The Earthquake/Seismic Activity Log

April 7, 2011

I will add in updates as they appear:

http://quakes.globalincidentmap.com/


Friday April 8 2011, 01:27:14 UTC 13 minutes ago Southern California 1.4 22.6 Detail
Friday April 8 2011, 00:56:53 UTC 44 minutes ago Banda Sea 5.0 248.9 Detail
Friday April 8 2011, 00:28:24 UTC 72 minutes ago Arkansas 2.9 2.2 Detail
Friday April 8 2011, 00:28:22 UTC 72 minutes ago Arkansas 2.9 5.0 Detail
Friday April 8 2011, 00:28:22 UTC 72 minutes ago Arkansas 2.9 5.0 Detail
Thursday April 7 2011, 23:37:07 UTC 2 hours ago Puerto Rico 2.7 40.0 Detail
Thursday April 7 2011, 23:11:45 UTC 2 hours ago Central California 1.0 7.3 Detail
Thursday April 7 2011, 23:11:09 UTC 2 hours ago Arkansas 3.9 6.1 Detail
Thursday April 7 2011, 23:11:09 UTC 2 hours ago Arkansas 4.0 2.6 Detail
Thursday April 7 2011, 22:41:50 UTC 2 hours ago Central California 1.3 7.9 Detail
Thursday April 7 2011, 22:39:41 UTC 3 hours ago Northern California 2.4 3.1 Detail
Thursday April 7 2011, 22:35:03 UTC 3 hours ago Southern California 1.4 9.1 Detail
Thursday April 7 2011, 22:27:35 UTC 3 hours ago Central California 1.3 3.4 Detail
Thursday April 7 2011, 22:17:41 UTC 3 hours ago Southern California 1.4 4.9 Detail
Thursday April 7 2011, 22:15:46 UTC 3 hours ago Central California 1.3 9.2 Detail
Thursday April 7 2011, 22:02:19 UTC 3 hours ago near the east coast of Honshu, Japan 5.2 34.0 Detail
Thursday April 7 2011, 22:01:03 UTC 3 hours ago Northern California 1.2 3.6 Detail
Thursday April 7 2011, 21:49:34 UTC 3 hours ago Island of Hawaii, Hawaii 3.0 35.1 Detail
Thursday April 7 2011, 21:33:20 UTC 4 hours ago Greater Los Angeles area, California 1.5 15.9 Detail
Thursday April 7 2011, 21:15:18 UTC 4 hours ago Southern California 1.1 17.2 Detail
Thursday April 7 2011, 21:06:05 UTC 4 hours ago north of Honduras 5.0 16.2 Detail
Thursday April 7 2011, 20:41:54 UTC 4 hours ago north of Honduras 5.8 19.5 Detail
Thursday April 7 2011, 19:58:17 UTC 5 hours ago Island of Hawaii, Hawaii 2.5 5.7 Detail
Thursday April 7 2011, 19:31:07 UTC 6 hours ago Central California 1.7 5.5 Detail
Thursday April 7 2011, 19:03:03 UTC 6 hours ago Northern California 1.3 8.4 Detail
Thursday April 7 2011, 19:02:29 UTC 6 hours ago Central California 1.0 8.0 Detail
Thursday April 7 2011, 19:00:01 UTC 6 hours ago Central California 1.0 0.8 Detail
Thursday April 7 2011, 18:53:23 UTC 6 hours ago Central Alaska 2.1 10.5 Detail
Thursday April 7 2011, 18:53:23 UTC 6 hours ago Central Alaska 2.1 10.5 Detail
Thursday April 7 2011, 18:51:26 UTC 6 hours ago Central California 2.5 6.0 Detail
Thursday April 7 2011, 18:36:08 UTC 7 hours ago Central California 1.8 9.0 Detail
Thursday April 7 2011, 18:22:16 UTC 7 hours ago Central California 1.8 10.8 Detail
Thursday April 7 2011, 18:12:36 UTC 7 hours ago Southern California 1.3 0.0 Detail
Thursday April 7 2011, 17:51:58 UTC 7 hours ago Northern California 1.0 1.9 Detail
Thursday April 7 2011, 17:45:01 UTC 7 hours ago Island of Hawaii, Hawaii 1.9 35.7 Detail
Thursday April 7 2011, 17:40:21 UTC 8 hours ago Central Alaska 2.0 7.2 Detail
Thursday April 7 2011, 17:06:47 UTC 8 hours ago Northern California 2.4 6.4 Detail
Thursday April 7 2011, 16:57:04 UTC 8 hours ago Central Alaska 1.7 3.3 Detail
Thursday April 7 2011, 16:57:04 UTC 8 hours ago Central Alaska 1.7 3.5 Detail
Thursday April 7 2011, 16:44:29 UTC 8 hours ago Central California 1.1 6.0 Detail
Thursday April 7 2011, 16:40:50 UTC 9 hours ago Central Alaska 4.4 119.2 Detail
Thursday April 7 2011, 16:40:50 UTC 9 hours ago Central Alaska 4.4 123.0 Detail
Thursday April 7 2011, 16:39:03 UTC 9 hours ago Central California 2.9 4.8 Detail
Thursday April 7 2011, 16:39:03 UTC 9 hours ago Central California 2.9 5.0 Detail
Thursday April 7 2011, 16:31:03 UTC 9 hours ago Southeastern Alaska 1.6 17.9 Detail
Thursday April 7 2011, 16:06:43 UTC 9 hours ago Southern Alaska 2.4 27.8 Detail
Thursday April 7 2011, 15:35:25 UTC 10 hours ago Utah 1.7 11.1 Detail
