Tag Archive: Philippine Sea


Earth Watch Report –  Earthquakes

 
Taiwan  -  6.3mag EQ  October  31st  2013 photo Taiwan-63MagEQOctober31st2013_zpsc254a131.jpg
  3 earthquakes in map area

  1. M 4.7 – 42km SSW of Hualian, Taiwan

    2013-10-31 10:47:28 UTC-05:00 4.4 km

  2. M 6.3 – 45km SSW of Hualian, Taiwan

    2013-10-31 07:02:09 UTC-05:00 12.0 km

  3. M 4.5 – 18km SSE of Hualian, Taiwan

    2013-10-27 03:27:13 UTC-05:00 47.1 km

……….

M 6.3 – 45km SSW of Hualian, Taiwan

2013-10-31 12:02:09 UTC

Earthquake location 23.591°N, 121.443°E

Event Time

  1. 2013-10-31 12:02:09 UTC
  2. 2013-10-31 20:02:09 UTC+08:00 at epicenter
  3. 2013-10-31 07:02:09 UTC-05:00 system time

Location

23.591°N 121.443°E depth=12.0km (7.5mi)

Nearby Cities

  1. 45km (28mi) SSW of Hualian, Taiwan
  2. 63km (39mi) SE of Buli, Taiwan
  3. 72km (45mi) ESE of Lugu, Taiwan
  4. 87km (54mi) ESE of Nantou, Taiwan
  5. 761km (473mi) ENE of Hong Kong, Hong Kong

…..

Instrumental Intensity

ShakeMap Intensity Image

…..
Taiwan  -  6.3 Mag EQ  October 31st  2013 photo Taiwan-63MagEQOctober31st2013_zps1ab19726.jpg
…..

Tectonic Summary

The October 31, 2013 M 6.3 earthquake southwest of Hualian, Taiwan occurred as the result of shallow oblique-thrust faulting near the central-east coast of the island of Taiwan and the boundary between the Philippine Sea and Eurasia plates. East of the October 31 earthquake, plate boundary tectonics are dominated by the westward subduction of the Philippine Sea Plate beneath Eurasia along the Ryukyu Trench, which runs from southwest Japan to Taiwan. Some authors infer that this subduction continues beneath the east coast of Taiwan. South of the island towards the Philippines, the plate boundary reflects arc-continent collision more than traditional subduction. The October 31 earthquake occurred at the transition between these tectonic regimes, and is a consequence of the convergence between these major plates. At the location of this earthquake, the Philippine Sea plate moves to the northwest with respect to Eurasia at a velocity of approximately 77 mm/yr.

This region of Taiwan is familiar with moderate to large earthquake activity, and has hosted over 60 events of M6 or greater within 250 km of the October 31 event in the past 40 years. Seven of these were M7 or greater, including a M7.4 earthquake 40 km to the north of the October 31 event in November 1986, which caused 13 fatalities.

Seismotectonics of the Philippine Sea and Vicinity

The Philippine Sea plate is bordered by the larger Pacific and Eurasia plates and the smaller Sunda plate. The Philippine Sea plate is unusual in that its borders are nearly all zones of plate convergence. The Pacific plate is subducted into the mantle, south of Japan, beneath the Izu-Bonin and Mariana island arcs, which extend more than 3,000 km along the eastern margin of the Philippine Sea plate. This subduction zone is characterized by rapid plate convergence and high-level seismicity extending to depths of over 600 km. In spite of this extensive zone of plate convergence, the plate interface has been associated with few great (M>8.0) ‘megathrust’ earthquakes. This low seismic energy release is thought to result from weak coupling along the plate interface (Scholz and Campos, 1995). These convergent plate margins are also associated with unusual zones of back-arc extension (along with resulting seismic activity) that decouple the volcanic island arcs from the remainder of the Philippine Sea Plate (Karig et al., 1978; Klaus et al., 1992).

South of the Mariana arc, the Pacific plate is subducted beneath the Yap Islands along the Yap trench. The long zone of Pacific plate subduction at the eastern margin of the Philippine Sea Plate is responsible for the generation of the deep Izu-Bonin, Mariana, and Yap trenches as well as parallel chains of islands and volcanoes, typical of circum-pacific island arcs. Similarly, the northwestern margin of the Philippine Sea plate is subducting beneath the Eurasia plate along a convergent zone, extending from southern Honshu to the northeastern coast of Taiwan, manifested by the Ryukyu Islands and the Nansei-Shoto (Ryukyu) trench. The Ryukyu Subduction Zone is associated with a similar zone of back-arc extension, the Okinawa Trough. At Taiwan, the plate boundary is characterized by a zone of arc-continent collision, whereby the northern end of the Luzon island arc is colliding with the buoyant crust of the Eurasia continental margin offshore China.

Along its western margin, the Philippine Sea plate is associated with a zone of oblique convergence with the Sunda Plate. This highly active convergent plate boundary extends along both sides the Philippine Islands, from Luzon in the north to the Celebes Islands in the south. The tectonic setting of the Philippines is unusual in several respects: it is characterized by opposite-facing subduction systems on its east and west sides; the archipelago is cut by a major transform fault, the Philippine Fault; and the arc complex itself is marked by active volcanism, faulting, and high seismic activity. Subduction of the Philippine Sea Plate occurs at the eastern margin of the archipelago along the Philippine Trench and its northern extension, the East Luzon Trough. The East Luzon Trough is thought to be an unusual example of a subduction zone in the process of formation, as the Philippine Trench system gradually extends northward (Hamburger et al., 1983). On the west side of Luzon, the Sunda Plate subducts eastward along a series of trenches, including the Manila Trench in the north, the smaller less well-developed Negros Trench in the central Philippines, and the Sulu and Cotabato trenches in the south (Cardwell et al., 1980). At its northern and southern terminations, subduction at the Manila Trench is interrupted by arc-continent collision, between the northern Philippine arc and the Eurasian continental margin at Taiwan and between the Sulu-Borneo Block and Luzon at the island of Mindoro. The Philippine fault, which extends over 1,200 km within the Philippine arc, is seismically active. The fault has been associated with major historical earthquakes, including the destructive M7.6 Luzon earthquake of 1990 (Yoshida and Abe, 1992). A number of other active intra-arc fault systems are associated with high seismic activity, including the Cotabato Fault and the Verde Passage-Sibuyan Sea Fault (Galgana et al., 2007).

