Buildings collapse in coastal Taiwan M=6.4 quake

By David Jacobson, Temblor

Check your hazard rank

collapsed building taiwan
This picture shows the 270 Marshal Hotel, whose lower floors collapsed in today’s M=6.4 earthquake. (Photo from: KULAS_TW)

 

A second large earthquake in 2 days strikes Eastern Taiwan

Just before midnight local time, a M=6.4 earthquake struck Eastern Taiwan, toppling buildings, collapsing ground floors, and buckling streets. The quake, which comes just two days after a M=6.1 approximately 20 km to the southeast, occurred at a depth of 10 km and registered very strong shaking in the city of Hualien according to the Taiwan Central Weather Bureau. Hualien is home to over 100,000 people. Yesterday, when we wrote about the M=6.1 over the weekend, we pointed out that its location marks the intersection of the Longitudinal Valley Fault and the Ryukyu Trench. Because of this, the area is prone to experiencing large magnitude earthquakes, meaning this quake should not be considered surprising. Further, earthquakes at fault junctions and tips are slightly more likely to trigger still larger shocks than others.

google-earth-taiwan-earthquake
This Google Earth image shows the location of today’s M=6.4 earthquake near the city of Hualien, which is home to over 100,000 people.

 

Significant damage within Hualien

taiwan earthquake damage
This picture shows a partially-collapsed building in the city of Hualien, on Taiwan’s eastern coast. The earthquake which caused this damage was a M=6.4 quake which struck just two days after a M=6.1 just 15 km to the southeast.

 

collapsed-building-taiwan
This picture from The Guardian shows a building which suffered at least a first story collapse in today’s M=6.4 earthquake north of Taiwan’s city of Hualien.

 

Based on early reports and pictures, there is significant damage in Hualien, at least two people are confirmed to have been killed, and over 200 people were injured, 27 of them seriously according to the New York Times. Additionally, NPR announced that seven buildings had collapsed and while people remain trapped beneath the collapsed buildings, the National Fire Agency announced that they had rescued 149 people trapped in the rubble. However, people remain trapped in a partially-collapsed hotel. The photos above show some of the major damage sustained in the earthquake.

The reported damage is higher than forecast by the USGS PAGER system, which anticipated less than $1 million in damage. This is likely due to an underestimation of the amount of shaking around Hualien. The ShakeMap produced by Taiwan’s Central Weather Bureau can be seen below.

taiwan-shakemap
This figure shows the ShakeMap produced by Taiwan’s Central Weather Bureau. In the city of Hualien, shaking reached Intensity Level 7.

 

A yet-larger earthquake could still occur

taiwan-earthquake
This Temblor map shows the location of the recent earthquake on Taiwan’s eastern coast. Both of the recent M=6+ quakes occurred at the northern tip of the Longitudinal Valley Fault, Taiwan’s longest and most active fault.

 

While the earthquake over the weekend was predominantly compressional in nature, today’s event was nearly pure strike-slip, according to both the USGS and GFZ-Potsdam. Because of this, today’s quake may have struck at the northern tip of the Longitudinal Valley Fault, which is known to have both compressional and left-lateral motion. As we said yesterday, 30% of all earthquakes in Taiwan occur on or near this fault. It also has the highest slip rate of all faults in Taiwan.

 

Domino Theory?

While the M=6.4 shock occurred offshore at the northern tip of the Longitudinal Valley Fault, several of its large aftershocks occurred 20 km (12 miles) to the south, beneath Hualien, also on or near the Longitudinal Valley Fault. So, there appears to be a seismic propagation of aftershocks along the Longitudinal Valley Fault. This raises concerns that these events themselves could be foreshocks to still larger earthquakes that could rupture south along Taiwan’s longest, and most active fault.

Today’s shock should not come as a surprise. The Taiwan Earthquake Model, a university, government, and industry consortium that uses the tools and libraries of the Global Earthquake Model (GEM Foundation), is shown below. The area around the recent earthquakes has one of the highest hazards in the entire country. Therefore, residents of Eastern Taiwan should be prepared for potentially larger, more damaging earthquakes, perhaps propagating to the south.

Taiwan-hazard-map
This figure shows the Taiwan Earthquake Model. What is evident in this figure is that the location of today’s earthquake is in a location of extremely high hazard. (Figure from Cheng et al)

 


The video above shows damage sustained in today’s M=6.4 earthquake near the city of Hualien

 

References
Taiwan’s Central Weather Bureau
EMSC
Taiwan Earthquake Model from, Thomas (Chin-Tung) Cheng et al., Disaster Prevention Technology Research Center, Sinotech Engineering Consultants, Inc. – Link
Kate Huihsuan Chen, Shinji Toda, and Ruey-Juin Rau, A leaping, triggered sequence along a segmented fault: The 1951 ML 7.3 Hualien-Taitung earthquake sequence in eastern Taiwan, JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 113, B02304, doi:10.1029/2007JB005048, 2008
USGS
BBC
New York Times
The Guardian
NPR

  • Keith Koper

    Thanks for another interesting article. I didn’t realize the bit about earthquakes occurring at fault tips being more likely than average to precede even larger events. I too was surprised that PAGER was a little low for this event. One little bug is that in the “Domino Theory” section I think the first sentence of the second paragraph is missing a “not”. I am not trying to pick on this article, and I make a ton of typos myself, but this could be confusing to non-specialists that read the piece.

  • Robert H. Sydnor

    This is an excellent and timely report by Temblor seismologists. Like all breaking news stories of earthquakes that occur at midnight, it takes daylight to fully assess the structural damage and loss of life.

    We send our heartfelt condolences to the Chinese people who live in Hualien.

    Temblor has assembled the complete regional tectonic picture, and we recommend this to news media (newspapers and television) to cite this accurate seismology report by Temblor.

    Robert H. Sydnor
    California Certified Engineering Geologist #968
    Life Member, Seismological Society of America
    Life Member, American Geophysical Union

  • 洪瑞駿

    Some of our scientists in Taiwan suggest this event might be generated from Meilun Fault, which activated in 1951 and caused significant damages. The 1951 sequence started from three M7 events in Hualien offshore, then woke up other two major M6 events in the middle and southern part of the Longitudinal Valley fault mentioned in the article in two months.
    So.. Would the domino Theory become true? We have no idea. But, it did happen before.

  • Herrnhut

    Thank you for an excellent article. I would imagine the vertical components must be pretty substantive since at least two of the collapses have the ground floor perimeter columns essentially crushed in compression. Also the pancaked hotel suggest total loss of columns strength in lower floors.

    Also a few collapse sites are next to a local stream or river. Highly possible liquefaction for those sites. Sadly this is a repeat like two years ago in that both happened right before their new year festival. All the red lanterns were up. so sorry to have seen that.

    I notice Robert Sydnor has reviewed this article. Has to be a good article to get such review.

  • Andreas Schuerger

    Thanks a lot for the condolences. Most of the people affected here are Taiwanese though, with a Japanese group mentioned in connection with one of the two damaged Hotels. So far I didn’t hear about Chinese nationals living in Hualien affected.

  • Temblor

    Thank you for your comment and glad you liked the article. Also, you are right about potential liquefaction. At least 4 of the buildings which suffered heavy damage either caved in, tilted, or shifted significantly on their foundations, suggesting liquefaction did occur. This would not be surprising as Hualien is built on river deposits, which are extremely susceptible to liquefaction

  • Brendan Kennedy

    I’m living in Hualien now, and while my dormitory at Tzu Chi university was unharmed, I’m still quite apprehensive about the potential of another larger earthquake.