National Sun Yat-Sen University
National Sun Yat-Sen University
07/16/2024 | Press release | Distributed by Public on 07/15/2024 10:18
Hit on Hualien's submarine dust plumes: NSYSU supports nearshore earthquake research
2024-07-16
On April 3rd, 2024, Hualien was struck by its largest earthquake since the 1999 Chi-Chi Earthquake. In response, the College of Marine Sciences at National Sun Yat-sen University (NSYSU) swiftly organized an interdisciplinary research team aboard the R/V New Ocean Researcher 3 to record changes in the marine environment around the epicenter area. This mission marks the first time a Taiwanese research team has observed earthquake-triggered nepheloid layers (submarine dust plumes), which are crucial for understanding the geological record of major earthquakes. The team successfully collected and analyzed samples, aiming to make breakthroughs in the research of highly destructive nearshore earthquakes.
According to the College of Marine Sciences at NSYSU, previous studies have shown that fault dislocation may cause underground fluid leakage, leading to abnormal chemical compositions in seawater, and may induce large-scale submarine landslides and nepheloid layers. As these features fade over time, prompt hydrogeological surveys are essential. Inspired by the rapid hydrological survey conducted within one month following the 2011 Tōhoku earthquake and tsunami (also known as the "Japan's 311 Earthquake") and the deep drilling of faults within one year, the academic community in Taiwan mobilized quickly to conduct a post-earthquake study.
During the national holidays that followed the earthquake, NSYSU overcame all challenges associated with this urgent mission and mobilized R/V New Ocean Researcher 3 and related units, including the cruise affairs office, crew members, the Marine Instrument Center, and the shipping agency. An interdisciplinary team of geophysicists and geochemists from NSYSU, National Central University, Academia Sinica, and National Taiwan University was quickly assembled. Led by Associate Professor Yu-Shih Lin of the Department of Oceanography at NSYSU, the team set out for the waters off Hualien to conduct underwater exploration.
Lin, the team leader, said that they arrived at the survey area after a day's transit under poor weather conditions. Upon arrival, they first used a multibeam echosounder to conduct seafloor topography mapping and a sub-bottom profiler to scan shallow sediment strata. After confirming that the working environment was safe, the team deployed hydrological instruments and a sparker system, a high-resolution reflection seismic technology, to scan for fault dislocations hidden under the seabed.
During the five-day voyage, the team experienced multiple aftershocks and strong winds and waves. They searched for fault planes, mapped seafloor topography, and investigated immediate changes in the ocean environment caused by the earthquake. They completed 322 kilometers of topographic and sediment survey lines, 184 kilometers of seismic survey lines, and hydrological profiles at three stations in the mainshock and aftershock areas. They detected substrate disturbances caused by submarine landslides on many continental slopes, discovered a thick nepheloid layer in the water column, and collected valuable seawater samples for subsequent analysis.
Lin emphasized that, unlike the study of faults on land, submarine faults and their resulting topographic changes cannot be observed visually or by satellites. High-precision equipment carried by research vessels is essential for collecting this information. Consequently, there is a lack of on-site investigations of nearshore earthquakes, and little is known about the faults displaced by the Hualien earthquake this time. Scientists typically rely on sediment observations and hypothesize that major earthquakes trigger landslides and submarine dust plumes, leading to unusual deposits on the seafloor. This mission marks the first time a Taiwanese scientific team has discovered a thick and widespread nepheloid layer after a major earthquake, providing direct scientific evidence to support previous studies. If the physical and chemical properties of submarine dust plumes differ from those of sediments deposited during non-earthquake periods, future studies can utilize such distinction to uncover the secrets of earthquake frequency and timing in the past.
Te-Yu Liao, Dean of the College of Marine Sciences at NSYSU, highlighted that besides affecting marine ecology, nepheloid layers play a crucial role in helping scientists decipher the record of major earthquakes in sediment strata. He described the mission as a significant milestone in marine research mobilization and interdisciplinary resource integration. Liao eagerly anticipates the outcomes from the observation data, emphasizing its importance as a reference for policy makers. He expressed hope that the mission will stimulate further research capacities, enabling Taiwan to lead cutting-edge studies on highly impactful nearshore earthquakes in the future.
