The magnitude 6.7 Northridge earthquake rocked Los Angeles in 1994, killing more than 60 people and injuring thousands. This temblor came from                  the rupture of what's known as a blind-thrust fault, the same type of fracture in Earth's crust addressed in the new study.                                  1994年，北岭7.6级地震震动了洛杉矶，造成60多人死亡，数千人受伤。 这个地震来自于所谓的盲逆断层的破裂，这是新研究中解决的地壳破裂类型。              

Hidden earthquake risk found lurking beneath Los Angeles

隐藏的地震风险发现潜伏在洛杉矶之下

The fault was once thought dead, but recent research suggests it’s likely still active—and poses a hazard to the metropolis above.

这个断层曾经被认为非活跃的，但最近的研究表明它可能仍然活跃 - 并对上述大都市造成危害。

THE PORTS OF Los Angeles and Long Beach bustle with activity—their colorful array of shipping containers are stacked and unstacked in a never-ending, multibillion-dollar game of Tetris. 

洛杉矶和长滩的港口熙熙攘攘 - 他们色彩斑斓的集装箱堆上去又卸下来如在一个永无止境的，价值数十亿美元的俄罗斯方块游戏中。

But a previously overlooked danger lurks below this frenzy: A fault capable of generating earthquakes magnitude 6.3 or greater.

但是，一种先前被忽视的危险潜伏在这种狂热之下：能够产生6.3或更大的地震的断层。

The Wilmington fault, as it’s called, is an elusive type of fracture.

所谓的威尔明顿断层是一种隐秘的断裂类型。

Unlike many faults, which crack Earth’s surface like an egg, the Wilmington fault is “blind,” which means it’s concealed beneath the surface, making it especially difficult to study.

与许多让地表像蛋一样破裂的断层不同，威尔明顿断层是“盲目的”，这意味着它隐藏在地表之下，使其特别难以研究。

So while scientists have long known the fault is present—stretching 12.4 miles under southern Los Angeles into San Pedro Bay—it was presumed to have sat quiet for millions of years.

因此，虽然科学家早就知道这个断层存在 - 在洛杉矶南部底下延伸12.4英里到圣佩德罗湾 - 它被认为已经沉寂了数百万年。

Now, a new analysis of the system, published in Bulletin of the Seismological Society of America, suggests that isn’t the case.

现在，一篇发表在美国地震学会公报上对该系统的新分析表明情况并非如此。（Seismological：地震学）

Using a cluster of clues incorporated into a three-dimensional model, the study authors posit that the fault has been active much more recently than once thought—and likely still poses a risk to people on the surface.

该研究的作者人员利用一系列线索并入三维模型中，断定此断层活跃的时间比他们设想的要更近而且还会威胁到地表的人。

“I hope bringing attention to it can potentially increase safety in the region,” says study author Franklin Wolfe, a doctoral candidate who is part of Harvard’s structural geology and Earth resources group.

哈佛大学结构地质学和地球资源组的博士候选人，该研究作者富兰克林沃尔夫说道：“我希望这份研究引起人们的关注可能会增加该地区的安全性。”

While the fault is slow moving and likely ruptures only once every 3,200 to 4,700 years, it underlies two of the United States’ busiest ports.

虽然断层缓慢移动，并且可能每3,200至4，700年仅断裂一次，但它是美国最繁忙的两个港口之下。

And researchers worry that the Wilmington could link with other nearby faults to produce a temblor as strong as a magnitude 7.4.

研究人员担心，威尔明顿断层可能会与附近的其他断层相连，产生7.4级强的地震。

Earthquakes are unpredictable and can strike with enough force to bring buildings down.

地震是不可预测的，其可以用足够的力量击倒建筑物。

Find out what causes earthquakes, why they're so deadly, and what's being done to help buildings sustain their hits.

找出导致地震的原因，为什么它们如此致命，以及做些什么可以帮助建筑物抵挡住地震的打击。

The study also emphasizes just how many faults crisscross Southern California, adds Chris Goldfinger, an earthquake geologist at Oregon State University, who was not part of the research team.

