The 2019 M-W 5.7 Changning Earthquake, Sichuan Basin, China: A Shallow Doublet With Different Faulting Styles

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F20%3A10420973" target="_blank" >RIV/00216208:11320/20:10420973 - isvavai.cz</a>

Výsledek na webu

<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=Lgrypc-fsf" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=Lgrypc-fsf</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1029/2019GL085408" target="_blank" >10.1029/2019GL085408</a>

Jazyk výsledku

angličtina

Název v původním jazyce

The 2019 M-W 5.7 Changning Earthquake, Sichuan Basin, China: A Shallow Doublet With Different Faulting Styles

Popis výsledku v původním jazyce

The increased seismic activity of the last similar to 10 years in Changning county of Sichuan Province comprised just small (mostly M-L &lt; 5.0) injection-induced earthquakes. The M-W 5.7 earthquake on June 17, 2019, is the largest event ever reported there. Moment tensor of the mainshock was remarkably dominated by a compensated linear vector dipole. We resolve its fine structure showing it was a doublet, allowing approximation by a thrust- and strike-slip subevent. The mainshock nucleated as thrust faulting, which (together with the largest aftershocks) can be linked with previously known reverse faults, favorably oriented to regional stress field. Contrarily, the strike-slip segment of the mainshock, less favorably oriented, was probably facilitated by elevated pore pressure due to previous injections. Shallow active strike-slip faulting, not yet mapped in the region, is a new feature, important for future hazard assessment. Plain Language Summary Changning county in Sichuan Basin belongs to major salt-producing resources, with water injection wells drilled to similar to 3-km depths. Enhanced occurrence of small earthquakes was observed in the last similar to 10 years. However, on June 17, 2019, a damaging earthquake struck the region. Seismic agencies reported diverse focal mechanisms and pointed to departures from shear faulting, typical for tectonic events. To understand these enigmatic features, we modeled records from 12 broadband seismic stations, adding over 100 first-motion polarities. We found that the earthquake was very shallow (similar to 4 km) and consisted of two shear events: the initial thrust faulting and the following strike-slip faulting along an SE-NW trending near-vertical plane, aligned with aftershocks. The initial episode was &quot;normal,&quot; expected on existing faults and supported by tectonic stresses of the region. Contrarily, the significant strike-slip faulting appears to be rather &quot;abnormal,&quot; probably facilitated by the initial shock and by elevated pressure of underground fluids. The 2019 earthquake provided a rare opportunity to illuminate interplay between long-lasting water injections, tectonic stress, complexity of existing faults, and their dynamic interactions. That is how seismology aims at making industrial activities sustainable and safe.

Název v anglickém jazyce

The 2019 M-W 5.7 Changning Earthquake, Sichuan Basin, China: A Shallow Doublet With Different Faulting Styles

Popis výsledku anglicky

The increased seismic activity of the last similar to 10 years in Changning county of Sichuan Province comprised just small (mostly M-L &lt; 5.0) injection-induced earthquakes. The M-W 5.7 earthquake on June 17, 2019, is the largest event ever reported there. Moment tensor of the mainshock was remarkably dominated by a compensated linear vector dipole. We resolve its fine structure showing it was a doublet, allowing approximation by a thrust- and strike-slip subevent. The mainshock nucleated as thrust faulting, which (together with the largest aftershocks) can be linked with previously known reverse faults, favorably oriented to regional stress field. Contrarily, the strike-slip segment of the mainshock, less favorably oriented, was probably facilitated by elevated pore pressure due to previous injections. Shallow active strike-slip faulting, not yet mapped in the region, is a new feature, important for future hazard assessment. Plain Language Summary Changning county in Sichuan Basin belongs to major salt-producing resources, with water injection wells drilled to similar to 3-km depths. Enhanced occurrence of small earthquakes was observed in the last similar to 10 years. However, on June 17, 2019, a damaging earthquake struck the region. Seismic agencies reported diverse focal mechanisms and pointed to departures from shear faulting, typical for tectonic events. To understand these enigmatic features, we modeled records from 12 broadband seismic stations, adding over 100 first-motion polarities. We found that the earthquake was very shallow (similar to 4 km) and consisted of two shear events: the initial thrust faulting and the following strike-slip faulting along an SE-NW trending near-vertical plane, aligned with aftershocks. The initial episode was &quot;normal,&quot; expected on existing faults and supported by tectonic stresses of the region. Contrarily, the significant strike-slip faulting appears to be rather &quot;abnormal,&quot; probably facilitated by the initial shock and by elevated pressure of underground fluids. The 2019 earthquake provided a rare opportunity to illuminate interplay between long-lasting water injections, tectonic stress, complexity of existing faults, and their dynamic interactions. That is how seismology aims at making industrial activities sustainable and safe.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10500 - Earth and related environmental sciences

Projekt

<a href="/cs/project/GC18-06716J" target="_blank" >GC18-06716J: BAIES - Bayesovská analýza parametrů zemětřesení: kinematické a dynamické modely zdroje konečných rozměrů</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2020

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Geophysical Research Letters

ISSN

0094-8276

e-ISSN

—

Svazek periodika

47

Číslo periodika v rámci svazku

4

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

9

Strana od-do

e2019GL085408

Kód UT WoS článku

000529120100061

EID výsledku v databázi Scopus

2-s2.0-85081017092