Tokyo-based Teijin Limited has developed two new fabrics of its Twaron and Technora para-aramid fibers that can protect facilities, such as lodges and evacuation shelters, from airborne volcanic fragments measuring as big as 4 inches. Protecting evacuation facilities and other structures from large volcanic fragments is an important issue in Japan – one of the world’s more active volcanic regions.

In simulation tests, the fabrics proved they could withstand “fist‐sized airborne fragments similar to those produced during the September 2014 eruption of Mt. Ontake.”

Teijin says it is the only company in the world manufacturing two types of lightweight, strong and heat-resistant para-aramid fibers. Japan’s Ministry of the Environment is currently using the fibers to refurbish the roof of the Ebino Eco Museum Center in Kirishima-Kinkowan National Park on the island of Kyushu in southern Japan. says Japan’s most active volcano, Mt. Aso, is located in Kyushu.

According to Teijin, high-performance composite materials are the best option for this type of application. Para-aramid fibers, such as Kevlar and Twaron, provide outstanding strength-to-weight ratios, and are better suited for harsh environments.

“While materials such as reinforced concrete and steel offer required levels of strength and durability, transporting heavy materials and large equipment to highlands can lengthen the construction period and raise construction costs,” Teijin said. “The deteriorating effect of severe weather on steel is another problem.”

Specifically, Teijin notes Twaron offers six times more tensile strength than steel of the same weight, as well as superior heat resistance and elastic modulus. Technora has even greater tensile strength and resistance to impact, fatigue and chemicals. Both fibers can withstand temperatures  up to 400 C. Teijin adds that the choice of which para-aramid fiber to use depends on the estimated level of protection needed for each facility, based on a specific volcano’s activity level, altitude and local weather patterns.