Earthquake, History.

Earthquakes – An Unpredictable Force of Destruction

Earthquakes have caused massive devastation, and amounted to huge numbers of human casualties since the beginning of recorded history. The problem with these natural disasters has become compounded by our cities becoming developed more vertically in the form of taller buildings without the proper respect given to earthquakes during the engineering process. Along with the previously mentioned factor, the general population that doesn’t live in earthquake prone areas won’t know what to do in a situation like this. You can learn more about how to prepare yourself, and what to do during an earthquake event in RedZone’s blog. This blog will hopefully assist in understanding the geoscience that is occurring before, during, and after one of these events takes place.

The Earth’s Crust and Earthquakes

Of the inner Earths four internal layers, the crust and the upper most portion of the mantle play the most vital roles in the unseen processes that power earthquakes. The Earth’s crust is made up of 12 major plates that are very dynamic in nature.

Tectonic plates and Earthquakes

This map displays the 12 major tectonic plates throughout the world.

It is here at the tectonic plate boundaries that the earthquakes originate. As the plate boundaries come to a resting place due to its jagged edges, the remaining portion of the plate remains in constant movement. When the energy from the movement of the rest of the plate becomes too much force for an area of the plate boundary to hold, the edges of these plates shift and this is what causes an earthquake. The earthquake we feel on the ground stems from the seismic waves that are produces when the tectonic plates shift.

There are two primary wave types that are produced by this tectonic shift, the P wave (primary) and S wave (secondary). P waves have also been called the compressional waves due to the way these waves push and pull the matter they are travelling through. S waves are the waves we feel on the surface that create the movement on the earth’s surface. S waves are much slower to appear than the P waves for a seismologist to read.

Seismographic Readings and Determining the Epicenter

Scientists with their particular field of study in earthquakes, track these waves to give the public a rating on the Richter scale of how strong in magnitude an earthquake is. These experts also utilize the seismographs to locate where exactly the epicenter was. Triangulation is used to determine the precise location where the epicenter is. Three seismographs measure the difference in times that the P waves arrive at the seismographs and compare them with the time it take for the S waves to arrive at the same location. A circle is then created around the three selected seismograph locations with the radius being determined off the aforementioned time difference in seismic wave arrival. The point at which each of the three seismographs calculated circles meet is the epicenter.

Epicenter of Earthquakes

This diagram depicts a visual representation of how the epicenter of an earthquake is found from three seismographs.

 

Predicting Earthquakes

Unfortunately scientists have been unsuccessful so far in the prediction of when the next earthquake will occur. Earthquake prediction is more often defined as the probabilistic assessment of general earthquake hazard, including the frequency and magnitude of damaging earthquakes in a given area over years or decades. Like many naturally-occurring phenomena, they are nearly impossible to accurately predict.  Prediction methods go back hundreds of years.j Methods generally involve precursors which among them include animal behavior, gas emissions, and even electromagnetic anomalies. Generally, Earthquake prediction is  thought of as an immature science with any claims of prediction found circumstantial and arguable.

Earthquake warning systems on the other hand have proven successful on a number of occasions especially in areas farther from an epicenter.  The effectiveness of the warning depends on the position of the receiver. After receiving a warning, a person may have a few seconds to a minute or more to take action. Areas near the epicenter may experience strong tremors before a warning is issued. Early warning systems have been prevalent in Japan, Mexico, Canada, and the United States for years.

Sources:

https://pubs.er.usgs.gov/publication/fs20163020

https://earthquake.usgs.gov/learn/kids/eqscience.php

https://earthquake.usgs.gov/learn/facts.php

https://www.nationalgeographic.com/environment/natural-disasters/earthquakes/

http://www.geo.mtu.edu/UPSeis/waves.html

osaka eq

Osaka Earthquake Rattles Whole Prefecture

Monday morning, began with a bang six hours south of Tokyo when a preliminary 6.1 magnitude earthquake rattled the Osaka Prefecture, killing five and injuring hundreds more. This is yet another for the list of “Ring of Fire” activities early this year, including the Guatemala and Hawaii Volcanic Eruptions. The Osaka earthquake was later downgraded by the Japan Meterological Agency (JMA) to a 5.9 Magnitude and to 5.5 by the United States Geological Survey (USGS). The Japan Meteorological Agency said the quake classified as a “6 Lower” at five observation stations in the Osaka-fu Hokubu Region and a “5 Upper” at another 14 stations in the Kyoto-fu Nambu. All 19 stations are located in the Osaka Prefecture.