On April 3rd, 2024, Hualien was struck by its largest earthquake since the 1999 Chi-Chi Earthquake. In response, the College of Marine Sciences at National Sun Yat-sen University (NSYSU) swiftly organized an interdisciplinary research team aboard the R/V New Ocean Researcher 3 to record changes in the marine environment around the epicenter area. This mission marks the first time a Taiwanese research team has observed earthquake-triggered nepheloid layers (submarine dust plumes), which are crucial for understanding the geological record of major earthquakes. The team successfully collected and analyzed samples, aiming to make breakthroughs in the research of highly destructive nearshore earthquakes.
According to the College of Marine Sciences at NSYSU, previous studies have shown that fault dislocation may cause underground fluid leakage, leading to abnormal chemical compositions in seawater, and may induce large-scale submarine landslides and nepheloid layers. As these features fade over time, prompt hydrogeological surveys are essential. Inspired by the rapid hydrological survey conducted within one month following the 2011 Tōhoku earthquake and tsunami (also known as the "Japan's 311 Earthquake") and the deep drilling of faults within one year, the academic community in Taiwan mobilized quickly to conduct a post-earthquake study.
During the national holidays that followed the earthquake, NSYSU overcame all challenges associated with this urgent mission and mobilized R/V New Ocean Researcher 3 and related units, including the cruise affairs office, crew members, the Marine Instrument Center, and the shipping agency. An interdisciplinary team of geophysicists and geochemists from NSYSU, National Central University, Academia Sinica, and National Taiwan University was quickly assembled. Led by Associate Professor Yu-Shih Lin of the Department of Oceanography at NSYSU, the team set out for the waters off Hualien to conduct underwater exploration.
Lin, the team leader, said that they arrived at the survey area after a day's transit under poor weather conditions. Upon arrival, they first used a multibeam echosounder to conduct seafloor topography mapping and a sub-bottom profiler to scan shallow sediment strata. After confirming that the working environment was safe, the team deployed hydrological instruments and a sparker system, a high-resolution reflection seismic technology, to scan for fault dislocations hidden under the seabed.
During the five-day voyage, the team experienced multiple aftershocks and strong winds and waves. They searched for fault planes, mapped seafloor topography, and investigated immediate changes in the ocean environment caused by the earthquake. They completed 322 kilometers of topographic and sediment survey lines, 184 kilometers of seismic survey lines, and hydrological profiles at three stations in the mainshock and aftershock areas. They detected substrate disturbances caused by submarine landslides on many continental slopes, discovered a thick nepheloid layer in the water column, and collected valuable seawater samples for subsequent analysis.
Lin emphasized that, unlike the study of faults on land, submarine faults and their resulting topographic changes cannot be observed visually or by satellites. High-precision equipment carried by research vessels is essential for collecting this information. Consequently, there is a lack of on-site investigations of nearshore earthquakes, and little is known about the faults displaced by the Hualien earthquake this time. Scientists typically rely on sediment observations and hypothesize that major earthquakes trigger landslides and submarine dust plumes, leading to unusual deposits on the seafloor. This mission marks the first time a Taiwanese scientific team has discovered a thick and widespread nepheloid layer after a major earthquake, providing direct scientific evidence to support previous studies. If the physical and chemical properties of submarine dust plumes differ from those of sediments deposited during non-earthquake periods, future studies can utilize such distinction to uncover the secrets of earthquake frequency and timing in the past.
Te-Yu Liao, Dean of the College of Marine Sciences at NSYSU, highlighted that besides affecting marine ecology, nepheloid layers play a crucial role in helping scientists decipher the record of major earthquakes in sediment strata. He described the mission as a significant milestone in marine research mobilization and interdisciplinary resource integration. Liao eagerly anticipates the outcomes from the observation data, emphasizing its importance as a reference for policy makers. He expressed hope that the mission will stimulate further research capacities, enabling Taiwan to lead cutting-edge studies on highly impactful nearshore earthquakes in the future.