1909 Anegawa earthquake

What Happened

On 14 August 1909, an earthquake struck Shiga Prefecture in central Japan. Its epicentre lay at coordinates 35.4° north, 136.3° east, in Gifu Prefecture, at an estimated focal depth of 15 km (9.3 mi). The moment magnitude is given as Mw 6.9.

The shaking killed at least 41 people and destroyed more than 1,000 homes. A tsunami 1.8 m (5.9 ft) high was recorded in Lake Biwa, the large inland lake that dominates Shiga Prefecture. Damage extended across Shiga and Gifu prefectures.

The event takes its common English name from the Anegawa, a river in the region, and is known in Japanese as the Anegawa jishin (姉川地震).

Background

The earthquake occurred during the Meiji period (明治時代, Meiji jidai), the era spanning 1868 to 1912, when Japan was ruled by the Meiji Emperor. In the Japanese era system, the year 1909 corresponds to Meiji 42 — the forty-second year of the era, counted from the emperor's accession in 1868.

The Meiji period was a time of rapid modernisation. Japan had begun importing and adapting Western science and engineering, and the study of earthquakes was among the fields transformed. Seismology had taken root in Japan in the late nineteenth century, driven partly by the frequency of damaging earthquakes and partly by the presence of foreign teachers hired by the new government. By 1909, Japanese scientists were routinely measuring and recording seismic events, which is why the Anegawa earthquake has a documented magnitude, epicentre, and focal depth rather than only a list of damage.

Shiga Prefecture occupies the area around Lake Biwa, Japan's largest freshwater lake, in the Kansai region. Gifu Prefecture lies immediately to the north and east. The two prefectures share a boundary, and the earthquake's effects crossed it: the epicentre was in Gifu, while Shiga, including the lake, experienced strong shaking and the tsunami.

Why It Mattered

The 1909 Anegawa earthquake is remembered chiefly for two things: the destruction of more than a thousand homes and the loss of at least 41 lives, and the tsunami it produced in Lake Biwa.

A tsunami in a lake is unusual enough to be worth noting. The 1.8 m (5.9 ft) wave recorded in Lake Biwa shows that seismic shaking can generate dangerous water movements in enclosed bodies of water, not only along ocean coasts. For communities on the lake shore, the hazard came from two directions at once — the ground shaking and the water it set in motion.

The earthquake also belongs to a broader pattern in Japanese history. Japan sits on several converging tectonic plates, and damaging earthquakes recur across the islands. Events like the Anegawa earthquake were part of the accumulating record that Japanese seismologists used to understand where and how often the ground would move. That record, built event by event through the Meiji period and after, shaped how Japan later approached earthquake-resistant construction, disaster response, and public warning.

The Name in Japanese

The Japanese name of the earthquake is 姉川地震.

• Kana reading: あねがわじしん
• Romaji: Anegawa jishin

Broken down character by character:

姉 — read here as ane. The character means "elder sister." It is the first element of the river's name.

川 — read here as gawa (a voiced form of kawa). The character means "river." Together, 姉川 (Anegawa) is the name of a river in the region, written with the characters for "elder sister" and "river."

地 — read here as ji. The character means "ground" or "earth."

震 — read here as shin. The character means "quake" or "shake."

Together, 地震 (jishin) is the ordinary Japanese word for "earthquake," built from the characters for "earth" and "quake." The full name 姉川地震 therefore means, literally, "Anegawa earthquake" — the earthquake named for the Anegawa.

Two points are worth noting for learners. First, the reading of 川 shifts from kawa to gawa when it follows another element in a compound name; this voicing change, called rendaku (連濁, rendaku), is common in Japanese place names and compounds. Second, 地震 is one of the most useful compounds a student of Japanese can learn, because it appears constantly in news, warnings, and everyday conversation about Japan's seismic activity.

Key Figures

• Date: 14 August 1909
• Magnitude: Mw 6.9
• Epicentre: 35.4° N, 136.3° E, in Gifu Prefecture
• Focal depth: 15 km (9.3 mi)
• Deaths: at least 41
• Homes destroyed: more than 1,000
• Tsunami: 1.8 m (5.9 ft) recorded in Lake Biwa
• Prefectures affected: Shiga and Gifu
• Japanese period: Meiji (1868–1912), year 42 of the Meiji era
• Japanese name: 姉川地震 (あねがわじしん, Anegawa jishin)