Last update: February 12, 2014 at 1:40 pm by By Armand Vervaeck
Update 13:24 UTC : Cattle is reportedly killed in the greater epicenter area. Some train connections where temporarily suspended in Xinjiang but where restored after inspection of the rails proved that no damage was inflicted (at a big distance from the epicenter).
the picture below shows the (beautiful) scenery in the valley near the epicenter. The epicenter is located in the (not visible) mountains behind this picture. People in Xinjiang are used to earthquakes, even strong earthquakes but primitive old houses are very vulnerable for damage.
Update 11:59 UTC : The Xinjiang seismological authority reports that several houses collapsed in the greater epicenter area. We expect more news from the rescue teams in 1 to 2 hours. The Chinese Earthquake response is one of the quickest and best organized in the world. China has a history of many cruel earthquakes sometimes with +100000 fatalities.
A new shake-map has been published by USGS. They are now reporting a IX MMI in the unpopulated epicenter area.
Update 11:33 UTC :
Official statement from the Xinjiang Earthquake authority :
Yutian County, 7.3 magnitude earthquake.
The Xinjiang autonomous Seismological Bureau immediately launched an emergency plan. We try to quickly find out what happened in the epicenter area and called Yutian County by telephone. Locations in Yutian county felt the earthquake strongly. Buildings in Yutian are reported with cracks. No word of casualties so far.
Officers have been send to the epicenter area to investigate the disaster. Autonomous Region Seismological Bureau intends to sent a 23 people on-site work team with a flight to conduct field work. Hotan Prefecture Earthquake Seismic Bureau has rushed staff to the quake zone to report on the disaster. China Seismological Bureau will sent 13 people for earthquake fieldwork and to assist the local governments to carry out emergency work days.
Update 10:27 UTC: A rescue team was sent by the Xinjiang government to check the affected area.
Update 09:54 UTC : An aftershock of M5.7 @ 5 km depth is just reported by one of my colleagues. Such an aftershock alone can be damaging in China!
Update 09:53 UTC : Max Wyss reports that he expects 0 to 50 fatalities and 0 to 120 injured but his data is based on the USGS data who report a Magnitude of 6.8 at 2 km. Chinese data are more dangerous at 7.3 at 12 km deep. Max Wyss also reports that only 1 small settlement is located within the 50 km radius around the epicenter.
Update 09:49 UTC : A similar strength earthquake along the same fault killed 100 people in 1924!
Update 09:41 UTC : CEIC, the seismological agency of the Chinese government is reporting a Magnitude of 7.3 at a depth of 12 km !
Update 09:39 UTC : The epicenter is located in a sparsely populated area, but the Magnitude is so strong that we expect serious damage and injured people in a radius of at least 50 km.
This earthquake is EXTREMELY DANGEROUS for all villages in a radius of 50 km around the epicenter. Slight damage can be expected in a radius as far as 150 km from the epicenter.
844 km NE of Ludhiāna, India / pop: 1,545,368 / local time: 14:49:48.0 2014-02-12
739 km NE of Shimla, India / pop: 173,503 / local time: 14:49:48.0 2014-02-12
277 km SE of Hotan, China / pop: 114,000 / local time: 17:19:48.0 2014-02-12
Most important Earthquake Data:
Magnitude : 6.9
Local Time (conversion only below land) : 2014-02-12 17:19:50
This report has also been compiled with the help of Ovidiu Pop
Update 04:29 UTC : Plate Tectonics at the North Island
Along the east side of New Zealand’s North Island the oceanic Pacific tectonic plate subducts westward at 4-5 cm/yr
More than a dozen slow slip events (also known as “silent” earthquakes) have been recorded in New Zealand between 2002 and 2012. Scientists have only been able to detect them recently due to the advent of global positioning system (GPS) equipment which can detect sub-centimetre changes in land movements. As part of the GeoNet project in New Zealand, continuously operating GPS have been installed throughout the country. The GeoNet cGPS data show that these silent earthquakes occurring deep under New Zealand are changing the shape of parts of the North Island over time periods of weeks to years. Read the full article here
A similar event than today occurred in 1990. The scientific in-depth report of this earthquake can be consulted here.
