Racing to the Quake

Thirty-two years and six hours after Mexico City was shaken by its most devastating earthquake, the city was rocked again, and this just two weeks after a strong quake shook the southern state of Chiapas.
Sept 7 & 19 earthquakes in Chiapas and Mexico City.
Photos: BBC

Immediately after the September 19, 2017 earthquake, hundreds of its citizens ran towards its many collapsed buildings.

The September 20, 2017 edition of The Takeaway begins with a detailed interview with a former Mexican diplomat, who explains the lessons residents of Mexico City have learned, and compares the experience of the capital with that of rural Chiapas, which was struck by a quake earlier this season. No longer available on WNYC, this segment is on iTunes.

A few days later, journalist Maya Kroth described the response in detail, especially the work of Los Topos (The Moles), the volunteers known for their extraordinary rescue efforts. Her interview with Todd Zwelick is followed by a conversation with Janise Rodgers, CEO of GeoHazards International, who discusses the vulnerability of schools throughout Latin America.
It is useful to consider the context of Mexico City, built as it is in a former lake bed. It is more than 7,000 miles above sea level, but it is at the bottom of a volcanic valley, built on unconsolidated sediment that has flowed from surrounding peaks. To get a sense of the scope of the affected area, begin in the map of the city center below, and gradually zoom out to the mountains.

It is vulnerable to the movements along the Middle America Trench, one of the world's most active tectonic convergence zones. Both the September 7 and September 19 earthquakes originated along this deep boundary, though the distance between them suggests no direct causal connection.
Map: BBC
The U.S. Geological Survey Earthquake Hazards Program provides real-time and follow-up information about earthquakes throughout the world. Its report on the September 19 earthquake reveals that it was an intraplate event, meaning that it happened within the Cocos plate, rather than at a plate boundary. Nonetheless, the event was very close to the boundary, 48.0 km below sea level and near a sharp bend in the plates.
Source: USGS, Ayulta event summary page
The USGS report on the Tres Picos Magnitude 8.2 September 7 event along the Chiapas coast does not include a comparable cross section, but it does report a similar depth and intraplate location. (Note: USGS gives a September 8 date, because all of its instruments follow Greenwich Mean Time.)

These thorough analyses by scientists based in the United States is possible because its network of seismic stations allows for detailed measurements of earthquake activity, regardless of its location on the planet. Similar efforts are devoted to the USGS Volcano Hazards Program, but the nature

Comments

Post a Comment

Popular posts from this blog

Balún: Sleep While Dancing

Image
Photo by way of PopGun I had not heard of the Puerto Rico-Brooklyn band until yesterday, when I caught this interview on the NPR program Studio 360 (which gave credit to Latino USA for the original story). The interview centers on the construction of the band's signature "dreambow" rhythms, particularly in the band's new song El Espanta . Angélica Negrón describes what she sees as the therapeutic value of this approach. I found it both enjoyable and instructive to listened to that song a few times before returning to the interview. The video of Balún's La Nueva Ciudad is an example of what the artists mean by dreambow, and is a perfect example of Negrón's expression "sleep while dancing." The lyrics describe a progressively more complicated metaphorical connection between the narrator and the stars, as her head, throat, and legs represent a telescope. The chorus laments a growing distance from a human subject. The longer video "Full Episode&q
Read more

Shanay-timpishka

Image
I started my Sunday with this discussion between journalist Guy Raz and volcanologist Andrés Ruzo, whose childhood conversations at home led him to an amazing discovery in the Amazon Basin of Peru. (Because it contains have of the basin, Brazil is the best-known of the Amazon countries, but several upstream neighbors also have vast tracts of the basin and its forests.) I recommend listening to the audio and then watching Dr. Ruzo's full TED Talk , given in 2014 in Rio de Janeiro. His story begins with curiosity, legend, and history. It provides insight into indigenous knowledge, geothermal science, ecology, and the concept of ecotourism. It even touches on coffee! And from the TED Radio summary, I learn of Dr. Ruzo's coffee connection. In addition to growing up in Peru, part of his childhood was near volcanoes in Nicaragua, which means he is not far removed from coffeelands. Andrés Ruzo has written his story in The Boiling River
Read more

Before the Flood

Image
I really did not want to see Before the Flood , even though I teach several courses that relate directly to it. I pictured myself viewing it like a kid (or me) at a scary movie, watching through little gaps between my fingers as I try to shield my eyes from the screen. I have watched An Inconvenient Truth  and its sequel a few times, and even with Al Gore's dry presentation, I found it nervous-making, at least. Melting Arctic ice. Some parts of the film actually are pretty frightening. So when I heard that a real film-maker had produced something very convincing about climate change, I knew that I had to see it and would want to avoid it, at the same time. Given the dramatic potential of climate change, I feared being sucked into an experience that would manipulate audience emotions with dramatic music and images of peril. Thankfully, this film does none of that, and I managed to watch it three times in a ten-day period, without being scarred. DiCaprio documents his travels as the
Read more