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

WildfireIntel.org is Quickly becoming a Trusted Source

Late June and early July added several new ignitions to a wildfire season that was already off to an ominous start. So far in 2018 major fires have already igniting across Texas, Oklahoma, and the Southwest. The recent heat wave that swept Red Flag fueled wildfires across the US resulting in evacuations and structure loss in Colorado, California, Utah, and  As we move deeper into the summer months, increasingly warm and dry conditions will continue to fuel the threat of wildfires. The National Inter-agency Fire Center released their fire potential outlook for summer months, predicting an above average fire season for all of the twelve western states making wildfire intelligence gathering even more essential.

A New Source for Wildfire Intelligence

Understanding the need for real-time wildfire intelligence, a conversation started between group of devout users and former moderators. This group came together to revive a forum that once popular among the fire community. For a variety of reasons they ultimately decided it was best to spin-off a new website. This new website, branded wildfireintel.org, was created as a non-profit with the mission to create a free public forum for discussing “topics important to the fire community”. Relevant subjects include fire related “incidents, jobs, industry, safety, and health”.

Wildfire Intelligence Forum Example

An example of how the forum is structured based off geographic regions.

Recent Fire Activity Drives Traffic and Additional Users to the Website

Although it’s still in the initial stages of development, wildfireintel.org is up and running and gaining traction. WildfireIntel.org is quickly becoming a trusted source for accurate, real-time information. Recent fire activity is helping increase traffic to the forum, with the last 30 days adding over 200 new users and almost a million page views. Knowing that forums survive by the active participation of its users the founders of the website are encouraging the fire community to continue to contribute to the site. The founders hope that with increased participation an “active and sustainable wildfire community” will again foster and provide much need wildfire intelligence. For more information, please visit the wildfireintel.org website and/or become more involved by registering.

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Wildfire Intelligence Logo

Spring Fire Ignites in Colorado

Colorado has already seen its fair share of wildfires this season. The 416 and Burro Fires ignited in early June and are still raging. Almost daily Red Flag conditions have punished the state and resulted in explosive fire growth. Late Wednesday evening (June 27th), strong winds and exceptionally dry conditions resulted in another new start close to the New Mexico border.

The Spring Fire broke out just east of Alamosa, Colorado and quickly began spreading towards the community of La Veta. On Thursday a sparse crew of firefighters accompanied by limited air resources attempted to gain the upper hand but had to retreat as the fire, pushed by 35+ mph winds, tore through over 4000 acres of rough terrain.

Today (Friday June 29th), fueled by another day of Red Flag conditions, the fire exploded to over 24,000 acres and has jumped CO 160, forcing the closure of the highway. Over 2,500 people have been evacuated from the area between Fort Garland and La Veta. A Type II Incident Management team arrived with additional resources this morning to manage the large out of control wild fire. 

Spring Fire

  • Location:10.2 Miles W of La Veta, CO, Huerfano County
  • Size: 33,956 acres
  • Containment: 0%
  • Fire Behavior: Rapid fire spread due to erratic winds, dry conditions, and high temperatures.
  • Structures Destroyed: Structures reported lost but no official number released at this time.
  • Incident Link: Inciweb
  • Weather Forecast: Weather.gov

Spring Fire – Current perimeter as of June 29th, 2018

The Red Flag Warning remains in effect until tonight at 2100 MDT but will likely be renewed tomorrow due to another day of high temperatures, low humidity, and winds reaching 20 mph. With temperatures being in the mid 80s well into next week, it’s not likely that crews will contain this wildfire anytime soon.

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

 

Wildfire near home in Possum Kingdom, TX

Will wildfire risk impact my home insurance?

Over the last thirty years, the length of wildfire season has increased by nearly 20% around the world. In California, the idea of wildfire ‘season’ is nearly laughable as large growth, damaging wildfires happen year-round on a regular basis now. While wildfires can happen just about anywhere, the western US States are usually at greater risk for experiencing wildfires. Higher rates result from this increased risk and, in some areas, the insurance companies may not offer coverage at all.