Based on our historic map below (major earthquakes since 1900) a M6.8 at a depth of 12 km! occurred close to today’s epicenter in 1917
Update 04:16 UTC : There are NO reports of injuries so far. Minor (hopefully insured) damage like cracks is reported from many locations.
The video below was recorded at a dog race. The camera shows the strong shaking at Sky Racing.
Update 04:04 UTC : Geonet has reviewed the hypocenter a second time and now reports a depth of 33 km.
More pictures of the mainly minor damage here.
Update 03:54 UTC : The picture below shows the strenth of the shaking in Masterton. Picture from Karen Monks via Twitter
Update 03:48 UTC : There are reports of rockfall in the Manawatau Gorge. TranzMetro has suspended all train services in the capital and is replacing them with buses.
Update 03:36 UTC : The earthquake occurred in a sparsely populated area of the North Island. The reports of people living closest to the epicenter are confirming our expectations. These people are reporting strong shaking but NO damage.
Update 03:32 UTC : The many aftershocks are now visible on the seismogram below
Update 03:25 UTC : the earthquake has been felt all over the North Island and the South Island. Geonet has now updated the depth to 50 km (from 65 earlier). We maintain our expectation that minor damage is still possible but that there will be no fatalities or seriously injured people. This is confirmed by the many Experience Reports who have reached Geonet (see below).
Image courtesy and copyright Geonet New Zealand
Update 03:20 UTC : Continuous aftershocks are reported by Geonet
Update 03:15 UTC : Geonet has a preliminary depth of 65 km. Other seismological agencies mostly report shallower depths. If the Geonet depth will be the final one, we expect at least some minor (insured) damage in an area of approx. 30 km from the epicenter. We do however not expect fatalities.
10 km north-west of Castlepoint (Geonet)
38km (24mi) NNE of Masterton, New Zealand (USGS)
39km (24mi) SSE of Palmerston North, New Zealand (USGS)
49km (30mi) E of Levin, New Zealand (USGS)
77km (48mi) ENE of Paraparaumu, New Zealand (USGS)
115km (71mi) NE of Wellington, New Zealand (USGS)
Most important Earthquake Data:
Magnitude : 6.3
Local Time (conversion only below land) : 2014-01-20 15:52:45
Very strong earthquake out of the coast of Puerto Rico – also felt in the Dominican Republic
Last update: January 13, 2014 at 11:46 am by By Ashish Khanal
Update 11:43 UTC : Many people living in the coastal areas auto-evacuated their houses in search for higher ground. An idea earthquake-report.com welcomes as waiting for official alerts always has a small risk.
Update 09:17 UTC : There were also power cuts who where restored shortly after the quake. Due these power cuts the Puerto Rico Seismic Network ceased operations a few seconds after the earthquake occurred !
Many people left their houses in search for higher grounds
Understanding the January 13 Puerto Rico earthquake
The January 13, 2014 M 6.4 earthquake north of Puerto Rico occurred as a result of oblique-thrust faulting. Preliminary faulting mechanisms for the event indicate it ruptured either a structure dipping shallowly to the south and striking approximately east-west, or a near-vertical structure striking northwest-southeast. At the location of this earthquake, the North America plate moves west-southwest with respect to the Caribbean plate at a velocity of approximately 20 mm/yr, and subducts beneath the Caribbean plate at the Puerto Rico Trench. The location, depth and mechanism of the earthquake are consistent with the event occurring on this subduction zone interface.
While the Puerto Rico Trench is known to be a significant seismic hazard, and is capable of hosting M8+ earthquakes, moderate-to-large events on the subduction zone are rare.
Over the past century, three such events have occurred nearby to the January 13, 2014 earthquake – a M 6.6 event in 1915, just to the east of the 2014 event; a M 7.0 earthquake 70 km to the west in 1917; and a M 7.6 earthquake in 1943 just northwest of the 2014 earthquake. Two earthquakes occurred in the Mona Passage approximately 100 km to the southwest of the 2014 earthquake in 1916 (M 7.0) and 1918 (M 7.3), while the 1946 M 7.9-8.0 Hispaniola earthquake struck 230 km to the west, also on the North America slab interface. The July 1943 North Mona Passage earthquake did not cause significant damage in Puerto Rico, though it did spawn a small tsunami, and was the first in a series of large events in the broader northern Caribbean region between central Hispaniola and Puerto Rico over the following decade, including the larger 1946 earthquake. The 1946 event is known to have caused significant damage in both Hispaniola and Puerto Rico, including destruction from a subsequent tsunami.