Relative plate motion vectors near the Philippines (about 80 mm/yr) is oblique to the plate boundary along the two plate margins of central Luzon, where it is partitioned into orthogonal plate convergence along the trenches and nearly pure translational motion along the Philippine Fault (Barrier et al., 1991). Profiles B and C reveal evidence of opposing inclined seismic zones at intermediate depths (roughly 70-300 km) and complex tectonics at the surface along the Philippine Fault.

Several relevant tectonic elements, plate boundaries and active volcanoes, provide a context for the seismicity presented on the main map. The plate boundaries are most accurate along the axis of the trenches and more diffuse or speculative in the South China Sea and Lesser Sunda Islands. The active volcanic arcs (Siebert and Simkin, 2002) follow the Izu, Volcano, Mariana, and Ryukyu island chains and the main Philippine islands parallel to the Manila, Negros, Cotabato, and Philippine trenches.

Seismic activity along the boundaries of the Philippine Sea Plate (Allen et al., 2009) has produced 7 great (M>8.0) earthquakes and 250 large (M>7) events. Among the most destructive events were the 1923 Kanto, the 1948 Fukui and the 1995 Kobe (Japan) earthquakes (99,000, 5,100, and 6,400 casualties, respectively), the 1935 and the 1999 Chi-Chi (Taiwan) earthquakes (3,300 and 2,500 casualties, respectively), and the 1976 M7.6 Moro Gulf and 1990 M7.6 Luzon (Philippines) earthquakes (7,100 and 2,400 casualties, respectively). There have also been a number of tsunami-generating events in the region, including the Moro Gulf earthquake, whose tsunami resulted in more than 5000 deaths.

More information on regional seismicity and tectonics

…..

6.6 quake hits Taiwan; no tsunami warning to US coast

6.6 quake hits Taiwan; no tsunami warning to US coast
 

by Associated Press

Posted on October 31, 2013 at 6:06 AM

 

TAIPEI, Taiwan (AP) — A strong earthquake hit eastern Taiwan on Thursday, shaking buildings over a wide area including the capital. There were no immediate reports of serious damage or casualties.

The U.S. Geological Survey said the earthquake measured magnitude 6.6 and struck in the evening. It was centered in a remote mountainous area 45 kilometers (28 miles) south-southwest of the coastal city of Hualian at a depth of just 9.3 kilometers (5.8 miles), it said.

In Taipei, the capital, buildings swayed for more than 10 seconds and startled residents ducked for cover.

Read More Here

…..

Enhanced by Zemanta

Earth Watch Report   –  Earthquakes

 photo Japan-60magMay18th2013_zpsa7cb048f.jpg

 

….

M6.0 – 52km NE of Namie, Japan

2013-05-18 05:47:59 UTC

Earthquake location 37.745°N, 141.494°E

Event Time

  1. 2013-05-18 05:47:59 UTC
  2. 2013-05-18 14:47:59 UTC+09:00 at epicenter
  3. 2013-05-18 00:47:59 UTC-05:00 system time

Location

37.745°N 141.494°E depth=34.3km (21.3mi)

Nearby Cities

  1. 52km (32mi) NE of Namie, Japan
  2. 65km (40mi) ESE of Watari, Japan
  3. 66km (41mi) ESE of Marumori, Japan
  4. 67km (42mi) ESE of Kakuda, Japan
  5. 279km (173mi) NE of Tokyo, Japan

….

Tectonic Summary

Seismotectonics of Japan and Vicinity

Japan and the surrounding islands straddle four major tectonic plates: Pacific plate; North America plate; Eurasia plate; and Philippine Sea plate. The Pacific plate is subducted into the mantle, beneath Hokkaido and northern Honshu, along the eastern margin of the Okhotsk microplate, a proposed subdivision of the North America plate. Farther south, the Pacific plate is subducted beneath volcanic islands along the eastern margin of the Philippine Sea plate. This 2,200 km-long zone of subduction of the Pacific plate is responsible for the creation of the deep offshore Ogasawara and Japan trenches as well as parallel chains of islands and volcanoes, typical of Circumpacific island arcs. Similarly, the Philippine Sea plate is itself subducting under the Eurasia plate along a zone, extending from Taiwan to southern Honshu that comprises the Ryukyu Islands and the Nansei-Shoto trench.

Subduction zones at the Japanese island arcs are geologically complex and produce numerous earthquakes from multiple sources. Deformation of the overriding plates generates shallow crustal earthquakes, whereas slip at the interface of the plates generates interplate earthquakes that extend from near the base of the trench to depths of 40 to 60 km. At greater depths, Japanese arc earthquakes occur within the subducting Pacific and Philippine Sea plates and can reach depths of nearly 700 km. Since 1900, three great earthquakes occurred off Japan and three north of Hokkaido. They are the M8.4 1933 Sanriku-oki earthquake, the M8.3 2003 Tokachi-oki earthquake, the M9.0 2011 Tohoku earthquake, the M8.4 1958 Etorofu earthquake, the M8.5 1963 Kuril earthquake, and the M8.3 1994 Shikotan earthquake.

More information on regional seismicity and tectonics

….

Instrumental Intensity

ShakeMap Intensity Image

….

Earth Watch Report  –  Earthquakes

 photo NorthernMarianaIslands-70magEQMay13th2013_zps7d7222f1.jpg

….

M7.0 – 42km W of Agrihan, Northern Mariana Islands 2013-05-14 00:32:25 UTC

Earthquake location 18.753°N, 145.261°E

Event Time

  1. 2013-05-14 00:32:25 UTC
  2. 2013-05-14 10:32:25 UTC+10:00 at epicenter
  3. 2013-05-13 19:32:25 UTC-05:00 system time

Location

18.753°N 145.261°E depth=603.4km (374.9mi)

Nearby Cities

  1. 42km (26mi) W of Agrihan, Northern Mariana Islands
  2. 395km (245mi) N of Northern Islands Municipality – Mayor’s Office, Northern Mariana Islands
  3. 395km (245mi) N of Saipan, Northern Mariana Islands
  4. 420km (261mi) N of JP Tinian Town pre-WW2, Northern Mariana Islands
  5. 578km (359mi) N of Yigo Village, Guam

….

