ingilizce dilinden some increased seismic activity may occur in the next few days, possibly low to mid 6 magnitude. from 16 to 18 february there is a high probability of very strong to major seismic activity, potentially reaching low to mid 7 magnitude, maybe larger. çevirisi
ingilizce dilinden some increased seismic activity may occur in the next few days, possibly low to mid 6 magnitude. from 16 to 18 february there is a high probability of very strong to major seismic activity, potentially reaching low to mid 7 magnitude, maybe larger. çevirisi Ne90'dan bulabilirsiniz
Why are we having so many earthquakes? Has naturally occurring earthquake activity been increasing? Does this mean a big one is going to hit? OR We haven't had any earthquakes in a long time; does this mean that the pressure is building up for a big one?
A temporary increase or decrease in seismicity is part of the normal fluctuation of earthquake rates. Neither an increase nor decrease worldwide is a positive indication that a large earthquake is imminent.
The ComCat earthquake catalog contains an increasing number of earthquakes in recent years--not because there are more earthquakes, but because there are more seismic instruments and they are able to record more earthquakes.
The National Earthquake Information Center now locates about 20,000 earthquakes around the globe each year, or approximately 55 per day. As a result of the improvements in communications and the increased interest in natural disasters, the public now learns about earthquakes more quickly than ever before.
According to long-term records (since about 1900), we expect about 16 major earthquakes in any given year. That includes 15 earthquakes in the magnitude 7 range and one earthquake magnitude 8.0 or greater. In the past 40-50 years, our records show that we have exceeded the long-term average number of major earthquakes about a dozen times.
The year with the largest total was 2010, with 23 major earthquakes (greater than or equal to magnitude 7.0). In other years the total was well below the annual long-term average of 16 major earthquakes. 1989 only had 6 major earthquakes and 1988 only had 7.
Learn more: Earthquake Lists, Maps and Statistics
Yazı kaynağı : www.usgs.gov
Magnitude 6.4 Earthquake in Puerto Rico | U.S. Geological Survey
Update - Wednesday, January 29 (in English; Spanish below)
In a new report released today, USGS experts estimated that aftershocks from the magnitude 6.4 Jan. 7, 2020, earthquake will persist for years to decades, although with decreasing frequency. Additionally, earthquakes will likely be felt on a daily basis for several more months.
The forecasts found in this report can be used to guide public policy decisions or other actions.
The report forecasts aftershock duration potential for up to ten years after the magnitude 6.4 mainshock in southwestern Puerto Rico. This sequence is very active, and the probabilities of magnitude 5 and 6 or greater aftershocks remain high now and into the future. More detailed findings are in bullets below.
Puerto Rico lies in a tectonically active region where earthquakes have occurred for centuries, but because Puerto Rico has not experienced a quake of this level of impact since 1918, the recent quakes, their aftershocks, and resulting damage took many islanders by surprise. About 7,500 people have left their homes for other kinds of shelter, including, in some cases, cars and tents.
“Puerto Rico’s recent large earthquake and its aftershocks were destructive and unsettling to people on the island,” said USGS Director Jim Reilly. “USGS and our partners at the Puerto Rico Seismic Network began deploying additional seismic stations shortly after the mainshock. We will continue to work diligently to provide timely earthquake information -- such as this aftershock duration report -- to help support and protect the local communities of our nation.”
The study results do not imply a change in the risk of earthquakes in other parts of Puerto Rico. The results in this report are based on the current behavior (as of January 17, 2020) of this aftershock sequence and may need to be modified if that behavior changes, including if a larger earthquake occurs.
Key findings of the report include:
¿Qué hacer después de un terremoto?
En un nuevo informe publicado hoy, los expertos del USGS estimaron que las réplicas del terremoto de magnitud 6.4 del 7 de enero de 2020 persistirán durante años o décadas, aunque con una frecuencia decreciente. Además, los terremotos probablemente se sentirán a diario durante varios meses más.
Los pronósticos que se encuentran en este informe se pueden usar como guía para lo toma de decisiones de política pública u otras acciones.
El informe pronosticaun potencial de duración de las réplicas de hasta diez años después del de magnitud 6.4 en el suroeste de Puerto Rico. Esta secuencia es muy activa, y las probabilidades de réplicas de magnitud 5 y 6 o mayores permanecen altas ahora y en el futuro. Los hallazgos más detallados están listados a continuación.
Puerto Rico se encuentra en una región tectónicamente activa donde los terremotos han ocurrido durante siglos, pero debido a que Puerto Rico no ha experimentado un terremoto de este nivel de impacto desde el 1918, los terremotos recientes, sus réplicas y el daño resultante tomaron por sorpresa a muchos isleños. Unas 7,500 personas han abandonado sus hogares para buscar otro tipo de refugio incluidos, en algunos casos, automóviles y tiendas de campaña.
"El reciente gran terremoto de Puerto Rico y sus réplicas fueron destructivas e inquietantes para la gente en la isla", dijo el director del USGS Jim Reilly. “El USGS y nuestros colaboradores en la Red Sísmica de Puerto Rico comenzaron a instalar estaciones sísmicas adicionales poco después del terremoto principal. Continuaremos trabajando diligentemente para proporcionar información oportuna sobre terremotos, como este informe de duración de réplicas, para ayudar a apoyar y proteger a las comunidades locales de nuestra nación".
Los resultados del estudio no implican un cambio en el riesgo de terremotos en otras partes de Puerto Rico. Los resultados en este informe se basan en el comportamiento actual (a partir del 17 de enero de 2020) de esta secuencia de réplicas y es posible que deba modificarse si ese comportamiento cambia, incluso si ocurre un terremoto más grande.