Thursday April 7 2011, 15:31:28 UTC 10 hours ago near the east coast of Honshu, Japan 4.6 67.2 Detail
Thursday April 7 2011, 15:25:13 UTC 10 hours ago near the east coast of Honshu, Japan 4.6 67.0 Detail
Thursday April 7 2011, 15:17:50 UTC 10 hours ago Central California 2.2 11.5 Detail
Thursday April 7 2011, 14:40:56 UTC 10 hours ago Greater Los Angeles area, California 1.6 8.3 Detail
Thursday April 7 2011, 14:32:41 UTC 11 hours ago near the east coast of Honshu, Japan 7.1 49.0 Detail
Thursday April 7 2011, 14:32:35 UTC 11 hours ago Central California 1.1 4.6 Detail
Thursday April 7 2011, 14:32:00 UTC 11 hours ago near the east coast of Honshu, Japan 7.4 40.0 Detail
Thursday April 7 2011, 14:32:00 UTC 11 hours ago near the east coast of Honshu, Japan 7.4 40.0 Detail
Thursday April 7 2011, 14:25:57 UTC 11 hours ago Southern California 1.0 0.1 Detail
Thursday April 7 2011, 13:40:59 UTC 11 hours ago Baja California, Mexico 4.3 10.0 Detail
Thursday April 7 2011, 13:11:24 UTC 12 hours ago Veracruz, Mexico 6.5 167.4 Detail
Thursday April 7 2011, 13:11:24 UTC 12 hours ago Veracruz, Mexico 6.5 167.4 Detail
Thursday April 7 2011, 13:11:12 UTC 12 hours ago Southern California 1.9 2.0 Detail
Thursday April 7 2011, 13:08:45 UTC 12 hours ago Oregon 2.1 6.8 Detail
Thursday April 7 2011, 13:03:27 UTC 12 hours ago Utah 1.8 11.8 Detail
Thursday April 7 2011, 12:54:47 UTC 12 hours ago Central California 1.4 2.7 Detail
Thursday April 7 2011, 12:31:05 UTC 13 hours ago Northern California 1.0 2.6 Detail
Thursday April 7 2011, 12:30:07 UTC 13 hours ago Central California 1.1 3.3 Detail
Thursday April 7 2011, 12:28:57 UTC 13 hours ago Central California 1.3 3.3 Detail
Thursday April 7 2011, 12:28:27 UTC 13 hours ago Central Alaska 1.9 72.0 Detail
Thursday April 7 2011, 12:20:48 UTC 13 hours ago Central California 2.9 1.9 Detail
Thursday April 7 2011, 12:01:34 UTC 13 hours ago Northern California 1.3 3.5 Detail
Thursday April 7 2011, 11:33:42 UTC 14 hours ago Southern California 1.5 10.3 Detail
Thursday April 7 2011, 11:13:54 UTC 14 hours ago Greater Los Angeles area, California 2.7 7.1 Detail
Thursday April 7 2011, 11:13:53 UTC 14 hours ago Greater Los Angeles area, California 2.6 12.9 Detail
Thursday April 7 2011, 10:52:13 UTC 14 hours ago near the east coast of Honshu, Japan 4.7 35.5 Detail
Thursday April 7 2011, 10:50:19 UTC 14 hours ago Seattle-Tacoma urban area, Washington 1.9 29.0 Detail
Thursday April 7 2011, 10:47:26 UTC 14 hours ago Northern California 1.0 3.5 Detail
Thursday April 7 2011, 10:03:34 UTC 15 hours ago Arkansas 2.5 3.2 Detail
Thursday April 7 2011, 09:48:00 UTC 15 hours ago Arkansas 2.2 4.0 Detail
Thursday April 7 2011, 09:36:33 UTC 16 hours ago Southern Yukon Territory, Canada 2.0 3.5 Detail
Thursday April 7 2011, 09:33:09 UTC 16 hours ago Southern California 1.5 7.0 Detail
Thursday April 7 2011, 08:59:28 UTC 16 hours ago Southern California 1.4 7.6 Detail
Thursday April 7 2011, 08:55:36 UTC 16 hours ago Southern California 1.9 12.0 Detail
Thursday April 7 2011, 08:26:18 UTC 17 hours ago western Montana 1.0 0.0 Detail
Thursday April 7 2011, 08:25:06 UTC 17 hours ago near the east coast of Honshu, Japan 4.6 30.8 Detail
Thursday April 7 2011, 07:56:41 UTC 17 hours ago Kodiak Island region, Alaska 1.9 55.5 Detail
Thursday April 7 2011, 07:49:14 UTC 17 hours ago Utah 1.8 7.0 Detail
Thursday April 7 2011, 07:31:02 UTC 18 hours ago Southern California 2.2 9.6 Detail
Thursday April 7 2011, 07:26:30 UTC 18 hours ago Southern California 1.5 18.0 Detail
Thursday April 7 2011, 07:16:12 UTC 18 hours ago off the east coast of the South Island of New Zealand 5.1 14.1 Detail
Thursday April 7 2011, 07:12:10 UTC 18 hours ago Southern California 1.1 10.6 Detail
Thursday April 7 2011, 06:58:54 UTC 18 hours ago Oregon 1.1 18.9 Detail
Thursday April 7 2011, 06:43:37 UTC 18 hours ago Utah 2.4 0.1 Detail
Thursday April 7 2011, 06:40:47 UTC 19 hours ago Utah 2.0 11.8 Detail

