Internet Impacts of Hurricanes Harvey, Irma, and Maria

September 25, 2017 David Belson

Hurricane Irene - Dyn Uptime

Devastation caused by several storms during the 2017 Atlantic hurricane season has been significant, as Hurricanes Harvey, Irma, and Maria destroyed property and took lives across a number of Caribbean island nations, as well as Texas and Florida in the United States. The strength of these storms has made timely communication of information all the more important, from evacuation orders, to pleas for help and related coordination among first responders and civilian rescuers, to insight into open shelters, fuel stations, and grocery stores. The Internet has become a critical component of this communication, with mobile weather applications providing real-time insight into storm conditions and locations, social media tools like Facebook and Twitter used to contact loved ones or ask for assistance, “walkie talkie” apps like Zello used to coordinate rescue efforts, and “gas tracker” apps like GasBuddy used to crowdsource information about open fuel stations, gas availability, and current prices.

As the Internet has come to play a more pivotal role here, the availability and performance of Internet services has become more important as well.  While some “core” Internet components remained available during these storms thanks to hardened data center infrastructure, backup power generators, and comprehensive disaster planning, local infrastructure – the so-called “last mile” – often didn’t fare as well. This local infrastructure, both fixed and mobile, plays a critical role in enabling end users to access the Internet, and in many cases, it experienced significant availability issues due to the high winds, excessive rain, and other havoc wreaked by these recent hurricanes.  This was especially the case among some of the hardest hit Caribbean islands, although networks in Florida and Texas were impacted as well.

The monitoring and measurement performed by Oracle Dyn allows us to see network availability issues in near-real time. By analyzing BGP data shared by network peers in over 700 locations around the world, as well as traceroutes performed from over 300 locations across the global Internet, we can identify network outages as they occur, and use our geolocation tools to understand where they have the most significant impact.  Based on this data, as well as the analysis of data from our authoritative/secondary and open recursive DNS services, we were able to see the impact of Hurricanes Harvey, Irma, Jose, and Maria on Internet connectivity in affected areas.

It is worth keeping in mind that core network availability is a necessary, but not sufficient, condition for Internet access. Just because a core network is up doesn’t mean that users have Internet access—but if it isn’t up, then users definitely don’t have access.

Harvey

Hurricane Harvey made landfall on the evening of August 25, near the small town of Rockport, Texas. Over the next several days, it slowly made its way north, essentially parking itself over Houston on the 26th and 27th, dropping record amounts of rain.  As the figure below shows, the number of network prefixes geolocated to Texas that became unavailable during that period grew significantly, from approximately 40 to over 120 at peak. Widespread power outages due to the hurricane forced some local network infrastructure offline, but repair efforts were swift, bringing many network prefixes back online by the 27th.

Irma

Less than a week later, Tropical Storm Irma intensified into a hurricane, and within days into a Category 5 storm. Hurricane warnings were issued for the U.S. Virgin Islands and Puerto Rico on September 4, and a hurricane watch was issued for the Turks and Caicos Islands on September 5.  Within a day, the eye of Hurricane Irma began to pass over island nations in the Caribbean, with Saint Barthelemy and Saint Martin/Sint Maarten among the first hit. As the figures below show, two of the three available networks on Saint Barthelemy saw outages, lasting from September 6 until the 9th. On Sint Maarten, most of the 30 available networks went offline starting around 10:00 UTC, with a brief complete outage, although availability largely returned on the 9th. Networks on Saint Martin, which shares the island with Sint Maarten, suffered a similar level of outages over the same time frame.

Hurricane Irma also pounded Anguilla with 185 mph winds, but as the figure below shows, the impact to network availability on that island appeared to be significantly less severe, with just a few networks becoming unavailable between September 6-9. As it moved northwest towards Florida, Irma also impacted network availability on the Turks and Caicos Islands, hitting the islands with sustained winds of 175 mph on September 7. Similar to Anguilla, only a fraction of the total available networks went offline, but they were unavailable for a longer period of time, with connectivity appearing to return late on September 11.

After moving through the Caribbean, Hurricane Irma made landfall in the Florida Keys as a Category 4 storm during the morning of September 10. As the figure below shows, Internet activity in Monroe County, as measured by geolocated requests to Dyn Oracle’s DNS services, drops off significantly at around the same time, presumably due to power outages and damaged local infrastructure.

Evacuation orders for counties across Florida began to take effect on September 7 and 8 – some orders were mandatory, while others were made voluntary. The figure below shows query volume to Oracle Dyn’s Internet Guide open recursive DNS service, aggregated from IP addresses geolocated to the state of Florida. As it illustrates, the evacuation orders appeared to drive residents offline, as they prepared to flee the hurricane and find shelter elsewhere.  Query traffic clearly begins to decline on September 7, hitting its lowest volumes on the 10th and 11th as Irma roared across the state.  Request volume began to recover on the 12th, as Irma moved north, power was restored, and residents began to return to their homes.

Maria

Less than two weeks after Irma, Hurricane Maria also hit islands in the Caribbean, inflicting significant damage on both Dominica and Puerto Rico. On Monday, September 18, Hurricane Maria intensified into a Category 5 storm, and made landfall on Dominica, with winds near 160 mph causing widespread devastation. As the figure below shows, network instability on the island increased significantly just after 06:00 UTC, leaving just a fraction of the networks available thereafter.  Two days later, Maria made landfall on Puerto Rico, resulting in a rapid decline in the number of available networks seen from the island, as shown in the figure below.

Later that morning, widespread power outages resulting from Hurricane Maria caused a near complete Internet outage in Puerto Rico, as the figures below show. Queries to Dyn’s Internet Guide open recursive DNS service from Puerto Rican IP addresses dropped to near zero at 11:30 UTC, while traceroutes to endpoints in Liberty Puerto Rico (a cable and broadband Internet service provider on the island) saw the number of responding targets also drop to near zero at around the same time, indicating that the target endpoint systems, or the networks they were connected to, were offline.  

 

Further network instability was observed on the morning of September 21, likely due to ongoing power outages, as the number of available network prefixes dropped from near 600 to around 350 just after 03:00 UTC, as shown below.

Admittedly, graphs showing Internet volatility resulting from hurricane damage in no way compare to the actual physical devastation caused by the storms. However, social media sites and applications, as well as the broader Internet, have come to play a greater role in preparedness, communications, and global dissemination of information, photos, and videos about the impacts of these natural disasters. As such, it remains important to monitor, measure, and understand how these storms affect local Internet connectivity and availability in those regions. The @DynResearch Twitter account has been posting this type of information, including many of the graphs included above, and is an excellent resource for understanding how natural and physical disasters, as well as actions by state actors and other network ‘events’, impact local and global Internet connectivity. Although the 2017 Atlantic hurricane season doesn’t end until November 30, we hope that this is our last post on this topic for the season.

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