Los hallazgos más importantes del informe incluyen:
Evening Update - Friday, January 17 (**Last routine update**)
New Top Story: As Aftershocks Continue in Puerto Rico, USGS Supports Quake Recovery
7-Day Aftershock Forecast
The USGS aftershock forecast indicates there is a 3 percent chance of a magnitude 6.4 or larger aftershock over the next 7 days.
30-Day Aftershock Scenarios (Revised: Jan 17; English | Spanish)
Based on our aftershock forecasts, USGS has modeled three possible scenarios for this earthquake sequence as it evolves over the next month. These scenarios represent what could happen from January 18 to February 18, 2020. Only one of these scenarios will occur. The earthquakes in these scenarios would occur in the areas near where aftershocks are happening now. Regardless of scenario, earthquakes will continue to occur for days, months, or potentially years to come. It is very unlikely the aftershocks will cease completely within the next month.
Scenario One (most likely): 79 percent chance [same as yesterday]
The most likely scenario is that aftershocks will continue to decrease in frequency over the next 30 days, with no further earthquakes similarly sized to the M 6.4 that occurred on Jan. 7, 2020 (i.e., will be less than M 6.0). Some of these moderately sized aftershocks (M 5.0+) may cause localized damage, particularly in weak structures. Smaller magnitude earthquakes (M 3.0+), when at shallow depth, may be felt by people close to the epicenters.
Scenario Two (less likely): 18 percent chance [same as yesterday]
A less likely scenario is an earthquake occurring of similar size as the M 6.4 event. This is called a “doublet”: when two large earthquakes of similar size occur closely in time and location. This earthquake could cause additional damage in the same region and increases the number of aftershocks.
Scenario Three (least likely): 3 percent chance [same as yesterday]
A much less likely scenario than the previous two scenarios is that recent earthquakes could trigger an earthquake significantly larger than the M 6.4 that occurred Jan. 7, 2020 (i.e., M 7.0 and above). While this is a small probability, if such an earthquake were to occur, it would have serious impacts on communities nearby. This sized earthquake would also trigger its own aftershock sequence, so the rate of small and moderate earthquakes would increase again.
Evening Update - Thursday, January 16
7-Day Aftershock Forecast
The USGS aftershock forecast indicates there is a 3 percent chance of a magnitude 6.4 or larger aftershock over the next 7 days.
30-Day Aftershock Scenarios (Revised: Jan 16; English | Spanish)
Based on our aftershock forecasts, USGS has modeled three possible scenarios for this earthquake sequence as it evolves over the next month. These scenarios represent what could happen from January 17 to February 17, 2020. Only one of these scenarios will occur. The earthquakes in these scenarios would occur in the areas near where aftershocks are happening now. Regardless of scenario, earthquakes will continue to occur for days, months, or potentially years to come. It is very unlikely the aftershocks will cease completely within the next month.
Scenario One (most likely): 79 percent chance [same as yesterday]
The most likely scenario is that aftershocks will continue to decrease in frequency over the next 30 days, with no further earthquakes similarly sized to the M 6.4 that occurred on Jan. 7, 2020 (i.e., will be less than M 6.0). Some of these moderately sized aftershocks (M 5.0+) may cause localized damage, particularly in weak structures. Smaller magnitude earthquakes (M 3.0+), when at shallow depth, may be felt by people close to the epicenters.
Scenario Two (less likely): 18 percent chance [same as yesterday]
A less likely scenario is an earthquake occurring of similar size as the M 6.4 event. This is called a “doublet”: when two large earthquakes of similar size occur closely in time and location. This earthquake could cause additional damage in the same region and increases the number of aftershocks.
Scenario Three (least likely): 3 percent chance [same as yesterday]
A much less likely scenario than the previous two scenarios is that recent earthquakes could trigger an earthquake significantly larger than the M 6.4 that occurred Jan. 7, 2020 (i.e., M 7.0 and above). While this is a small probability, if such an earthquake were to occur, it would have serious impacts on communities nearby. This sized earthquake would also trigger its own aftershock sequence, so the rate of small and moderate earthquakes would increase again.
Evening Update - Wednesday, January 15
7-Day Aftershock Forecast
The USGS aftershock forecast indicates there is a 4 percent chance of a magnitude 6.4 or larger aftershock over the next 7 days.
30-Day Aftershock Scenarios (Revised: Jan 15; English | Spanish)
Based on our aftershock forecasts, USGS has modeled three possible scenarios for this earthquake sequence as it evolves over the next month. These scenarios represent what could happen from January 16 to February 16, 2020. Only one of these scenarios will occur. The earthquakes in these scenarios would occur in the areas near where aftershocks are happening now. Regardless of scenario, earthquakes will continue to occur for days, months, or potentially years to come. It is very unlikely the aftershocks will cease completely within the next month.
Scenario One (most likely): 79 percent chance [same as yesterday]
The most likely scenario is that aftershocks will continue to decrease in frequency over the next 30 days, with no further earthquakes similarly sized to the M 6.4 that occurred on Jan. 7, 2020 (i.e., will be less than M 6.0). Some of these moderately sized aftershocks (M 5.0+) may cause localized damage, particularly in weak structures. Smaller magnitude earthquakes (M 3.0+), when at shallow depth, may be felt by people close to the epicenters.
Scenario Two (less likely): 18 percent chance [same as yesterday]
A less likely scenario is an earthquake occurring of similar size as the M 6.4 event. This is called a “doublet”: when two large earthquakes of similar size occur closely in time and location. This earthquake could cause additional damage in the same region and increases the number of aftershocks.