Tectonic Summary

Seismotectonics of the Philippine Sea and Vicinity

The Philippine Sea plate is bordered by the larger Pacific and Eurasia plates and the smaller Sunda plate. The Philippine Sea plate is unusual in that its borders are nearly all zones of plate convergence. The Pacific plate is subducted into the mantle, south of Japan, beneath the Izu-Bonin and Mariana island arcs, which extend more than 3,000 km along the eastern margin of the Philippine Sea plate. This subduction zone is characterized by rapid plate convergence and high-level seismicity extending to depths of over 600 km. In spite of this extensive zone of plate convergence, the plate interface has been associated with few great (M>8.0) ‘megathrust’ earthquakes. This low seismic energy release is thought to result from weak coupling along the plate interface (Scholz and Campos, 1995). These convergent plate margins are also associated with unusual zones of back-arc extension (along with resulting seismic activity) that decouple the volcanic island arcs from the remainder of the Philippine Sea Plate (Karig et al., 1978; Klaus et al., 1992).

South of the Mariana arc, the Pacific plate is subducted beneath the Yap Islands along the Yap trench. The long zone of Pacific plate subduction at the eastern margin of the Philippine Sea Plate is responsible for the generation of the deep Izu-Bonin, Mariana, and Yap trenches as well as parallel chains of islands and volcanoes, typical of circum-pacific island arcs. Similarly, the northwestern margin of the Philippine Sea plate is subducting beneath the Eurasia plate along a convergent zone, extending from southern Honshu to the northeastern coast of Taiwan, manifested by the Ryukyu Islands and the Nansei-Shoto (Ryukyu) trench. The Ryukyu Subduction Zone is associated with a similar zone of back-arc extension, the Okinawa Trough. At Taiwan, the plate boundary is characterized by a zone of arc-continent collision, whereby the northern end of the Luzon island arc is colliding with the buoyant crust of the Eurasia continental margin offshore China.

Along its western margin, the Philippine Sea plate is associated with a zone of oblique convergence with the Sunda Plate. This highly active convergent plate boundary extends along both sides the Philippine Islands, from Luzon in the north to the Celebes Islands in the south. The tectonic setting of the Philippines is unusual in several respects: it is characterized by opposite-facing subduction systems on its east and west sides; the archipelago is cut by a major transform fault, the Philippine Fault; and the arc complex itself is marked by active volcanism, faulting, and high seismic activity. Subduction of the Philippine Sea Plate occurs at the eastern margin of the archipelago along the Philippine Trench and its northern extension, the East Luzon Trough. The East Luzon Trough is thought to be an unusual example of a subduction zone in the process of formation, as the Philippine Trench system gradually extends northward (Hamburger et al., 1983). On the west side of Luzon, the Sunda Plate subducts eastward along a series of trenches, including the Manila Trench in the north, the smaller less well-developed Negros Trench in the central Philippines, and the Sulu and Cotabato trenches in the south (Cardwell et al., 1980). At its northern and southern terminations, subduction at the Manila Trench is interrupted by arc-continent collision, between the northern Philippine arc and the Eurasian continental margin at Taiwan and between the Sulu-Borneo Block and Luzon at the island of Mindoro. The Philippine fault, which extends over 1,200 km within the Philippine arc, is seismically active. The fault has been associated with major historical earthquakes, including the destructive M7.6 Luzon earthquake of 1990 (Yoshida and Abe, 1992). A number of other active intra-arc fault systems are associated with high seismic activity, including the Cotabato Fault and the Verde Passage-Sibuyan Sea Fault (Galgana et al., 2007).

Relative plate motion vectors near the Philippines (about 80 mm/yr) is oblique to the plate boundary along the two plate margins of central Luzon, where it is partitioned into orthogonal plate convergence along the trenches and nearly pure translational motion along the Philippine Fault (Barrier et al., 1991). Profiles B and C reveal evidence of opposing inclined seismic zones at intermediate depths (roughly 70-300 km) and complex tectonics at the surface along the Philippine Fault.

Several relevant tectonic elements, plate boundaries and active volcanoes, provide a context for the seismicity presented on the main map. The plate boundaries are most accurate along the axis of the trenches and more diffuse or speculative in the South China Sea and Lesser Sunda Islands. The active volcanic arcs (Siebert and Simkin, 2002) follow the Izu, Volcano, Mariana, and Ryukyu island chains and the main Philippine islands parallel to the Manila, Negros, Cotabato, and Philippine trenches.

Seismic activity along the boundaries of the Philippine Sea Plate (Allen et al., 2009) has produced 7 great (M>8.0) earthquakes and 250 large (M>7) events. Among the most destructive events were the 1923 Kanto, the 1948 Fukui and the 1995 Kobe (Japan) earthquakes (99,000, 5,100, and 6,400 casualties, respectively), the 1935 and the 1999 Chi-Chi (Taiwan) earthquakes (3,300 and 2,500 casualties, respectively), and the 1976 M7.6 Moro Gulf and 1990 M7.6 Luzon (Philippines) earthquakes (7,100 and 2,400 casualties, respectively). There have also been a number of tsunami-generating events in the region, including the Moro Gulf earthquake, whose tsunami resulted in more than 5000 deaths.

More information on regional seismicity and tectonics

….

Instrumental Intensity

ShakeMap Intensity Image

….

 

by David Corrigan

Pacific Tsunami Warning Center reports an earthquake with a magnitude of 7.0 occurred in the area of the Mariana Islands around 2:49 p.m. Hawaii Time. Based on all available data a destructive Pacific-wide tsunami has not been generated. There is no tsunami threat to Hawaii.

– See more at: http://www.hawaiiscoops.com/2013/05/13/no-tsunami-after-7-0-earthquake-in-mariana-islands/#sthash.Pw4Dvl30.dpuf

by David Corrigan

Pacific Tsunami Warning Center reports an earthquake with a magnitude of 7.0 occurred in the area of the Mariana Islands around 2:49 p.m. Hawaii Time. Based on all available data a destructive Pacific-wide tsunami has not been generated. There is no tsunami threat to Hawaii.