Why is wildfire coverage important?

Home built in the WUI

Many communities are building farther into the wilderness (Credit: Google Earth)

As approximately one-third of homes in the United States are in the Wildland Urban Interface (WUI), insurance companies are updating what is and is not covered in cases of wildfire. Insurance companies may factor in wildfire history in the area, home construction materials, vegetation, and topography, for example. In a few of the highest risk areas in the country, some insurance companies have opted to avoid writing policy coverage at all!

When structuring your policy, be sure to ask questions to know what is covered and how you are protected in case of wildfire. Policies may cover additional living expenses (ALE, in case damages or loss make your home uninhabitable), fire department service charges, or repairs and debris removal after a covered loss. There may be an additional option for fire insurance specifically for your non-primary residence. Different carriers offer different protections and add-ons, so be sure to know what you need.

What property features are considered?

Construction materials, surrounding vegetation, and landscape features are a few considerations when determining wildfire risk. (Credit: Oregon State University)

Construction materials, surrounding vegetation, and landscape features are a few considerations when determining wildfire risk. (Credit: Oregon State University)

Vegetation, alone, on your property isn’t necessarily a cause for concern. Insurers will typically take into account the location and type, as well as density, of the surrounding vegetation. Fire stations and hydrants near your home alleviate some levels of risk as there are preventative resources near the home should a wildfire emergency occur. Topographical features could play heavily on your potential extra costs. If you live in or near notable high risk areas, such as a canyon or the deep woods, additional insurance charges may be added to cover the increased risk to your home from wildfire. Roof type, along with eaves and siding materials, may also play a factor. For example, a wood roof (even if treated) is at much higher risk of catching fire from embers than a clay tile roof.

Homeowners can ensure they maintain significant defensible space that can help slow or stop a wildfire from spreading to your home and property.

Can I do anything to help protect myself?

Do not be discouraged! There are steps you can take to help make your home more fire-resistant. Programs like the Wildfire Partners Program out of Boulder County, Colorado, give homeowners a property assessment with specific tips, updates, landscaping, and removals that decrease their risk to a wildfire. Additionally, some insurance companies have specialists that perform consultations and provide the homeowner a report with recommended improvements to eaves, patios and decks, roofs, and vegetation. In areas with high wildfire risk, insurance companies may require this kind of consultation and follow up work in order to authorize writing the policy. As always, be your own advocate, and take the first steps to giving your home the best chance of survival from a wildfire. However, if you choose to live in a high wildfire risk area, be prepared to pay a bit higher premium to have proper insurance coverage in case of a destructive wildfire.

Source(s):

https://disastersafety.org/wildfire/preventing-fire-damage-other-roofing-tips/

http://www.readyforwildfire.org/Defensible-Space/

http://www.wildfirepartners.org/our-program/

 

CalFire Finds Cause for Fire Siege, But Questions Remain

The legal battles begin as California still reels and begins to recover from what became the worst fire season in living memory last year. CalFire released a report on the first of several fire investigations from 2017’s northern California fire “siege”. The investigation specifically covers the four fires in Butte and Nevada Counties: La Porte, McCourtney, Lobo, and Honey fires. Investigators determined that tree branches coming into contact with power lines caused all four fires. In three of the fires, with La Porte being the exception, CalFire found Pacific Gas and Electric in violation of Public Resources Code section 4293, which concerns tree clearance management along power lines.

The ramifications of these and future investigations could end in big payouts by Pacific Gas and Electric for structure losses caused by the fires. The Napa/Sonoma Fire Siege, which included about 170 individual fire starts, caused an estimated $15 billion in damages. If Pacific Gas and Electric is found responsible for the fire starts, they could be on the hook for a large chunk of those damages. Property law can get pretty tricky when dealing with privately run public utilities. In the past, utility companies were able to pass the cost of damages along to ratepayers as part of providing service, but a recent case with San Diego Gas and Electric may put an end to this practice.