Scenario Three (least likely): 3 percent chance [same as yesterday]
A much less likely scenario than the previous two scenarios is that recent earthquakes could trigger an earthquake significantly larger than the M 6.4 that occurred Jan. 7, 2020 (i.e., M 7.0 and above). While this is a small probability, if such an earthquake were to occur, it would have serious impacts on communities nearby. This sized earthquake would also trigger its own aftershock sequence, so the rate of small and moderate earthquakes would increase again.
Evening Update - Tuesday, January 14
7-Day Aftershock Forecast
The USGS aftershock forecast indicates there is a 3% chance of a magnitude 6.4 or larger aftershock over the next 7 days.
30-Day Aftershock Scenarios (Revised: Jan 14; English | Spanish)
Based on our aftershock forecasts, USGS has modeled three possible scenarios for this earthquake sequence as it evolves over the next month. These scenarios represent what could happen from January 14 to February 14, 2020. Only one of these scenarios will occur. The earthquakes in these scenarios would occur in the areas near where aftershocks are happening now. Regardless of scenario, earthquakes will continue to occur for days, months, or potentially years to come. It is very unlikely the aftershocks will cease completely within the next month.
Scenario One (most likely): 79 percent chance [-2% from yesterday]
The most likely scenario is that aftershocks will continue to decrease in frequency over the next 30 days, with no further earthquakes similarly sized to the M 6.4 that occurred on Jan. 7, 2020 (i.e., will be less than M 6.0). Some of these moderately sized aftershocks (M 5.0+) may cause localized damage, particularly in weak structures. Smaller magnitude earthquakes (M 3.0+), when at shallow depth, may be felt by people close to the epicenters.
Scenario Two (less likely): 18 percent chance [+1% from yesterday]
A less likely scenario is an earthquake occurring of similar size as the M 6.4 event. This is called a “doublet”: when two large earthquakes of similar size occur closely in time and location. This earthquake could cause additional damage in the same region and increases the number of aftershocks.
Scenario Three (least likely): 3 percent chance [+1% from yesterday]
A much less likely scenario than the previous two scenarios is that recent earthquakes could trigger an earthquake significantly larger than the M 6.4 that occurred Jan. 7, 2020 (i.e., M 7.0 and above). While this is a small probability, if such an earthquake were to occur, it would have serious impacts on communities nearby. This sized earthquake would also trigger its own aftershock sequence, so the rate of small and moderate earthquakes would increase again.
Evening Update - Monday, January 13
7-Day Aftershock Forecast
The USGS aftershock forecast indicates there is a 3% chance of a magnitude 6.4 or larger aftershock over the next 7 days.
30-Day Aftershock Scenarios (Revised: Jan 13; English | Spanish)
Based on our aftershock forecasts, USGS has modeled three possible scenarios for this earthquake sequence as it evolves over the next month. These scenarios represent what could happen from January 13 to February 13, 2020. Only one of these scenarios will occur. The earthquakes in these scenarios would occur in the areas near where aftershocks are happening now. Regardless of scenario, earthquakes will continue to occur for days, months, or potentially years to come. It is very unlikely the aftershocks will cease completely within the next month.
Scenario One (most likely): 81 percent chance [+5% from yesterday]
The most likely scenario is that aftershocks will continue to decrease in frequency over the next 30 days, with no further earthquakes similarly sized to the M 6.4 that occurred on Jan. 7, 2020 (i.e., will be less than M 6.0). Some of these moderately sized aftershocks (M 5.0+) may cause localized damage, particularly in weak structures. Smaller magnitude earthquakes (M 3.0+), when at shallow depth, may be felt by people close to the epicenters.
Scenario Two (less likely): 17 percent chance [-4% from yesterday]
A less likely scenario is an earthquake occurring of similar size as the M 6.4 event. This is called a “doublet”: when two large earthquakes of similar size occur closely in time and location. This earthquake could cause additional damage in the same region and increases the number of aftershocks.
Scenario Three (least likely): 2 percent chance [-1% from yesterday]
A much less likely scenario than the previous two scenarios is that recent earthquakes could trigger an earthquake significantly larger than the M 6.4 that occurred Jan. 7, 2020 (i.e., M 7.0 and above). While this is a small probability, if such an earthquake were to occur, it would have serious impacts on communities nearby. This sized earthquake would also trigger its own aftershock sequence, so the rate of small and moderate earthquakes would increase again.
Morning Update - Monday, January 13
Aftershock Forecast
The USGS aftershock forecast, updated on Jan. 13, indicates the likelihood of a M 6.0 or larger aftershock over the next 7 days is 8 percent [down 3% from yesterday]. There continues to be a high likelihood of M 3.0+ aftershocks this week. The rate of aftershocks will continue to decline over time.
Estimates for other magnitude ranges and time periods can be found in the forecast.
30-Day Aftershock Scenarios (Revised: Jan 13; English | Spanish)
Based on our aftershock forecasts, USGS has modeled three possible scenarios for this earthquake sequence as it evolves over the next month. These scenarios represent what could happen from January 13 to February 13, 2020. Only one of these scenarios will occur. The earthquakes in these scenarios would occur in the areas near where aftershocks are happening now. Regardless of scenario, earthquakes will continue to occur for days, months, or potentially years to come. It is very unlikely the aftershocks will cease completely within the next month.
Scenario One (most likely): 81 percent chance [+5% from yesterday]
The most likely scenario is that aftershocks will continue to decrease in frequency over the next 30 days, with no further earthquakes similarly sized to the M 6.4 that occurred on Jan. 7, 2020 (i.e., will be less than M 6.0). Some of these moderately sized aftershocks (M 5.0+) may cause localized damage, particularly in weak structures. Smaller magnitude earthquakes (M 3.0+), when at shallow depth, may be felt by people close to the epicenters.
