Ha Long Bay islet at risk of collapse

By Phuc Trinh   August 10, 2023 | 03:15 am PT
Visible cracks at Trong Mai Islet in Ha Long Bay have prompted experts to warn of possible collapse without protective actions.

Ho Tien Chung, Head of the Department of Tectonics and Geomorphology at the Institute of Geosciences and Mineral Resources, notes the islet's vulnerability during low tide, as its supporting base erodes, increasing collapse risks.

Tàu du lịch đưa du khách vào gần khu vực hòn Trống Mái để chụp ảnh. Khoảng cách các tàu khá sát nhau, khó quay đầu nên phải đi tiếp về hướng hòn Trống Mái. Ảnh: Tú Nguyễn

Signs of erosion at the bottom part of Trong Mai Islet, with poli's stellate barnacle sticking to the bottom surface. Photo courtesy of the Institute of Geosciences and Mineral Resources

Trong Mai Islet, resembling a pair of a rooster (trong) and a hen (mai), is a famous location in Ha Long Bay, a famous UNESCO heritage site. It is about 5 kilometers from Tuan Chau International Port.

Chung's team also found many cracks, which are causing the rocks on the islet to break and shatter, increasing the risk of collapse. Once cracks form, they provide entry points for water and wind, triggering erosion and corrosion.

A report from July by the Institute of Geosciences and Mineral Resources examined the safety of Trong Mai Islet, pointing out that 40 blocks within the area might fall, with 11 blocks on Trong Islet and 29 blocks on Mai Islet.

Human activities have contributed to faster erosion and potential landslides on Trong Mai Islet. Fishing continues in the area, exploiting marine resources due to insufficient supervision and protection, it said.

A block at risk of collapse in the northern section of Trong Islet. Photo courtesy of the Institute of Geosciences and Mineral Resources

The fractures and cracks (indicated by the red lines) on Trong Mai Islet. Photo courtesy of the Institute of Geosciences and Mineral Resources

The islet also faces negative effects from ships, tourist boats, and canoes, even though tourists aren't allowed to land on the islet, according to the report.

During research, a photo captured a cruise ship stopping just 19.79 meters from the islet for tourists to take pictures. This caused a buildup of other ships behind it, potentially leading to risks of hitting the islet.

The report said big canoes with 4-8 people at 30 km/h can create water columns of 40-60 centimeters while larger speedboats at the same speed from 100 meters away make waves over 80 centimeters, affecting Trong Mai Islet. These impacts, lasting a minute or two, lead to long-term erosion on the islet's surface, it said.

Experts propose protecting Trong Mai Islet by anchoring rocks, injecting cement into cracks, using concrete walls, and mixing concrete with plastic fibers to reduce erosion.

For tourism, suggestions include changing routes, controlling boat stops, and limiting speeds within 200-300 meters of the island to 5-10 km/h. Raising fishermen's awareness is also advised.

The loss of Swan Islet and Islet 649 in Ha Long Bay underscores the need to safeguard Trong Mai Islet, they said.

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