Magnitude 5.0
Date-Time
Thursday, April 07, 2011 at 21:06:05 UTC
Thursday, April 07, 2011 at 03:06:05 PM at epicenter
Time of Earthquake in other Time Zones
Location 17.181°N, 85.091°W
Depth 16.2 km (10.1 miles)
Region NORTH OF HONDURAS
Distances
125 km (77 miles) WSW of Swan Island
167 km (103 miles) NNE of Trujillo, Honduras
391 km (242 miles) E of BELMOPAN, Belize
1508 km (937 miles) E of MEXICO CITY, D.F., Mexico
Location Uncertainty horizontal +/- 15.1 km (9.4 miles); depth +/- 6.1 km (3.8 miles)
Parameters NST=218, Nph=221, Dmin=417.4 km, Rmss=0.83 sec, Gp= 50°,
M-type=body wave magnitude (Mb), Version=7
Source
USGS NEIC (WDCS-D)
Event ID
usc0002l6n

Magnitude 4.0
Date-Time Thursday, April 07, 2011 at 23:11:09 UTC
Thursday, April 07, 2011 at 06:11:09 PM at epicenter
Location 35.215°N, 92.391°W
Depth 2.6 km (1.6 miles) (poorly constrained)
Region ARKANSAS
Distances
15 km (9 miles) NNE of Conway, Arkansas
53 km (32 miles) N of LITTLE ROCK, Arkansas
59 km (36 miles) W of Searcy, Arkansas
68 km (42 miles) E of Russellville, Arkansas
Location Uncertainty
horizontal +/- 11.9 km (7.4 miles); depth +/- 3.7 km (2.3 miles)
Parameters
NST= 51, Nph= 57, Dmin=2.2 km, Rmss=0.55 sec, Gp= 36°,
M-type="Nuttli" surface wave magnitude (mbLg), Version=6
Source

USGS NEIC (WDCS-D)

Event ID

usc0002lbn

Magnitude 5.0
Date-Time Friday, April 08, 2011 at 00:56:53 UTC
Friday, April 08, 2011 at 08:56:53 AM at epicenter
Time of Earthquake in other Time Zones

Location 7.830°S, 123.397°E
Depth 248.9 km (154.7 miles)
Region BANDA SEA
Distances 222 km (137 miles) ENE of Ende, Flores, Indonesia
252 km (156 miles) WNW of DILI, Timor-Leste
259 km (160 miles) N of Kupang, Timor, Indonesia
962 km (597 miles) WNW of DARWIN, Northern Territory, Australia

Location Uncertainty horizontal +/- 13.7 km (8.5 miles); depth +/- 2.3 km (1.4 miles)
Parameters NST= 70, Nph= 78, Dmin=155.8 km, Rmss=0.79 sec, Gp= 36°,
M-type=body wave magnitude (Mb), Version=6
Source USGS NEIC (WDCS-D)


Event ID usc0002ldh

Fracking in Arkansas -

Arkansas Earthquakes Decline After 'Fracking' Injection Well Closures
LOOK AT THE LOGS AND TELL ME IF THIS IS THE CASE...


LITTLE ROCK, Ark. -- The number and strength of earthquakes in central Arkansas have noticeably dropped since the shutdown of two injection wells in the area, although a state researcher says it's too early to draw any conclusions.

"We have definitely noticed a reduction in the number of earthquakes, especially the larger ones," said Scott Ausbrooks, geohazards supervisor for the Arkansas Geological Survey. "It's definitely worth noting."

The Center for Earthquake Research and Information recorded around 100 earthquakes in the seven days preceding the shutdown earlier this month, including the largest quake to hit the state in 35 years – a magnitude 4.7 on Feb. 27. A dozen of the quakes had magnitudes greater than 3.0. In the days since the shutdown, there have been around 60 recorded quakes, with only one higher than a magnitude 3.0. The majority were between magnitudes 1.2 and 2.8.

The two injection wells are used to dispose of wastewater from natural-gas production. One is owned by Chesapeake Energy, and the other by Clarita Operating. They agreed March 4 to temporarily cease injection operations at the request of the Arkansas Oil and Gas Commission.

