PHOTO EARTHQUAKE EFFECT WARNING

Eartquake NORTHERN CALIFORNIA Magnitude 3.5

noreply@blogger.com (Network Corp) — Wed, 13 May 2009 21:12:10 PDT

Lats Week we hear about Magnitude 2.6 - PUERTO RICO REGION, but now I want to share about earthquake in Caifornina. Here there are:

Earthquake Details

Magnitude	3.5
Date-Time	Thursday, April 30, 2009 at 22:50:54 UTC Thursday, April 30, 2009 at 03:50:54 PM at epicenter Time of Earthquake in other Time Zones
Location	37.254°N, 121.636°W
Depth	6.6 km (4.1 miles)
Region	NORTHERN CALIFORNIA
Distances	14 km (9 miles) N (3°) from Morgan Hill, CA 18 km (11 miles) ESE (102°) from Seven Trees, CA 19 km (12 miles) N (350°) from San Martin, CA 25 km (15 miles) ESE (113°) from San Jose City Hall, CA
Location Uncertainty	horizontal +/- 0.1 km (0.1 miles); depth +/- 0.3 km (0.2 miles)
Parameters	Nph=116, Dmin=3 km, Rmss=0.08 sec, Gp= 32°, M-type=regional moment magnitude (Mw), Version=3
Source	California Integrated Seismic Net: USGS Caltech CGS UCB UCSD UNR

Solution reviewed by rick

Hypocentral Location:
Event ID	51220793
Origin Time	2009/04/30 22:50:55
Latitude	37.2538
Longitude	-121.6383
Depth (TT)	5.5 km
Depth (MT; not authoritative)	8 km fixed

Magnitudes:
Md	3.64 (not authoritative)
Ml	3.72 (not authoritative)
Mw	3.51 (authoritative)

Deviatoric Solution:
Scale	10**21 Dyne-cm
Axis	Value	Plunge	Azimuth
T	2.421	2	281
N	-0.213	87	69
P	-2.207	2	191

Source Composition:
Type	Percent
DC	82
CLVD	18
Iso	(null)

Moment Tensor:
Moment	2.31e+21 Dyne-cm
Scale	1.0e+21 Dyne-cm
Mxx	-2.038
Mxy	-0.862
Mxz	0.073
Myy	2.248
Myz	-0.103
Mzz	-0.210
Variance Reduction	75%

Best-fit Double Couple Solution
Plane	Strike	Rake	Dip
NP1	56	3	89
NP2	326	179	87

Moment Tensor:
Moment	2.31e+21 Dyne-cm
Scale	1.0e+21 Dyne-cm
Mxx	-2.038
Mxy	-0.862
Mxz	0.073
Myy	2.248
Myz	-0.103
Mzz	-0.210
Variance Reduction	75%

Waveform data (solid line) and synthetic data (dashed line) from the moment tensor inversion:

Magnitude 2.6 - PUERTO RICO REGION

noreply@blogger.com (Network Corp) — Sat, 25 Apr 2009 03:02:05 PDT

Earthquake Details

Magnitude 2.6 - PUERTO RICO REGION

Magnitude	2.6
Date-Time	Saturday, April 25, 2009 at 02:02:16 UTC Friday, April 24, 2009 at 10:02:16 PM at epicenter
Location	18.947°N, 67.021°W
Depth	44.8 km (27.8 miles)
Region	PUERTO RICO REGION
Distances	50 km (31 miles) N (0°) from Isabela, PR 53 km (33 miles) N (351°) from Quebradillas, PR 53 km (33 miles) N (7°) from Rafael Hernández, PR 107 km (66 miles) WNW (299°) from SAN JUAN, Puerto Rico
Location Uncertainty	horizontal +/- 1.7 km (1.1 miles); depth +/- 3.8 km (2.4 miles)
Parameters	Nph=018, Dmin=53.9 km, Rmss=0.26 sec, Gp=292°, M-type=duration magnitude (Md), Version=1
Source	Puerto Rico Seismic Network, University of Puerto Rico
Event ID	prp0911502

Earthquake Magnitude 6.7 On 2009 April 16 14:57:06 UTC SOUTH SANDWICH ISLANDS REGION

noreply@blogger.com (Network Corp) — Mon, 20 Apr 2009 11:04:38 PDT

Earthquake Details

Magnitude	6.7
Date-Time	Thursday, April 16, 2009 at 14:57:06 UTC Thursday, April 16, 2009 at 12:57:06 PM at epicenter Time of Earthquake in other Time Zones
Location	60.187°S, 26.845°W
Depth	20 km (12.4 miles) set by location program
Region	SOUTH SANDWICH ISLANDS REGION
Distances	135 km (85 miles) S of Bristol Island, South Sandwich Islands 390 km (240 miles) S of Visokoi Island, South Sandwich Islands 885 km (550 miles) SE of Grytviken, South Georgia 3330 km (2070 miles) N of South Pole, Antarctica
Location Uncertainty	horizontal +/- 6.9 km (4.3 miles); depth fixed by location program
Parameters	NST=149, Nph=149, Dmin=>999 km, Rmss=0.79 sec, Gp= 43°, M-type=centroid moment magnitude (Mw), Version=A
Source	USGS NEIC (WDCS-D)
Event ID	us2009fma2