Update 06:53 UTC : Some minor damage is reported from Puerto Rico. Nothing serious, but people are mentioning cracks in walls.
Twitter damage image from Puerto Rico
Update 05:06 UTC : USGS has lowered the shaking intensity after recalculations. We do confirm that the new numbers are much more reflecting what our readers are telling us.
Update 05:04 UTC : NO reports of serious damage has reached us so far. Broken falling objects are reported bu that happens often in case of moderate shaking.
Update 04:59 UTC : It would be wise NOT to swim in the ocean the next hours as strong currents could have been generated by the earthquake. Almost nobody will do so as it is night at the moment in Puerto Rico
Update 04:58 UTC : The earthquake occurred in the deep Ocean Trench. This was not the strongest earthquake in the area so far. As can be seen on our bottom map, a M7.3 Magnitude earthquake happened right below Puerto Rico in 1918!
Official Tsunami statement of the PTWC :
A DESTRUCTIVE WIDESPREAD TSUNAMI THREAT DOES NOT EXIST BASED ON HISTORICAL EARTHQUAKE AND TSUNAMI DATA.
HOWEVER – THERE IS THE SMALL POSSIBILITY OF A LOCAL TSUNAMI THAT COULD AFFECT COASTS LOCATED USUALLY NO MORE THAN A HUNDRED KILOMETERS FROM THE EARTHQUAKE EPICENTER. AUTHORITIES IN THE REGION NEAR THE EPICENTER SHOULD BE MADE AWARE OF THIS POSSIBILITY.
Update 04:39 UTC : The pictures below are showing the theoretical shaking intensity. In general we can say that this was a lucky escape for Puerto Rico. 30 km more to the south and serious damage could have been expected at the Northern Puerto Rico coast.
Update : The shaking intensities as reported by our readers in Puerto Rico are leveraging a light to moderate shaking – weak shaking in the Dominican Republic
NO risk for a tsunami
Theoretical calculations from USGS are expecting a strong shaking at the northern coast of Puerto Rico
56km (35mi) N of Hatillo, Puerto Rico
58km (36mi) NNE of Isabela, Puerto Rico
59km (37mi) NNW of Arecibo, Puerto Rico
67km (42mi) NNW of Barceloneta, Puerto Rico
96km (60mi) NW of San Juan, Puerto Rico
Strong earthquake in Colombia at intermediate depth (felt in Cali and Medellin)
Last update: January 5, 2014 at 6:44 am by By Ashish Khanal
Update 06:39 UTC: The red cross of Colombia reports that1 house was affected in Balboa and there are visible cracks in the fire station of Quinchía in Risaralda .
Update 06:26 UTC: A landslide blocked the route between Yumbo and Mediacanoa.
Update 04:33 UTC : Local sources are locating the epicenter in Sipí, Chocó. The Fire Departments of the region have not received any calls of damage yet. Based on our experience 2 to 3 hours is at least needed to assess eventual damage, although we expect NO serious damage or injuries from this earthquake
Update 04:12 UTC : Ingeominas Colombia reports a Magnitude of M5.2 at a depth of 32 km, less than initially reported by some international agencies.
Update 04:06 UTC : Based on the (back office) MMI shaking values people have felt the earthquake as a moderate to strong shaking in the populated areas closest to the epicenter.
Update 03:58 UTC : Preliminary Magnitude as reported by USGS : M5.3 at a depth of 61 km. Based on the available data at this moment, we do not think that this earthquake will generate serious damage.
Strong earthquake in Colombia at intermediate depth
The depth of the earthquake is the reason that the earthquake was felt in a wide radius.