The commission said preliminary studies showed evidence potentially linking injection activities with nearly 1,000 quakes in the region over the past six months.

But Ausbrooks said it's too soon to tell if the decline in quakes is directly related to the injection well closures, adding that the drop could just be a normal low period of the swarm cycle.

"Either way, I wouldn't expect (the earthquakes) to quit immediately," he said. "If there is a relationship, the seismic activity could go on for weeks, months or even years."

Chesapeake Energy has said it does not believe there is a connection between the injection wells and the area's seismic activity.

A six-month moratorium on new injection wells in the area took effect in January to allow time to determine what relationship, if any, there is between the wells and the earthquakes.

The Fayetteville Shale, an organically-rich rock formation underlying the region, is a major source of natural gas in Arkansas. Drillers free up the gas by using hydraulic fracturing or "fracking," which requires injecting pressurized water to create fractures deep in the ground. The two injection wells at issue dispose of "frack" water when it can no longer be re-used by injecting it into the ground.

The state's Oil and Gas Commission will reconsider the issue at a meeting March 29 when both sides will get to testify.


http://www.huffingtonpost.com/2011/03/15/arkansas-earthquakes-2011-fracking_n_835868.html

___________

Just today -



MAP 3.5 2011/04/08 16:46:19 35.258 -92.376 6.2 3 km ( 2 mi) NNE of Greenbrier, AR
MAP 2.4 2011/04/08 15:36:06 35.251 -92.350 3.0 4 km ( 3 mi) NE of Greenbrier, AR
MAP 4.2 2011/04/08 14:56:32 35.261 -92.362 6.3 4 km ( 3 mi) NE of Greenbrier, AR
MAP 2.6 2011/04/08 13:16:48 35.236 -92.366 6.0 2 km ( 1 mi) ENE of Greenbrier, AR
MAP 2.6 2011/04/08 12:46:39 35.237 -92.366 3.5 2 km ( 1 mi) ENE of Greenbrier, AR
MAP 3.0 2011/04/08 10:12:53 35.252 -92.391 5.2 3 km ( 2 mi) N of Greenbrier, AR
MAP 2.5 2011/04/08 09:13:57 35.254 -92.360 4.6 4 km ( 2 mi) NE of Greenbrier, AR
MAP 2.4 2011/04/08 08:17:08 35.239 -92.349 5.2 4 km ( 2 mi) ENE of Greenbrier, AR
MAP 2.4 2011/04/08 07:57:33 35.229 -92.347 4.6 4 km ( 2 mi) E of Greenbrier, AR
MAP 2.5 2011/04/08 06:47:43 35.243 -92.360 3.5 3 km ( 2 mi) ENE of Greenbrier, AR
MAP 2.9 2011/04/08 04:35:04 35.253 -92.357 4.6 4 km ( 2 mi) NE of Greenbrier, AR
MAP 2.2 2011/04/08 03:30:34 35.258 -92.368 4.9 4 km ( 2 mi) NNE of Greenbrier, AR
MAP 3.2 2011/04/08 03:27:58 35.257 -92.389 5.5 3 km ( 2 mi) N of Greenbrier, AR
MAP 2.9 2011/04/08 00:28:24 35.246 -92.368 2.2 3 km ( 2 mi) NE of Greenbrier, AR

MAP 5.3 2011/04/08 18:42:31 43.896 147.468 63.4 KURIL ISLANDS
MAP 5.2 2011/04/08 18:29:16 13.892 120.080 24.2 MINDORO, PHILIPPINES

Carol's thread re: Carribbean (she is going to make experts of all of us).

Note: Transform and strike-slip are the same thing.


http://www.themistsofavalon.net/t2336-caribbean-plate-tension-increasing-7-seismic-swarms-erupting-across-the-planet#42946

This is a great thread Troy. Ken thinks Japan will have another big on on 4/11 which just happens to be the date that the solar fallout reached earth.

Troy do you think it's possible that magma is moving under the geysers?

Carol wrote:This is a great thread Troy. Ken thinks Japan will have another big on on 4/11 which just happens to be the date that the solar fallout reached earth.

Thanks.

The other day there were two, 4.0 quakes at the same time in Arkansas (different depths). Strang, eh?

MargueriteBee wrote:Troy do you think it's possible that magma is moving under the geysers?

The Geysers in my area do sit over the Clearlake Volcanic field. It is about 8 miles in diameter. However, it is not being fed by the ocean/Pacific Plate moving under California (Shasta and Lassen are being actively fed fresh ocean crust).

I am not sure of the situation in Arkansas. I will check it out after I get some sleep.