Magnitude 5.2 KYRGYZSTAN on Sunday, April 19, 2009 at 04:08:20 UTC

noreply@blogger.com (Network Corp) — Sat, 18 Apr 2009 21:57:05 PDT

Major Tectonic Boundaries: Subduction Zones -purple, Ridges -red and Transform Faults -green

Earthquake Location KYRGYZSTAN

Preliminary Earthquake Report
U.S. Geological Survey, National Earthquake Information Center
World Data Center for Seismology, Denver

Earthquake Details

Magnitude	5.2
Date-Time	Sunday, April 19, 2009 at 04:08:20 UTC Sunday, April 19, 2009 at 10:08:20 AM at epicenter Time of Earthquake in other Time Zones
Location	41.300°N, 78.221°E
Depth	27.2 km (16.9 miles)
Region	KYRGYZSTAN
Distances	135 km (85 miles) S of Karakol (Przhevalsk), Kyrgyzstan 175 km (105 miles) W of Aksu, Xinjiang, China 185 km (115 miles) E of Naryn, Kyrgyzstan 335 km (210 miles) ESE of BISHKEK (Frunze), Kyrgyzstan
Location Uncertainty	horizontal +/- 7.9 km (4.9 miles); depth +/- 18.3 km (11.4 miles)
Parameters	NST= 65, Nph= 65, Dmin=282.4 km, Rmss=0.95 sec, Gp= 94°, M-type=body wave magnitude (Mb), Version=7
Source	USGS NEIC (WDCS-D)
Event ID	us2009fqai

Optical in the New York Times?!

noreply@blogger.com (Network Corp) — Thu, 12 Feb 2009 21:02:40 PST

If you need a cheap pair of glasses, optical Zenni is the place. For this reason, NewYork Times recommends to us to buy the cheap monocle but the best quality of optical Zenni. Zenni Optical in the New York Times?! Yes, you can read it Seeing Straight Without Breaking Bank

Prescription eyeglasses for only $8! You can visit the optical site of Zenni to find your glasses preferred.

I like this pair of glasses. It is metal alloy of Full-Rim with the hinge of spring. The price is only $9.95.

Holiday Glass Frames

noreply@blogger.com (Network Corp) — Tue, 25 Nov 2008 05:30:09 PST

Remember the popular online eyeglasses shop that I mentioned few posts earlier? Besides the well known $ 8 Complete Rx Eyeglasses, there are now Holiday Glass Frames from Zenni Optical. Doesn't that put a smile on your face? Christmas is coming real soon and a pair of new glasses that matches the holiday spirit will definitely add some spark in the celebration. Shop on!

Zenni Optical was on FOX news!

noreply@blogger.com (Network Corp) — Thu, 06 Nov 2008 11:10:33 PST

Zenni Optical was on FOX news! And why not? They are the only online store which offers Great Eyeglasses For Less . They have also many designs to the mode to choose and in almost any color you can think of. You can also chose many Variable Dimension Frames From Zenni.

If you want to check it video about them, observe Zenni on Fox.

Help for Essay

noreply@blogger.com (Network Corp) — Thu, 02 Oct 2008 03:50:47 PDT

customer writing offers professional essays writing company, research papers and term papers templates writing, editing and proofreading for college, school and university students. We have professional as custom essay writer in UK and US writers, all our written assignments are 100% plagiarism free. Students can use our professionally written assignments to write their own A+ work. More information can be found on our website.

Earthquake Bay Area

noreply@blogger.com (Network Corp) — Fri, 06 Jun 2008 04:34:57 PDT

You'll never have warned that an earthquake. To ensure that you and your house are prepared, you should:

* Secure cabinets and bookcases against the wall with screws. Also try to keep heavy objects on lower shelves, so they do not fall on you during an earthquake.
* Make sure the boiler is fixed to a wall. In this way it will not fall during an earthquake and hurt someone or a fire.
* If you live in an area that for a large proportion of earthquakes, make sure that your house is bolted to your foundation. While this may expensive, can save you from a lot of damage to your house during an earthquake. More information.
* Have a disaster.

