An earthquake of magnitude of 7.7 occurred off the Mariana Islands. The epicenter was located in the ocean and lies at a depth of 212 km.
Saipan, Northern Mariana Islands
366.3 km (227.6 mi) N
San Jose Village, Northern Mariana Islands
392.7 km (244.0 mi) N
Yigo Village, Guam
555.2 km (345.0 mi) N
Dededo Village, Guam
557.9 km (346.7 mi) N
Tamuning-Tumon-Harmon Village, Guam
Mariana Islands — group of Islands in the Western Pacific, in Micronesia. Includes 15 large Islands and several smaller Islands and cays. Total area of about 1018 km2 and a population of 213 of 241 people. On the Islands there are two political entities: GUAM (541 km2) and the Northern Mariana Islands (477 km2). Both areas have the status of unincorporated organized U.S. territories (Northern Mariana Islands have the status of Commonwealth).
Geologically, the Islands can be divided into two groups: the older southern island arc (GUAM, Rota, Tinian, Agian, Saipan) and young volcanic Northern arc (the remaining Islands of the archipelago). The South island was formed approximately 15-20 million years ago (late Eocene — early Miocene). They all have similar structure and covered with a layer of limestone remains of ancient coral reefs. The band has experienced several rises. The Northern group is part of the Mariana arc where the Pacific plate goes under the Philippine. All the Islands of this group are stratovolcanoes. Most of the Islands are surrounded by coral reefs. Reefs of the southern Islands are older and better developed. In the area of the Islands located about 50 underwater volcanoes and the 11 volcanoes form Islands.