Earthquakes and volcanoes can provide us with surprising and unexpected new data. Just within this century, several dramatic events have increased our understanding of these natural hazards, including the catastrophic 2004 Sumatra-Andaman earthquake and tsunami in Indonesia, and the 2011 Tohoku earthquake in Japan. Now, examination of the events leading up to a 2021 volcanic eruption has brought new – and sobering - information.
The title says it all: “The Mw 5.1, 9 August 2020, Sparta Earthquake, North Carolina: The First Documented Seismic Surface Rupture in the Eastern United States”. Lots of information is packed into those words. Importantly, it provides evidence of our limited knowledge about the hazards presented by earthquakes.
The tsunami associated with Hunga Tonga eruption has sparked renewed interest in hazards associated with earthquakes, volcanoes, and tsunamis. A recent article about geologic hazards and preparedness especially caught my attention: “A Tsunami Could Kill Thousands. Is Escape Possible?” in the New York Times. The focus is on the Pacific Northwest- –specifically coastal communities along the states of Washington, Oregon, and northernmost California.
Our planet has a high level of tectonic activity. In the past few decades, disastrous earthquakes have captured our attention. A careful look at historical records, however, demonstrates that a major volcanic eruption would cause immensely more devastation that any natural event our world has experienced recently.
Large earthquakes, volcanic eruptions, and tsunamis can create shock waves felt around the world – literally. The blast from the volcanic eruption on January 15, 2022, near Tonga caused spikes in air pressure recorded around the planet. We can add this eruption in a remote part of the Pacific Ocean to our knowledge of pandemics, climate change, and numerous other interconnections that tie our planet and our societies together.
Five great earthquakes of M9 or larger have been recorded in the past century and each was followed by a major tsunami, along with vast devastation and many deaths. These events have provided information to help mitigate the effects of future great earthquakes - including what to keep in the back of your mind if you experience strong earthquake shaking in coastal areas worldwide.
When an M8.2 earthquake struck offshore of the Alaska Peninsula on July 28, the eerie sound of sirens warning of a possible tsunami sent people along the coast scrambling for higher ground. Authorities lifted the warning within a few hours, and damage from ground shaking was limited. Viewed from a broad perspective, this event was only a minor distraction, but many earthquakes that are this powerful result in major disasters.
The volcano recently erupting in Africa–Mount Nyiragongo–is one of the most active on our planet. Eruptions in 1977, 2002 and now beginning in May 2021, have resulted in a significant number of fatalities and extensive damage in the nearby and densely populated city of Goma. If scientists were calling the shots, they would relocate Goma and designate the region beneath this active volcano as a national park.
The deep and steep-walled Rio Grande gorge in northern New Mexico is remarkable. This large gash is developing because the Earth’s crust is pulling apart, creating a linear depression, or rift, that provides a convenient location for a large river to develop. On a recent trip I admired the river -- and desert bighorn sheep.
Volcano-watchers have had lots of excitement lately with the ongoing eruptions on the Reykjavik Peninsula in Iceland and Soufriere, on the West Indies island of Saint Vincent. So far both eruptions are fairly small. Colorful graphic representations of the relative sizes of volcanic eruptions are intriguing, although variability in natural events confounds human attempts to assign neat boxes or bubbles to these phenomena.