Here are some tips on what to do during an earthquake:

* Ga not outwards. You could get hurt falling glass or parts of buildings. If you are outside, stay away from buildings and power lines.
* Use a desk, table or some other large and stable piece of furniture. Hold on. Or, stand in a doorway and brace yourself.
* Keep away from windows, heavy furniture, appliances, mirrors, photos, and anything else that could fall and hurt you. Also stay away from open fires. You can lose your balance and hurt yourself on the fire.
* If you are driving when an earthquake happens, stop the car when it was safe. Stay in your car until the earthquake stops, and not driving in the vicinity of bridges or tunnels. Do not try to stop by power lines, light posts, signs, or trees. This could fall and hurt you.
* Stay alert for falling objects. Most people injured by falling objects during an earthquake, not by shaking itself.
* Do NOT use matches, lighters or candles. If there is a broken gas line, which you could ignite a fire or explosion.
* Do NOT use elevators. There would be a power outage caused by the earthquake, and you could get stuck in the lift.

After the earthquake stops, here is what you should do:

* Check yourself and others for injuries. Call 911 if you or someone else should seek medical help. If the telephone lines do not work, try using a mobile phone.
* Make sure the electrical, water, gas and lines have been damaged. If so, cut off from the valves. If you smell gas, and discover what to do.
* Stay away from damaged buildings and sites. You could get hurt by broken glass and falling objects.
* Listen to the radio for more information.

Blogged with Flock

Earthquake 5.9 Mw 5 Februari 2008

noreply@blogger.com (Network Corp) — Wed, 13 Feb 2008 06:02:55 PST

A friend telephoned from Balikpapan told how an earthquake was a moment ago felt by him in the oil city, coal, and this wood.

After being checked in the USGS site, this earthquake happened struck 13,56 WITA (struck 12,56 WIB) have a force 5,9 Mw (6.2 SR) with the depth hiposentrum 44,8 km.

The earthquake was located in middle sea of the Makassar Strait the southern part, a line with the Majene city in Sulawesi Barat.

It was not yet known whether this earthquake triggered the tsunami.

Possibly not, the earthquake was still being not stronger.

The history of torque tensor from database USGS also did not show the existence of the mechanism of the earthquake with the fault pure the fault rose in this territory.

This kind fault was known that often caused the tsunami.

Along with the quotation of the details data about the earthquake came from the USGS site:
Earthquake Details Magnitude 5.9 Date-Time
Tuesday, February 05, 2008 at 05:56:51 UTC
Tuesday, February 05, 2008 at 01:56:51 PM at epicenter
Time of Earthquake in other Time Zones Location 3.498°S, 118.117°E
Depth 44.8 km (27.8 miles) Region SULAWESI, INDONESIA Distances 235 km
(145 miles) NW of Ujung Pandang, Sulawesi, Indonesia
285 km (180 miles) SSE of Balikpapan, Kalimantan, Indonesia
345 km (215 miles) SW of Palu, Sulawesi, Indonesia
1290 km (800 miles) ENE of JAKARTA, Java, Indonesia
Location Uncertainty horizontal +/- 14.3 km (8.9 miles); depth +/- 17.2 km
(10.7 miles) Parameters Nst= 49, Nph= 49, Dmin=>999 km, Rmss=1.17 sec, Gp=
83°,
M-type=moment magnitude (Mw), Version=7 Source USGS NEIC (WDCS-D)

Geologically, the location hiposentrum the exact earthquake was in the east bank the Paternoster micro-continent that at the same time limiting the South Makassar Basin to the west.

This position was the weak zone that accommodated the Makassar Strait opening the southern part for Paleogen; also had a position to the crack pattern other in the east bank of the Sundanese Mainland (Sundaland) that at the moment had a direction BL-Tenggara and SBD-UTL. Tectonically, then could be said that hiposentrum was in lineasi2 weak tectonics.

The distribution of the epicenter in this territory for the last 20 years not until ten points with the depth in general hiposentrum below 35 km and magnitude around 5 Mw.

The location of the distribution of the centers of this earthquake was arranged in all the patterns lineasi tectonics that has been known by us until now like the Adang Fault, retakan2 in Makassar Selatan, and lineasi Meratus.

Crack the stable Paternoster continent was avoided by the earthquake.

This found it easy to be understood because of the earthquake most happened in unit banks tectonics-geology.

But, understood because kinematics of this earthquake was not easy.

Earthquakes that were located all along the Adang Fault and crossed to the Walanae Fault in South Sulawesi still could be understood because these big faults formed a kind freeway down to Sumba Fracture that was previous hub to sub diction fault the Indian Ocean under Nusa Tenggara.

This earthquake incident showed a reality that the east bank of the Sundanese Mainland in forever did not yet die moving although was locked by the Buton collision and Banggai-Sula on the south-east and east Sulawesi.

There is lineasi2 latent geology that evidently still could be awakened by the style whether from where.

Chille Earthquake

noreply@blogger.com (Network Corp) — Wed, 13 Feb 2008 05:45:35 PST

The earthquake had the force of 6,6 in the Richter scale has shook the Chille northern part and according to the seismology body, the earthquake happened close to the Peruvian border.
The Nation Emergency of Chle office said was gathering information in the area where the earthquake was felt, but did not have the report on early about casualties and damage.