– See more at: http://www.hawaiiscoops.com/2013/05/13/no-tsunami-after-7-0-earthquake-in-mariana-islands/#sthash.Pw4Dvl30.dpuf

….

Earth Watch Report  –  Earthquakes

 photo MarianaIslands-51MagEQMay12th2013_zpsab88c863.jpg

….

M5.1 – 189km NW of Farallon de Pajaros, Northern Mariana Islands 2013-05-12 23:05:28 UTC

 

Earthquake location 21.914°N, 143.807°E

Event Time

  1. 2013-05-12 23:05:28 UTC
  2. 2013-05-13 09:05:28 UTC+10:00 at epicenter
  3. 2013-05-12 18:05:28 UTC-05:00 system time

Location

21.914°N 143.807°E depth=175.6km (109.1mi)

Nearby Cities

  1. 189km (117mi) NW of Farallon de Pajaros, Northern Mariana Islands
  2. 769km (478mi) NNW of Northern Islands Municipality – Mayor’s Office, Northern Mariana Islands
  3. 769km (478mi) NNW of Saipan, Northern Mariana Islands
  4. 792km (492mi) NNW of JP Tinian Town pre-WW2, Northern Mariana Islands
  5. 934km (580mi) N of Yigo Village, Guam

 

Tectonic Summary

Seismotectonics of the Philippine Sea and Vicinity

 

The Philippine Sea plate is bordered by the larger Pacific and Eurasia plates and the smaller Sunda plate. The Philippine Sea plate is unusual in that its borders are nearly all zones of plate convergence. The Pacific plate is subducted into the mantle, south of Japan, beneath the Izu-Bonin and Mariana island arcs, which extend more than 3,000 km along the eastern margin of the Philippine Sea plate. This subduction zone is characterized by rapid plate convergence and high-level seismicity extending to depths of over 600 km. In spite of this extensive zone of plate convergence, the plate interface has been associated with few great (M>8.0) ‘megathrust’ earthquakes. This low seismic energy release is thought to result from weak coupling along the plate interface (Scholz and Campos, 1995). These convergent plate margins are also associated with unusual zones of back-arc extension (along with resulting seismic activity) that decouple the volcanic island arcs from the remainder of the Philippine Sea Plate (Karig et al., 1978; Klaus et al., 1992).

 

South of the Mariana arc, the Pacific plate is subducted beneath the Yap Islands along the Yap trench. The long zone of Pacific plate subduction at the eastern margin of the Philippine Sea Plate is responsible for the generation of the deep Izu-Bonin, Mariana, and Yap trenches as well as parallel chains of islands and volcanoes, typical of circum-pacific island arcs. Similarly, the northwestern margin of the Philippine Sea plate is subducting beneath the Eurasia plate along a convergent zone, extending from southern Honshu to the northeastern coast of Taiwan, manifested by the Ryukyu Islands and the Nansei-Shoto (Ryukyu) trench. The Ryukyu Subduction Zone is associated with a similar zone of back-arc extension, the Okinawa Trough. At Taiwan, the plate boundary is characterized by a zone of arc-continent collision, whereby the northern end of the Luzon island arc is colliding with the buoyant crust of the Eurasia continental margin offshore China.

 

Along its western margin, the Philippine Sea plate is associated with a zone of oblique convergence with the Sunda Plate. This highly active convergent plate boundary extends along both sides the Philippine Islands, from Luzon in the north to the Celebes Islands in the south. The tectonic setting of the Philippines is unusual in several respects: it is characterized by opposite-facing subduction systems on its east and west sides; the archipelago is cut by a major transform fault, the Philippine Fault; and the arc complex itself is marked by active volcanism, faulting, and high seismic activity. Subduction of the Philippine Sea Plate occurs at the eastern margin of the archipelago along the Philippine Trench and its northern extension, the East Luzon Trough. The East Luzon Trough is thought to be an unusual example of a subduction zone in the process of formation, as the Philippine Trench system gradually extends northward (Hamburger et al., 1983). On the west side of Luzon, the Sunda Plate subducts eastward along a series of trenches, including the Manila Trench in the north, the smaller less well-developed Negros Trench in the central Philippines, and the Sulu and Cotabato trenches in the south (Cardwell et al., 1980). At its northern and southern terminations, subduction at the Manila Trench is interrupted by arc-continent collision, between the northern Philippine arc and the Eurasian continental margin at Taiwan and between the Sulu-Borneo Block and Luzon at the island of Mindoro. The Philippine fault, which extends over 1,200 km within the Philippine arc, is seismically active. The fault has been associated with major historical earthquakes, including the destructive M7.6 Luzon earthquake of 1990 (Yoshida and Abe, 1992). A number of other active intra-arc fault systems are associated with high seismic activity, including the Cotabato Fault and the Verde Passage-Sibuyan Sea Fault (Galgana et al., 2007).

 

 

….

 

 

 

 

Earth Watch Report  –  Earthquakes

5.8 magnitude earthquake - 29km E of Itbayat, Philippines photo 58Magnitudeearthquake-29kmEofItbayatPhilippinesApril10th2013_zps0beb3d53.jpg

5.8 29km E of Itbayat, Philippines 2013-04-10 20:20:26 20.819°N 122.120°E 4.2

4.3 23km ENE of Itbayat, Philippines 2013-04-10 22:53:53 20.847°N 122.058°E 14.3

4.5 31km ENE of Itbayat, Philippines 2013-04-11 05:57:21 20.920°N 122.106°E 12.9

….