USGS
40km (25mi) W of El Dovio, Colombia
51km (32mi) WNW of Roldanillo, Colombia
55km (34mi) W of La Union, Colombia
57km (35mi) W of Toro, Colombia
279km (173mi) W of Bogota, Colombia
EMSC
129 km N of Cali, Colombia / pop: 2,392,877 / local time: 22:36:41.0 2014-01-04
40 km S of Nóvita, Colombia / pop: 1,898 / local time: 22:36:41.0 2014-01-04
Most important Earthquake Data:
Magnitude : 5.4
Local Time (conversion only below land) : 2014-01-04 22:36:36
Rare earthquake lights are more likely to occur on or near rift environments, where subvertical faults allow stress-induced electrical currents to flow rapidly to the surface, according to a new study published in the Jan./Feb. issue of Seismological Research Letters.
An earthquake light is an unusual luminous aerial phenomenon that reportedly appears in the sky at or near areas of tectonic stress, seismic activity, or volcanic eruptions. Once commonly challenged, it was not until photographs were taken during the Matsushiro earthquake swarm in Nagano, Japan (which occurred from 1965 through 1967) that the seismology community acknowledged their occurrence.
From the early days of seismology, the luminous phenomena associated with some earthquakes have intrigued scholars. Earthquake lights (EQL) appear before or during earthquakes, but rarely after.
Earthquake lights from Tagish Lake, Yukon-Alaska border region, around the 1st of July, probably 1972 or 1973 (exact date unknown). Estimated size: 1m diameter. Closest orbs slowly drifted up the mountain to join the more distant ones.
Credit: Photo credit: Jim Conacher, used with permission
EQL take a variety of forms, including spheres of light floating through the air. Seconds before the 2009 L’Aquila, Italy earthquake struck, pedestrians saw 10-centimeter high flames of light flickering above the stone-paved Francesco Crispi Avenue in the town’s historical city center. On Nov. 12, 1988, a bright purple-pink globe of light moved through the sky along the St. Lawrence River near the city of Quebec, 11 days before a powerful quake. And in 1906, about 100 km northwest of San Francisco, a couple saw streams of light running along the ground two nights preceding that region’s great earthquake.
Continental rift environments now appear to be the common factor associated with EQL. In a detailed study of 65 documented EQL cases since 1600 A.D., 85 percent appeared spatially on or near rifts, and 97 percent appeared adjacent to subvertical faults (a rift, a graben, strike-slip or transform fault). Intraplate faults are associated with just 5 percent of Earth’s seismic activity, but 97 percent of documented cases of earthquake lights.
“The numbers are striking and unexpected,” said Robert Thériault, a geologist with the Ministère des Ressources Naturelles of Québec, who, along with colleagues, culled centuries of literature references, limiting the cases in this study to 65 of the best-documented events in the Americas and Europe.
“We don’t know quite yet why more earthquake light events are related to rift environments than other types of faults,” said Thériault, “but unlike other faults that may dip at a 30-35 degree angle, such as in subduction zones, subvertical faults characterize the rift environments in these cases.”
Two of the 65 EQL events are associated with subduction zones, but Thériault suggests there may be an unknown subvertical fault present. “We may not know the fault distribution beneath the ground,” said Thériault. “We have some idea of surface structures, but sedimentary layers or water may obscure the underlying fault structure.”
While the 65 earthquakes ranged in magnitude, from M 3.6 to 9.2, 80 percent were greater than M 5.0. The EQL varied in shape and extent, though most commonly appeared as globular luminous masses, either stationary or moving, as atmospheric illuminations or as flame-like luminosities issuing from the ground.
Timing and distance to the epicenter vary widely. Most EQL are seen before and/or during an earthquake, but rarely after, suggesting to the authors that the processes responsible for EQL formation are related to a rapid build-up of stress prior to fault rupture and rapid local stress changes during the propagation of the seismic waves. Stress-activated mobile electronic charge carriers, termed positive holes, flow swiftly along stress gradients. Upon reaching the surface, they ionize air molecules and generate the observed luminosities.
Eyewitness reports and security cameras captured a large number of light flashes during the 2007 Pisco, Peru M 8.0 earthquake. Together with seismic records obtained on a local university campus, the automatic security camera records allow for an exact timing and location of light flashes that illuminated a large portion of the night sky. The light flashes identified as EQL coincided with the passage of the seismic waves.
Thériault likes the account of a local L’Aquila resident, who, after seeing flashes of light from inside his home two hours before the main shock, rushed his family outside to safety.