Mexico Earthquake Report

noreply@blogger.com (Network Corp) — Tue, 12 Feb 2008 09:34:32 PST

The earthquake had the force of 5.4 in the scale richter shook the Californian Steel peninsula in Mexico.
Several buildings were it was reported broken and the electricity current was for hundreds of thousands of houses interrupted.
Was still not gotten the report about the number of injury casualties or again bigger damage.
The jolt was also felt in the Californian state and Arizona in the USA.

The Danau Kivu Earthquake

noreply@blogger.com (Network Corp) — Sun, 10 Feb 2008 09:44:14 PST

The Danau Kivu earthquake 2008 was the earthquake that shook several countries in the Big Lake Africa territory in struck 07:34:12 (UTC) on February 3.
This earthquake had the strength of 6.0 Richter scales and shook for 15 seconds.
Epicenter was located 20 kilometers next east Bukavu in the Kivu Lake in the Demokratik Kongo Republic.

The earthquake shook Rwanda and the Democratic Republic Congo (DRC), on Sunday (2-2) local time or on Monday WIB, claimed 38 souls and damaged 550 people, said several officials.

Two earthquakes happened in time that was adjacent in the Great Lakes region all along the west Great Rift Valley fracture.

The first earthquake, that had the force of 6 SR (the Richter scale) and concentrated in DRC, happened struck 10,30 local time (struck 14,30 WIB), that was followed with the second earthquake in the area had a solid population in South Rwandan struck 13,56 (struck 17,56 WIB).

"The number of deaths (in Rwanda) increased to 33 and more than 400 people" of the "serious injury," said the Deputy the Head of Rwandan police of Mary Gahonzire to Reuters.

Rescue efforts were still continuing to be carried out.

The official Governor Province South Kivu Kongo Bernard Watunakanza said to the Reuters news agency through the telephone from the east Bukavu territory city, aftershocks happened every time 20 or 30 minutes.

"Up to now had five people who were killed and 149 people" of the "serious injury."

Many people experienced the trauma, he said.

An official of the peacekeeper's UN mission in Kongo that was known as MONUC, to say buildings were destroyed in Bukavu.

"Much damage."

Many buildings were affected.

Many houses were fully destroyed, said the spokesperson MONUC Jacqueline Chenard.

The normal earthquake happened in the west Great Rift Valley region in the area of the seismic fracture active that was located between Uganda west, DRC Timur, Rwanda, and his neighbouring country, Tanzania.

In 1994, the earthquake 6 Richter scales in the Rwenzori region of the mountainous valley, Ugandan Barat, killed six people.

In 1996, the earthquake had the force of 7 Richter scales killed 157 people and damaged more than 1,300 people in Semliki Valley, also in Uganda west.

September 2007 Sumatra earthquakes

noreply@blogger.com (Network Corp) — Mon, 12 Nov 2007 03:53:55 PST

The September 2007 Sumatra earthquakes were a series of earthquakes that struck the Java Trench off the coast of Sumatra, Indonesia, three greater than magnitude 7. A series of tsunami bulletins was issued for the area.

Timeline

The first earthquake occurred at 11:10:26 UTC (18:10 local time) on 12 September 2007, and was an 8.4 Mw[1] earthquake on the moment magnitude scale. It was centered about 34 km underground, at [show location on an interactive map] 4.520° S 101.374° E, about 130 km southwest of Bengkulu on the southwest coast of Sumatra, Indonesia, and some 600 km west-northwest of Indonesia's capital city, Jakarta. It was followed by several earthquakes of magnitude 5 through 6 along the same fault, west of Sumatra.

The second largest earthquake, 7.9 Mw,[3] occurred later the same day at 23:49:04 UTC (06:49:04 local time the following day). It was centred about 10 km underground, at [show location on an interactive map] 2.506° S 100.906° E, some 185 km (115 miles) south-southeast of Padang, Indonesia and about 205 km northwest of Bengkulu (about 225 km northwest of the magnitude 8.4 earthquake).

After further aftershocks above magnitude 5, a third earthquake, 7.0 Mw,[4] occurred at 03:35:26 UTC (10:35:26 local time) on 13 September. It was centred about 10 km underground, at [show location on an interactive map] 2.160° S 99.851° E, some 165 km south-southwest of Padang and 345 km west-northwest of Bengkulu.

Aftershocks continued into 13 September and 14 September , with more earthquakes ranging up to magnitude 6.4.[5] Most of the aftershocks have been northwest of the original magnitude 8.4 earthquake.

Tidal buoys[6] positioned in the Indian Ocean and other seismic tools have led scientists to issue a series of tsunami bulletins.