Scenario Two (less likely): 16 percent chance [-5% from yesterday]
A less likely scenario is an earthquake occurring of similar size as the M 6.4 event. This is called a “doublet”: when two large earthquakes of similar size occur closely in time and location. This earthquake could cause additional damage in the same region and increases the number of aftershocks.
Scenario Three (least likely): 3 percent chance [0% from yesterday]
A much less likely scenario than the previous two scenarios is that recent earthquakes could trigger an earthquake significantly larger than the M 6.4 that occurred Jan. 7, 2020 (i.e., M 7.0 and above). While this is a small probability, if such an earthquake were to occur, it would have serious impacts on communities nearby. This sized earthquake would also trigger its own aftershock sequence, so the rate of small and moderate earthquakes would increase again.
Puerto Rico Earthquake Update - Sunday, January 12
Aftershock Forecast
The USGS aftershock forecast, updated on Jan. 12, indicates the likelihood of a M 6.0 or larger aftershock over the next 7 days is 11 percent. There is also a high likelihood of M 3.0+ aftershocks in the coming week; these M 3.0+ quakes may be felt near the epicenters. The rate of aftershocks will continue to decline over time. A large aftershock or new mainshock would, once again, increase the frequency and magnitude of aftershocks. Estimates for other magnitude ranges and time periods can be found in the forecast.
30-Day Aftershock Scenarios (Revised: Jan 12; English | Spanish)
Based on our aftershock forecasts, USGS has modeled three possible scenarios for this earthquake sequence as it evolves over the next month. These scenarios represent what could happen from January 12 to February 12, 2020. Only one of these scenarios will occur. The earthquakes in these scenarios would occur in the areas near where aftershocks are happening now. Regardless of scenario, earthquakes will continue to occur for days, months, or potentially years to come. It is very unlikely the aftershocks will cease completely within the next month.
Scenario One (most likely): 76 percent chance
The most likely scenario is that aftershocks will continue to decrease in frequency over the next 30 days, with no further earthquakes similarly sized to the M 6.4 that occurred on Jan. 7, 2020 (i.e., will be less than M 6.0). Some of these moderately sized aftershocks (M 5.0+) may cause localized damage, particularly in weak structures. Smaller magnitude earthquakes (M 3.0+), when at shallow depth, may be felt by people close to the epicenters.
Scenario Two (less likely): 21 percent chance
A less likely scenario is an earthquake occurring of similar size as the M 6.4 event. This is called a “doublet”: when two large earthquakes of similar size occur closely in time and location. This earthquake could cause additional damage in the same region and increases the number of aftershocks.
Scenario Three (least likely): 3 percent chance
A much less likely scenario than the previous two scenarios is that recent earthquakes could trigger an earthquake significantly larger than the M 6.4 that occurred Jan. 7, 2020 (i.e., M 7.0 and above). While this is a small probability, if such an earthquake were to occur, it would have serious impacts on communities nearby. This sized earthquake would also trigger its own aftershock sequence, so the rate of small and moderate earthquakes would increase again.
Morning Update on January 11
Aftershock Forecast
The USGS aftershock forecast, updated on Jan. 11, indicates the likelihood of a M 6.0 or larger aftershock over the next 7 days is 12 percent. There is also a high likelihood of M 3.0+ aftershocks in the coming week; these M 3.0+ quakes may be felt near the epicenters. The rate of aftershocks will continue to decline over time. A large aftershock or new mainshock would, once again, increase the frequency and magnitude of aftershocks. Estimates for other magnitude ranges and time periods can be found in the forecast.
30-Day Aftershock Scenarios (Revised: Jan 11; Spanish-language version)
Based on our aftershock forecasts, USGS has modeled three possible scenarios for this earthquake sequence as it evolves over the next month. These scenarios represent what could happen from January 11 to February 11, 2020. Only one of these scenarios will occur. The earthquakes in these scenarios would occur in the areas near where aftershocks are happening now. Regardless of scenario, earthquakes will continue to occur for days, months, or potentially years to come. It is very unlikely the aftershocks will cease completely within the next month.
Scenario One (most likely): 75 percent within the next 30 days
The most likely scenario is that aftershocks will continue to decrease in frequency over the next 30 days, with no further earthquakes similarly sized to the M 6.4 that occurred on Jan. 7, 2020 (i.e., will be less than M 6.0). Some of these moderately sized aftershocks (M 5.0+) may cause localized damage, particularly in weak structures. Smaller magnitude earthquakes (M 3.0+), when at shallow depth, may be felt by people close to the epicenters.
Scenario Two (less likely): 22 percent within the next 30 days
A less likely scenario is an earthquake occurring of similar size as the M 6.4 event. This is called a “doublet”: when two large earthquakes of similar size occur closely in time and location. This earthquake could cause additional damage in the same region and increases the number of aftershocks.
Scenario Three (least likely): 3 percent within the next 30 days
A much less likely scenario than the previous two scenarios is that recent earthquakes could trigger an earthquake significantly larger than the M 6.4 that occurred Jan. 7, 2020 (i.e., M 7.0 and above). While this is a small probability, if such an earthquake were to occur, it would have serious impacts on communities nearby. This sized earthquake would also trigger its own aftershock sequence, so the rate of small and moderate earthquakes would increase again.
Afternoon Update on January 10
Ongoing Research
USGS and Puerto Rico Seismic Network (PRSN) experts are on the ground today near the south coast of Puerto Rico, working quickly to install six sets of seismometers that will help seismologists better monitor earthquakes, document the strength of ground shaking, estimate potential earthquake damage, and forecast aftershocks. The seismometers -- solar-powered and ready to travel in suitcase-sized kits -- were sent from the USGS’ Albuquerque Seismological Laboratory to Puerto Rico on January 7, the same day a magnitude 6.4 earthquake struck the southwest part of the island, causing extensive damage.