不隶属研究小组的一名俄勒冈州立大学的地震地质学家Chris Goldfinger补充说，这项研究还强调了南加州有多少断层错误。

Scientists have made major strides characterizing the geology of the region, but there’s still more to do.

科学家在描绘该地区的地质学方面取得了重大进展，但还有更多工作要做。

“Just by itself, if you take the implications of a relatively slow-moving fault like this, it won’t change the hazard very much,” he says.

“就其本身而言，如果你像这样看待一个相对缓慢移动的断层的含义，它危险程度不会改变多少。

But the discovery that the Wilmington fault is likely still active, he says, “sort of leaves this big hanging question mark: What about all the others?”

但当发现威尔明顿断层可能仍然活跃，他说到：“这样引发出一个大问题：那其他断层呢？”

Tectonic smashup

地质构造粉碎

When most people think about California earthquakes, they think of the San Andreas fault.

当大多数人想到加州地震时，他们会想到圣安德烈亚斯的断层。

The mighty feature formed some 30 million years ago as the North American plate swallowed almost all of what’s known as the Farallon plate.

强大的特征形成于大约3000万年前，因为北美板块几乎吞噬了Farallon板块。

Ever since, the North American plate has met face to face with the Pacific plate, the two grinding past each other at a boundary called a strike-slip fault. (Learn what's happening as the Farallon plate dies under Oregon.)

从那以后，北美板块与太平洋板块紧挨着，两者在一个称为走滑断层的边界上相互磨合。（了解当Farallon板块在俄勒冈州下被吞噬的过程。）

This sent North America for a wild ride: Its west coast first stretched out then sections later compressed.

这使北美洲陷入了疯狂的困境：它的西海岸首先伸展开来然后部分受到压缩。

 That means the faults in the basin where Los Angeles sits today first slid in one direction and then reversed, forming thrust faults in which blocks of land are shoved on top of others.

这意味着今天洛杉矶所在的盆地中的断层首先在一个方向上滑动然后反转，形成逆冲断层，其中土块被推到其他地方之上。

It’s as if “you put the whole thing it in a vise and started turning the handle,” says Goldfinger.

这就好像“你把整个东西放在虎钳中并开始转动手柄，”Goldfinger说。

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Lava spews out of a fissure in the Virunga mountains in the Democratic Republic of the Congo. The Virunga chain is part of the East African Rift Valley system, which marks the boundary between two plates: the Nubian plate to the west and the Somalian plate to the east. The rift valley is a                                                                              classic example of a divergent plate boundary.                                                                                                      熔岩在刚果民主共和国维龙加山脉的裂缝喷出。维龙加链是东非大裂谷系统的一部分，标志着两块板块之间的边界：连接西边的努比亚板块和连接                                                      东边的索马里板块。裂谷是发散板块边界的典型例子。                                                                           

A river of molten lava flows through a channel in hardened lava after an eruption at Mount Etna in Sicily, Italy. Mount Etna, one of Europe's most active volcanoes, was created by the subduction of part of the northward-moving African plate beneath the Eurasian plate.                                            在意大利西西里岛的埃特纳火山喷发后，一股熔岩流经硬化熔岩中的通道。埃特纳火山是欧洲最活跃的火山之一，是由欧亚板块下方北移非洲板块的俯                           冲而形成的。                                                     

Hikers walk in the shadow of cliffs in Iceland's Thingvellir National Park. The divergent Mid-Atlantic Ridge rises above sea level at Thingvellir, with the                                                        North American plate to the west and the Eurasian plate to the east.                                                                                  徒步旅行者在冰岛的Thingvellir国家公园的悬崖阴影下散步。分散的中大西洋海脊在Thingvellir海拔高度上升，西面是北美板块，东面是欧亚板块。

