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Earthquake Summary
The following is a release by the United States Geological Survey, National Earthquake Information Center: An earthquake occurred NEAR THE WEST COAST OF HONSHU, JAPAN, about 70 km (45 miles) WSW of Niigata or 245 km (155 miles) NNW of TOKYO at 7:13 PM MDT, Jul 15, 2007 (Jul 16 at 10:13 AM local time in Japan). The magnitude and location may be revised when additional data and further analysis results are available.
Felt Reports
At least 150 people injured. Buildings collapsed, roads and bridges damaged at Kashiwazaki. 50-cm waves were reported on coastal areas close to epicenter. Felt (IV) at Niigata and (III) at Tokyo.
Tectonic Summary
This recent magnitude 6.6 earthquake occurred near the west coast of Honshu, Japan in the crust of the Okhotsk plate. This plate lies between the Pacific Ocean and the Eurasian landmass. This thrust event was caused by the release of compressional stress built within the crust of the Okhotsk plate as the Pacific plate subducts beneath it at a rate of 9 cm per year. The subduction initiates at the north-south trending Japan trench which lies 450 km to the east of the quake.
This shallow crustal earthquake was followed 13 hours later by a deep focus magnitude 6.8 quake roughly 330 km to the west, 350 km below the Sea of Japan. The two earthquakes were generated by different mechanisms. The first earthquake was caused by deformation within the crust of the Okhotsk plate and the second quake was likely caused by faulting resulting from internal deformation of the subducted Pacific plate. Given their different mechanisms and physical separation of at least 10 rupture lengths, the second earthquake is not considered an aftershock of the first.
Shallow earthquakes cause more damage than intermediate- and deep-focus ones since the energy generated by the shallow events is released closer to the surface and therefore produces stronger shaking than by quakes that are deeper within the Earth.
Other deadly earthquakes have occurred in this region: In 2004, a magnitude 6.6 earthquake occurred in the Niigata Prefecture, 50 km to the southeast of the recent quake, killing 40 people and injuring about 3,000. In June, 1964, a M7.5 earthquake occurred about 100 km to the west of the recent quake killing 37 people; and in April, 1995 a M5.4 earthquake 80 km to the northeast, injured at least 39 people.
During the 20th century Japan has suffered nine devastating earthquakes that killed more that 1000 people each. Among these are the 1923 M7.9 earthquake that triggered the great Tokyo fire that killed 143,000 people and the more recent 1995 M6.9 Kobe earthquake that killed about 5,500 people.
Earthquake Information for Asia
Earthquake Information for Japan
Carte des intensités du premier tremblement de terre. L'étoile indique l'épicentre.

Selon l'United States Geological Survey (USGS), deux importants séismes atteignant au moins 6,7 et 6,8 degrés sur l'échelle de Richter ont secoué la côte est de Honshu (Japon), tuant 8 personnes et en blessant plusieurs centaines.
Un incendie de deux heures s'est produit dans le transformateur du réacteur n°6 de la centrale nucléaire de Kashiwazaki-Kariwa, qui est la plus grande centrale nucléaire du monde, produisant une fuite d'eau radioactive dans la mer. La direction de la centrale prévoit que cette eau pourrait causer des dégâts dans l'environnement immédiat de la centrale.
L'épicentre du premier séisme a été localisé à 65 km au sud ouest de la ville de Niigata, une grande ville de la côte ouest de Honshu, à une profondeur de 55,4 km. Le second a été enregistré 12 heures plus tard environ, à 140 km au nord-ouest de l'île de Fukui, à une profondeur de 350,7 km.
, a indiqué le Premier ministre japonais, Shinzo Abe.
Le centre de prévention des tsunamis du Pacifique du National Oceanic and Atmospheric Administration (NOAA)  a indiqué qu'aucun raz-de-marée majeur n'est attendu, mais que de petites vagues pourraient frapper localement des zones proches de l'épicentre. Des petits (50 cm) tsunamis , a indiqué un comuniqué de l'USGS sur son site internet, qui ajoute aussi qu'à Kashiwazaki, . L'USGS a indiqué que les dégâts étaient de .