Historical Precedent: San Diego Gas and Electric

2007 Witch Fire

Regulators, investors, insurers, and homeowner victims are closely following the now decade-long legal process following three massive fires in San Diego County in 2007. The Witch, Guejito, and Rice fires together destroyed 1,300 homes and left San Diego Gas and Electric (SDG&E) with a $2.4 billion bill. The utility company and its insurers already paid the damage claims, but SDG&E is trying to recoup about $379 million of its losses through a structured increase in the ratepayer bill over 6 years. They argued that the wind event was unprecedented and so severe that the fires could not have been avoided. The California Public Utilities Commission disagreed and rejected the plan, stating that SDG&E was not a prudent manager of its infrastructure. CPUC was clear in their statements that their decision does not represent SDG&E’s current wildfire management. SDG&E has since invested heavily in wildfire planning, intelligence, and response.

The positive changes at SDG&E are precisely the reason that the California Public Utilities Commission does not want to allow utilities to pass the damages to the ratepayers. It would disincentivize the utility companies to invest in better wildfire prevention.

Investors worry that the SDG&E decision will set a precedent to determine if PG&E will be held liable and if they can force ratepayers to cover the cost. Whether Pacific Gas and Electric will be found responsible for a majority of the losses in the larger Napa/Sonoma fires is still unclear. Even if they are found liable, who will pay?

 

Source(s):

http://calfire.ca.gov/communications/downloads/newsreleases/2018/2017_WildfireSiege_Cause%20v2%20AB%20(002).pdf

http://www.latimes.com/business/la-fi-utility-wildfires-20171017-story.html

https://www.bloomberg.com/news/articles/2017-11-28/for-a-look-at-pg-e-s-fate-after-fires-watch-this-san-diego-case

http://www.sandiegouniontribune.com/business/energy-green/sd-fi-sdge-wildfirecaseruling-20171130-story.html

http://www.cbs8.com/story/37043932/lilac-fire-powerful-debate-over-sdge-cutting-off-electricity

 

hurricane harvey spins in gulf

2018 Hurricane Season Begins June 1st

Hurricane season arrived early this year, as Subtropical Storm Alberto became the first named storm of the season late last week. Alberto ruined a Memorial Day weekend for the majority of the Gulf Coast as it doused the area with rain and even flooding. This anomaly subtropical storm actually came slightly earlier than the official start date of hurricane season. The official hurricane season runs from June 1st to November 30th for the Atlantic Ocean, and May 15th through November 30th for Eastern Pacific Ocean. After last fall’s major hurricane impacts, RedZone wanted to relay what the hurricane forecasts are predicting about the upcoming hurricane season.

Colorado State University releases an “Extended Range Forecast of Atlantic Seasonal Hurricane Activity and Landfall Strike Probability” report each year. This report is based off models that incorporate 30 years of atmospheric conditions, and hurricane data for statistical analysis. The current conditions in the Atlantic Ocean seem to be in a weak La Niña currently. This means that the oceans temperatures are relatively cooler than average. This is not conducive for hurricane formation and strengthening.  As a reminder, ENSO, otherwise known as the El Niño and the Southern Oscillation, is the periodic fluctuation of sea surface temperature. The worry from the Oceanic forecast, though, is that the ENSO transitional phase will occur during the summer months. The thinking is, the transition from La Niña conditions into even a mild El Niño (warmer sea surface temperatures) could result in above normal hurricane activity this hurricane season.

named storm predictions

This figure is the results from the model that Colorado State uses to predict the hurricane forecast.

This figure depicts the final analysis made by Colorado State University in totality regarding numbers related to the upcoming hurricane season. As you can see this year is expected to be above the 30 year average in every category that is shown. Below is a figure depicting FEMA’s modeling outlook for the Hurricane season. FEMA’s model shows very little variation from what Colorado State’s results were.