Offset streams cut into the Carrizo Plain along the San Andreas Fault in California. The fault, which runs more than 700 miles (1,100 kilometers), is the boundary between the Pacific and North American tectonic plates. The stretch of the fault that runs through Carrizo Plain is very well defined                                                                 because the land is arid and the fault has not been significantly eroded.                                                                       沿着加利福尼亚的圣安德烈亚斯断层，偏离的溪流切入Carrizo平原。  该断层长达700多英里（1,100公里），是太平洋和北美构造板块之间的边界。贯穿Carrizo Plain的断层延伸非常明确，因为土地干旱且断层没有明显受到侵蚀。

Raplee Ridge, part of the Monument Upwarp in southeastern Utah, is a long, narrow, folded anticline that formed about 70 million to 50 million years                                                                                                    ago.                                                                                                                                           Raplee Ridge是犹他州东南部隆起的一部分，是一条长而窄的折叠背斜，形成于7000万至5000万年前。

An eelpout fish swims near tubeworms at the Mid-Atlantic Ridge in the Atlantic Ocean. The Mid-Atlantic Ridge is an example of a divergent plate                                                                                     boundary and is an area where new seafloor is being created.                                                                   一条江鱈在大西洋中大西洋海脊的管虫附近游动。 大西洋中脊是一个发散板块边界的例子，是一个新海底正在建立的区域。

Sunrise warms the icy southern end of the Andes during a rare break in the weather in Chile's Torres del Paine National Park. The Andes mountains,               which span the entire western coast of South America, formed when the Nazca plate subducted under the South American plate.                    在智利托雷斯德尔潘恩国家公园的天气罕见休息期间，日出温暖了安第斯山脉冰冷的南端。 横跨整个南美洲西海岸的安第斯山脉形成于纳斯卡板块在南美板块下俯冲时形成的。

Sulfur, salt, and other minerals color the crater of Dallol volcano, part of the Danakil Depression in Ethiopia. At 157 feet (48 meters) below sea level,                                                                                   Dallol is Earth's lowest land volcano.                                                                                                   硫磺，盐和其他矿物质为Dallol火山的火山口上色，这是埃塞俄比亚Danakil萧条的一部分。 在海拔157英尺（48米）处，达洛尔是地球上最低的陆地火山。

An airplane casts a shadow over the red waters of Lake Natron in Tanzania, part of the East African Rift Valley. The water's red hue is due to algae that live on salts spewed from nearby volcanoes. The East African Rift Valley system begins in northern Syria and extends across East Africa into                                                                                                 Mozambique.                                                                                                                                一架飞机在坦桑尼亚的Natron湖的红色水域投下阴影，这是东非大裂谷的一部分。 水的红色是由于藻类生活在附近火山喷出的盐上。 东非大裂谷系统始于叙利亚北部，并延伸到东非，进入莫桑比克。

In the Persian Gulf, two tectonic plates collide. The Arabian plate (lower left) is running up on the Eurasian plate (upper right). The Persian Gulf (top) and the Gulf of Oman (bottom) were once the site of a rift, a place where two plates pull apart from each other, and the Indian Ocean filled in the widening gap between the two plates. However, the process then reversed, and about 20 million years ago, the gulf began to close up. The collision                                                                    of the two continental plates gives Iran its mountainous terrain.                                                                        在波斯湾，两个构造板块发生碰撞。阿拉伯板块（左下方）在欧亚板块（右上方）上运行。 波斯湾（上图）和阿曼湾（下图）曾经是一个裂缝的地方，两个板块相互拉开的地方，印度洋填补了两个板块之间的扩大间隙。 然而，这个过程随后发生逆转，大约在2000万年前，海湾开始关闭。 两块大陆板块的碰撞使伊朗成为多山的地形。

A mosque dominates the farming villages of Adi Caieh, Eritrea. Rift escarpments in the distance, now heavily eroded, once adjoined the Arabian Peninsula before the Red Sea opened. The escarpments shifted when the continental crust moved west, as the Red Sea formed in stop-start action                                                                                      during a 30-million-year period.                                                                                                            一座清真寺占据了厄立特里亚Adi Caieh农村。在红海开放之前，曾经严重侵蚀的裂谷悬崖曾经与阿拉伯半岛相邻。 当大陆地壳向西移动时，悬崖转移，因为红海在3000万年期间形成了停止开始行动。

One such thrust fault was the focus of this latest work, but it’s still hidden below ground. 