Effects

The tremors of the 8.4 Mw earthquake lasted for several minutes. It caused buildings to sway in Jakarta, and some buildings were reported to have collapsed in the city of Bengkulu, Province Bengkulu, about 100 km from the epicentre. Tremors felt in Jakarta were described as being "violent".[8] It was reported that several high-rise buildings were evacuated.[9] At least one person was killed, having been struck by a falling tree during evacuation, and dozens were injured. The earthquake also led to a power outage in Bengkulu, which has crippled communications. Consequently, the extent of damage in areas near the epicenter remains largely unknown.[9] The death toll of the earthquakes is 21 with 88 people injured. [10]

Tremors were felt in neighbouring countries as far away as Southern Thailand.[11][12] In Singapore, which is about 670 km from the epicenter, the tremor was felt at around 11:10 UTC (19:10 local time).[13] Most of the Central and Eastern part of Singapore has felt the tremor.[14] In Peninsular Malaysia, tremors were reported after 19:15 local time, including Kuala Lumpur, Putrajaya, Johor Bahru, Malacca and Penang. Like Singapore, the tremors were most severe on high-rises, resulting in minor panic and evacuations. No casualties were reported in the country, as of September 13.

Tsunami

Sea level readings indicated that a tsunami was generated. A total of 4 tsunami alerts were issued in 24 hours. After the first, and largest, earthquake, the Pacific Tsunami Warning Centre issued a tsunami alert for much of the Indian Ocean basin. A tsunami approximately 1 metre high was reported at Padang, Indonesia.[17] A small tsunami, some 15 cm high, was reported at the Cocos Islands.[18] Sumatra was taken off tsunami alert after two hours.

Tsunami warnings were also issued in India and other countries around the Indian Ocean soon after the earthquake. The Government of India asked the states of Tamil Nadu, Kerala, Andhra Pradesh and the union territories of Andaman and Nicobar Islands and Puducherry to be on high alert.[19] By late September 12, the tsunami warning was recalled.[20] Similarly, a tsunami alert was issued in Peninsular Malaysia at 20:50 (local time) for the coastal areas of Perlis, Kedah, Perak and Penang; the alert was lifted two hours later. However, Malaysian authorities had detected a 1-3m high tsunami heading away from the epicentre of the earthquake.

Tectonic summary

According to the US Geological Survey,[21] the earthquake was caused by thrust faulting on the boundary between the Australian Plate and the Sunda Plate. At the location of the earthquake, offshore of the west coast of Sumatra, the Australia plate moves northeast with respect to the Sunda Plate at a velocity of about 69 mm/year, oblique to the orientation of the plate boundary. The component of plate motion perpendicular to the boundary produces thrust faulting on the offshore plate-boundary.

The magnitude 7.9 earthquake was also a result of thrust faulting on the same plate boundary. It occurred about 225 km northwest of the magnitude 8.4 earthquake, at the northern end of the aftershock zone.[22]

The magnitude 8.4 earthquake was the most powerful earthquake of 2007 to date, more powerful than the two March 2007 Sumatra earthquakes nearby and the 2007 Peru earthquake. It was the second most powerful earthquake since the magnitude 9.3 2004 Indian Ocean earthquake, exceeded only by the magnitude 8.6 2005 Sumatra earthquake. The two largest earthquakes were the fourth and fifth earthquakes with magnitude 7.9 or greater to have occurred on or near the plate boundaries offshore of western Sumatra in 7 years, the others being the magnitude 7.9 earthquake of June 4, 2000; the magnitude 9.3 2004 Indian Ocean earthquake on December 26, 2004; and the magnitude 8.6 2005 Sumatra earthquake on March 28, 2005.

According to data from the Japanese PALSAR microwave sensor aboard the Daichi(ALOS) satelite, South Pagai Island was uplifted, creating 6 new islands, and exposing previously submerged coral reefs as well as enlarging existing islands.

Earthquake

noreply@blogger.com (Network Corp) — Mon, 12 Nov 2007 03:49:37 PST

An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. Earthquakes are recorded with a seismometer, also known as a seismograph. The moment magnitude of an earthquake is conventionally reported, or the related and mostly obsolete Richter magnitude, with magnitude 3 or lower earthquakes being mostly imperceptible and magnitude 7 causing serious damage over large areas. Intensity of shaking is measured on the modified Mercalli scale.

At the Earth's surface, earthquakes manifest themselves by a shaking and sometimes displacement of the ground. When a large earthquake epicenter is located offshore, the seabed sometimes suffers sufficient displacement to cause a tsunami. The shaking in earthquakes can also trigger landslides and occasionally volcanic activity.

In its most generic sense, the word earthquake is used to describe any seismic event—whether a natural phenomenon or an event caused by humans—that generates seismic waves. Earthquakes are caused mostly by rupture of geological faults, but also by volcanic activity, landslides, mine blasts, and nuclear experiments.

An earthquake's point of initial rupture is called its focus or hypocenter. The term epicenter means the point at ground level directly above this.