The temporary seismometers will supplement information on real-time earth movement already being collected by the PRSN, a permanent array of instruments in Puerto Rico and the Virgin Islands. USGS partners with the PRSN and the Puerto Rico Strong Motion Program at University of Puerto Rico Mayaguez to collect seismic data and monitor earthquakes in the region.
Aftershock Forecast
The forecast for Jan. 10 indicates the likelihood of large magnitude aftershocks continues to decrease as we move further away from the Jan. 7, 2020, M 6.4 earthquake. Over the next 7 days there is now only a 3 percent chance of one or more aftershocks larger than M 6.4. However, there is still a high likelihood of M 3.0+ aftershocks in the coming week; these M 3.0+ quakes may be felt near the epicenters. The rate of aftershocks will continue to decline over time. A large aftershock or new mainshock would, once again, increase the frequency and magnitude of aftershocks.
Since this series of events began in December 2019, more than 139 earthquakes M 3.0+ have occurred in this region, six of which were M 5.0+, including the largest M 6.4 event.
This earthquake sequence is consistent with expectations of seismicity in the region. Historically the region has seen moderate seismicity, but Puerto Rico is tectonically active, and infrequent naturally occurring large earthquakes are expected. Before this sequence, within the last 50 years and within 31 miles of the M 6.4 quake’s epicenter, there have been 10 earthquakes M 4.0+. Historical seismicity in the region can be searched here.
View the USGS aftershock forecast here.
Afternoon Update on January 9
Damaging earthquakes, like the ones in Puerto Rico, can be unsettling, destructive, and often tragic to the communities they affect. This is why the USGS continues to work diligently toward improving public safety by providing emergency responders and others with the scientific resources they need to better respond to ongoing hazards.
Here is the latest aftershock forecast for the M 6.4 that occurred January 7, 2020.
About Aftershock Scenarios
Based on our aftershock forecasts, USGS has modeled three possible scenarios for this earthquake sequence as it evolves over the next month. These scenarios represent what could happen from January 9 to February 9, 2020. Only one of these scenarios will occur. The earthquakes in these scenarios would occur in the areas near where aftershocks are happening now. Regardless of scenario, earthquakes will continue to occur for days, months, or potentially years to come. It is very unlikely the aftershocks will cease completely within the next month.
Scenario One (most likely): 84 percent within the next 30 days
The most likely scenario is that aftershocks will continue to decrease in frequency over the next 30 days, with no further earthquakes similarly sized to the M 6.4 that occurred on Jan. 7, 2020 (i.e., will be less than M 6.0). Some of these moderately sized aftershocks (M 5.0+) may cause localized damage, particularly in weak structures. Smaller magnitude earthquakes (M 3.0+), when at shallow depth, may be felt by people close to the epicenters.
Scenario Two (less likely): 14 percent within the next 30 days
A less likely scenario is an earthquake occurring of similar size as the M 6.4 event. This is called a “doublet”: when two large earthquakes of similar size occur closely in time and location. This earthquake could cause additional damage in the same region and increases the number of aftershocks.
Scenario Three (least likely): 2 percent within the next 30 days
A much less likely scenario than the previous two scenarios is that recent earthquakes could trigger an earthquake significantly larger than the M 6.4 that occurred Jan. 7, 2020 (i.e., M 7.0 and above). While this is a small probability, if such an earthquake were to occur, it would have serious impacts on communities nearby. This sized earthquake would also trigger its own aftershock sequence, so the rate of small and moderate earthquakes would increase again.
Afternoon Update on January 8
Aftershock Forecast
Today's forecast [as of 03:24:26 EST] estimates that over the next 1 Week there is a 4 percent chance of one or more aftershocks that are larger than magnitude 6.4. It is highly likely that there will be many smaller earthquakes (M>3) over the next 1 Week. Magnitude 3 and above events are large enough to be felt near the epicenter. The rate of aftershocks will decline over time, but a large aftershock can increase the numbers again, temporarily.
Our forecasts change as time passes due to decline in the frequency of aftershocks, larger aftershocks that may trigger further earthquakes, and changes in forecast modeling based on the data collected for this earthquake sequence.
Afternoon Update on January 7
The USGS National Earthquake Information Center is preparing to deploy six portable seismometers to Puerto Rico to supplement the seismometers already part of the Puerto Rico Seismic Network. These seismometers, which will be used to help better monitor earthquakes in this area, may be operational by the end of this week. Observations from seismic monitoring equipment will improve our ability to characterize and forecast earthquakes which will help protect lives and property. USGS works in partnership with the PRSN and the Puerto Rico Strong Motion Program at University of Puerto Rico Mayaguez to collect seismic data and monitor earthquakes in the region.
"After the devastating Hurricane Maria occurred in Puerto Rico, the federal government invested in rebuilding damaged seismic stations in the region," said USGS Director Jim Reilly. “These stations have made it possible for the USGS and our partners at the Puerto Rico Seismic Network to provide more accurate and rapid information about the earthquakes and their possible impacts along with better forecasts of potentially damaging aftershocks.”
Since the M 4.7 event on December 28, 2019, over 500 M 2+ earthquakes have occurred in this region (as of 2PM EST, 01/07/20), 32 of which were M 4+, including the January 6th M 5.8 and the M 6.4 event on January 7th and its aftershocks.
Aftershock Forecast
Earthquake forecasts are created using a statistical analysis based on past earthquakes and are presented in terms of probabilities of earthquakes of a given size occurring. The current forecast, issued at 15:24 eastern on Jan 7, 2020, estimates that over the next 1 Week there is a 7 percent chance of one or more aftershocks that are larger than magnitude 6.4. It is highly likely that there will be many smaller earthquakes (M>3) over the next 1 Week. Magnitude 3 and above events are large enough to be felt near the epicenter. The rate of aftershocks will decline over time, but a large aftershock can increase the numbers again, temporarily. This forecast may change as the earthquake sequence continues to develop.
