Journal Highlights

Mapping a Valparaíso Earthquake from Foreshock to Aftershock

From Eos.org: Research Spotlights—

Using seismic data recorded along the Chilean coast, scientists retrace the development of a recent earthquake. 

A massive arc of seismic activity—stretching from Australia to Japan, up toward Alaska, and down along the west coast of the Americas—is known among geologists as the Ring of Fire. Roughly 90% of the world’s earthquakes occur there. 

In April 2017, a swift but powerful magnitude 7 earthquake hit off the coast of Valparaíso, Chile, near the base of the Ring of Fire. About 2 days before it began, scientists detected intense seismic activity in the region. In a new study, Ruiz et al. zeroed in on this earthquake to better understand the formation, or nucleation, of earthquakes, as scientists do not know exactly why or how earthquakes start, become larger, and stop. 

Using data collected by a large network of GPS and broadband stations (suites of instruments taking seismic measurements at a broad range of frequencies) along the coast of Chile, the researchers studied the nucleation of the Valparaíso quake in great detail, as well as its rupture dynamic: the movement, deformation, and breakage of rock as an earthquake develops. 

The researchers analyzed seismic data from the days leading up to the most intense point of the earthquake, or mainshock. They also used a series of GPS readings from before, during, and after the mainshock to determine that the earthquake was triggered by a slow-slip event, which is characterized by a slower velocity rupture in comparison with a regular earthquake. Essentially, the team created a detailed map of the Valparaíso seismic sequence, charting the landscape of seismic movement—from the first foreshocks to the mainshock to the final aftershocks

This study provides the first clear picture of the dynamics of a slow-slip earthquake in the central Chile zone, where the last tsunamigenic megathrust earthquake occurred in 1730. It is also one of the best records in existence of the nucleation phase of an earthquake. This is an important step toward understanding how earthquakes develop and could help scientists predict seismic events with more accuracy. 

-- Sarah Witman, Freelance Writer,

RSS

Recent Highlights Across AGU Publications

Eos.org: Earth & Space Science News

View more Earth and space science news from Eos

Download the App

New Android App Available!

Google Play Store Logo

Download the Geophysical Research Letters app from the Google Play Store

iOS App for iPad or iPhone

GRL IOS App

Download the Geophysical Research Letters app from the Apple store


AGU Career Center


AGU Unlocked


Featured Special Collection

A Census of Atmospheric Variability from Seconds to Decades 

The atmosphere varies naturally on all length scales from millimeters to thousands of kilometers, and on all time scales from seconds to decades and longer.  This special collection of Geophysical Research Letters synthesizes and summarizes that variability through a phenomenological census.  The collection brings together some of the most influential and definitive papers to have been published in this journal in recent years.  The topics covered include turbulence on time scales of seconds and minutes, gravity waves on time scales of hours, weather systems on time scales of days, atmospheric blocking on time scales of weeks, the Madden–Julian Oscillation on time scales of months, the Quasi-Biennial Oscillation and El Niño–Southern Oscillation on time scales of years, and the North Atlantic, Arctic, Antarctic, Pacific Decadal, and Atlantic Multi-decadal Oscillations on time scales of decades.  The collection is accompanied by a Commentary article, which provides an authoritative, concise, and accessible point of reference for the most important modes of atmospheric variability.

A Census of Atmospheric Variability from Seconds to Decades