MAP 4.7 2011/04/09 13:32:41 -36.318 -73.218 29.1 OFFSHORE BIO-BIO, CHILE
MAP 6.1 2011/04/09 12:57:49 30.013 131.810 21.3 KYUSHU, JAPAN
MAP 3.1 2011/04/09 10:42:28 32.607 -115.731 10.0 BAJA CALIFORNIA, MEXICO
MAP 5.4 2011/04/09 09:42:21 38.262 141.701 59.6 NEAR THE EAST COAST OF HONSHU, JAPAN
MAP 4.1 2011/04/09 08:58:49 32.604 -115.721 10.3 BAJA CALIFORNIA, MEXICO
MAP 2.5 2011/04/09 06:39:54 19.289 -156.407 11.8 HAWAII REGION, HAWAII
MAP 4.6 2011/04/09 02:59:34 38.671 141.750 35.0 NEAR THE EAST COAST OF HONSHU, JAPAN
MAP 4.7 2011/04/09 02:33:50 39.716 143.320 32.8 OFF THE EAST COAST OF HONSHU, JAPAN
MAP 4.8 2011/04/09 02:31:04 39.909 143.144 23.8 OFF THE EAST COAST OF HONSHU, JAPAN
MAP 3.5 2011/04/09 02:19:38 18.333 -68.453 173.1 MONA PASSAGE, DOMINICAN REPUBLIC

HigherLove wrote:MAP 6.1 2011/04/09 12:57:49 30.013 131.810 21.3 KYUSHU, JAPAN

I just looked on Google Earth, and this quake occurred offshore, on the same narrow shelf as the Honshu quakes, but obviously, much further south. Is this new to this area? I know for a long time people have questioned why quakes have not been moving up and down the fault, remaining centered near Honshu. ?????????

Carol wrote:http://quakes.globalincidentmap.com/

I know. That is the first link I check. The answer is no. This is new. It does not appear to be directly related to volcanic activity. i.e. it's on the move. I like the hybrid feature of the link, but the full application is a lot more fun. Either way, the Pacific plate is most distinct.
______________

Greetings! If a picture says 1,000 words, how much does a picture of a picture say?

Yes...a friendly country town. After they slaughterd the locals. Now you can go wine tasting and drink away that guilt. :op

Note: stop watching "Dante's Peak".

LOS ANGELES (LALATE) – Today’s Japan earthquake has not prompted a tsunami advisory for the southern section of the country. A Japan earthquake struck today April 11, 2011 in a substantially different region of the country than previous earthquake activity. Most quakes have been centered off the east coast of Honshu, generally east of Yamagata, Sendai and Fukushima; they have typically been roughly three hundred miles north east of Tokyo. Today’s quake, however, struck south of Tokyo. Local news Saturday is not reporting any damages nor injuries currently.


Shortly before 10 pm local time Saturday, the Kyushu section of Japan suffered a 6.1 magnitude earthquake. Local news reports that the quake was centered east of the Kyushu section of the country, only thirteen miles below the earth’s surface. The quake struck roughly one hundred miles south of Miyazaki and east of Kagoshima.

The quake was roughly five hundred miles from Seoul, South Korea and six hundred miles south west of Tokyo.

Following the quake, the Japan Meteorological Agency did not issue to news as Tsunami Warning nor Tsunami Advisory. Just last week, following the country’s powerful 7.4 magnitude quake, the Agency issued a brief “Tsunami Warning” for the Miyagi Pref. and a “Tsunami Advisory” for the Pacific Coast of Aomori Pref, Iwate, Fukushima, and Ibaraki.

http://news.lalate.com/2011/04/09/japan-earthquake-today-does-not-prompt-tsunami-advisory/

There was an ad for "Dancing w/the stars" on this site, and a tasteless graphic for breaking news that shows a crack in the ground.

MAP 6.1 2011/04/09 12:57:49 30.013 131.810 21.3 KYUSHU, JAPAN

http://en.wikipedia.org/wiki/Kyushu



http://www.glgarcs.net/intro/kys.html



http://en.wikipedia.org/wiki/Mount_Aso

This site is new to me. They claim to be the best non-government quake site around.

http://earthquake-report.com/

There is a great link on this site to an Earthquake Glossary of Terms.

Sorry if it is a repeat. :op

PEACE

MAP 4.8 2011/04/10 00:08:44 32.481 134.612 29.8 SHIKOKU, JAPAN




Magnitude 4.8
Date-Time Sunday, April 10, 2011 at 00:08:44 UTC
Sunday, April 10, 2011 at 09:08:44 AM at epicenter
Time of Earthquake in other Time Zones

Location 32.481°N, 134.612°E
Depth 29.8 km (18.5 miles)
Region SHIKOKU, JAPAN
Distances 156 km (96 miles) SE of Kochi, Shikoku, Japan
176 km (109 miles) S of Tokushima, Shikoku, Japan
200 km (124 miles) SSW of Wakayama, Honshu, Japan
592 km (367 miles) SW of TOKYO, Japan

Location Uncertainty horizontal +/- 16.8 km (10.4 miles); depth +/- 4.5 km (2.8 miles)
Parameters NST= 37, Nph= 37, Dmin=357.3 km, Rmss=0.67 sec, Gp= 61°,
M-type=body wave magnitude (Mb), Version=4
Source USGS NEIC (WDCS-D)


Event ID usc0002mjl


MAP 4.9 2011/04/10 00:00:56 35.750 141.495 45.6 NEAR THE EAST COAST OF HONSHU, JAPAN
MAP 4.9 2011/04/09 21:23:05 35.667 140.045 64.6 NEAR THE EAST COAST OF HONSHU, JAPAN
MAP 6.1 2011/04/09 12:57:49 30.013 131.810 21.3 KYUSHU, JAPAN