M5.8 – 29km E of Itbayat, Philippines 2013-04-10 20:20:26 UTC

Earthquake location 20.819°N, 122.120°E

Event Time

  1. 2013-04-10 20:20:26 UTC
  2. 2013-04-11 04:20:26 UTC+08:00 at epicenter
  3. 2013-04-10 15:20:26 UTC-05:00 system time

Location

20.819°N 122.120°E depth=4.2km (2.6mi)

Nearby Cities

  1. 29km (18mi) E of Itbayat, Philippines
  2. 193km (120mi) SE of Hengchun, Taiwan
  3. 237km (147mi) SSE of Taitung City, Taiwan
  4. 267km (166mi) NNE of Claveria, Philippines
  5. 698km (434mi) N of Manila, Philippines

Tectonic Summary

Seismotectonics of the Philippine Sea and Vicinity

The Philippine Sea plate is bordered by the larger Pacific and Eurasia plates and the smaller Sunda plate. The Philippine Sea plate is unusual in that its borders are nearly all zones of plate convergence. The Pacific plate is subducted into the mantle, south of Japan, beneath the Izu-Bonin and Mariana island arcs, which extend more than 3,000 km along the eastern margin of the Philippine Sea plate. This subduction zone is characterized by rapid plate convergence and high-level seismicity extending to depths of over 600 km. In spite of this extensive zone of plate convergence, the plate interface has been associated with few great (M>8.0) ‘megathrust’ earthquakes. This low seismic energy release is thought to result from weak coupling along the plate interface (Scholz and Campos, 1995). These convergent plate margins are also associated with unusual zones of back-arc extension (along with resulting seismic activity) that decouple the volcanic island arcs from the remainder of the Philippine Sea Plate (Karig et al., 1978; Klaus et al., 1992).

Instrumental Intensity

ShakeMap Intensity Image

Earth Watch Report –  Earthquakes

5.4 Mag  Earthquake Japan4.05.2013 photo 54MagEarthquakeJapan4052013GoogleEarthImage_zpscbeafbaf.jpg

5.4 51km SE of Iwaki, Japan 2013-04-05 20:00:52 36.781°N 141.354°E 45.9

M5.4 – 51km SE of Iwaki, Japan 2013-04-05 20:00:52 UTC

Earthquake location 36.781°N, 141.354°E

Event Time

  1. 2013-04-05 20:00:52 UTC
  2. 2013-04-06 05:00:52 UTC+09:00 at epicenter
  3. 2013-04-05 15:00:52 UTC-05:00 system time

Location

36.781°N 141.354°E depth=45.9km (28.5mi)

Nearby Cities

  1. 51km (32mi) SE of Iwaki, Japan
  2. 53km (33mi) E of Kitaibaraki, Japan
  3. 57km (35mi) E of Takahagi, Japan
  4. 65km (40mi) ENE of Hitachi, Japan
  5. 192km (119mi) NE of Tokyo, Japan

Tectonic Summary

Seismotectonics of Japan and Vicinity

Japan and the surrounding islands straddle four major tectonic plates: Pacific plate; North America plate; Eurasia plate; and Philippine Sea plate. The Pacific plate is subducted into the mantle, beneath Hokkaido and northern Honshu, along the eastern margin of the Okhotsk microplate, a proposed subdivision of the North America plate. Farther south, the Pacific plate is subducted beneath volcanic islands along the eastern margin of the Philippine Sea plate. This 2,200 km-long zone of subduction of the Pacific plate is responsible for the creation of the deep offshore Ogasawara and Japan trenches as well as parallel chains of islands and volcanoes, typical of Circumpacific island arcs. Similarly, the Philippine Sea plate is itself subducting under the Eurasia plate along a zone, extending from Taiwan to southern Honshu that comprises the Ryukyu Islands and the Nansei-Shoto trench.

Subduction zones at the Japanese island arcs are geologically complex and produce numerous earthquakes from multiple sources. Deformation of the overriding plates generates shallow crustal earthquakes, whereas slip at the interface of the plates generates interplate earthquakes that extend from near the base of the trench to depths of 40 to 60 km. At greater depths, Japanese arc earthquakes occur within the subducting Pacific and Philippine Sea plates and can reach depths of nearly 700 km. Since 1900, three great earthquakes occurred off Japan and three north of Hokkaido. They are the M8.4 1933 Sanriku-oki earthquake, the M8.3 2003 Tokachi-oki earthquake, the M9.0 2011 Tohoku earthquake, the M8.4 1958 Etorofu earthquake, the M8.5 1963 Kuril earthquake, and the M8.3 1994 Shikotan earthquake.

Earth Watch Report  –  Earthquakes

 photo 3D-World-picture-3d-dunya-resmi_zpsfd0f3e72.jpg

Image Source Randy  Johnson @ ease.com

6.0 107km E of Miyako, Japan 2013-04-01 18:53:17 39.528°N 143.196°E 12.5

M6.0 – 107km E of Miyako, Japan 2013-04-01 18:53:17 UTC

Earthquake location 39.528°N, 143.196°E

Event Time

  1. 2013-04-01 18:53:17 UTC
  2. 2013-04-02 04:53:17 UTC+10:00 at epicenter
  3. 2013-04-01 13:53:17 UTC-05:00 system time

Location

39.528°N 143.196°E depth=12.5km (7.8mi)

Nearby Cities

  1. 107km (66mi) E of Miyako, Japan
  2. 107km (66mi) E of Yamada, Japan
  3. 112km (70mi) E of Otsuchi, Japan
  4. 116km (72mi) ENE of Kamaishi, Japan
  5. 526km (327mi) NE of Tokyo, Japan

5.1 103km E of Miyako, Japan 2013-04-01 20:04:30 39.580°N 143.156°E 8.6

….

5.2 110km E of Miyako, Japan 2013-04-02 02:08:48 39.551°N 143.234°E 20.3

4.6 105km E of Miyako, Japan 2013-04-02 13:06:02 39.592°N 143.177°E 28.7

4.4 111km E of Miyako, Japan 2013-04-02 13:41:10 39.537°N 143.240°E 37.6

4.7 114km E of Yamada, Japan 2013-04-02 14:52:48 39.438°N 143.284°E 40.0

Instrumental Intensity

ShakeMap Intensity Image

Tectonic Summary

Seismotectonics of Japan and Vicinity

Japan and the surrounding islands straddle four major tectonic plates: Pacific plate; North America plate; Eurasia plate; and Philippine Sea plate. The Pacific plate is subducted into the mantle, beneath Hokkaido and northern Honshu, along the eastern margin of the Okhotsk microplate, a proposed subdivision of the North America plate. Farther south, the Pacific plate is subducted beneath volcanic islands along the eastern margin of the Philippine Sea plate. This 2,200 km-long zone of subduction of the Pacific plate is responsible for the creation of the deep offshore Ogasawara and Japan trenches as well as parallel chains of islands and volcanoes, typical of Circumpacific island arcs. Similarly, the Philippine Sea plate is itself subducting under the Eurasia plate along a zone, extending from Taiwan to southern Honshu that comprises the Ryukyu Islands and the Nansei-Shoto trench.

