, Japan Institute of Architectural Research

Zhang Xuan, Assistant Engineer, Jilin Earthquake Station, Jilin Province Earthquake Bureau

Yan Hengqi, Jilin Earthquake Station, Jilin Province Earthquake Bureau, Assistant Engineer

Daniel O Senior Researcher, Vesuvius Observatory, Naples, Italy

Mimmo P Senior Researcher at the Etna Observatory in Catania, Italy

Xu Zhikai, Postdoctoral Fellow, Institute of Oceanology, Chinese Academy of Sciences

Zhang Kun Postdoctoral fellow, School of Geographical Sciences, Northeast Normal University

Gu Guohui, Engineer, Institute of Volcanology, China Earthquake Administration, Jilin Province Earthquake Bureau

Yonggang Sun, Postdoctoral Fellow, School of Earth and Space Sciences, University of Science and Technology of China

Chu Xiaolei, PhD, School of Computer Science and Engineering, Southeast University

Arsène T.S. Assistant Researcher, Goma Volcano Observatory, Democratic Republic of Congo

Guan Sheng, Engineer, Institute of Volcanology, China Earthquake Administration, Jilin Province Earthquake Bureau

Matteo S. Italian Institute of Geophysics and Volcanology (Rome) PhD, University of Lyon 1 (Faculty of Natural Sciences), France

Priyeshu S. Indian Institute of Geomagnetic Research (Mumbai, India)

Disclaimer: All pictures and texts in this article are for public benefit and do not have any commercial value.