Letter
Nature 442, 188-191 (13 July 2006) | doi:10.1038/nature04931; Received 17 January 2006; Accepted 18 May 2006

Low-frequency earthquakes in Shikoku, Japan, and their relationship to episodic tremor and slip
David R. Shelly1, Gregory C. Beroza1, Satoshi Ide2 and Sho Nakamula3

Top of pageNon-volcanic seismic tremor was discovered in the Nankai trough subduction zone in southwest Japan1 and subsequently identified in the Cascadia subduction zone2. In both locations, tremor is observed to coincide temporally with large, slow slip events on the plate interface downdip of the seismogenic zone2, 3, 4, 5, 6, 7. The relationship between tremor and aseismic slip remains uncertain, however, largely owing to difficulty in constraining the source depth of tremor. In southwest Japan, a high quality borehole seismic network allows identification of coherent S-wave (and sometimes P-wave) arrivals within the tremor, whose sources are classified as low-frequency earthquakes. As low-frequency earthquakes comprise at least a portion of tremor, understanding their mechanism is critical to understanding tremor as a whole. Here, we provide strong evidence that these earthquakes occur on the plate interface, coincident with the inferred zone of slow slip. The locations and characteristics of these events suggest that they are generated by shear slip during otherwise aseismic transients, rather than by fluid flow. High pore-fluid pressure in the immediate vicinity, as implied by our estimates of seismic P- and S-wave speeds, may act to promote this transient mode of failure. Low-frequency earthquakes could potentially contribute to seismic hazard forecasting by providing a new means to monitor slow slip at depth.

http://www.nature.com/nature/journal/v442/n7099/abs/nature04931.html

MAP 4.9 2011/04/10 12:03:01 46.474 152.879 38.3 KURIL ISLANDS
MAP 2.7 2011/04/10 12:00:28 32.075 -115.238 13.0 BAJA CALIFORNIA, MEXICO
MAP 3.2 2011/04/10 09:48:54 38.761 -122.737 1.2 NORTHERN CALIFORNIA
MAP 3.1 2011/04/10 09:33:42 40.324 -106.947 5.0 COLORADO
MAP 5.2 2011/04/10 09:02:44 31.412 100.846 13.6 WESTERN SICHUAN, CHINA
MAP 4.7 2011/04/10 05:23:31 36.975 143.334 40.9 OFF THE EAST COAST OF HONSHU, JAPAN
MAP 5.0 2011/04/10 04:45:22 -28.754 -176.962 31.6 KERMADEC ISLANDS REGION
MAP 4.4 2011/04/10 04:12:32 36.312 141.172 33.0 NEAR THE EAST COAST OF HONSHU, JAPAN
MAP 4.8 2011/04/10 03:59:35 -30.493 -68.561 78.9 SAN JUAN, ARGENTINA
MAP 2.7 2011/04/10 01:09:12 32.393 -115.542 23.2 BAJA CALIFORNIA, MEXICO
MAP 4.7 2011/04/10 00:50:48 36.814 140.580 65.9 NEAR THE EAST COAST OF HONSHU, JAPAN
MAP 4.8 2011/04/10 00:08:45 32.481 134.612 29.8 SHIKOKU, JAPAN
MAP 4.9 2011/04/10 00:00:57 35.750 141.495 45.6 NEAR THE EAST COAST OF HONSHU, JAPAN


Magnitude 3.1
Date-Time Sunday, April 10, 2011 at 09:33:42 UTC
Sunday, April 10, 2011 at 03:33:42 AM at epicenter

Location 40.324°N, 106.947°W
Depth 5 km (3.1 miles)
Region COLORADO
Distances 6 km (4 miles) N (9°) from Oak Creek, CO
19 km (12 miles) N (350°) from Yampa, CO
20 km (12 miles) SSW (211°) from Steamboat Springs, CO
160 km (100 miles) W (261°) from Fort Collins, CO
181 km (113 miles) WNW (292°) from Denver, CO

Location Uncertainty horizontal +/- 12.1 km (7.5 miles); depth +/- 2.6 km (1.6 miles)
Parameters NST= 34, Nph= 36, Dmin=128 km, Rmss=1.07 sec, Gp= 68°,
M-type=local magnitude (ML), Version=4
Source U.S. Geological Survey, National Earthquake Information Center:
World Data Center for Seismology, Denver

Event ID

Thank You Troy - Actually I WAS awake at 3 :30 Am - awakened by hail and rain and thunder and lightening - did NOT feel earth rumbling, but it was a powerful thunder and lightning and we do not usually get this - I had the thought - well we're getting the cesium and xenon raining down on us now, and the sound of the thunder and rumbling was so strange I wondered if they were doing HAARP earthquake as well. Your timestamp said 3:33 AM - - too bizarre...

It's beautiful now..