NOAA Hurricane Season Outlook

NOAA’s Hurricane Season Outlook is predicting an average to above average year

Sources:

https://www.cnn.com/2018/05/27/us/weather-storm-alberto/index.html

https://www.livescience.com/57671-hurricane-season.html

https://oceanservice.noaa.gov/facts/ninonina.html

https://www.ncdc.noaa.gov/teleconnections/enso/enso-tech.php

A New Source for Wildfire Intelligence and Discussion

The 2018 wildfire season is already off to a strong start. So far this year major fires have already igniting across Texas, Oklahoma, and the southwest. As we move into the summer months, increasingly warm and dry conditions will continue to fuel the threat of wildfires. The National Inter-agency Fire Center released their fire potential outlook for summer months, predicting an above average fire season for all of the twelve western states making wildfire intelligence gathering even more essential. This foreboding outlook comes on the heels of an oft dubbed “unprecedented” 2017 wildfire season that shattered multiple records.

A Trusted Source Lost

2017 thrust the threat of wildfires back into the public spotlight. Numerous fires across the United States grabbed nationwide media attention but none more than the two most significant California fires; The October Fire Siege in Napa/Sonoma and the Thomas Fire in the Ventura/Santa Barbara area. With broadcast and social media flooding in, one trusted source of wildfire intelligence was surprisingly absent from the conversation. Without notice, during the late season chaos of the Thomas fire, the WildlandFire.com forum was taken offline and all the data was lost.

What was WildlandFire.com?

WildlandFire.com was conceived in the early nineties as a way to provide, “a quick, reliable system to allow firefighters and other employees (and their families) the ability to voice their thoughts, ideas, experiences, or even ask a few simple questions.”. By the late nineties the forum gained traction, soon becoming a trusted source within the firefighting community.

Wildfire Intelligence Forum

Understanding the essential role this type of web forum plays, a conversation started on how to revive the website. A group of “devout users and former moderators” ultimately decided it was best to spin-off a new website. This new website, branded wildfireintel.org, was created as a non-profit with the mission to create a forum for discussing “topics important to the fire community”. Relevant subjects include fire related “incidents, jobs, industry, safety, and health”.

Wildfire Intelligence Forum Example

An example of how the forum is structured based off geographic regions.

For More Information and How to Register

Although it’s still in the initial stages of development, wildfireintel.org is now up and running. Knowing that forums survive by the active participation of its users the founders of the website are encouraging the fire community to contribute to the site. The founders hope that with increased participation an “active and sustainable wildfire community” will again foster. For more information, please visit the wildfireintel.org website and/or become more involved by registering.

logo

Wildfire Intelligence Logo

fire on the horizon

Do the First Five Feet Matter Most?

Experiments, models, and post-fire studies have shown homes ignite during wildfires due to the condition of the home and its surroundings, up to 200′ from the foundation. The last couple of years, fire researchers have found more and more cases of homes burning down due to combustibles directly linked (first five feet) to the structure. Specifically, embers and small flames from low intensity surface fires are igniting adjacent combustibles which are, in turn, igniting homes. Therefore, the Home Ignition Zone receiving the most attention lately, is the area within 0-5 feet of the home.

H I Z

The Home Protection Zone as suggested in the Wildfire Home Assessment Checklist published by Insurance Institute for Business & Home Safety (Source: http://disastersafety.org/wp-content/uploads/wildfire-checklist_IBHS.pdf)

First Five Feet Defined

The actual home, including roof and deck, along with the area within five feet of the zone makes up what the NFPA refers to as the “Immediate Zone”. According to the site, science has proven that this is the most important zone to take action on as it is the most vulnerable to embers and therefore home ignition. The group also provides a few suggestions for this zone which will help the survivability of a home during a wildfire event.