“It’s one of the very few documented accounts of someone acting on the presence of earthquake lights,” said Thériault. “Earthquake lights as a pre-earthquake phenomenon, in combination with other types of parameters that vary prior to seismic activity, may one day help forecast the approach of a major quake,” said Thériault.
Very Strong earthquake in the Mediterranean Sea in between Cyprus and Turkey
Last update: December 28, 2013 at 7:11 pm by By Ashish Khanal
IMPORTANT UPDATE 18:59 UTC : RUMORS are currently circulating that a massive earthquake might strike soon along the Turkish coast. We want to stress that NOBODY in the world can currently predict the time and the strength of an earthquake. Aftershocks are a normal process and may go on for days and even weeks. Most of them will not be felt as they are occurring below the sea floor. So, PLEASE NEVER BELIEVE RUMORS AND BE ALWAYS PREPARED FOR A STRONG EARTHQUAKE.
Update 18:14 UTC : Somebody reported that the power failures in some places were due to a thunderstorm and NOT the earthquake
Update 17:14 UTC : Some shore locations in Turkey (like Sorgun) have a power failure and are hotels are currently working on emergency diesel generators.
Update 16:55 UTC : Numerous aftershocks are occurring in the epicenter area in the sea. Only a few of them will have been felt by people.
Update 16:41 UTC : Power failures are reported in parts of Cyprus. Until now we have not received (as expected) any report of injuries or serious damage.
Update 16:32 UTC : Instead of panicking during the shaking of an earthquake, people (also tourists) should read on “what to do if shaking starts”. Internationally accepted measures are definitely NOT running outside. In case of a very strong earthquake you can’t even walk anymore! Click here to read the instructions (in case it happens again)
Update 16:23 UTC : Reports of panic are being received. Other reports are confirming cracks in walls of hotels (and probably also of residential houses).
Update 16:22 UTC : Contrary to what could be expected based on the theoretical intensity values of the map below, our readers are reporting in average a light to moderate shaking (MMI IV and V) ! We know from our experience that earthquakes with a rupture point at an intermediate depth of 50 km are perceived as stronger than theoretically calculated.
Update 15:57 UTC : We have received an experience report from a reader in Side who has seen some small fissures in the wall. Anyone else seeing this kind of small damage, please send in your Experience report with the form below.
Update : This is how this earthquake looks like on a seismogram of the region.
The light blue shaded area on the map shows the theoretical shaking (max. weak shaking) of this earthquake.
Update 15:31 UTC : USGS has just published even better numbers than initially reported. The Magnitude has been decreased to 5.8 at a depth of 51 km. This makes that it was felt in a wide radius, BUT that it will normally NOT generate serious damage.
Update 15:28 UTC : There is NO danger for a tsunami at this magnitude.
Update 15:26 UTC : Based on the preliminary data we see at this moment, we expect NO serious damage in Cyprus or Turkey as the epicenter is below the Mediterranean Sea at a depth of 40 to 50 km.
80km (50mi) SSW of Avsallar, Turkey
86km (53mi) SW of Alanya, Turkey
89km (55mi) S of Manavgat, Turkey
93km (58mi) SE of Tekirova, Turkey
204km (127mi) WNW of Nicosia, Cyprus
Very strong dangerous (shallow) earthquake in Hualien County, Taiwan
Last update: October 31, 2013 at 3:30 pm by By Armand Vervaeck and James Daniell
Update 15:19 UTC : – A man in Hualien County was crushed by furniture and has been taken to a hospital
– 8 people were trapped in an elevator when the earthquake struck
– The overall damage / injuries are looking fairly good at this time although it is still too soon to be conclusive as we need daylight to have a good overview.
Fallen products from shelves in a supermarket in New Taipei City – image courtesy cqnews.net
Update 14:56 UTC : Taiwan Railways reports that 46 trains affecting 9500 people have been delayed due to the earthquake
Update 14:51 UTC : The nuclear power plants in Taiwan are not affected.
Update 14:49 UTC : The Max Wyss theoretical damage engine gave the following values :
ESTIMATE OF HUMAN LOSSES
Injured Exp. min/max: 50/600
Fatalities Exp. min/max: 0/100
These results are mainly based on historical events – ER expects lower values than the minimum values of this calculation
Update 14:41 UTC : The earthquake occurred during darkness (8:02 PM). It is almost midnight right now and we do not expect a lot of news before the early morning hours, but we will of course continue to search for it.