Naturally occurring earthquakes

Most naturally occurring earthquakes are related to the tectonic nature of the Earth. Such earthquakes are called tectonic earthquakes. The Earth's lithosphere is a patchwork of plates in slow but constant motion caused by the release to space of the heat in the Earth's mantle and core. The heat causes the rock in the Earth to become flow on geological timescales, so that the plates move slowly but surely. Plate boundaries lock as the plates move past each other, creating frictional stress. When the frictional stress exceeds a critical value, called local strength, a sudden failure occurs. The boundary of tectonic plates along which failure occurs is called the fault plane. When the failure at the fault plane results in a violent displacement of the Earth's crust, energy is released as a combination of radiated elastic strain seismic waves, frictional heating of the fault surface, and cracking of the rock, thus causing an earthquake. This process of gradual build-up of strain and stress punctuated by occasional sudden earthquake failure is referred to as the Elastic-rebound theory. It is estimated that only 10 percent or less of an earthquake's total energy is radiated as seismic energy. Most of the earthquake's energy is used to power the earthquake fracture growth or is converted into heat generated by friction. Therefore, earthquakes lower the Earth's available elastic potential energy and raise its temperature, though these changes are negligible compared to the conductive and convective flow of heat out from the Earth's deep interior.[1]

The majority of tectonic earthquakes originate at depths not exceeding tens of kilometers. In subduction zones, where older and colder oceanic crust descends beneath another tectonic plate, Deep focus earthquakes may occur at much greater depths (up to seven hundred kilometers). These seismically active areas of subduction are known as Wadati-Benioff zones. These are earthquakes that occur at a depth at which the subducted lithosphere should no longer be brittle, due to the high temperature and pressure. A possible mechanism for the generation of deep focus earthquakes is faulting caused by olivine undergoing a phase transition into a spinel structure.[2]

Earthquakes also often occur in volcanic regions and are caused there both by tectonic faults and by the movement of magma in volcanoes. Such earthquakes can serve as an early warning of volcanic eruptions.

Sometimes a series of earthquakes occur in a sort of earthquake storm, where the earthquakes strike a fault in clusters, each triggered by the shaking or stress redistribution of the previous earthquakes. Similar to aftershocks but on adjacent segments of fault, these storms occur over the course of years, and with some of the later earthquakes as damaging as the early ones. Such a pattern was observed in the sequence of about a dozen earthquakes that struck the North Anatolian Fault in Turkey in the 20th century, the half dozen large earthquakes in New Madrid in 1811-1812, and has been inferred for older anomalous clusters of large earthquakes in the Middle East and in the Mojave Desert.

Size and frequency of occurrence

Small earthquakes occur nearly constantly around the world in places like California and Alaska in the U.S., as well as in Chile, Peru, Indonesia, Iran, the Azores in Portugal, New Zealand, Greece and Japan.[3] Large earthquakes occur less frequently, the relationship being exponential; for example, roughly ten times as many earthquakes larger than magnitude 4 occur in a particular time period than earthquakes larger than magnitude 5. In the (low seismicity) United Kingdom, for example, it has been calculated that the average recurrences are:

* an earthquake of 3.7 - 4.6 every year
* an earthquake of 4.7 - 5.5 every 10 years
* an earthquake of 5.6 or larger every 100 years.

The number of seismic stations has increased from about 350 in 1931 to many thousands today. As a result, many more earthquakes are reported than in the past because of the vast improvement in instrumentation (not because the number of earthquakes has increased). The USGS estimates that, since 1900, there have been an average of 18 major earthquakes (magnitude 7.0-7.9) and one great earthquake (magnitude 8.0 or greater) per year, and that this average has been relatively stable.[4] In fact, in recent years, the number of major earthquakes per year has actually decreased, although this is likely a statistical fluctuation. More detailed statistics on the size and frequency of earthquakes is available from the USGS.[5]

Most of the world's earthquakes (90%, and 81% of the largest) take place in the 40,000-km-long, horseshoe-shaped zone called the circum-Pacific seismic belt, also known as the Pacific Ring of Fire, which for the most part bounds the Pacific Plate.[6][7] Massive earthquakes tend to occur along other plate boundaries, too, such as along the Himalayan Mountains.

Effects/impacts of earthquakes
Chūetsu earthquake.
Chūetsu earthquake.
Smoldering after the 1906 San Francisco earthquake.
Smoldering after the 1906 San Francisco earthquake.
Man walking around in ruins after tsunami.
Man walking around in ruins after tsunami.

There are many effects of earthquakes including, but not limited to the following:

Shaking and ground rupture

Shaking and ground rupture are the main effects created by earthquakes, principally resulting in more or less severe damage to buildings or other rigid structures. The severity of the local effects depends on the complex combination of the earthquake magnitude, the distance from epicenter, and the local geological and geomorphological conditions, which may amplify or reduce wave propagation. The ground-shaking is measured by ground acceleration.