LeeEllisMusic wrote:Thank You Troy - Actually I WAS awake at 3 :30 Am - awakened by hail and rain and thunder and lightening - did NOT feel earth rumbling, but it was a powerful thunder and lightning and we do not usually get this - I had the thought - well we're getting the cesium and xenon raining down on us now, and the sound of the thunder and rumbling was so strange I wondered if they were doing HAARP earthquake as well. Your timestamp said 3:33 AM - - too bizarre...

It's beautiful now..

Quakes from Montanta form sort of a "little dipper" down through Colorado, Missouri, Arkansas, and into Tennessee. Just in the last day.

Per the report, Western Colorado is quite seismically active -

http://www.colorado.edu/GeolSci/faculty/pdf/sheehanhughes.pdf

_________________

November 15, 1999
Prepared by the Earthquake Subcommittee
Colorado Natural Hazards Mitigation Council


Introduction

Colorado is comprised of areas with low to moderate potential for damaging earthquakes, based on research by geologists and geophysicists who specialize in seismology. There are about 90 potentially active faults that have been identified in Colorado, with documented movement within the last 1.6 million years. However, there are several thousand other faults that have been mapped in Colorado that have not been sufficiently studied to know whether they are capable of generating earthquakes or not. It is not possible to accurately estimate the timing or location of future dangerous earthquakes in Colorado. The lack of an adequate network of seismometers in Colorado makes it difficult to detect and locate earthquakes. Moreover, the historical record is quite short (~150 years). Nevertheless, the available seismic hazard information can provide a basis for a reasoned and prudent approach to seismic safety.


Faulting

Sudden movement on faults is responsible for large earthquakes. By studying the geologic characteristics of faults, geoscientists can often determine when the fault last moved and estimate the magnitude of the earthquake that produced the last movement. In some cases, it is possible to evaluate how frequently large earthquakes occurred on a specific fault during the recent geological past.


Geological studies in Colorado indicate that there are about 90 faults that moved during the Quaternary Period (the last 1.6 million years) and should be considered potentially active. The Sangre de Cristo Fault, which lies at the base of the Sangre de Cristo Mountains along the eastern edge of the San Luis Valley, and the Sawatch Fault, which runs along the eastern margin of the Sawatch Range, are two of the most prominent potentially active faults in Colorado. Not all of Colorado’s potentially active faults are in the mountains and some can not be seen at the earth’s surface. For example, the Cheraw Fault, which is in the Great Plains in southeast Colorado, appears to have had movement during the recent geologic past. The Derby Fault near Commerce City lies thousands of feet below the earth’s surface but has not been recognized at ground level.


Several potentially active faults in Colorado are thought to be capable of causing earthquakes as large as magnitude 6½ to 7¼. In comparison, California has hundreds of hazardous faults, some of which can cause earthquakes of magnitude 8 or larger. The time interval between large earthquakes on faults in Colorado is generally much longer than on faults in California.


Past and Possible Future Earthquakes

More than 500 earthquake tremors of magnitude 2½ or higher have been recorded in Colorado since 1867. More earthquakes of magnitude 2½ to 3 probably occurred during that time, but were not recorded because of the sparse distribution of population and limited instrumental coverage in much of the state. For comparison, more than 20,500 similar-sized events have been recorded in California during the same time period. The largest known earthquake in Colorado occurred on November 7, 1882 and had an estimated magnitude of 6½. The location of this earthquake was in the northern Front Range west of Fort Collins.



COLORADO’S LARGEST HISTORIC EARTHQUAKES
(Records date back to 1867)

* = magnitude estimated for older earthquake; based on historical felt reports

Although many of Colorado’s earthquakes occurred in mountainous regions of the state, some have been located in the western valley and plateau region or east of the mountains. The most economically damaging earthquake in Colorado’s history occurred on August 9, 1967 in the northeast Denver metropolitan area. This magnitude 5.3 earthquake, which was centered near Commerce City, caused more than a million dollars damage in Denver and the northern suburbs. This earthquake is believed to have been induced by the deep injection of liquid waste into a borehole at Rocky Mountain Arsenal. It was followed by an earthquake of magnitude 5.2 three months later in November 1967. Although these events cannot be classified as major earthquakes, they should not be discounted as insignificant. They occurred within Colorado’s Front Range Urban Corridor, an area where nearly 75% of Colorado residents and many critical facilities are located. Since March 1971, well after the initial flurry of seismic activity, 15 earthquakes of approximate magnitude 2½ or larger have occurred in the vicinity of the northern Denver suburbs. At least two published articles propose that a magnitude 6.0 earthquake is possible on the Derby fault. Such an earthquake would cause more than $10 billion dollars damage.