Subduction zones at the Japanese island arcs are geologically complex and produce numerous earthquakes from multiple sources. Deformation of the overriding plates generates shallow crustal earthquakes, whereas slip at the interface of the plates generates interplate earthquakes that extend from near the base of the trench to depths of 40 to 60 km. At greater depths, Japanese arc earthquakes occur within the subducting Pacific and Philippine Sea plates and can reach depths of nearly 700 km. Since 1900, three great earthquakes occurred off Japan and three north of Hokkaido. They are the M8.4 1933 Sanriku-oki earthquake, the M8.3 2003 Tokachi-oki earthquake, the M9.0 2011 Tohoku earthquake, the M8.4 1958 Etorofu earthquake, the M8.5 1963 Kuril earthquake, and the M8.3 1994 Shikotan earthquake.

More information on regional seismicity and tectonics

Earth Watch Report  –  Earthquakes

TSMC Factories Evacuated After 6.1 Magnitude Quake Hits Taiwan              Image Source

6.0 21km SE of Buli, Taiwan 2013-03-27 02:03:20 23.840°N 121.135°E 20.7

M6.0 – 21km SE of Buli, Taiwan 2013-03-27 02:03:20 UTC

Earthquake location 23.840°N, 121.135°E

Event Time

  1. 2013-03-27 02:03:20 UTC
  2. 2013-03-27 10:03:20 UTC+08:00 at epicenter
  3. 2013-03-26 21:03:20 UTC-05:00 system time

Location

23.840°N 121.135°E depth=20.7km (12.9mi)

Nearby Cities

  1. 21km (13mi) SE of Buli, Taiwan
  2. 40km (25mi) ENE of Lugu, Taiwan
  3. 47km (29mi) ESE of Zhongxing New Village, Taiwan
  4. 48km (30mi) E of Nantou, Taiwan
  5. 735km (457mi) ENE of Hong Kong, Hong Kong

Tectonic Summary

Seismotectonics of the Philippine Sea and Vicinity

The Philippine Sea plate is bordered by the larger Pacific and Eurasia plates and the smaller Sunda plate. The Philippine Sea plate is unusual in that its borders are nearly all zones of plate convergence. The Pacific plate is subducted into the mantle, south of Japan, beneath the Izu-Bonin and Mariana island arcs, which extend more than 3,000 km along the eastern margin of the Philippine Sea plate. This subduction zone is characterized by rapid plate convergence and high-level seismicity extending to depths of over 600 km. In spite of this extensive zone of plate convergence, the plate interface has been associated with few great (M>8.0) ‘megathrust’ earthquakes. This low seismic energy release is thought to result from weak coupling along the plate interface (Scholz and Campos, 1995). These convergent plate margins are also associated with unusual zones of back-arc extension (along with resulting seismic activity) that decouple the volcanic island arcs from the remainder of the Philippine Sea Plate (Karig et al., 1978; Klaus et al., 1992).

South of the Mariana arc, the Pacific plate is subducted beneath the Yap Islands along the Yap trench. The long zone of Pacific plate subduction at the eastern margin of the Philippine Sea Plate is responsible for the generation of the deep Izu-Bonin, Mariana, and Yap trenches as well as parallel chains of islands and volcanoes, typical of circum-pacific island arcs. Similarly, the northwestern margin of the Philippine Sea plate is subducting beneath the Eurasia plate along a convergent zone, extending from southern Honshu to the northeastern coast of Taiwan, manifested by the Ryukyu Islands and the Nansei-Shoto (Ryukyu) trench. The Ryukyu Subduction Zone is associated with a similar zone of back-arc extension, the Okinawa Trough. At Taiwan, the plate boundary is characterized by a zone of arc-continent collision, whereby the northern end of the Luzon island arc is colliding with the buoyant crust of the Eurasia continental margin offshore China.

Instrumental Intensity

ShakeMap Intensity Image

By Tim Culpan & Adela Lin – Mar 26, 2013 10:19 PM CT

Taiwan Semiconductor Manufacturing Co. evacuated factories after a magnitude 6.1 earthquake struck central Taiwan’s Nantou county at 10:03 a.m. Buildings shook in Taipei, about 153 kilometers from the epicenter.

The evacuations were triggered by emergency response mechanisms, company spokesman Michael Kramer told Bloomberg by phone today. A factory in the city of Taichung and another in Hsinchu were evacuated following the tremor, and both operate 8- inch wafer production equipment, he said.

Kuo Kai-wen, director of Seismology Center, speaks to the press at the central Weather Bureau in Taipei on March 27, 2013. A magnitude 6.1 earthquake struck central Taiwan’s Nantou county at 10:03 a.m. Photographer: Sam Yeh/AFP/Getty Images

The earthquake’s epicenter was 38.8 kilometers east of Nantou county’s government at a depth of 15.4 kilometers, Taiwan’s Central Weather Bureau reported. It was followed by three aftershocks measuring from 3.7 to 3.9 in magnitude. Three people were injured and one fire was reported in central Taiwan, Lin Kuan-cheng, a spokesman for the National Fire Agency said by phone today. Landslides blocked a highway in Nantou, the transportation department said.

The Taiwan dollar was unchanged at NT$29.850 as of 10:51 a.m. in Taipei trading. Taiwan’s Taiex rose 0.3 percent to 7,876.94 as of 10:54 a.m. local time.

The U.S. Geological Survey recorded the earthquake’s magnitude as 6.0 and occurring at a depth of 20 kilometers.

To contact the reporters on this story: Tim Culpan in Taipei at tculpan1@bloomberg.net; Adela Lin in Taipei at alin95@bloomberg.net

More News

Earth Watch Report  –  Earthquakes

 

English.news.cn   2013-02-25 15:35:20

TOKYO, Feb. 25 (Xinhua) — An earthquake measuring 6.2 on the Richter scale jolted central Japan on Monday, said the Japan Meteorological Agency (JMA).