Update 14:38 UTC : A 79 years old woman fell and broke something
Falling tiles are also being reported but nothing else so far.
Update 14:25 UTC : We expect landslides to damage some areas severely.
– USGS has decreased the Magnitude from the original M6.7 to M6.3 – Depth has been changed from 10 km to 12 km.
– Below the CWB list of aftershocks at the time of writing :
Update 11:20 UTC : – CWB Taiwan is reporting a Magnitude of 6.3 at a depth of 20 km, still very dangerous but less dangerous than the USGS values.
The earthquake is very dangerous and below land !
Pacific Tsunami message (NOT for the Taiwan coast) : NO DESTRUCTIVE WIDESPREAD TSUNAMI THREAT EXISTS BASED ON HISTORICAL EARTHQUAKE AND TSUNAMI DATA.
HOWEVER – EARTHQUAKES OF THIS SIZE SOMETIMES GENERATE LOCAL TSUNAMIS THAT CAN BE DESTRUCTIVE ALONG COASTS LOCATED WITHIN
A HUNDRED KILOMETERS OF THE EARTHQUAKE EPICENTER. AUTHORITIES IN THE REGION OF THE EPICENTER SHOULD BE AWARE OF THIS
POSSIBILITY AND TAKE APPROPRIATE ACTION.
Taiwan Intensity scale
Taiwan uses a scale which is more or less similar than Japan. Shaking values of 6 can be compared with JMA5+ which ER considers as potentially damaging : CWB 6 or Very Strong shaking (Hualien County) : – People have trouble walking due to violent rocking.
– Damage to some buildings; heavy furniture overturns; doors and windows bend.
– Drivers have trouble steering; sand and clay blasts occur. CWB 5 or Strong Shaking (Nantou, Yilan and Central Hualien Counties) : – Most people are considerably frightened.
– Walls crack; heavy furniture may overturn.
– Noticeably felt by drivers; some chimneys and large archways topple over.
61km (38mi) SSW of Hualian, Taiwan
61km (38mi) SSE of Buli, Taiwan
62km (39mi) ESE of Lugu, Taiwan
79km (49mi) SE of Nantou, Taiwan
744km (462mi) ENE of Hong Kong, Hong Kong
162 km S of Taipei, Taiwan / pop: 7,871,900 / local time: 20:02:09.0 2013-10-31
46 km S of Hualian, Taiwan / pop: 350,468 / local time: 20:02:09.0 2013-10-31
Most important Earthquake Data:
Magnitude : 6.3
Local Time (conversion only below land) : 2013-10-31 20:02:08
Massive extremely dangerous earthquake in Bohol, Philippines – At least 198 people killed, 11 missing, over 600 injured, around 4 billion PHP damage, 7 billion PHP reconstruction costs.
Last update: October 24, 2013 at 9:33 am by By Armand Vervaeck and James Daniell
Understanding the Bohol, Philippines earthquake
What happened exactly in Bohol?
At 8:12 AM on 15 October 2013, Tuesday, a destructive earthquake of magnitude 7.2 shook the island of Bohol and nearby provinces. Smaller-magnitude earthquakes followed afterwards, and as of 1:00 pm, 16 October 2013, 885 earthquakes have been recorded by the PHIVOLCS seismic monitoring network. At least 15 events were reportedly felt in the epicentral area. The main shock and succeeding aftershocks were located in the vicinity of Bohol. These recorded events were shallow, with a depth of at most 32 kilometers. Based on spatial distribution of succeeding events and characteristics of the earthquake, the event is tectonic in origin.
Based on preliminary intensity reports, the strongest ground shaking at PEIS VII (comparable with MMI VIII) was felt at Tagbilaran City and several cities in the province of Cebu. Neighboring island provinces of Cebu, Negros Occidental, Negros Oriental, Camiguin, Panay, Leyte, and several areas in northeastern Mindanao felt the earthquake at varying intensities of PEIS I-VI.
Moderate-magnitude (M5 to 6.9) earthquakes have also affected Bohol Island in the past!