Relative to other western states, Colorado’s earthquake hazard is higher than Kansas or Oklahoma, but lower than Utah, and certainly much lower than Nevada and California. Even though the seismic hazard in Colorado is low to moderate, it is likely that future damaging earthquakes will occur. It is prudent to expect future earthquakes as large as magnitude 6.5, the largest event of record. Calculations based on the historical earthquake record and geological evidence of recent fault activity suggest that an earthquake of magnitude 6 or greater may be expected somewhere in Colorado every several centuries.
Summary and Conclusions

Based on the historical earthquake record and geologic studies in Colorado, an event of magnitude 6½ to 7¼ could occur somewhere in the state. Scientists are unable to accurately predict when the next major earthquake will occur in Colorado, only that one will occur. The major factor preventing the precise identification of the time or location of the next damaging earthquake is the limited knowledge of potentially active faults. Given Colorado’s continuing active economic growth and the accompanying expansion of population and infrastructure, it is prudent to continue the study and analysis of earthquake hazards. Existing knowledge should be used to incorporate appropriate levels of seismic safety in building codes and practices. The continued and expanded use of seismic safety provisions in critical and vulnerable structures and in emergency planning statewide is also recommended. Concurrently, we should expand earthquake monitoring, geological and geophysical research, and mitigation planning.


The information contained herein is intended to provide general information to the public and should not be used for site-specific engineering purposes. Seismic hazard assessment for a particular location should incorporate an appropriate engineering evaluation.


Further Published Information
The Colorado Geological Survey has several publications on Colorado earthquakes and potentially active faults, and maintains a reference collection on Colorado seismicity that includes reports by consultants or agencies. A listing of the reports can be viewed at the CGS web site, http://geosurvey.state.co.us/Default.aspx?tabid=296


Last Updated : 12/20/2004

http://geosurvey.state.co.us/Default.aspx?tabid=303

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For the moment, links to the USGS in Golden, Colorado are not working...

MAP 5.3 2011/04/10 16:18:19 -23.559 179.854 520.4 SOUTH OF THE FIJI ISLANDS
MAP 5.0 2011/04/10 04:45:22 -28.754 -176.962 31.6 KERMADEC ISLANDS REGION


Magnitude 5.3
Date-Time Sunday, April 10, 2011 at 16:18:19 UTC
Monday, April 11, 2011 at 04:18:19 AM at epicenter

Location 23.559°S, 179.854°E
Depth 520.4 km (323.4 miles)
Region SOUTH OF THE FIJI ISLANDS
Distances 622 km (386 miles) SSE (166°) from SUVA, Fiji
1558 km (968 miles) NNE (20°) from Auckland, New Zealand

Location Uncertainty horizontal +/- 17.5 km (10.9 miles); depth +/- 9.6 km (6.0 miles)
Parameters NST=160, Nph=165, Dmin=671.3 km, Rmss=0.77 sec, Gp= 97°,
M-type=body wave magnitude (Mb), Version=7
Source U.S. Geological Survey, National Earthquake Information Center:
World Data Center for Seismology, Denver

Event ID usc0002mnc



Magnitude 5.0
Date-Time Sunday, April 10, 2011 at 04:45:22 UTC
Sunday, April 10, 2011 at 04:45:22 PM at epicenter
Time of Earthquake in other Time Zones

Location 28.754°S, 176.962°W
Depth 31.6 km (19.6 miles)
Region KERMADEC ISLANDS REGION
Distances 108 km (67 miles) ENE of Raoul Island, Kermadec Islands
351 km (218 miles) NNE of L'Esperance Rock, Kermadec Islands
862 km (535 miles) SSW of NUKU`ALOFA, Tonga
1187 km (737 miles) NE of Auckland, New Zealand

Location Uncertainty horizontal +/- 22.4 km (13.9 miles); depth +/- 7.7 km (4.8 miles)
Parameters NST= 92, Nph= 98, Dmin=>999 km, Rmss=0.69 sec, Gp= 58°,
M-type=body wave magnitude (Mb), Version=7
Source USGS NEIC (WDCS-D)


Event ID usc0002mle

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http://www.fijitimes.com/story.aspx?id=167847

Daily tremors good for Fiji
Avinesh Gopal
Wednesday, March 09, 2011

TREMORS in the Fiji Group are recorded almost every day by seismologists but they're often minor to moderate in size and cannot be felt on the earth's surface.

The epicentre of the tremors is between 400 and 500 kilometres within the earth's inner crust and most measure around three on the Richter scale.

"It's good to have small ones like that because the energy is released from right down below," Sefanaia Seru, a seismologist with the Mineral Resources Department, said.

"We normally record tremors every day but most are minor to moderate in size and people can't feel it on the surface because it's deep down.

"There are actually two major active fault lines - one is above the Yasawa Group and extends to Taveuni while the other is in the South of Kadavu.

"In reality, we can't forecast earthquakes like cyclones and even seismologists globally can't predict it - that's the major problem.

"Only when it happens then we can tell and how frequently it happens is all a matter of timing."

Mr Seru said Fiji was unfortunate to sit on the Pacific Ring of Fire, which includes Vanuatu and the Tonga region.

"Because the trench where the two big tectonic plates meet is far from us, the Tonga and Vanuatu trenches are the tsunami triggering zones and if there's a tsunami from there then we in Fiji have sufficient time to be warned," he said.

"We have active fault lines in Fiji that can generate a tsunami like in 1953 but the probability is low."

Mr Seru said the only way people could prepare themselves from an earthquake was by strengthening buildings and reinforcing their houses.

"For a tsunami, people in low-lying areas should have their own evacuation routes to higher ground whenever there is a warning," he said.