Specific local geological, geomorphological, and geostructural features can induce high levels of shaking on the ground surface even from low-intensity earthquakes. This effect is called site or local amplification. It is principally due to the transfer of the seismic motion from hard deep soils to soft superficial soils and to effects of seismic energy focalization owing to typical geometrical setting of the deposits.

Ground rupture is a visible breaking and displacement of the earth's surface along the trace of the fault, which may be of the order of few metres in the case of major earthquakes. Ground rupture is a major risk for large engineering structures such as dams, bridges and nuclear power stations and requires careful mapping of existing faults to identify any likely to break the ground surface within the life of the structure.

Landslides and avalanches

Earthquakes can cause landslides and avalanches, which may cause damage in hilly and mountainous areas.

Fires

Following an earthquake, fires can be generated by break of the electrical power or gas lines. In the event of water mains rupturing and a loss of pressure, it may also become difficult to stop the spread of a fire once it has started.

Soil liquefaction

Soil liquefaction occurs when, because of the shaking, water-saturated granular material temporarily loses its strength and transforms from a solid to a liquid. Soil liquefaction may cause rigid structures, as buildings or bridges, to tilt or sink into the liquefied deposits.

Tsunamis

Undersea earthquakes and earthquake-triggered landslides into the sea, can cause Tsunamis. See, for example, the 2004 Indian Ocean earthquake.

Human impacts

Earthquakes may result in disease, lack of basic necessities, loss of life, higher insurance premiums, general property damage, road and bridge damage, and collapse of buildings or destabilization of the base of buildings which may lead to collapse in future earthquakes.

This can cause total devistation for those affected as the country may not have the funds for the regeneration of people lives and possesions. An earthquake can ruin someones life forever, only 3% of buildings in kobe, for instance, have earthquake insurance; therefore un-enabling them to get back ont their feet again.

Earthquake

noreply@blogger.com (Network Corp) — Mon, 12 Nov 2007 03:40:51 PST

An earthquake is the result of a sudden release of energy in the Earth's crust that creates seismic waves. Earthquakes are recorded with a seismometer, also known as a seismograph. The moment magnitude of an earthquake is conventionally reported, or the related and mostly obsolete Richter magnitude, with magnitude 3 or lower earthquakes being mostly imperceptible and magnitude 7 causing serious damage over large areas. Intensity of shaking is measured on the modified Mercalli scale.

At the Earth's surface, earthquakes manifest themselves by a shaking and sometimes displacement of the ground. When a large earthquake epicenter is located offshore, the seabed sometimes suffers sufficient displacement to cause a tsunami. The shaking in earthquakes can also trigger landslides and occasionally volcanic activity.

In its most generic sense, the word earthquake is used to describe any seismic event—whether a natural phenomenon or an event caused by humans—that generates seismic waves. Earthquakes are caused mostly by rupture of geological faults, but also by volcanic activity, landslides, mine blasts, and nuclear experiments.

An earthquake's point of initial rupture is called its focus or hypocenter. The term epicenter means the point at ground level directly above this.

Naturally occurring earthquakes
Fault types
Fault types

Most naturally occurring earthquakes are related to the tectonic nature of the Earth. Such earthquakes are called tectonic earthquakes. The Earth's lithosphere is a patchwork of plates in slow but constant motion caused by the release to space of the heat in the Earth's mantle and core. The heat causes the rock in the Earth to become flow on geological timescales, so that the plates move slowly but surely. Plate boundaries lock as the plates move past each other, creating frictional stress. When the frictional stress exceeds a critical value, called local strength, a sudden failure occurs. The boundary of tectonic plates along which failure occurs is called the fault plane. When the failure at the fault plane results in a violent displacement of the Earth's crust, energy is released as a combination of radiated elastic strain seismic waves, frictional heating of the fault surface, and cracking of the rock, thus causing an earthquake. This process of gradual build-up of strain and stress punctuated by occasional sudden earthquake failure is referred to as the Elastic-rebound theory. It is estimated that only 10 percent or less of an earthquake's total energy is radiated as seismic energy. Most of the earthquake's energy is used to power the earthquake fracture growth or is converted into heat generated by friction. Therefore, earthquakes lower the Earth's available elastic potential energy and raise its temperature, though these changes are negligible compared to the conductive and convective flow of heat out from the Earth's deep interior.[1]

The majority of tectonic earthquakes originate at depths not exceeding tens of kilometers. In subduction zones, where older and colder oceanic crust descends beneath another tectonic plate, Deep focus earthquakes may occur at much greater depths (up to seven hundred kilometers). These seismically active areas of subduction are known as Wadati-Benioff zones. These are earthquakes that occur at a depth at which the subducted lithosphere should no longer be brittle, due to the high temperature and pressure. A possible mechanism for the generation of deep focus earthquakes is faulting caused by olivine undergoing a phase transition into a spinel structure.[2]

Earthquakes also often occur in volcanic regions and are caused there both by tectonic faults and by the movement of magma in volcanoes. Such earthquakes can serve as an early warning of volcanic eruptions.