The quake took place at 4:23 p.m. local time and the epicenter was initially determined at degree 36.9 north latitude, 139.4 degree east longitude, with a depth of 10 km.

The temblor was marked upper 5 in JMA seismic intensity of 7 in the area near the epicenter in the northern Tochigi Prefecture.

A 4.7-magnitude aftershock took place at 4:34 p.m. in the same area, with a very shallow depth.

No tsunami alert was issued and no damage and injuries have been reported so far. There were also no abnormalities in nuclear facilities after the quake.

The U.S. Geological Survey measured the earthquake 5.7 on the Richter scale.

Editor: Zhu Ningzhu

4.6 81km ENE of Namie, Japan 2013-02-25 03:52:34 37.663°N 141.889°E 22.2

5.7 33km NNE of Numata, Japan 2013-02-25 07:23:56 36.892°N 139.251°E 9.9

4.5 30km ESE of Muikamachi, Japan 2013-02-25 07:32:02 36.951°N 139.195°E 10.0

4.6 32km WNW of Nikko, Japan 2013-02-25 07:34:44 36.913°N 139.308°E 9.8

5.4 194km SSE of Nishinoomote, Japan 2013-02-25 16:00:19 29.034°N 131.495°E 43.5

4.7 32km E of Ishinomaki, Japan 2013-02-25 16:19:27 38.392°N 141.676°E 60.5

….

Instrumental Intensity

ShakeMap Intensity Image

Contributed by USGS National Earthquake Information Center

….

Tectonic Summary

Seismotectonics of the Philippine Sea and Vicinity

The Philippine Sea plate is bordered by the larger Pacific and Eurasia plates and the smaller Sunda plate. The Philippine Sea plate is unusual in that its borders are nearly all zones of plate convergence. The Pacific plate is subducted into the mantle, south of Japan, beneath the Izu-Bonin and Mariana island arcs, which extend more than 3,000 km along the eastern margin of the Philippine Sea plate. This subduction zone is characterized by rapid plate convergence and high-level seismicity extending to depths of over 600 km. In spite of this extensive zone of plate convergence, the plate interface has been associated with few great (M>8.0) ‘megathrust’ earthquakes. This low seismic energy release is thought to result from weak coupling along the plate interface (Scholz and Campos, 1995). These convergent plate margins are also associated with unusual zones of back-arc extension (along with resulting seismic activity) that decouple the volcanic island arcs from the remainder of the Philippine Sea Plate (Karig et al., 1978; Klaus et al., 1992).

South of the Mariana arc, the Pacific plate is subducted beneath the Yap Islands along the Yap trench. The long zone of Pacific plate subduction at the eastern margin of the Philippine Sea Plate is responsible for the generation of the deep Izu-Bonin, Mariana, and Yap trenches as well as parallel chains of islands and volcanoes, typical of circum-pacific island arcs. Similarly, the northwestern margin of the Philippine Sea plate is subducting beneath the Eurasia plate along a convergent zone, extending from southern Honshu to the northeastern coast of Taiwan, manifested by the Ryukyu Islands and the Nansei-Shoto (Ryukyu) trench. The Ryukyu Subduction Zone is associated with a similar zone of back-arc extension, the Okinawa Trough. At Taiwan, the plate boundary is characterized by a zone of arc-continent collision, whereby the northern end of the Luzon island arc is colliding with the buoyant crust of the Eurasia continental margin offshore China.

Along its western margin, the Philippine Sea plate is associated with a zone of oblique convergence with the Sunda Plate. This highly active convergent plate boundary extends along both sides the Philippine Islands, from Luzon in the north to the Celebes Islands in the south. The tectonic setting of the Philippines is unusual in several respects: it is characterized by opposite-facing subduction systems on its east and west sides; the archipelago is cut by a major transform fault, the Philippine Fault; and the arc complex itself is marked by active volcanism, faulting, and high seismic activity. Subduction of the Philippine Sea Plate occurs at the eastern margin of the archipelago along the Philippine Trench and its northern extension, the East Luzon Trough. The East Luzon Trough is thought to be an unusual example of a subduction zone in the process of formation, as the Philippine Trench system gradually extends northward (Hamburger et al., 1983). On the west side of Luzon, the Sunda Plate subducts eastward along a series of trenches, including the Manila Trench in the north, the smaller less well-developed Negros Trench in the central Philippines, and the Sulu and Cotabato trenches in the south (Cardwell et al., 1980). At its northern and southern terminations, subduction at the Manila Trench is interrupted by arc-continent collision, between the northern Philippine arc and the Eurasian continental margin at Taiwan and between the Sulu-Borneo Block and Luzon at the island of Mindoro. The Philippine fault, which extends over 1,200 km within the Philippine arc, is seismically active. The fault has been associated with major historical earthquakes, including the destructive M7.6 Luzon earthquake of 1990 (Yoshida and Abe, 1992). A number of other active intra-arc fault systems are associated with high seismic activity, including the Cotabato Fault and the Verde Passage-Sibuyan Sea Fault (Galgana et al., 2007).

Earth Watch Report  –  Earthquakes

Japan

 

Seismic Hazard Map

Seismic Hazard Map

4.8

43km ENE of Ishinomaki, Japan

2013-02-13 02:21:37

38.500°N

141.792°E

63.0

M4.8 – 43km ENE of Ishinomaki, Japan 2013-02-13 02:21:37 UTC

Earthquake location 38.500°N, 141.792°E

Event Time

  1. 2013-02-13 02:21:37 UTC
  2. 2013-02-13 11:21:37 UTC+09:00 at epicenter
  3. 2013-02-12 20:21:37 UTC-06:00 system time

Location

38.500°N 141.792°E depth=63.0km (39.2mi)

Nearby Cities

  1. 43km (27mi) ENE of Ishinomaki, Japan
  2. 50km (31mi) E of Yamoto, Japan
  3. 57km (35mi) E of Wakuya, Japan
  4. 63km (39mi) S of Ofunato, Japan
  5. 363km (226mi) NNE of Tokyo, Japan