Morning Update on January 7
On Jan. 7, a magnitude 6.4 earthquake struck the region at 4:24 am local time (08:24:26 UTC). Significant damage is possible. Over the past several weeks, hundreds of small earthquakes have occurred in the Puerto Rico region, beginning in earnest with a M 4.7 earthquake late on December 28 and a M 5.0 event a few hours.
The magnitude 6.4 earthquake was widely felt. According to ShakeMap, strong to very strong shaking occurred across parts of Southern Puerto Rico closest to the event and moderate shaking occurred across the rest of the island. The NOAA Tsunami Warning System states no tsunami warning or advisory. The USGS summary page on this earthquake includes an aftershock forecast. Aftershocks will continue near the mainshock.
Over the past several weeks, hundreds of small earthquakes have occurred in this same region, beginning in earnest with a M 4.7 earthquake late on December 28 and a M 5.0 event a few hours later. Since the M 4.7 event, over 400 M 2+ earthquakes have occurred in this region, ten of which were M 4+, including today’s M 6.4 event and yesterday's 5.8 quake. The preliminary location of today's 6.4 earthquake is within about 7.5 miles (12 km) of the January 6, 2020, M 5.8 earthquake. The proximity of these events to Puerto Rico, and their shallow depth, mean that dozens of these events have been felt on land, though with the exception of the latest two earthquakes, the M 6.4 and the M 5.8, none are likely to have caused significant damage.
The January 6 and 7, 2020, M 5.8 and M 6.4 earthquakes offshore of southwest Puerto Rico occurred as the result of oblique strike slip faulting at shallow depth. At the location of this event, the North America plate converges with the Caribbean plate at a rate of about 20 mm/yr towards the west-southwest. The location and style of faulting for the event is consistent with an intraplate tectonic setting within the upper crust of the Caribbean plate, rather than on the plate boundary between the two plates.
Tectonics in Puerto Rico are dominated by the convergence between the North America and Caribbean plates, with the island being squeezed between the two. To the north of Puerto Rico, North America subducts beneath the Caribbean plate along the Puerto Rico trench. To the south of the island, and south of today’s earthquake, Caribbean plate upper crust subducts beneath Puerto Rico at the Muertos Trough. The January 6 earthquake, and other recent nearby events, are occurring in the offshore deformation zone bound by the Punta Montalva Fault on land and the Guayanilla Canyon offshore.
Visit the USGS event page for more information. For estimates of casualties and damage, visit the USGS Prompt Assessment of Global Earthquakes for Response (PAGER) website. If you felt any of these earthquakes, report your experience on the “USGS Did You Feel It?” website for this event.
USGS scientists expect that this event will trigger aftershocks, but these will decrease in frequency over time. You can view the aftershock forecast here.
The USGS operates a 24/7 National Earthquake Information Center in Colorado that can be reached for more information at 303-273-8500. Learn more about the USGS Earthquake Hazards Program.
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Earthquakes in Turkey and Syria: What we know — and don’t know — about earthquakes - Vox
A powerful magnitude 7.8 earthquake rattled across Turkey and Syria early Monday morning. Another quake with a magnitude of 7.7 rocked the region a few hours later. The quakes killed more than 19,000 people and toppled more than 6,600 buildings in the region. Survivors left homeless are now facing freezing weather.
Dramatic videos on social media captured collapsing buildings and scattered rubble. Turkish President Recep Tayyip Erdogan said it was his country’s worst disaster in decades.
Turkey, however, is no stranger to earthquakes. Two major fault lines cross the country and trigger shocks on a regular basis. According to the US Geological Survey, Turkey experienced more than 60 earthquakes with a magnitude greater than 2.5 in the past day. “The region where the February 6 earthquake occurred is seismically active,” USGS reported on Monday.
Larger quakes are less frequent, but still a regular occurrence. Last November, Turkey suffered a magnitude 5.9 quake. A magnitude 7.0 quake rocked the Aegean Sea between Turkey and Greece in 2020.
The Monday quake happened because two parcels of the earth’s crust moved past each other horizontally across a fault line, a phenomenon known as strike-slip faulting. Rescuers are still desperately working through the rubble and freezing cold, but it’s likely the death toll will climb higher.
Turkey revised many of its building codes in 2000 to resist tremors, but many older buildings remained vulnerable and fell in the recent quakes. “Those that have collapsed date prior to the year 2000,” Mustafa Erdik, professor at Bogazici University’s Kandilli Observatory and Earthquake Research Institute in Istanbul, told Al Jazeera.
In light of the recent disasters, here’s a refresher on earthquakes, along with some of the latest science on measuring and predicting them.
1) What causes earthquakes
An earthquake occurs when massive blocks of the earth’s crust suddenly move past each other. These blocks, called tectonic plates, lie on top of the earth’s mantle, a layer that behaves like a very slow-moving liquid over millions of years.
That means tectonic plates jostle each other over time. They can also slide on top of each other, a phenomenon called subduction. The places on the planet where one plate meets another are the most prone to earthquakes. The specific surfaces where parcels of earth slip past each other are called faults. As plates move, pressure builds up across their boundaries, while friction holds them in place. When the former overwhelms the latter, the earth shakes as the pent-up energy dissipates.
Scientists understand these kinds of earthquakes well, which include those stemming from the San Andreas Fault in California and the East Anatolian Fault in Turkey. However, earthquakes can also occur within tectonic plates, as pressure along their edges cause deformations in the middle. These risks are harder to detect and measure.