osaka earthquake 1

Osaka Earthquake from June 18th and shaking intensity across the nearby Sub Regions of Southern Honshu

Osaka Earthquake Tragedy in Takatsuki

Later in the week, an interesting story developed regarding one of the quake-related deaths. According to local news in Osaka, it was reported by the local education board that school authorities had known for three years a “substandard concrete wall” would be a danger if a major earthquake happened near the Juei Elementary School in Takatsuki. Unfortunately, as predicted, 9-year-old Rina Miyakewas was tragically crushed to death after the wall collapsed.  Miyake was merely headed into the school when the quake struck Monday. In a related development Friday, the Japan Times reported the local education board in quake-hit Takatsuki, Osaka Prefecture, also said it had discovered another 15 public schools where substandard concrete walls on their premises could pose a danger to students in the event of powerful earthquakes.  Seen as a major wake up call to the rest of the schools, the board added that the remaining walls “will be removed in a few weeks”.

osaka earthquake shakemap

Shakemap showing the Osaka Earthquake and Juei Elementary school near the epicenter

Officials Warn Threat May Not Be Over

Worried that the earthquake could be the predecessor to a bigger one, officials warned the public to be on their toes. It was determined this week’s Osaka Earthquake was part of the same fault line that produced the Great Hanshin Earthquake in 1995. That tragic event claimed more than 6,400 lives. Luckily, experts are claiming the probability is low for another, larger seismic movement in the coming days. They did, however, cite a magnitude 6.5 earthquake two years ago in Kumamoto Prefecture and surrounding areas of Kyushu which preceded a magnitude 7.3 temblor two days later. 50 died from the Kumamoto quakes.

Sources:

CNN

The Japan Times

United States Geological Survey (USGS)

Japan Meterological Agency

 

Earthquake Shakes Southern California, Reminding Residents to be Prepared

The largest earthquake to jolt Southern California in over four years struck just after noon near Santa Cruz Island on Thursday. The 5.3 earthquake shook the California coast from San Luis Obispo to San Clemente. Local fire departments quickly scrambled engines to survey damages and prepare for any aftershocks but there have been no reports of injuries or damage. So far, no aftershocks have been recorded but there is a small chance that Thursday’s tremor could be the catalyst for a larger quake to occur.

Epicenter and shakemap of the 5.3 Earthquake – 29km SW of Santa Cruz Is., CA

  • Magnitude: 5.3
  • Origin Time: 05 Apr 2018 12:29:16 PDT
  • Epicenter: 853, -119.695
  • Depth: 9 km
  • Location: 26km SW of Santa Cruz Island
  • Impact: No casualties or significant damage.
  • Incident Page: USGS Overview
  • News Article: KTLA News

New Early Warning System Being Developed

A still underdevelopment earthquake early warning (EEW) system, from Caltech’s Seismology lab in Pasadena, gave some Southern California residents roughly 10 seconds to prepare for the tremors. The earthquake early warning system called ShakeAlert provides real-time earthquake information which will eventually generate alerts via mobile apps, email, and text. The warning time of these EEWs normally range from 0 to 20 seconds but this is time can be critical in saving lives and infrastructure. Early warnings alerts can also be integrated onto public utilities and industrial systems, automatically shutting down vulnerable systems. The crucial seconds provided by early warning systems is another layer of protection which is further multiplied by individuals taking the necessary steps to be prepared.

Be Prepared

Fortunately, Thursday’s earthquake impact was minimal but it serves as a reminder that earthquakes happen with little to no warning and in California it is not a matter of “if” but “when” the next one will come.

