|
June 14, 2006 |
| * | There was no remarkable activity. to supplementary reports |
| * | On May 12, there was a M5.0 earthquake at a depth of approximately 55km off-shore southeast of the Nemuro Peninsula. This event is related to the subduction of the Pacific plate. to supplementary reports | |
| There was no remarkable activity. to supplementary reports |
| * | On May 1, there was a M4.4 earthquake at a depth of approximately 60km near the border between Ibaraki and Saitama prefectures [under northern Saitama prefecture]*. | |
| * | On May 20, there was a M4.7 earthquake at a depth of approximately 75km under southern Chiba prefecture. The focal mechanism had a compression axis in a NW-SE direction. This event is related to the subduction of the Pacific plate. | |
| * | The seismic activity
off-shore east of the Izu Peninsula that started on April 17 declined
gradually, and now it has mostly returned to the previous level. On May
2, there was a M5.1 earthquake off-shore east of the Izu Peninsula
(off-shore north of the Izu Oshima Island), approximately 10km to the
east of the main active region. The focal mechanism showed a
strike-slip fault with a compression axis in a NNW-SSE direction. The
aftershock activity has been subsiding. The changes that appeared on the GPS, strainmeter and tiltmeter data, have mostly ended since the beginning of May. |
|
| * | The long-term changes that have been observed since 2001 in the continuous GPS data in the Tokai region, appear to have nearly stopped recently. to supplementary reports | |
| *On May 15, there was a M4.5 earthquake at a depth of approximately 5km in northern Wakayama prefecture. The focal mechanism had a compression axis in a WNW-ESE direction. to supplementary reports |
| There was no remarkable activity. to supplementary reports |
| * | On June 3, there was a M4.1 earthquake at a depth of approximately 5km in the Reinan region, Fukui prefecture. | ||
| * | On June 12, there was a M6.2 earthquake at a depth of approximately 150km under central Oita prefecture. Maximum seismic intensity 5 Lower was recorded in Oita, Ehime and Hiroshima prefectures. The focal mechanism had a tension axis in the direction of the subducting plate. This event occurred within the Philippine Sea plate. The aftershock activity is at a low level. According to the GPS data, there were no remarkable changes before and after this event. This event occurred in the deepest portion of the active region within the subducting Philippine Sea plate. Since August 1923, there have been only a M6.6 earthquake in 1983 and a M6.0 earthquake in 1978, for events equal to or larger than M6.0 observed at the same depth within a range of 50km from the recent event. | ||
| * | On June 13, there was a M4.7 (preliminary) earthquake at a depth of approximately 85km under central Tokachi subprefecture. | |
|
June 14, 2006
The following are the numbers of earthquakes by magnitude that occurred in Japan and the surrounding area during May 2006.
| M4.0 or greater: 56 (106 events occurred in April) | |
| M5.0 or greater: 4 (15 events occurred in April) | |
| M6.0 or greater: 0 (There has been a total of 5 events for 2006 by the end of May.) |
(reference) Average numbers of earthquake occurrences over the past thirty years (1971 - 2000)
| M4.0 or greater: 46 / month | |
| M5.0 or greater: 8 / month | |
| M6.0 or greater: 1.3 / month, approximately 16 / year |
The following regions have been noted as having significant seismic activity during the period from May 2005 to the end of April 2006.
| - Amakusa Ashikita region, Kumamoto prefecture | M4.8 on June 3, 2005 (depth approximately 10km) | |
| - Northwestern Chiba prefecture | M6.0 on July 23, 2005 (depth approximately 75km) | |
| - Off-shore of Miyagi prefecture | M7.2 on August 16, 2005 (depth approximately 40km) | |
| - Chuetsu region, Niigata prefecture | M5.0 on August 21, 2005 (depth approximately 15km) | |
| - Off-shore of Ibaraki prefecture | M6.3 on October 19, 2005 (depth approximately 50km) | |
| - Off-shore of Sanriku | M7.2 on November 15, 2005 | |
| - Hyuganada | M5.5 on March 27, 2006 (depth approximately 35km) | |
| - Off-shore east of the Izu Peninsula | seismic activity with M5.8 on April 21 and M4.5 on April 30, 2006 |
"The long-term changes that have been observed since 2001 in the
continuous GPS data in the Tokai region, appear to have nearly stopped
recently." :
According to the GPS data, the Pacific side of the Tokai-Chubu region
maintained a steady rate with movement to the WNW, consistent with the
subduction of the Philippine Sea plate toward the northwest. The
results, from observations in the area centered on western Shizuoka
prefecture, have been showing a trend of moderate change since about
April 2001. This long-term changes seem to have nearly stopped
recently. (This evaluation is in agreement with the views presented at
the procedural meeting on May 29 of the Assessment Committee for Areas
under Intensified Measures against Earthquake Disaster. (see reference
below))
(reference) "Recent seismic and crustal activity in the Tokai region
and its vicinity" (Japan Meteorological Agency, Department of
Seismology and Volcanology, May 29, 2006)
"So far, there have been no changes of activity which are likely to be associated with the so-called Tokai earthquake.
There was no remarkable seismic activity in general. The seismicity continues at a level lower than normal directly under the area from eastern Hamana lake through central Shizuoka prefecture. In other regions, seismic activity is generally at a normal level.
The long-term crustal movements from the slow slip at the plate boundary in the Tokai region and its neighboring area, seem to have nearly stopped recently."
"On May 15, there was a M4.5
earthquake at a depth of approximately
5km in northern Wakayama prefecture. The focal mechanism had a
compression axis in a WNW-ESE direction.":
There is almost steady seismic activity observed in this vicinity,
including the occurrence of a M4.1 earthquake on March 2, 2006. Lately
the seismicity increased temporarily with the recent earthquake and a
M3.9 earthquake at a depth of approximately 5km on May 20, to the west
of the event in March. This sequence of activity mostly subsided in
June.
- There is no supplementary information for the Kyushu - Okinawa region.
"On June 12, there was a M6.2
earthquake at a depth of approximately 150km under central Oita
prefecture. Maximum seismic intensity 5 Lower was observed in Oita,
Ehime and Hiroshima prefectures. (excerpted) Since August 1923, there
have been only a M6.6 earthquake in 1983 and a M6.0 earthquake in 1978,
for events equal to or larger than M6.0, observed at the same depth
within a range of 50km from the recent event.":
The Philippine Sea plate which is subducting from the east to
the west, transmits seismic waves well. This caused strong shaking in the areas
to the east of the epicenter.
| Reference 1 Earthquakes that are described in the "Evaluation of Seismic Activity"(Monthly Report of Seismic Activity in Japan) are events of M6.0 and greater, or events of M4.0 and greater (M5.0 or greater off-shore) that have maximum intensity of 3 or greater. Reference 2 Information that is described in the "Supplementary Information to the Evaluation" includes:
|