On 08 February 1990, a magnitude 6.8 earthquake occurred at Bohol generated by an offshore reverse fault east of the island. Sixteen municipalities felt the strongest intensity of ground shaking at PEIS VIII. There were reports of severe property damages, numerous casualties, hundreds injured, and several thousands homeless. The towns of Jagna, Duero, Guindulman, Garcia Hernandez, and Valencia experienced tsunami inundation.
Why do earthquakes occur in Bohol?
Bohol Island is one of the seismically active areas in the country. Instrumental monitoring of earthquakes for the past century has detected many small to moderate-magnitude earthquakes in Bohol Island. There is at least one known earthquake generator on the island, the East Bohol Fault. In addition, there are other local faults which can be sources of small to large magnitude earthquakes. Earthquakes can also occur offshore or undersea because of local offshore faults near the island or trenches in the vicinity of the region.
Can these present earthquakes indicate volcanic activity? No. There are no volcanoes in Bohol Island.
What can we expect from the current earthquake activity?
The current seismic trend indicates that the magnitude 7.2 earthquake on 15 October 2013 is the mainshock, and the succeeding small magnitude earthquakes are the aftershocks. Aftershocks are expected, some of which will be felt (ER:and some of them might be dangerous). These may continue for weeks to months, but diminishing in number and strength as time passes. In this case, a higher magnitude earthquake related to this event is no longer expected to occur (ER: True, not related to this event, but as earthquakes cannot be predicted and as the Philippines have many fault systems, a new powerful earthquake can never be excluded).
What can we expect after a large-magnitude/high-intensity earthquake like this?
People are reminded to be cautious of structures visibly weakened or with signs of damage by the 15 October 2013 earthquake, as these may be further damaged by succeeding earthquakes. Strong ground shaking may cause extensive damage to or even the collapse of houses, buildings, bridges, and other infrastructures. Collapsed structures usually account for most of the casualties during a strong earthquake. Falling objects may also cause injuries.
Congratulations to Phivolcs Philippines for their very good explanation of this earthquake
Why are some places sinking and is the sea retreating away from the shore in other locations ?
Answer : deformation and partly liquefaction. In some locations
Isla Batasan is one of the islands located between Bohol and Cebu. It is experiencing sudden floods, causing its residents to believe that their island is slowly sinking. Phivolcs explains that there is indeed a big possibility that some islands may start sinking after the earthquake, due to liquefaction and earthquake deformation. Liquefaction happens when the soil loses its strength and stiffness due to an earthquake, causing it to soften and behave like liquid. Earthquake deformation, on the other hand, refers to a change in the original shape of a material.
Retreating sea : This can only be explained by an upthrust of some parts of the island. More detailed measurements in the near future will show serious deformations as can be seen on the images below. The focal mechanism below shows a mainly thrust earthquake = 2 parts of the fault are pressed into each other. The earthquake was triggered when the extreme forces became too big. The released energy did create all the deformations.
Retreating see in the thrust part of the island
Sinkholes are also generated by the shaking of the underground. Some sinkholes are produced when underground caves are caving in (the island of Bohol had a lot of caves) others are made by the shaking of loose material (some sources say that limestone is abundant in the islands).
Tectonic summary according to the USGS (a little more detailed)
The October 15, 2013 M 7.1 earthquake near the city of Catigbian on Bohol Island, Philippines, occurred as the result of shallow reverse faulting on a moderately inclined fault dipping either to the northwest, or to the southeast. The depth of the event indicates it ruptured a fault within the crust of the Sunda plate, rather than on the deeper subduction zone plate boundary interface. At the latitude of this earthquake, the Philippine Sea plate moves towards the west-northwest with respect to the Sunda plate at a rate of approximately 10 cm/yr, subducting beneath the Philippine Islands several hundred kilometers to the east of the October 15 earthquake at the Philippine Trench.
The Philippine Islands straddle a region of complex tectonics at the intersection of three major tectonic plates (the Philippine Sea, Sunda and Eurasia plates). As such, the islands are familiar with large and damaging earthquakes, and the region within 500 km of the October 15 earthquake has hosted 19 events of M6 or greater, a dozen of which have been shallow (0-70 km).