4 Step Plan to Become More Earthquake Safe

1:  Secure your space.

2:  Plan to be safe.

3:  Organize disaster supplies. 

4:  Minimize Financial Hardship

Learn More

To learn more about earthquakes and how to prepare for them, visit these informative websites:

ShakeOut.org. The central website for the ShakeOut event also has a wealth of additional resources.  The website contains information on how to hold drills suited for different environments, as well as specific safety recommendations for people with disabilities.

EarthquakeCountry.org. ECA provides information and resources to help improve preparedness, mitigation and resiliency for everyone who lives, works, or travels in earthquake prone areas.

US Geological Survey.  The USGS Hazards website houses information on real-time seismic activity and information on earthquake prone areas, in addition to may other tools to help monitor the causes and effects of earthquakes.

Ready.gov.  Official website of the Department of Homeland Security which has a section on earthquake specific emergency preparedness.

Sources

http://losangeles.cbslocal.com/2018/04/05/earthquake-california-los-angeles-channel-islands/

http://ktla.com/2018/04/05/earthquake-with-preliminary-magnitude-5-3-hits-off-channel-islands-is-felt-in-los-angeles-area/

http://www.scsn.org/index.php/2018/04/05/04-05-2018-m5-3-near-santa-cruz-is/

http://www.sandiegouniontribune.com/news/california/la-me-la-quake-explainer-20180405-story.html

Major Quake Rattles North Canturbury, New Zealand

New Zealand Earthquake Situation

Residents in the North Canterbury region on the South Island of New Zealand were awakened by a major earthquake just after midnight on Monday morning (11/14). The 14-mile-deep quake, which killed two people, triggered a small tsunami, twenty aftershocks, and tens of thousands of landslides across the region. In the two days since, officials have been assessing the situation as the quake and subsequent aftershocks have caused widespread damage to the region. Early cost estimates of the impact are in the hundreds of millions, if not billions.

Following the initial tremor, four aftershocks over 6.0-magnitude (and another sixteen under 6.0) also rattled the area, helping set off thousands of landslides in the steep and coastal terrain.  The coastal town of Kaikoura, north of the epicenter, seems one of the hardest hit with both roads in and out of town cut off by the moving earth.  Heavy rains Tuesday have also complicated rescue and aid efforts.  The situation has prompted a massive evacuation operation by air and sea for the small coastal city’s 2,000 residents. The latest reports state that some locals (and infamous cows) remain stranded with limited supplies. Several New Zealand Navy ships, as well as a US destroyer, are set to help provide needed supplies as well as allow tourists and others to leave Wednesday morning.

Canterbury area, New Zealand Earthquake and aftershocks (Source: USGS Latest Earthquakes)

Canterbury area, New Zealand Earthquake and aftershocks (Source: USGS Latest Earthquakes)


Long Term Impact

Similar to the Christchurch disaster of 2011, New Zealand will undoubtedly feel an economic punch from this week’s events. Countless residents have been displaced and infrastructure and land damages are widespread. At least dozens of homes and businesses in the region have been red- and yellow-taped for structural vulnerability. But, unlike the February 2011 quake, the rural epicenter and comparably miniscule population of the affected areas should ease some of the economic and insurance cost concerns.

The hardest hit areas affected by this week’s disaster total a populous only in the thousands, whereas Christchurch’s population is around 370,000. Economists expect the overall impact on the fast growing economy will be small and nowhere near the 45 billion dollar bill from five years prior. What is certain, however, are negative future impacts on tourism for the beautiful Kaikoura area (see below), which lay in crumbles.