“Our understanding of these within-plate earthquakes is not as good,” said Stanford University geophysics professor Greg Beroza. An earthquake within a tectonic plate has fewer telltale signs than those that occur at fault lines, he added.
2) The Richter scale isn’t the only measurement game in town anymore
The Richter scale, developed by Charles Richter in 1935 to measure quakes in Southern California, has fallen out of fashion.
It uses a logarithmic scale, rather than a linear scale, to account for the fact that there is such a huge difference between the tiniest tremors and tower-toppling temblors. On a logarithmic scale, a magnitude 7 earthquake is 10 times more intense than a magnitude 6 and 100 times more intense than a magnitude 5.
The Richter scale is actually measuring the peak amplitude of seismic waves, making it an indirect estimate of the earthquake itself. So if an earthquake is like a rock dropped in a pond, the Richter scale is measuring the height of the largest wave, not the size of the rock nor the extent of the ripples.
And in the case of an earthquake, the ripples aren’t traveling through a homogenous medium like water, but through solid rock that comes in different shapes, sizes, densities, and arrangements. Solid rock also supports multiple kinds of waves. (Some geologic structures can dampen big earthquakes while others can amplify lesser tremors.)
While Richter’s scale, calibrated to Southern California, was useful to compare earthquakes at the time, it provides an incomplete picture of risks and loses accuracy for stronger events. It also misses some of the nuances of other earthquake-prone regions in the world, and it isn’t all that useful for people trying to build structures to withstand them.
“We can’t use that in our design calculations,” said Steven McCabe, leader of the earthquake engineering group at the National Institute of Standards and Technology. “We deal in displacements.”
Displacement, or how much the ground actually moves, is one alternative way to describe earthquakes. Another is the moment magnitude scale. It accounts for multiple types of seismic waves, drawing on more precise instruments and better computing to provide a reliable measuring stick to compare seismic events.
When you hear about an earthquake’s magnitude in the news — like Turkey’s recent magnitude 7.8 quake — moment magnitude is usually the scale being used.
But this is still a proxy for the size of the earthquake. And with only indirect measurements, it can take up to a year to decipher the scale of an event, like the 2004 Indian Ocean earthquake, said Marine Denolle, an earthquake researcher at Harvard University.
“We prefer to use peak ground acceleration,” she said. This is a metric that measures how the speed and direction of the ground changes and has proven the most useful for engineers.
So, yes, earthquake scales have gotten a lot more complicated and specific over time. But that’s also helped scientists and engineers take much more precise measurements — which makes a big difference in planning for them.
3) We can’t really anticipate them all that well
Predicting earthquakes is a touchy issue for scientists, in part because it has long been a game of con artists and pseudoscientists who claim to be able to forecast earthquakes. (Their declarations have, of course, withered under scrutiny.)
Scientists do have a good sense of where earthquakes could happen. Using historical records and geologic measurements, they can highlight potential seismic hot spots and the kinds of tremors they face. (You can check out the US Geological Survey’s interactive map of fault lines and NOAA’s interactive map of seismic events.)
As for when quakes will hit, that’s still murky.
“Lots of seismologists have worked on that problem for many decades. We’re not predicting earthquakes in the short term,” said Beroza. “That requires us to know all kinds of information we don’t have.”
It’s difficult to figure out when an earthquake will occur, since the forces that cause them happen slowly over a vast area but are dispersed rapidly over a narrow region. What’s amazing is that forces built up across continents over millions of years can hammer cities in minutes.
Forecasting earthquakes would require high-resolution measurements deep underground over the course of decades, if not longer, coupled with sophisticated simulations. And even then, it’s unlikely to yield an hour’s worth of lead time. So there are ultimately too many variables at play and too few tools to analyze them in a meaningful way.
Some research shows that foreshocks can precede a larger earthquake, but it’s difficult to distinguish them from the hundreds of smaller earthquakes that occur on a regular basis.
On shorter time scales, texts and tweets can actually race ahead of seismic waves. In the 2011 Tohoku earthquake in Japan, for example, warnings from near the epicenter reached Tokyo 232 miles away, buying residents about a minute of warning time.
Many countries are now setting up warning systems to harness modern electronic communications to detect tremors and transmit alerts ahead of shaking ground, buying a few precious minutes to seek shelter.
Meanwhile, after a large earthquake, aftershocks often rock the afflicted region. “If we just had a big one, we know there will be smaller ones soon,” Denolle said.
When it comes to prediction, researchers understandably want to make sure they don’t overpromise and underdeliver, especially when thousands of lives and billions of dollars in damages are at stake. But even this caution has had consequences.
In 2012, six Italian scientists were sentenced to six years in prison for accurately saying the risks of a large earthquake in the town of L’Aquila were low after a small cluster of earthquakes struck the region in 2009. Six days after the scientists convened to assess the risk, a large quake struck and killed 309 people. Those convictions were later overturned and the ordeal has become a case study for how scientists convey uncertainty and risk to the public.
4) Sorry, your pets can’t predict earthquakes either
Reports of animals acting strange ahead of earthquakes date back to ancient Greece. But a useful pattern remains elusive. Feathered and furry forecasters emerge every time there’s an earthquake and there’s a cute animal to photograph, but this phenomenon is largely confirmation bias. Animals do weird things (by our standards) all the time and we don’t attach any significance to them until an earthquake happens.
“On any given day, there will be hundreds of pets doing things they’ve never done before and have never done afterward,” Beroza said. Bottom line: Don’t wait for weird animal behavior to signal that an earthquake is coming.
