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Earthquake Estimated magnitude 48 earthquake rattles the Central Valley

Earthquake Estimated magnitude 48 earthquake rattles the Central Valley

earthquake in california, earthquake bay area

Earthquake Estimated magnitude 48 earthquake rattles the Central Valley

A Fixed Smartphone Network Offers Inexpensive Earthquake Early … Thu, 08 Jul 2021 16:00:00 -0700-FRESNO, Calif. (KSEE/KGPE) — An earthquake rattled the Central Valley Thursday and could be felt across the area. The earthquake is an estimated 4.8 …

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5.9 magnitude earthquake near California-Nevada border

July 08, 2021

by: Nexstar Media Wire

Posted: Jul 8, 2021 / 04:44 PM PDT / Updated: Jul 8, 2021 / 04:47 PM PDT

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(U.S. Geological Survey)

(NEXSTAR) – A magnitude 5.9 earthquake shook up residents across Northern California and parts of Nevada Thursday, according to the U.S. Geological Survey.

The temblor struck at 3:49 p.m. near Markleeville, California, roughly 30 miles south of Lake Tahoe, and was followed by more than 10 aftershocks in California.

The depth of the initial quake was roughly 6 miles, according to the USGS.

There were no preliminary reports of damage or injuries, according to the California Governor’s Office of Emergency Services, but officials with the office called it a “rapidly evolving situation.”

Reports on social media and from the USGS showed the quake was felt as far away as the San Francisco Bay Area and east of Carson City, Nevada.

This is a developing story and will be updated.

Copyright 2021 Nexstar Media Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

by: Nexstar Media Wire

Posted: Jul 8, 2021 / 04:44 PM PDT / Updated: Jul 8, 2021 / 04:47 PM PDT

image
(U.S. Geological Survey)

(NEXSTAR) – A magnitude 5.9 earthquake shook up residents across Northern California and parts of Nevada Thursday, according to the U.S. Geological Survey.

The temblor struck at 3:49 p.m. near Markleeville, California, roughly 30 miles south of Lake Tahoe, and was followed by more than 10 aftershocks in California.

The depth of the initial quake was roughly 6 miles, according to the USGS.

There were no preliminary reports of damage or injuries, according to the California Governor’s Office of Emergency Services, but officials with the office called it a “rapidly evolving situation.”

Reports on social media and from the USGS showed the quake was felt as far away as the San Francisco Bay Area and east of Carson City, Nevada.

This is a developing story and will be updated.

Copyright 2021 Nexstar Media Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.


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Estimated magnitude 4.8 earthquake rattles the Central Valley Thu, 08 Jul 2021 16:00:00 -0700-In late 2019, a research team assembled 82 smartphones, strapped them to walls and floors in buildings across Costa Rica and waited six months. After a …

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A Fixed Smartphone Network Offers Inexpensive Earthquake Early Warning Potential

In late 2019, a research team assembled 82 smartphones, strapped them to walls and floors in buildings across Costa Rica and waited six months. After a careful analysis, they discovered that they had created an effective and inexpensive Earthquake Early Warning system that could provide communities with up to tens of seconds of warning that an earthquake occurred and shaking is imminent. 

“We wanted to explore the inexpensive end of the Earthquake Early Warning spectrum,” Benjamin Brooks, lead author and USGS research geophysicist, said. “It turns out that the system can also be quite effective at that end of the spectrum, too,” he said.  

Out of your pocket, onto the floor 

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A smartphone for earthquake early warning boxed and plugged in to a wall in Costa Rica. 

(Public domain.)

Building on previous research that first tested smartphone sensors for earthquake early warning, the new study moved smartphones from jostling pockets to stationary floors and walls. Instead of relying on crowdsourced data, the new approach relies on a fixed smartphone network. 

“The smartphones stopped being telephones,” said Marino Protti, director of the Costa Rica Volcanological and Seismological Observatory at the National University (OVSICORI-UNA) and co-author of the study. Instead, the phones’ on-board accelerometers, or mini motion sensors, captured the acceleration of the ground as earthquake waves propagated from an earthquake’s epicenter.  

Over a six-month period from December 2019 to June 2020, the Alerta Sismica Temprana Utilizando Telefonos Inteligentes network successfully captured five  magnitude-4.8 – 5.3 earthquakes across Costa Rica and sent a short, labeled message with enough time for a group of beta testers to be able to take a protective action, like drop, cover and hold on.  

Smartphone networks are less sensitive than scientific-grade networks and usually detect movement from secondary-waves (s-waves). Scientific-grade networks, on the other hand, are typically able to provide more warning time by first detecting subtler primary-waves (p-waves), which are less destructive and travel more quickly though Earth’s crust, arriving before more destructive s-waves.  

However, the Costa Rican smartphone network also detected two quakes by p-waves, which is comparable to scientific-grade networks and encouraging for potential similar systems in the future. The network sensed three quakes by s-waves, which means there would have been a shorter, but still beneficial, amount of warning time. 

The smartphone network is intended for strong motion quakes. Although data from Costa Rica’s scientific-grade network were not used in this study, data from the former helped validate data from the latter.  

An ideal testing environment  

In addition to beautiful tropical beaches, Costa Rica also offers an ideal setting to test an Earthquake Early Warning system. The country experiences over 1,000 earthquakes a month, of which 15 can usually be felt. “We have the best tectonic laboratory in the world,” Protti said.  

The Central American country’s seismic hazard is primarily due to the subduction of the Cocos plate below the Caribbean and Panama plates along the Middle America Trench.  

The team prioritized installing the smartphones in areas to best detect and warn for Middle America Trench earthquakes, which have the highest probability of affecting the largest percentage of the population, especially in San Jose.  

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(a) Middle America Trench offshore Nicaragua and Costa Rica. Highlighted dashed circle is the bin used to select ray bottoming locations for the outer‐rise anisotropy solutions. Thick lines mark published 2D seismic tomograms. Colored large circles mark the location of the profiles in (b). Small white and black circles mark OBS locations. White circles are sites used in the anisotropy solutions.

(Public domain.)

International collaboration 

While the smartphones were collecting information across Costa Rica, scientists in California processed the data.  

“This international work has been funded since its inception 5 years ago by the USAID Bureau of Humanitarian Assistance,” Brooks said. “The project aligns with its and USGS interests of international scientific and technological capacity and relationship building.” 

The team is particularly excited for the smartphone network’s potential to provide Earthquake Early Warning capabilities to countries with limited resources. “Our project shows that a resource-limited country could provide the sensing necessary to implement some form of earthquake alerting with smartphones from the local mall, for example,” Brooks said.   

For next steps, the researchers plan to invite approximately 1,000 people in Costa Rica to test a new app that will use data from the smartphone and scientific-grade network to send alerts. “The tricky and most important aspect to take into account is determining how people will respond to and interact with alerting systems,” Brooks said.  

The findings were published in the journal, AGU Advances


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– July 9, 2021
earthquake in california, earthquake bay area

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