North Canterbury coastal town Kaikoura, NZ hit hardest by Monday’s 7.9 Magnitude Earthquake

North Canterbury’s Kaikoura, NZ hit hardest by Monday’s 7.9 Magnitude Earthquake (source: newzealand.com)


New Zealand Earthquake Statistics

  • Magnitude: 7.9
  • Origin Time: 1103 UTC – Nov 13 2016
  • Epicenter: 42.8 South 173.4 East
  • Depth: 23 km
  • Location: near South Island, New Zealand
  • Impact: Two confirmed deaths, widespread damage and power outages, hundreds evacuated
  • Incident Page: USGS Overview
  • News Article: The Weather Channel

Sources: USGS, CNN, The Weather Channel, stuff.co.nz, Radio New Zealand

Fault Connection Reveals Risk to Bay Area

Newly-discovered Fault Connection

It has been 27 years since the 6.9-magnitude Loma Prieta earthquake on the San Andreas fault rattled the San Francisco Bay Area, killing 63, injuring over 3,700, and famously interrupting that year’s World Series.  Four scientists with the United States Geological Survey have recently discovered a connection between two fault lines under the Bay that were previously believed to be unlinked, revealing a fault connection they say could lead to an even larger future earthquake.

Underwater surveys conducted in shallow portions of the northern San Francisco Bay discovered a section of the Hayward Fault that connects to the western segment of the Rodgers Creek Fault.  The Hayward Fault extends for 62 miles from San Jose to San Pablo Bay, passing directly under the densely-populated urban areas of Berkeley and Oakland.  The Rodgers Creek fracture runs north from the bay, 56 miles through the heart of wine country.

The worry is that the 188-mile connection between the two faults will make the effects of a rupture along either fault more intense and impact substantially more people.


7 million Could Be Drastically Affected

Explained in detail in a recent journal article, the study is the first evidence that the two major faults are linked. The fault connection discovery was published in the October 19th edition of the journal Science Advances. The USGS team led by Janet Watt stated that the next major earthquake to the strike the Bay Area will likely come from the (now-connected) Hayward and neighboring Rodgers Creek faults. The scientists used integrated geophysical interpretation and kinematic modeling to show that the Hayward and Rodgers Creek faults are directly connected at the surface (in San Pablo Bay), and the coinciding geometric relationship has significant implications for earthquake dynamics and seismic hazard.

They argue that the discovered link enables a simultaneous rupture along their combined 188 miles, potentially producing a quake as large as 7.4 in magnitude–five times stronger than the Loma Prieta event. According to their findings, the worst case scenario event would cause extensive damage and loss of life with global economic impact. An estimated 7 million people could be drastically affected.

 

Maps showing the Hayward and Rodgers Creek fault connection

Maps showing the Hayward and Rodgers Creek fault connection


Sources:

http://advances.sciencemag.org/content/2/10/e1601441

http://www.theverge.com/2016/10/19/13335816/earthquake-faults-san-francisco-oakland-bay-area-san-andreas-hayward

https://en.wikipedia.org/wiki/1989_Loma_Prieta_earthquake

Earthquake Preparation – Be Ready for the Next Big One

Nearly half the population of the United States is exposed to a risk of a damaging earthquakes. The US Geological Survey recently released a report outlining the increased probability of a large earthquake impacting California, and there has been a dramatic increase in human-induced earthquakes across the central United States. This increased risk has further highlighted the importance of earthquake preparation.   Earthquakes rarely give any advanced warning, therefore the key to surviving a major sesmic event is to be prepared. Every year on the third Thursday of October, the Great ShakeOut event aims to help facilitate this preparation.

Earthquake Preparation is Key to Survival

Founded in 2008 by the USGS , the Great ShakeOut began in California and now boasts participants in 45 states and more than 70 countries.   The ShakeOut is a regionally organized event used to simulate a mock earthquake event.  At a specified time, participants envision a major earthquake occurring and practice the “drop, cover and hold on” drill.

earthquake preparation drill

Drop, Cover and Hold On!

Drop to the ground, find a sturdy object such as a desk or table to crawl under, and hold on until the shaking stops.  If no cover can be found, the drill recommends individuals find an interior wall and protect their head and neck with their arms.

In the ShakeOut event, participants “hold on” for 60 seconds and use this time to scan their surroundings. While scanning, individuals imagine what damage may be occurring as a result of the quake.  What heavy objects have the potential to fall and cause injury? What damage may be occurring to structures due to the violent shaking? Will there be a way to escape the impacted area after the quake?