Sometimes a series of earthquakes occur in a sort of earthquake storm, where the earthquakes strike a fault in clusters, each triggered by the shaking or stress redistribution of the previous earthquakes. Similar to aftershocks but on adjacent segments of fault, these storms occur over the course of years, and with some of the later earthquakes as damaging as the early ones. Such a pattern was observed in the sequence of about a dozen earthquakes that struck the North Anatolian Fault in Turkey in the 20th century, the half dozen large earthquakes in New Madrid in 1811-1812, and has been inferred for older anomalous clusters of large earthquakes in the Middle East and in the Mojave Desert.

Size and frequency of occurrence

Small earthquakes occur nearly constantly around the world in places like California and Alaska in the U.S., as well as in Chile, Peru, Indonesia, Iran, the Azores in Portugal, New Zealand, Greece and Japan.[3] Large earthquakes occur less frequently, the relationship being exponential; for example, roughly ten times as many earthquakes larger than magnitude 4 occur in a particular time period than earthquakes larger than magnitude 5. In the (low seismicity) United Kingdom, for example, it has been calculated that the average recurrences are:

* an earthquake of 3.7 - 4.6 every year
* an earthquake of 4.7 - 5.5 every 10 years
* an earthquake of 5.6 or larger every 100 years.

The number of seismic stations has increased from about 350 in 1931 to many thousands today. As a result, many more earthquakes are reported than in the past because of the vast improvement in instrumentation (not because the number of earthquakes has increased). The USGS estimates that, since 1900, there have been an average of 18 major earthquakes (magnitude 7.0-7.9) and one great earthquake (magnitude 8.0 or greater) per year, and that this average has been relatively stable.[4] In fact, in recent years, the number of major earthquakes per year has actually decreased, although this is likely a statistical fluctuation. More detailed statistics on the size and frequency of earthquakes is available from the USGS.[5]

Most of the world's earthquakes (90%, and 81% of the largest) take place in the 40,000-km-long, horseshoe-shaped zone called the circum-Pacific seismic belt, also known as the Pacific Ring of Fire, which for the most part bounds the Pacific Plate.[6][7] Massive earthquakes tend to occur along other plate boundaries, too, such as along the Himalayan Mountains.

Effects/impacts of earthquakes
Chūetsu earthquake.
Chūetsu earthquake.
Smoldering after the 1906 San Francisco earthquake.
Smoldering after the 1906 San Francisco earthquake.
Man walking around in ruins after tsunami.
Man walking around in ruins after tsunami.

There are many effects of earthquakes including, but not limited to the following:

Shaking and ground rupture

Shaking and ground rupture are the main effects created by earthquakes, principally resulting in more or less severe damage to buildings or other rigid structures. The severity of the local effects depends on the complex combination of the earthquake magnitude, the distance from epicenter, and the local geological and geomorphological conditions, which may amplify or reduce wave propagation. The ground-shaking is measured by ground acceleration.

Specific local geological, geomorphological, and geostructural features can induce high levels of shaking on the ground surface even from low-intensity earthquakes. This effect is called site or local amplification. It is principally due to the transfer of the seismic motion from hard deep soils to soft superficial soils and to effects of seismic energy focalization owing to typical geometrical setting of the deposits.

Ground rupture is a visible breaking and displacement of the earth's surface along the trace of the fault, which may be of the order of few metres in the case of major earthquakes. Ground rupture is a major risk for large engineering structures such as dams, bridges and nuclear power stations and requires careful mapping of existing faults to identify any likely to break the ground surface within the life of the structure.

Landslides and avalanches

Earthquakes can cause landslides and avalanches, which may cause damage in hilly and mountainous areas.

Fires

Following an earthquake, fires can be generated by break of the electrical power or gas lines. In the event of water mains rupturing and a loss of pressure, it may also become difficult to stop the spread of a fire once it has started.

Soil liquefaction

Soil liquefaction occurs when, because of the shaking, water-saturated granular material temporarily loses its strength and transforms from a solid to a liquid. Soil liquefaction may cause rigid structures, as buildings or bridges, to tilt or sink into the liquefied deposits.

Tsunamis

Undersea earthquakes and earthquake-triggered landslides into the sea, can cause Tsunamis. See, for example, the 2004 Indian Ocean earthquake.

Human impacts

Earthquakes may result in disease, lack of basic necessities, loss of life, higher insurance premiums, general property damage, road and bridge damage, and collapse of buildings or destabilization of the base of buildings which may lead to collapse in future earthquakes.

This can cause total devistation for those affected as the country may not have the funds for the regeneration of people lives and possesions. An earthquake can ruin someones life forever, only 3% of buildings in kobe, for instance, have earthquake insurance; therefore un-enabling them to get back ont their feet again.