Update 23.10.2013 13:20 UTC:
Bad news once again with now 209 presumed dead. The other numbers remain the same.
The infrastructure cost has risen to 1.426 billion PHP counted (approx. 35 million USD).
Update 23.10.2013 04:35 UTC:
Unfortunately again we have had a rising death toll without reducing the missing. 195 dead and 12 missing is the current count.
– 651 have been injured
– 53,000 homes have been damaged – 14,000 of these have been destroyed.
– The public infrastructure loss including all hospitals, buildings, roads, flood control, schools is 1.097 billion PHP (25.47 million USD)
– 344,437 people are displaced (approximately the same amount of people as after the Tohoku earthquake.
Update 22.10.2013 07:35 UTC:
– All towns are now fully accessible by road given the hard work of DPWH in the last week. This is a huge accomplishment and will make it easier for relief to flow.
– The estimates of homeless range from 70,000 to 150,000 long term, with 377,000 currently displaced.
– The affected number has dropped below 3 million with a few barangays removing their “affected status”.
Update 22.10.2013 03:05 UTC:
The fault has been found! A previously unknown fault caused the Bohol earthquake. It caused at least 3m movement across a road in Inabanga. Click above to view the news article (GMA).
– The total number of destroyed buildings is at 14,253 (extra buildings in Loon and Maribojoc counted). It is still expected to rise further.
– The total number of damaged buildings is at 39,186.
for more information and to see others affected, photos, current conditions, etc., go to: http://earthquake-report.com/2013/10/15/very-strong-earthquake-mindanao-philippines-on-october-15-2013/
Last update: October 11, 2013 at 2:19 pm by By Ashish Khanal
Pour votre information : Une plume pour Le Télégramme qui font un très bon rapport de ce tremblement de terre. Congratulations.
Update 14:11 UTC (16:11 en France) : Lorsque la presse locale écrit maintenant “aucun dommage n’a été encore signalé”, cela doit être considéré comme un rapport provisoire et non comme un rapport final. Notre expérience montre que dans les pays développés, nous avons besoin d’au moins 6 à 10 heures avant que nous ayons une idée définitive de la situation.
When the local press writes now “no damage has been reported yet”, this has to be seen as a temporary report and not as a final report. Our experience shows that in developed countries, we need at least 6 to 10 hours before we have a conclusive idea of the situation.
Update : Il faut savoir que des séismes de Magnitude 4.0 ou plus sont vraiment rare en France. Tous ceux et celles qui l’ont sentis aujourd’hui ont vécu un évenement assez spéciale
Update : Important aussi est de savoir que le calcul exacte de l’epicentre est très difficile et qu’il faut toujours considerer un erreur de plusiers km. Selon les relevés français, l’épicentre se situe à Loperhet, autres sources disent Saint-Thonan.
Update : our opinion : “slight damage possible” because of the type of houses in Bretagne. Maximum radius for damage approx. 10 km. Damage will be mainly crcks in walls, fallen objects inside the house, fallen chimneys and fallen roof tiles.
Notre avis: “légers dégâts possible” en raison du type de maisons en Bretagne. Rayon maximum de dommages env. 10 km. Dommages sera principalement des fissures dans les murs, les objets tombés à l’intérieur de la maison, cheminées tombées etc.
Update : Nos lecteurs nous informent qu’il y avait une replique juste après le premier choque.
Une séisme relativement severe (Magnitude 4) s’est produit a un peu plus de 20 km de Brest. Basée sur notre experience, le Magnitude en relation avec le profondeur de 5 km est just en dessous du niveau de dégats. Esperons cela.
Nous nous excusons pout nôtre Français. On est conscient que c’est pas fameux, mais ons pense qu’il est mieux comme ca que d’écrire en Anglais
Plan de detail avec epicentre
181 km SW of Saint Peter Port, Guernsey / pop: 16,488 / local time: 13:52:40.0 2013-10-11
33 km N of Quimper, France / pop: 63,849 / local time: 14:52:40.0 2013-10-11
4 km SW of Le Faou, France / pop: 1,703 / local time: 14:52:40.0 2013-10-11
Most important Earthquake Data:
Magnitude : 4
Local Time (conversion only below land) : 2013-10-11 14:52:40