The ShakeOut drill helps to generate awareness of potential dangers in the home, school and workplace.  This awareness leads to better planning and mitigation which are essential for survival and recovery after a major earthquake. The Earthquake Country Alliance recommends these four steps to help be better prepaped before the next earthquake occurs.

4 Step Plan to Become More Earthquake Safe

1:  Secure your space.

2:  Plan to be safe.

3:  Organize disaster supplies. 

4:  Minimize Financial Hardship

Learn More

To learn more about earthquakes and how to prepare for them, visit these informative websites:

ShakeOut.org. The central website for the ShakeOut event also has a wealth of additional resources.  The website contains information on how to hold drills suited for different environments, as well as specific safety recommendations for people with disabilities.

EarthquakeCountry.org. ECA provides information and resources to help improve preparedness, mitigation and resiliency for everyone who lives, works, or travels in earthquake prone areas.

US Geological Survey.  The USGS Hazards website houses information on real-time seismic activity and information on earthquake prone areas, in addition to may other tools to help monitor the causes and effects of earthquakes.

Ready.gov.  Official website of the Department of Homeland Security which has a section on earthquake specific emergency preparedness.

Human-Induced Earthquakes in the Central US

Residents of California are all too familiar with the uneasy feeling of unstable ground under foot.  California, however, is not alone.  The Central United States has seen a dramatic increase in human-induced earthquakes activity in recent years.

In 2015, the central United States experienced over a thousand earthquakes measuring 3.0 or larger on the Richter Scale.  This record setting amount of earthquakes was 42 times more then the average number of yearly quakes experienced between 1973 to 2008.  Oklahoma actually had more earthquakes in 2015 than the historically shaky California.

What is the Cause of all this Increased Earthquake Activity?

Human-induced earthquakes are to blame for the increased seismic activity threatening more than 7 million people in the central and eastern portions of the United States. Human-induced earthquakes are commonly linked with the controversial practice of fracking.  Fracking is a process in which water pressure is used to force oil out of previously untapped deposits.  The majority of the induced earthquakes, however, are actually the result of the relatively recent industrial process of disposing of contaminated water by injecting the fluids into the ground. The contaminated water is a by-product of all oil and gas extraction and not unique to fracking. The injected wastewater elevates the in-ground fluid pressure increasing the likelihood of fault slippage. 

 Earthquakes since 1980 and Human-Induced Earthquakes

Faults can occur in areas where they haven’t historically been recorded.  Normally tectonic stress will hold the faults together, but the injected waste water can essentially push the plates apart.

The increased risk of damaging earthquakes prompted the USGS to include human-induced earthquakes in their hazard forecasts for the first time.

Human-Induced Earthquakes and a Potential for Disaster

Most of the earthquakes are minor but a recent 5.6 magnitude earthquake recently rocked the region near Pawnee, Oklahoma. The earthquake was felt across 6 additional states and is the largest magnitude quake recorded in Oklahoma since 2011. The Federal Emergency Management Agency estimates that a similar sized event hitting a metropolitan area, like the Dallas metroplex, could devastate the city leading to substantial damage, economic loss and potential loss of life.

The 2016 USGS study suggests that the central United States will face a 5-12% chance of damage from additional earthquakes in 2016.

Sources

https://www2.usgs.gov/blogs/features/usgs_top_story/induced-earthquakes-raise-chances-of-damaging-shaking-in-2016/

https://www.washingtonpost.com/news/speaking-of-science/wp/2016/03/28/new-seismic-hazard-map-includes-fracking-related-quakes-for-the-first-time/

https://www2.usgs.gov/blogs/features/usgs_top_story/6-facts-about-human-caused-earthquakes/

http://money.cnn.com/2016/03/29/investing/earthquakes-fracking-usgs-oil-gas/

http://www.cnn.com/2016/09/03/us/oklahoma-earthquake/