一个这样的推力，断层是这项最新工作的重点，但它仍然隐藏在地下。

Slow growing and breaking through soft sedimentary rocks, the Wilmington fault hasn’t yet breached the surface.

威尔明顿断层缓慢生长并穿过软沉积岩，尚未突破地表。

“Sorting out where we have these sneaky active faults is a challenge,” says Kate Scharer, an earthquake geologist at the U.S. Geological Survey who was not part of the research team.

非研究小队的美国地质调查局的地震地质学家Kate Scharer说：“分辨出这些鬼祟的活动断层的位置是一项挑战。”

In urban L.A. buildings and roads make surveying difficult—and the lack of a surface break adds another layer of complexity to the hunt for slow-moving faults.

在洛杉矶中，建筑物和道路使测量变得困难 - 缺乏表面断裂为寻找缓慢移动的断层增加了另一层复杂性。

Assembling the geologic jigsaw

By sending waves of energy that penetrate the ground and watching how they bounce back—a process similar to an ultrasound—researchers can examine the warping of different layers and read the rocks’ deep geologic past, Wolfe explains.

沃尔夫解释说，通过发送穿透地面的能量波并观察它们如何反弹 - 一个类似于超声波的过程 - 研究人员可以检查不同层的翘曲并读取岩石的深层地质过去。

The early versions of these Earth sonograms came from the oil and gas industry, which was interested in finding the ancient organic material trapped beneath the folded layers that would produce petroleum.

这些地球超声波图的早期版本来自石油和天然气行业，它有兴趣发现被困在生产石油的折叠层下面的古老有机材料。

These images revealed a distinct subsurface fold above the fault, which points to a period of early activity.

这些图像揭示了断层上方的明显的地下褶皱，指向早期活动的时期。

As the basin is squished, stresses build until they hit a breaking point and the Earth gives way both as movement along the fault in ground-rattling earthquakes, as well as in folding of the rock layers—like the pages of a paperback that’s squeezed from the sides, says Kimberly Blisniuk, an earthquake geologist at San José State University who was not involved in the work.

圣何塞州立大学的地震地质学家Kimberly Blisniuk说：当盆地被压扁时，压力会一直持续到它们达到一个断裂点，并且地球在地震嘎嘎作响的地震中沿着断层运动，以及在岩石层的折叠中让位 - 就像平面的页面被压缩一样。

But these curved layers were capped with what seemed to be nearly horizontal rocks. 

但是这些弯曲的层被覆盖着似乎几乎水平的岩石。

“That’s what led to this idea that it’s no longer active,” says study author John Shaw, a structural geologist at Harvard University with extensive experience studying the complexities of blind-thrust faults.

研究作者约翰肖（John Shaw）是哈佛大学的结构地质学家，他研究了盲推断层的复杂性，他说：“这就是导致这种想法，断层不再活跃。”

Hints of a fold linger in the shallow rocks at the southern tip of the fault, Shaw says.

Shaw说，在断层南端浅层岩石中留下一丝褶皱。

But the instruments used in the oil and gas industry focus on the deeper rocks, where petroleum is most likely to lurk.

但石油和天然气行业使用的工具主要集中在石油最有可能潜伏的深层岩石上。

To know if the fault was recently active, they needed better images of the layers just beneath the surface.

要知道断层最近是否有活动，他们需要在表面下获得更好的图像。

This next piece of the geologic jigsaw clicked into place at a conference about a decade back when Shaw ran into Dan Ponti, a co-author on the new study and a geologist with the USGS.

这个地质拼图的下一篇文章在大约十年前的一次会议上被点击，当Shaw遇到Dan Ponti时，他是新研究的合着者和USGS的地质学家。

Ponti had been mapping groundwater near California’s coast and noticed something curious: Some of the shallow rock layers of the aquifer were warped.

