Long‐term seismicity in a certain region can be estimated from the number of felt earthquakes obtained from seismic intensity measurements or historical documents. To obtain a homogeneous estimate, continuous records with a uniform detection threshold are required. Seismic intensity data in Tokyo, which are measured by professional observers and archived by the Japan Meteorological Agency (JMA) since 1885, indicate that the mean annual number of felt earthquakes with intensities ≥1 and ≥2 on the JMA scale is 45 and 14, respectively. The database of felt earthquakes can be extended back to more than 200 yr using historical daily records. During the Edo period from 1603 to 1867, numerous historical documents in Edo (former Tokyo) recorded information about damaging earthquakes, such as the 1703 Kanto earthquake and the 1855 Edo earthquake. Several feudal clans documented daily weather and felt earthquakes in Edo. Among them, daily records documented by the Tsugaru and Sakakibara clans cover a period of ∼200 yr⁠. Although these records do not cover the entire period and weather reports for several years are missing, the Tsugaru and Sakakibara clans documented ∼1600 and ∼700 earthquakes, respectively. Using these data, we determined that a total of ∼2000 felt earthquakes occurred between 1668 and 1867, thereby yielding a mean rate of ∼10 earthquakes per year. When we exclude the missing period of daily records, the average rate increased to 11 per year, which is similar to the annual number of earthquakes with seismic intensities ≥2 in the modern JMA record. These data of felt earthquakes in Tokyo are considered to be more homogeneous than the previous estimates, although the total number is smaller, and can be used to study the long‐term seismicity rate change.

中文翻译：

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从历史资料中进行长期地震的均质估计：自1668年以来东京的毡震数量

可以根据从地震烈度测量结果或历史文献中获得的毡状地震的数量来估计某个地区的长期地震活动。为了获得均匀的估计，需要具有统一检测阈值的连续记录。东京的地震烈度数据是由专业观察员测量的，并自1885年以来由日本气象厅（JMA）进行存档，结果表明，在JMA规模上，≥1和≥2的毡状地震的年均数量为45和14。分别。使用历史每日记录，可以将毡状地震数据库扩展到200多年。在1603年至1867年的江户时代，江户（前东京）的许多历史文献记录了有关破坏性地震的信息，例如1703年关东地震和1855年江户地震。几位封建氏族记载了江户每天的天气和地震。其中，津轻氏族和Sakakibara氏族记录的日常记录约200年。尽管这些记录不能涵盖整个时期，并且缺少几年的气象报告，但津轻和Sakakibara氏族分别记录了大约1600和700次地震。利用这些数据，我们确定在1668年至1867年之间总共发生了约2000次毛毡地震，因此平均每年发生约10次地震。当我们排除每日记录的缺失期时，平均发生率增加到每年11次，这与现代JMA记录中地震强度≥2的年地震数相似。这些东京毡状地震的数据被认为比以前的估计更为均匀，