5.5

63km SE of Nishinoomote, Japan

2013-02-13 03:57:47

30.281°N

131.404°E

41.5

M5.5 – 63km SE of Nishinoomote, Japan 2013-02-13 03:57:47 UTC

Earthquake location 30.281°N, 131.404°E

Event Time

  1. 2013-02-13 03:57:47 UTC
  2. 2013-02-13 12:57:47 UTC+09:00 at epicenter
  3. 2013-02-12 21:57:47 UTC-06:00 system time

Location

30.281°N 131.404°E depth=41.5km (25.8mi)

Nearby Cities

  1. 63km (39mi) SE of Nishinoomote, Japan
  2. 127km (79mi) SE of Ibusuki, Japan
  3. 131km (81mi) S of Kushima, Japan
  4. 133km (83mi) SSE of Kanoya, Japan
  5. 905km (562mi) SSE of Seoul, South Korea

Related Links

 

Tectonic Summary

Seismotectonics of the Philippine Sea and Vicinity

The Philippine Sea plate is bordered by the larger Pacific and Eurasia plates and the smaller Sunda plate. The Philippine Sea plate is unusual in that its borders are nearly all zones of plate convergence. The Pacific plate is subducted into the mantle, south of Japan, beneath the Izu-Bonin and Mariana island arcs, which extend more than 3,000 km along the eastern margin of the Philippine Sea plate. This subduction zone is characterized by rapid plate convergence and high-level seismicity extending to depths of over 600 km. In spite of this extensive zone of plate convergence, the plate interface has been associated with few great (M>8.0) ‘megathrust’ earthquakes. This low seismic energy release is thought to result from weak coupling along the plate interface (Scholz and Campos, 1995). These convergent plate margins are also associated with unusual zones of back-arc extension (along with resulting seismic activity) that decouple the volcanic island arcs from the remainder of the Philippine Sea Plate (Karig et al., 1978; Klaus et al., 1992).

South of the Mariana arc, the Pacific plate is subducted beneath the Yap Islands along the Yap trench. The long zone of Pacific plate subduction at the eastern margin of the Philippine Sea Plate is responsible for the generation of the deep Izu-Bonin, Mariana, and Yap trenches as well as parallel chains of islands and volcanoes, typical of circum-pacific island arcs. Similarly, the northwestern margin of the Philippine Sea plate is subducting beneath the Eurasia plate along a convergent zone, extending from southern Honshu to the northeastern coast of Taiwan, manifested by the Ryukyu Islands and the Nansei-Shoto (Ryukyu) trench. The Ryukyu Subduction Zone is associated with a similar zone of back-arc extension, the Okinawa Trough. At Taiwan, the plate boundary is characterized by a zone of arc-continent collision, whereby the northern end of the Luzon island arc is colliding with the buoyant crust of the Eurasia continental margin offshore China.

Along its western margin, the Philippine Sea plate is associated with a zone of oblique convergence with the Sunda Plate. This highly active convergent plate boundary extends along both sides the Philippine Islands, from Luzon in the north to the Celebes Islands in the south. The tectonic setting of the Philippines is unusual in several respects: it is characterized by opposite-facing subduction systems on its east and west sides; the archipelago is cut by a major transform fault, the Philippine Fault; and the arc complex itself is marked by active volcanism, faulting, and high seismic activity. Subduction of the Philippine Sea Plate occurs at the eastern margin of the archipelago along the Philippine Trench and its northern extension, the East Luzon Trough. The East Luzon Trough is thought to be an unusual example of a subduction zone in the process of formation, as the Philippine Trench system gradually extends northward (Hamburger et al., 1983). On the west side of Luzon, the Sunda Plate subducts eastward along a series of trenches, including the Manila Trench in the north, the smaller less well-developed Negros Trench in the central Philippines, and the Sulu and Cotabato trenches in the south (Cardwell et al., 1980). At its northern and southern terminations, subduction at the Manila Trench is interrupted by arc-continent collision, between the northern Philippine arc and the Eurasian continental margin at Taiwan and between the Sulu-Borneo Block and Luzon at the island of Mindoro. The Philippine fault, which extends over 1,200 km within the Philippine arc, is seismically active. The fault has been associated with major historical earthquakes, including the destructive M7.6 Luzon earthquake of 1990 (Yoshida and Abe, 1992). A number of other active intra-arc fault systems are associated with high seismic activity, including the Cotabato Fault and the Verde Passage-Sibuyan Sea Fault (Galgana et al., 2007).

Relative plate motion vectors near the Philippines (about 80 mm/yr) is oblique to the plate boundary along the two plate margins of central Luzon, where it is partitioned into orthogonal plate convergence along the trenches and nearly pure translational motion along the Philippine Fault (Barrier et al., 1991). Profiles B and C reveal evidence of opposing inclined seismic zones at intermediate depths (roughly 70-300 km) and complex tectonics at the surface along the Philippine Fault.

Several relevant tectonic elements, plate boundaries and active volcanoes, provide a context for the seismicity presented on the main map. The plate boundaries are most accurate along the axis of the trenches and more diffuse or speculative in the South China Sea and Lesser Sunda Islands. The active volcanic arcs (Siebert and Simkin, 2002) follow the Izu, Volcano, Mariana, and Ryukyu island chains and the main Philippine islands parallel to the Manila, Negros, Cotabato, and Philippine trenches.

Seismic activity along the boundaries of the Philippine Sea Plate (Allen et al., 2009) has produced 7 great (M>8.0) earthquakes and 250 large (M>7) events. Among the most destructive events were the 1923 Kanto, the 1948 Fukui and the 1995 Kobe (Japan) earthquakes (99,000, 5,100, and 6,400 casualties, respectively), the 1935 and the 1999 Chi-Chi (Taiwan) earthquakes (3,300 and 2,500 casualties, respectively), and the 1976 M7.6 Moro Gulf and 1990 M7.6 Luzon (Philippines) earthquakes (7,100 and 2,400 casualties, respectively). There have also been a number of tsunami-generating events in the region, including the Moro Gulf earthquake, whose tsunami resulted in more than 5000 deaths.

More information on regional seismicity and tectonics