  1. Clean roofs and gutters of dead leaves, debris and pine needles that could catch embers.
  2. Replace or repair any loose or missing shingles or roof tiles to prevent ember penetration.
  3. Reduce embers that could pass through vents in the eaves by installing 1/8 inch metal mesh screening.
  4. Clean debris from exterior attic vents and install 1/8 inch metal mesh screening to reduce embers.
  5. Repair or replace damaged or loose window screens and any broken windows Screen or box-in areas below patios and decks with wire mesh to prevent debris and combustible materials from accumulating.
  6. Move any flammable material away from wall exteriors – mulch, flammable plants, leaves and needles, firewood piles – anything that can burn. Remove anything stored underneath decks or porches
six keys to the first five feet

The six keys to safety in the 0-5 foot zone


Sources:

Disaster Safety Organization

NFPA

NFPA Xchange Blog

This Friday, May 4, 2018, aerial image released by the U.S. Geological Survey, at 12:46 p.m. HST, a column of robust, reddish-brown ash plume occurred after a magnitude 6.9 South Flank of Kīlauea earthquake shook the Big Island of Hawaii, Hawaii. The Kilauea volcano sent more lava into Hawaii communities Friday, a day after forcing more than 1,500 people to flee from their mountainside homes, and authorities detected high levels of sulfur gas that could threaten the elderly and people with breathing problems. (U.S. Geological Survey via AP)

Kilauea Volcano Continues to Erupt

The Kilauea Volcano on the Big Island of Hawaii erupted last week Thursday, May 3rd, breaking open rifts and opening lava vents. While Kilauea has been continuously active for the last 35 years, this recent episode occurred alongside a 6.9 earthquake. Nearby neighborhoods were evacuated as fissures began releasing lava that spread throughout Leilani Estates and Lanipuna Gardens.

This Friday, May 4, 2018, aerial image released by the U.S. Geological Survey, at 12:46 p.m. HST, a column of robust, reddish-brown ash plume occurred after a magnitude 6.9 South Flank of Kīlauea earthquake shook the Big Island of Hawaii, Hawaii. The Kilauea volcano sent more lava into Hawaii communities Friday, a day after forcing more than 1,500 people to flee from their mountainside homes, and authorities detected high levels of sulfur gas that could threaten the elderly and people with breathing problems. (U.S. Geological Survey via AP)

Kilauea Eruption – Friday, May 4, 2018, 12:46 p.m. HST (U.S. Geological Survey via AP)

Due to the rate that lava spreads compared to other typical natural disasters such as hurricanes or wildfire, people were able to safely leave their homes. Photos and videos show the progression of destruction through the neighborhood as the lava pushes through homes and new fires ignite. One homeowner had been working on a car on his property and was unable to move it out of the way, but the true loss — the R2D2 mailbox his daughter had made him for Christmas. The impact was caught in this time-lapse video.

Fissure locations under Leilani Estates

Fissure locations under Leilani Estates east of the main active crater

Confirmed losses from Kilauea

As of May 10th, 36 structures have been destroyed, mostly in the Leilani Estates area. Despite the overall ongoing spread of lava, scientists are now warning area residents that ballistic projectiles may be emitted in the next few weeks. This would occur as the lava sinks in the crater lake and interacts explosively with the groundwater. The “projectiles” could range in size from pebbles to boulders weighing several tons. With so many unpredictable dangers from these ballistic projectiles to poisonous gases of the lava and ash to earthquakes, homeowners who still have a home to return to will not be sleeping easily any time soon.

USGS is alerting nearby residents about the possibilities of ballistic rocks.

USGS is alerting nearby residents about the possibilities of ballistic rocks.

 

Read Further

  • http://www.hawaiinewsnow.com/story/38087728/new-kilauea-eruption-triggers-house-fires-as-hundreds-evacuate-area
  • https://www.cnn.com/2018/05/10/us/hawaii-kilauea-volcano/index.html
  • https://www.cnn.com/interactive/2018/05/us/hawaii-kilauea-volcano-eruption-cnnphotos/index.html