nature

昨日の地震に関するCNNの記事からの引用です。natureというと「自然」という意味が想起されますが，その他に「種類, 種別」という意味があります（『プログレッシブ英和中辞典』小学館）。ここではnature of their injuriesで「怪我の詳細」と解釈できるのではないでしょうか。
静岡の実家に帰省していましたが，静岡でもかなりの揺れを感じました。（Koyamamoto）

Strong earthquake shakes Japan's Nagano area
Tokyo (CNN) -- A strong earthquake shook central Japan on Saturday night, injuring several people as their homes collapsed in a village west of Nagano, an official said.
Reports of the intensity of the quake, centered in the Nagano area at 10:08 p.m., differed. The Japan Meteorological Agency reported it was a 6.8 magnitude temblor; the U.S. Geological Survey (USGS) said it was magnitude 6.2.
Near the epicenter, the quake caused at least five homes to collapse in the village of Hakuba, about 30 kilometers (less than 20 miles) west of Nagano, according to a local official who spoke on condition of anonymity, as is customary in Japan.
At least five people were rescued from the homes and taken to a hospital with injuries, the official said. The nature of their injuries wasn't immediately known.
http://edition.cnn.com/2014/11/22/world/asia/japan-earthquake/index.html?hpt=hp_t3