庞蒂一直在绘制加利福尼亚海岸附近的地下水，并注意到一些奇怪的事情：含水层的一些浅层岩石被扭曲了。

“He didn’t have an immediate understanding or explanation of why that would be,” Shaw says.

“他没有立即理解或解释为什么会这样，”肖说。

Located near the Wilmington fault, it was possible the folds in these shallow layers pointed to recent activity.

位于威尔明顿断层附近，这些浅层中的褶皱有可能指向最近的活动。

But the direct connection between these two-dimensional slices of Earth and the overall fault structure hadn’t yet fallen into place.

但是这些二维地球切片与整体断层构造之间的直接联系尚未到位。

That’s where Wolfe came in. As a first-year graduate student at Harvard University, he eagerly began compiling all the data he could get his hands on, including the recent USGS seismic profiles, incorporating the information into a three-dimensional model.

这就是沃尔夫切入的角度。作为哈佛大学的一年级研究生，他急切地开始编写他可以掌握的所有数据，包括最近的USGS地震剖面，将信息整合到一个三维模型中。

Finally, the picture was clear: It was all part of the Wilmington fault.

最后，图片很清楚：这都是威明顿断层的一部分。

Evil earthquake twin

邪恶的地震双胞胎

From their analysis, the team estimates the Wilmington fault has moved an average of just 0.16 millimeters per year over the last 500,000 years, and it likely hosts an earthquake every few thousand years.

根据他们的分析，该团队估计威尔明顿断层在过去50万年中平均每年仅移动0.16毫米，并且可能每隔几千年发生一次地震。

For comparison, the San Andreas fault is estimated to move 30 to 50 millimeters each year, with an average time between earthquakes of around 150 years. (Learn about an earthquake in Turkey that lasted 50 days.)

相比之下，San Andreas断层估计每年移动30至50毫米，地震之间的平均时间约为150年。 （了解土耳其持续50天的地震。）

“This thing is the slowest horse on the race track,” says Scharer. 

“这是赛道上最慢的马，”Scharer说。

“The party’s over, and everyone goes home before this thing comes back to the stables—but that doesn’t mean it doesn’t come back.”

“聚会结束了，所有人都回家了，马还没回到马厩 - 但这并不意味着它不会回来。”

That is, while it’s slow moving, it shouldn’t be ignored. For one, there’s the type of motion thrust faults produce, which is more of a vertical shove than the horizontal back and forth of a strike-slip fault, Wolfe says.

也就是说，虽然它移动缓慢，但不应该被忽视。 沃尔夫说，其中一个是运动推力断层产生的类型，更多的是垂直推力，而不是走滑断层的水平来回。

Buildings can sway a little, but the up-down motions can be devastating.

建筑物可以左右摇摆一点，但上下运动可能是毁灭性的。

Such intense impacts were seen during the magnitude 6.7 Northridge earthquake that rattled from a blind-thrust fault in 1994, killing more than 60 people and injuring thousands.

这种强烈冲击发生在1994年北岭地震6.7级地震中，由于盲目突击断层而震动，造成60多人死亡，数千人受伤。

The Wilmington fault is also located directly below two important ports and other infrastructure, Shaw notes.

Shaw指出，威尔明顿断层也位于两个重要港口和其他基础设施的正下方。

And a disruption of operations could have major impacts. 

而且作业中断可能会产生重大影响。

While more work is necessary to further tease apart the Wilmington’s earthquake potential, the latest study emphasizes the import of studying slow-moving blind faults.

虽然需要做更多的工作来进一步梳理威尔明顿的地震潜力，但最新的研究强调了研究缓慢移动的盲断层的重要性。

“While we’re all focused on strike-slip faults, which come to the surface,” Goldfinger says, “the L.A. basin’s evil twin hiding in the subsurface might be just as hazardous.”

虽然我们都专注于走滑断层，以及其露出地面。”Goldfinger说，“隐藏在地下的洛杉矶盆地的邪恶双断层可能同样危险。”