5) Some earthquakes are definitely man-made
The gargantuan expansion of hydraulic fracturing across the United States has left an earthquake epidemic in its wake. It’s not the actual fracturing of shale rock that leads to tremors, but the injection of millions of gallons of wastewater underground.
Scientists say the injected water makes it easier for rocks to slide past each other. “When you inject fluid, you lubricate faults,” Denolle said.
The US Geological Survey calls these “induced earthquakes” and reported that in Oklahoma, the number of earthquakes surged to 2,500 in 2014, 4,000 in 2015, and 2,500 in 2016.
“The decline in 2016 may be due in part to injection restrictions implemented by the state officials,” the USGS wrote in a release. “Of the earthquakes last year, 21 were greater than magnitude 4.0 and three were greater than magnitude 5.0.”
This is up from an average of two earthquakes per year of magnitude 2.7 or greater between 1980 and 2000. (“Natural” earthquakes, on the other hand, are not becoming more frequent, according to Beroza.)
Humans are causing earthquakes another way, too: Rapidly drawing water from underground reservoirs has also been shown to cause quakes in cities like Jakarta, Denolle said.
6) Climate change could have a tiny effect on earthquakes
In general, scientists haven’t measured any effect on earthquakes from climate change. But they’re not ruling out the possibility.
As average temperatures rise, massive ice sheets are melting, shifting billions of tons of water from exposed land into the ocean and allowing land masses to rebound. That global rebalancing could have seismic consequences, but signals haven’t emerged yet.
“What might occur is enough ice melts that could unload the crust,” Beroza said, but added there is no evidence for this, nor for which parts of the world will reveal a signal. Denolle agreed that this could be a mechanism, but if there is any impact from climate change on earthquakes, she says she suspects it will be very small.
7) We’ve gotten better reducing earthquake risks and saving lives
About 90 percent of the world’s earthquakes occur in the Ring of Fire, the region around the Pacific Ocean running through places like the Philippines, Japan, Alaska, California, Mexico, and Chile. The ring is also home to three-quarters of all active volcanoes.
Mexico is an especially interesting case study. The country sits on top of three tectonic plates, making it seismically active. In 1985, an earthquake struck the capital, killing more than 10,000. Denolle noted that the geology of the region makes it so that tremors from nearby areas are channeled toward Mexico City, making any seismic activity a threat.
The Mexican capital is built on the site of the ancient Aztec city of Tenochtitlan, an island in the middle of a lake. The dry lakebed that is now the foundation of the modern metropolis amplifies shaking from earthquakes.
The 1985 earthquake originated closer to the surface, and the seismic waves it produced had a relatively long time between peaks and valleys. This low-frequency vibration sends skyscrapers swaying, according to Denolle. “The recent earthquakes were deeper, so they had a higher frequency,” she said.
The biggest factor in preventing deaths from earthquakes is building codes. Designing buildings to move with the earth while remaining standing can save thousands of lives, but putting them into practice can be expensive and frequently becomes a political issue.
“Ultimately, that information has got to get implemented, and you can pretty much get that implemented in new construction,” McCabe said. “The trickier problem is existing buildings and older stock.”
Earthquake-prone countries know this well: Japan has been aggressive about updating its building codes regularly to withstand earthquakes. The revised standards have in part fueled Japan’s construction boom despite its declining population.
Mexico has also raised standards for new construction. Laws enacted after the 1985 earthquake required builders to account for the soft lakebed soil in the capital and tolerate some degree of movement.
Meanwhile, Iran has gone through several versions of its national building standards for earthquake resilience. And Alaska has been developing earthquake damage mitigation strategies and response plans for years.
But codes are not always enforced, and the new rules only apply to new buildings. A school that collapsed in a 2017 Mexico City earthquake apparently was an older building that was not earthquake-resistant. And because the more recent earthquakes in Mexico shook the ground in a different way, even some of the buildings that survived the 1985 earthquake collapsed after tremors in 2017.
In countries like Iran, there is a wide gulf between how buildings are constructed in cities versus the countryside. More than a quarter of the country’s population lives in rural areas, where homes are built using traditional materials like mud bricks and stone rather than reinforced concrete and steel. This is a big part of why casualties are so high when earthquakes strike remote parts of the country.
The biggest risks fall to countries that don’t have a major earthquake in living memory and therefore haven’t prepared for them, or don’t have the resources to do so. A lack of a unified building code led to many of the more than 150,000 deaths in Haiti stemming from the 2010 magnitude 7.0 earthquake.
8) The big one really is coming to the United States (someday)
The really big one you keep hearing about is real.
The New Yorker won a Pulitzer Prize in 2015 for its reporting on the potential for massive earthquake that would rock the Pacific Northwest — “the worst natural disaster in the history of North America,” which would impact 7 million people and span a region covering 140,000 square miles.
The potential quake could reach a magnitude between 8.7 and 9.2, bigger than the largest expected earthquake from the San Andreas Fault, which scientist expect to top out at magnitude 8.2.
Large earthquakes are also in store for Japan, New Zealand, and other parts of the Ring of Fire. We don’t know when these earthquakes will rock us; we just have a rough estimate of the average time between them, which changes from region to region.
“In the business, we’ve been talking about that [Pacific Northwest] scenario for decades,” Beroza said. “I wouldn’t say we’re overdue, but it could happen at any time.”
“It is a threat,” echoed Denolle. “We forget about this threat because we have not had an earthquake there for a while.” “A while” means more than 300 years.
So while California has long been steeling itself for big earthquakes with building codes and disaster planning, the Pacific Northwest may be caught off guard, though the author of the New Yorker piece, Kathryn Schulz, helpfully provided a guide to prepare.
Update, February 6, 2:20 pm: This story was originally published in 2018 and has been updated to include news of the earthquakes in Turkey and Syria.
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